Comparative assessment of racial disparity in 30-day outcomes for Asian Americans undergoing carotid endarterectomy

OBJECTIVE

Carotid endarterectomy (CEA) is an effective treatment for carotid stenosis. All previous studies on racial disparity of CEA outcomes omitted Asian Americans. This study aimed to address this gap by investigating racial disparities in 30-day outcomes following CEA among Asian Americans.

METHODS

Asian American and Caucasian patients who underwent CEA were identified in the American College of Surgeons National Surgical Quality Improvement Program targeted database from 2011 to 2021. Patients with age less than 18 years old were excluded. Patients with symptomatic and asymptomatic carotid stenosis were examined separately. A 1:5 propensity-score matching was used to address preoperative differences. Thirty perioperative outcomes were assessed.

RESULTS

There were 380 Asian Americans (2.27%) and 13,250 Caucasians (79.18%) with symptomatic carotid stenosis who underwent CEA. Also, 289 Asian Americans (1.40%) and 18,257 Caucasians (88.14%) with asymptomatic carotid stenosis had CEA. Asian Americans undergoing CEA presented with higher comorbid burdens and more severe symptomology. Also, asymptomatic Asian Americans were more likely to undergo surgeries for mild stenosis (<50%), which is not in line with practice guidelines. After 1:5 propensity-matching, all symptomatic Asian Americans were matched to 1550 Caucasian patients, and all asymptomatic Asian Americans were matched to 1445 Caucasians; preoperative differences were addressed. Asian Americans exhibited low overall 30-day mortality (symptomatic, 1.61%; asymptomatic, 0.35%) and stroke (symptomatic, 2.26%; asymptomatic, 0.69%). All perioperative outcomes were comparable to Caucasians, with the exception that Asian Americans experienced longer operation times.

CONCLUSIONS

Evidence suggested that Asian Americans with asymptomatic stenosis were underrepresented in CEA. After propensity-score matching, Asian Americans demonstrated comparable 30-day outcomes to Caucasians. These suggest that, when afforded equal access to quality health care, CEA serves as an effective treatment for carotid stenosis among Asian Americans. Therefore, efforts may be aimed at addressing health care access, potentially in the screening for asymptomatic carotid stenosis in Asian Americans. This would ensure they have equitable benefits from CEA. Nevertheless, the exact preoperative differences and long-term CEA outcomes in Asian Americans should warrant further examination in future studies.

The 5-Factor Modified Frailty Index is a Concise and Effective Predictor of 30-Day Adverse Outcomes in Carotid Endarterectomy

INTRODUCTION

Frailty is a clinically identifiable condition characterized by heightened vulnerability. The 5-item Modified Frailty Index provides a concise calculation of frailty that has proven effective in predicting adverse perioperative outcomes across a variety of surgical disciplines. However, there is a paucity of research examining the validity of 11-item Modified Frailty Index (mFI-5) in carotid endarterectomy (CEA). This study aimed to investigate the association between mFI-5 and 30-day outcomes of CEA.

METHODS

Patients underwent CEA were identified from American College of Surgeons National Surgical Quality Improvement Program targeted database from 2012 to 2021. Patients with age<18 were excluded. Patients were stratified into four cohorts based on their mFI-5 scores: 0, 1, 2, or 3+. Multivariable logistic regression was used to compare 30-day perioperative outcomes adjusting for preoperative variables with P value<0.1.

RESULTS

Compared to controls (mFI-5 = 0), patients mFI-5 = 1 had higher risk of stroke (adjusted odds ratio [aOR] = 1.333, P = 0.02), unplanned operation (aOR = 1.38, P < 0.01), and length of stay (LOS) > 7 days (aOR = 0.814, P < 0.01). Patients with mFI-5 = 2 had higher stroke (aOR = 1.719, P < 0.01), major adverse cardiovascular events (MACE) (aOR = 1.315, P = 0.01), sepsis (aOR = 2.243, P = 0.01), discharge not to home (aOR = 1.200, P < 0.01), 30-day readmission (aOR = 1.405, P < 0.01). Compared with controls, patients with mFI-5≥3 had higher mortality (aOR = 1.997 P = 0.02), MACE (aOR = 1.445, P = 0.03), cardiac complications (aOR = 1.901, P < 0.01), pulmonary events (aOR = 2.196, P < 0.01), sepsis (aOR = 3.65, P < 0.01), restenosis (aOR = 2.606, P = 0.02), unplanned operation (aOR = 1.69, P < 0.01), LOS>7 days (aOR = 1.425, P < