Male kidney-specific BMAL1 knockout mice are protected from K+-deficient, high-salt diet-induced blood pressure increases.

The circadian clock protein basic helix-loop-helix aryl hydrocarbon receptor nuclear translocator-like protein 1 (BMAL1) is a transcription factor that impacts kidney function, including blood pressure (BP) control. Previously, we have shown that male, but not female, kidney-specific cadherin Cre-positive BMAL1 knockout (KS-BMAL1 KO) mice exhibit lower BP compared with littermate controls. The goal of this study was to determine the BP phenotype and immune response in male KS-BMAL1 KO mice in response to a low-K+ high-salt (LKHS) diet. BP, renal inflammatory markers, and immune cells were measured in male mice following an LKHS diet. Male KS-BMAL1 KO mice had lower BP following the LKHS diet compared with control mice, yet their circadian rhythm in pressure remained unchanged. Additionally, KS-BMAL1 KO mice exhibited lower levels of renal proinflammatory cytokines and immune cells following the LKHS diet compared with control mice. KS-BMAL1 KO mice were protected from the salt-sensitive hypertension observed in control mice and displayed an attenuated immune response following the LKHS diet. These data suggest that BMAL1 plays a role in driving the BP increase and proinflammatory environment that occurs in response to an LKHS diet.NEW & NOTEWORTHY We show here, for the first time, that kidney-specific BMAL1 knockout mice are protected from blood pressure (BP) increases and immune responses to a salt-sensitive diet. Other kidney-specific BMAL1 knockout models exhibit lower BP phenotypes under basal conditions. A salt-sensitive diet exacerbates this genotype-specific BP response, leading to fewer proinflammatory cytokines and immune cells in knockout mice. These data demonstrate the importance of distal segment BMAL1 in BP and immune responses to a salt-sensitive environment.

The structure of a Lactobacillus helveticus chlorogenic acid esterase and the dynamics of its insertion domain provide insights into substrate binding.

Chlorogenic acid esterases (ChlEs) are a useful class of enzymes that hydrolyze chlorogenic acid (CGA) into caffeic and quinic acids. ChlEs can break down CGA in foods to improve their sensory properties and release caffeic acid in the digestive system to improve the absorption of bioactive compounds. This work presents the structure, molecular dynamics, and biochemical characterization of a ChlE from Lactobacillus helveticus (Lh). Molecular dynamics simulations suggest that substrate access to the active site of LhChlE is modulated by two hairpin loops above the active site. Docking simulations and mutational analysis suggest that two residues within the loops, Gln145 and Lys164 , are important for CGA binding. Lys164 provides a slight substrate preference for CGA, whereas Gln145 is required for efficient turnover. This work is the first to examine the dynamics of a bacterial ChlE and provides insights on substrate binding preference and turnover in this type of enzyme.

Identification of alkaline-induced thiolyl-chlorogenic acid conjugates with cysteine and glutathione.

Alkaline reactions of chlorogenic acid (CGA) yield undesirable development of brown or green pigments, limiting the utilization of alkalized CGA-rich foods. Thiols such as cysteine and glutathione mitigate pigment formation through several mechanisms, including redox coupling to reduce CGA quinones, and thiol conjugation, which forms colorless thiolyl-CGA compounds that do not readily participate in color-generating reactions. This work provided evidence of the formation of both aromatic and benzylic thiolyl-CGA conjugate species formed with cysteine and glutathione under alkaline conditions in addition to hydroxylated conjugate species hypothesized to arise from reactions with hydroxyl radicals. Formation of these conjugates proceeds more quickly than CGA dimerization and amine addition reactions mitigating pigment development. Differentiation between aromatic and benzylic conjugates is enabled by characteristic fragmentation of CS bonds. Acyl migration and hydrolysis of the quinic acid moiety of thiolyl-CGA conjugates yielded a variety of isomeric species also identified through untargeted LC-MS methods.

Predictive Factors for Mortality Following Major Lower Extremity Amputation.

BACKGROUND: Despite advances in techniques and care, major amputation bears a high risk for mortality. Previously identified factors associated with increased risk of mortality include amputation level, renal function, and pre-operative white cell count. METHODS: A single center retrospective chart review was conducted identifying patients who had undergone a major amputation. Chi-squared, t-testing, and Cox proportional hazard modeling were performed examining death at 6 months and 12 months. RESULTS: Factors associated with an increased risk of six-month mortality include age (OR 1.01-1.05, P < .001), sex (OR 1.08-3.24, P < .01), minority race (OR 1.18-18.19, P < .01), chronic kidney disease (OR 1.40-6.06, P < .001), and use of pressors at the induction of anesthesia for index amputation (OR 2.09-7.85, P < .000). Factors associated with increased risk of 12 month mortality were similar. DISCUSSION: Patients undergoing major amputation continue to suffer high mortality. Those patients who received their amputation under physiologically stressful conditions were more likely to die within 6 months. Reliably predicting six-month mortality can assist surgeons and patients in making appropriate care decisions.

A Tiered Mentorship Program to Integrate Medical Students Into Clinical Research Projects.

OBJECTIVE: Herein we describe the development, implementation, and growth of our Vascular Research Training Program (VRTP), emphasizing the intentional involvement of medical students in clinical research. METHODS: We developed a VRTP focusing on medical student engagement to encompass 4 pillars: ownership, mentorship, experience, and independence within the research process. The program is organized by clinical projects with an attending surgeon, surgical trainee (fellow or resident), and medical student comprising each research project team. The VRTP program sought to facilitate a culture of learning, accountability, and mentorship to engage and encourage medical student involvement in clinical research. RESULTS: We reviewed the productivity of our current vascular surgery faculty by reviewing divisional records of faculty publications and conducting a literature search for the period of 2012 to 2019. The pre-VRTP model produced 13 included manuscripts in 2012-2015 (3.25 per year), while the implemented VRTP model yielded 43 articles (10.75 per year) from 2016-2019. There was no significant change in the impact factor (pre-VRTP mean ± SD was 1.8 ± 1.0 vs 2.2 ± 1.1, P = .17). Medical student productivity rose from 1.3 to 2.7 publications, with a similar rise in the number of students participating in more than one manuscript from 2 to 14. CONCLUSIONS: Deliberate involvement of medical trainees as a member of the clinical research team has the potential to generate subsequent increases in research productivity and effective mentorships. Academic surgical divisions should consider organized and intentional involvement of medical students as an essential component of clinical research.

The Caged Knickerbocker: A Novel Modification to Targeted False Lumen Management in Complex Aortic Dissection.

INTRODUCTION: Targeted false lumen management has been described for complex presentations of aortic dissection. The "Knickerbocker" technique is often referenced and includes dilating a focal portion of an oversized endograft in the true lumen to purposefully rupture the false lumen septum, but at the expense of increased risk for visceral propagation and malperfusion. This case series describes a novel modification of the Knickerbocker technique by caging the distal end of the endograft prior to focal dilation. METHODS: A retrospective chart review was conducted at a tertiary academic center from 2018-2020. Patients were included if they had a history or current presentation of aortic dissection and underwent a Caged Knickerbocker (CKB) repair. Data were collected to include demographics, indications for repair, technical success, perioperative outcomes, hospital course, mortality, and further aortic interventions. RESULTS: Five patients were included in our evaluation. Four patients (80%) presented with chronic Type B aortic dissection (cTBAD) and concomitant aneurysmal degeneration of the thoracic aorta; 1 patient (20%) presented with an acute rupture secondary to cTBAD. Three patients (60%) had previous aortic repairs, 2 of which were for Type A Aortic Dissection that additionally required redo sternotomy and total arch replacement prior to CKB. CKB was technically successful in all cases with no peri-operative complications. Two (40%) patients required further aortic intervention due to aneurysmal degeneration. CONCLUSION: Achieving complete false lumen thrombosis is a considerable challenge when managing complex aortic dissections. Our data demonstrate the technical feasibly and early successful outcomes with the CKB approach. Importantly, CKB facilitates future distal extension into the para-visceral aorta in cases of complex thoracoabdominal aortic aneurysms. Further research should focus on discerning individual patients who will benefit from targeted false lumen management and compare outcomes between different approaches.

A highly active esterase from Lactobacillus helveticus hydrolyzes chlorogenic acid in sunflower meal to prevent chlorogenic acid induced greening in sunflower protein isolates.

Chlorogenic acid (CGA) is an ester between caffeic and quinic acid. It is found in many foods and reacts with free amino groups in proteins at alkaline pH, leading to the formation of an undesirable green pigment in sunflower seed-derived ingredients. This paper presents the biochemical characterization and application of a highly active chlorogenic acid esterase from Lactobacillus helveticus. The enzyme is one of the most active CGA esterases known to date with a Km of 0.090 mM and a kcat of 82.1 s-1. The CGA esterase is easily expressed recombinantly in E. coli in large yields and is stable over a wide range of pH and temperatures. We characterized CGA esterase's kinetic properties in sunflower meal and demonstrated that the enzyme completely hydrolyzes CGA in the meal. Finally, we showed that CGA esterase treatment of sunflower seed meal enables the production of pale brown sunflower protein isolates using alkaline extraction. This work will allow for more widespread use of sunflower-derived products in applications where neutrally-colored food products are desired.

Resection of Anterior and Lateral Muscle Compartments Does Not Preclude Limb Salvage and Functions.

BACKGROUND: Fasciotomy with resection of nonviable muscle is often necessary when there is a delay in compartment syndrome (CS) diagnosis after revascularization. The reported rate of major amputation following missed CS or delayed fasciotomy ranges from 12% to 35%. Herein, the authors present a series of critically ill patients who experienced delayed CS diagnosis and required complete resection of the anterior and/or lateral compartments but still achieved limb salvage and function. METHODS: A retrospective chart review identified five patients from April 2018 to April 2019 within a single institution who met the inclusion criteria. Patient charts were reviewed for demographic data, risk factors, time to diagnosis following revascularization, muscle compartments resected, operative and wound care details, and functional outcome at follow-up. RESULTS: All of the patients developed CS of the lower extremity following revascularization secondary to acute limb ischemia and required two-incision, four-compartment fasciotomies. Further, they all required serial operative debridements to achieve limb salvage; however, there were no major amputations, and all of the patients were walking at follow-up. CONCLUSIONS: Delay in CS diagnosis can have devastating consequences, resulting in major amputation. In cases where myonecrosis is isolated to two or fewer compartments, complete compartment muscle resection can be safely performed, and limb preservation and function can be maintained with aggressive wound management and physical therapy.

Spontaneous Thrombosis of an Isolated Internal Iliac Artery Aneurysm.

BACKGROUND: Isolated internal iliac artery aneurysms (IIAAs) are uncommon but potentially morbid lesions that are a challenge to monitor and treat. However, given the small numbers of reported cases and high rates of incidentally discovered lesions, the natural history of isolated IIAAs is not well characterized. This case describes an atypical and previously unreported spontaneous thrombosis of an isolated IIAA, a lesion typically thought to progressively enlarge and rupture. METHODS: Medical records and imaging studies were retrospectively reviewed with the approval of our Institutional Review Board. A single patient underwent fluoroscopic angiography followed by computed tomography (CT) angiography, with no subsequent operative intervention. RESULTS: An isolated 5.5 cm left IIAA was discovered incidentally on CT scan and subsequently seen with fluoroscopic pelvic angiography. Three weeks following initial angiography, repeat pelvic angiography and CT scan demonstrated spontaneous thrombosis of the aneurysm. CONCLUSIONS: Isolated IIAAs are conditions for which the natural history remains uncertain despite their potential risk for rupture and mortality. Spontaneous thrombosis of these lesions is possible, suggesting that the natural history as previously described warrants further consideration.

Salvage of autogenous dialysis access with balloon-assisted thrombin injection.

Arteriovenous fistulas are known to be one of the most enduring and safe hemodialysis access modalities. However, access preservation can be challenging in the setting of degeneration, including the development of complex pseudoaneurysms. Prolonged compression or thrombin injection can risk thrombosis of the fistula, and covered stent use can predispose the access to infection and other stent complications. We present a case in which endovascular balloon occlusion was used to facilitate the use of ultrasound-guided thrombin injection to resolve a dialysis access pseudoaneurysm by transiently reducing flow and preventing thromboembolism. This method is a safe, effective, and minimally invasive technique that should be considered for salvage of autogenous access compromised by pseudoaneurysm development.

Type B Aortic Dissection Complicated by Intimo-Intimal Intussusception and Extensive Intimal Denuding: Case Report with Long-term Follow-up.

BACKGROUND: Acute aortic dissection rarely results in circumferential dissections of the aortic intima that may lead to intimo-intimal intussusception (IIS) with complete separation from the aortic wall. Circumferential dissection may then result in distal embolization of the involved intima and media, adding considerable complexity to the management of such cases. Despite the severity of this complication, the natural history of aortic disease following extensive intimal denuding and IIS is not well documented in the literature. Here we present a case with long-term follow-up of type B aortic dissection (TBAD) complicated by IIS and embolization of the intima into the distal aorta following thoracic endovascular aortic repair. METHODS: Medical records and imaging studies were retrospectively reviewed with the approval of the Institutional Review Board. A single patient underwent repair of a TBAD that was complicated by IIS, with follow-up for 6 years. Aortic recovery was monitored with serial computerized tomography scans. RESULTS: During endovascular stent deployment, the patient's dissection progressed circumferentially, leading to distal embolization of the intima and aortic occlusion. An open transabdominal aortic exploration was performed to extract the embolized intima. Despite this severe aortic structural disruption, the patient recovered well postoperatively and exhibited favorable aortic remodeling over long-term follow-up. The denuded aorta did not rupture or develop progressive worsening aneurysmal dilation and the diameter of the involved aortic segment remained stable during follow-up. CONCLUSIONS: Acute TBADs can progress to circumferential intimal separation and IIS when managed with endovascular stenting and balloon dilation. Continued endovascular management once IIS has occurred may lead to further intimal damage, resulting in distal embolization of the intima and aortic occlusion. Thus, IIS may require conversion to open repair. However, in the event that loss of the aortic intima does occur following IIS, it is possible for the denuded aorta to recover well and remain stable with favorable remodeling over long-term follow-up.

Successful Treatment of Acute Limb Ischemia Secondary to Iatrogenic Distal Embolization Using Catheter Directed Aspiration Thrombectomy.

Objective: Acute limb ischemia (ALI) due to thromboembolism is a limb- and life-threatening condition regularly encountered by vascular surgeons. Iatrogenic distal embolization is occasionally seen as a complication of various endovascular procedures. We present a series of four patients who developed ALI due to arterial embolization during cardiovascular procedures that were successfully treated via catheter directed aspiration embolectomy. Methods: Retrospective review of demographics, risk factors, and procedural outcomes was completed for 4 patients who presented with ALI due to distal embolization following cardiovascular procedures. All patients were successfully treated with catheter directed aspiration embolectomy using the Penumbra Indigo System (Penumbra Inc., Alameda, California). All patients had high-quality angiography demonstrating successful embolectomy and end-procedure patency. Results: Three patients presented with Rutherford 2A and one with Rutherford 2B ALI secondary to intraoperative distal embolization. Three patients presented with ALI secondary to distal embolization during peripheral vascular interventions, and one following emergent intra-aortic balloon pump (IABP) placement for myocardial infarction. All emboli were located in the infra-inguinal vasculature. Median post-operative ABIs were 0.94 (n = 4). Median length of stay was 2 days. There were no mortalities and no need for adjunctive fasciotomy, amputation, or bypass for limb salvage. All patients improved clinically after intervention, and returned to their reported pre-hospitalization functional status. Conclusion: All procedures achieved technical success with catheter-directed aspiration thrombectomy with or without adjunctive lysis. Catheter-directed aspiration embolectomy with the Penumbra Indigo System for ALI following an iatrogenic embolic event is a safe, less-invasive treatment option. The use of this technology may reduce the need for traditional open thrombectomy or thrombolytic therapy to address ALI.

Autogenous Femoral Vein for Secondary Repair of Subclavian Arteries: A Salvage Solution for Complex Clinical Scenarios.

BACKGROUND: Endovascular stent and prosthetic graft placement are commonplace techniques for correction of subclavian artery (SCA) lesions. However, when initial surgical repair of the SCA becomes complicated by subsequent infection or thrombosis of the repair site, stents and prosthetic grafts are no longer suitable for secondary repair due to the risk of recurrent failure and limited longevity. Autogenous tissue is more resistant to infection and has improved long-term patency, and thus may be a better option for secondary reconstruction in these complex clinical scenarios. The most commonly used autogenous conduit for SCA reconstruction is the great saphenous vein; however, the significant size mismatch makes this unsuitable in many circumstances. The autogenous femoral vein is a promising alternative conduit for SCA repair. Here we present 3 successful cases of its use as a salvage technique following iatrogenic complications of prior surgical repair. METHODS: From 2015 to 2019, 3 patients underwent harvest of the femoral vein for use in SCA repair, with 2 carotid-axillary bypasses and 1 carotid-subclavian bypass. Indications included a mycotic pseudoaneurysm secondary to an infected SCA stent, an SCA avulsion secondary to an infected carotid-subclavian bypass graft, and an occluded SCA stent in a young patient. Postoperative graft patency was monitored via clinical resolution of symptoms and maintenance of perfusion, intact pulses, and arterial duplex or computed tomography (CT) scan. RESULTS: All these patients had a good outcome following their procedures. Each had intact radial pulses immediately postoperatively and maintained normal perfusion to the upper extremity for the duration of follow-up, with bypass patency confirmed via CT scan or arterial duplex. The SCA repair also allowed for salvage of the upper extremity and symptomatic relief in all patients. None of the patients developed deep vein thrombosis in the donor extremity, and neither of the infected patients developed recurrent infection of the repair site. CONCLUSIONS: The success of these cases demonstrates that the autogenous femoral vein is an effective and safe option for SCA reconstruction. It is particularly useful for secondary salvage when prior surgical repair via standard techniques is complicated by infection or thrombosis, and when target vessel size precludes the use of the great saphenous vein. This is an excellent choice of conduit that vascular surgeons should consider for use in complex SCA repairs.

Modeling variability in the inferior vena cava into fenestrated endografts for retrohepatic caval injuries.

OBJECTIVE: Injury of the retrohepatic inferior vena cava (IVC) is rare, but extremely fatal. Open repair of these injuries is challenging. Various maneuvers, including atriocaval shunting and total vascular isolation, have been described, but are poorly tolerated in the severely injured patient. Endovascular repair is an attractive alternative strategy, but effective hemostasis of complex injuries requires an endograft that excludes the injury while permitting flow from the hepatic veins. Unfortunately, IVC and hepatic vein anatomy is highly variable and has not been clearly described in injured patients. Our purpose was to characterize critical human IVC morphology in trauma patients, and develop the design parameters of an off-the-shelf fenestrated endograft intended for caval deployment. METHODS: One hundred consecutive adult trauma patients with an admission computed tomography scan including a portal venous phase of the abdomen were reviewed. Specific anatomic measurements including segmental IVC lengths and diameters were obtained. Multiple theoretical endografts were modeled to optimize caval coverage in the retrohepatic segment, assuming 10% to 40% oversizing for seal. RESULTS: This sample population had a mean age of 50 years, height of 173 cm, and weight 84 kg. Seventy-one percent were male and 89% had a blunt mechanism of injury. The median caval length from the renal veins to right atrium was 111 mm (interquartile range [IQR], 102-120 mm), diameter was 22 mm (IQR, 19-26 mm), and hepatic venous orifice area was 336 mm2 (IQR, 267-432 mm2). All patients had a landing zone of at least 12 mm in the suprahepatic and 10 mm in the suprarenal segments. Three models of graft length were developed to accommodate patients with segmental and overall dimensions in the smallest half, third quartile, and fourth quartile. These could provide 95% of patients with coverage of the retrohepatic segment without risk of hepatic or renal vein occlusion. Four graft diameters were developed for cross-sectional fit. Graft diameters of 20, 24, 30, and 38 mm could provide adequate coverage in, respectively, 11%, 35%, 49%, and 16% of patients. These combinations of graft length and diameter would accommodate 93% of patients. CONCLUSIONS: We defined human IVC morphology essential for endovascular therapy and developed parameters for fenestrated IVC endografts to address retrohepatic caval injuries in trauma patients. Although additional study and testing are required, this proof-of-concept study supports the hypothesis that exclusion of the most devastating retrohepatic IVC injuries can be achieved with a reasonable number of off-the-shelf fenestrated endografts. These findings form the basis for additional research toward the development of novel devices for endovascular therapy of these often lethal injuries.

Intraoperative Fragmentation and Retention of Endovascular Devices: Clinical Consequences and Preventative Strategies.

BACKGROUND: Expanded applications and increasing volumes of complex endovascular procedures have increased the risk of unintended intraoperative fragmentation and retention of catheters and sheaths. We describe a series of retained or fragmented endovascular devices, a quality improvement program to address this unmet need for improved detection of catheter fragmentation, and the results of this program. METHODS: Cases utilizing endovascular devices that resulted in a retained catheter fragment were identified and analyzed during divisional quality improvement review. One consistent area of concern was operating room (OR) staff unfamiliarity with verifying the integrity of an endovascular device. In response, a slide-based training protocol of focused, endovascular nursing education was implemented. Following perceived lack of improvement after this approach, we developed a handheld visual reference display of the tips of common catheters and sheaths. Staff was surveyed before and after intervention to assess the educational value of the display and the impact on staff device familiarity. RESULTS: All 4 described cases resulted in an unplanned return to the OR for retrieval of the fragmented catheter or sheath. No thromboembolic complications were observed, although associated intra-arterial thrombus was noted in 2 cases. Thirty-four OR nurses were polled to trial the visual reference display initiative, with 70% of those reporting primary surgical assignments outside of cardiovascular ORs. Introduction of the new visual reference display improved staff confidence in their ability to identify a broken device (2.4-3.7, P < .001). This improvement was most significant in OR staff with primary assignments in noncardiovascular services. CONCLUSION: Current OR standard operating procedures fail to address the potential for unintentionally retained catheters and wires during endovascular procedures. Our novel visual reference display of common endovascular items rather than conventional in-service training improved the ability of staff to identify device fragmentation at the time of the index procedure.

Considerations beyond Stenosis for Carotid Endarterectomy in Treating Free-Floating Thrombus of the Carotid Artery.

BACKGROUND: Free-floating thrombus (FFT) of the carotid artery is an uncommon condition that can present with neurologic symptoms, often in the setting of ischemic stroke. The literature pertaining to the incidence and optimal treatment of this condition is limited. Herein, we report our contemporary experience with FFT across a range of degrees of carotid stenosis. METHODS: Medical records and imaging studies from a single academic medical center from January 2016 to July 2018 were retrospectively reviewed. Patient demographics, presentation, treatment, and follow-up were abstracted. RESULTS: Six cases of FFT of the carotid artery with and without hemodynamically significant atherosclerotic disease were identified. All cases presented with ischemic stroke; one case had a hemorrhagic conversion. In each case, the FFT was visualized by at least one imaging modality including computed tomography angiography, magnetic resonance angiography, and duplex ultrasound. Three patients had >50% carotid stenosis and three had <50%. All cases were treated with endarterectomy. Four of the six patients received preoperative anticoagulation. There were no postoperative complications. Median follow-up was 252 days, with one case lost to follow-up. Four of the six patients have been without restenosis, recurrence of the thrombus, nor worsening or recurrent stroke on follow-up. The fifth patient developed restenosis but remained clinically stable. CONCLUSIONS: Although current society guidelines do not recommend carotid endarterectomy as first-line treatment for symptomatic patients with <50% stenosis, it may be indicated in the context of FFT.

The myristoylated alanine-rich C kinase substrate differentially regulates kinase interacting with stathmin in vascular smooth muscle and endothelial cells and potentiates intimal hyperplasia formation.

OBJECTIVE: Restenosis limits the durability of all cardiovascular reconstructions. Vascular smooth muscle cell (VSMC) proliferation drives this process, but an intact, functional endothelium is necessary for vessel patency. Current strategies to prevent restenosis employ antiproliferative agents that affect both VSMCs and endothelial cells (ECs). Knockdown of the myristoylated alanine-rich C kinase substrate (MARCKS) arrests VSMC proliferation and paradoxically potentiates EC proliferation. MARCKS knockdown decreases expression of the kinase interacting with stathmin (KIS), increasing p27kip1 expression, arresting VSMC proliferation. Here, we seek to determine how MARCKS influences KIS protein expression in these two cell types. METHODS: Primary human coronary artery VSMCs and ECs were used for in vitro experiments. MARCKS was depleted by transfection with small interfering RNA. Messenger RNA was quantitated with the real-time reverse transcription polymerase chain reaction. Protein expression was determined by Western blot analysis. Ubiquitination was determined with immunoprecipitation. MARCKS and KIS binding was assessed with co-immunoprecipitation. Intimal hyperplasia was induced in CL57/B6 mice with a femoral artery wire injury. MARCKS was knocked down in vivo by application of 10 µM of small interfering RNA targeting MARCKS suspended in 30% Pluronic F-127 gel. Intimal hyperplasia formation was assessed by measurement of the intimal thickness on cross sections of the injured artery. Re-endothelialization was determined by quantitating the binding of Evans blue dye to the injured artery. RESULTS: MARCKS knockdown did not affect KIS messenger RNA expression in either cell type. In the presence of cycloheximide, MARCKS knockdown in VSMCs decreased KIS protein stability but had no effect in ECs. The effect of MARCKS knockdown on KIS stability was abrogated by the 26s proteasome inhibitor MG-132. MARCKS binds to KIS in VSMCs but not in ECs. MARCKS knockdown significantly increased the level of ubiquitinated KIS in VSMCs but not in ECs. MARCKS knockdown in vivo resulted in decreased KIS expression. Furthermore, MARCKS knockdown in vivo resulted in decreased 5-ethynyl-2'-deoxyuridine integration and significantly reduced intimal thickening. MARCKS knockdown enhanced endothelial barrier function recovery 4 days after injury. CONCLUSIONS: MARCKS differentially regulates the KIS protein stability in VSMCs and ECs. The difference in stability is due to differential ubiquitination of KIS in these two cell types. The differential interaction of MARCKS and KIS provides a possible explanation for the observed difference in ubiquitination. The effect of MARCKS knockdown on KIS expression persists in vivo, potentiates recovery of the endothelium, and abrogates intimal hyperplasia formation.

Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) Not Yet Applicable for Widespread Out-of-Hospital Use: A Case of Nonsurvivable Complication from Prolonged REBOA Inflation.

BACKGROUND: Resuscitative endovascular balloon occlusion of the aorta (REBOA) is being considered for temporizing catastrophic hemorrhage before arriving at a specialty center for definitive surgical management. CASE: We describe the clinical case of a 72-year-old male with a ruptured infrarenal aortic abdominal aneurysm initially stabilized with REBOA at an outside facility and transferred to our care. Transport time was >100 minutes. Despite successful surgical repair of the ruptured aneurysm, the patient expired from multiple-organ failure likely related to ischemia-reperfusion injuries from prolonged balloon occlusion of the aorta. CONCLUSIONS: Ischemia-mitigating techniques and therapies need to improve drastically before the clinical application of REBOA can be effectively extended to outside the vicinity of specialty centers.

A Novel Risk Score Predicts Operative Mortality After Acute Type A Aortic Dissection Repair.

BACKGROUND: Current stratification systems for patients presenting with acute type A aortic dissection rely on signs of malperfusion to predict mortality. The authors sought to develop an algorithm to readily risk stratify these patients using admission characteristics. METHODS: Two hundred sixty-nine consecutive patients who underwent type A repair between 2002 and 2015 were reviewed for easily obtainable preoperative demographics and laboratory values deemed a priori as potential predictors of operative mortality. Multiple logistic regression analysis was performed to determine independent significance, and linear regression was performed to generate the concomitant regression expression of the variables significant on bivariate analysis. RESULTS: Operative mortality was 16% (43/269) and was 29% (34/119) among patients who presented with malperfusion. Upon multivariate analysis, creatinine (p = 0.008), liver malperfusion (p = 0.006), and lactic acid level (p = 0.0007) remained independent significant predictors. Regression coefficients allowed the generation of a risk score as 5.5 × (lactic acid [mmol/L]) + 8 × (creatinine [mg/dL]) ± 8 (+ if liver malperfusion presents, - if no liver malperfusion). Upon receiver-operating characteristic curve analysis this model generated a c-statistic of 0.75. Operative mortality among patients within the lowest tertile (risk score < 7) was 4%, whereas patients in the middle (7 to 20) and highest (≥20) tertiles had mortality rates of 14% 37%, respectively. CONCLUSIONS: Although still requiring external validation, the innovative risk score presented necessitates knowledge of lactic acid, serum creatinine, and liver function tests. The algorithm predicts operative mortality with high accuracy and offers clinicians a novel tool to improve preoperative guidance and prognosis.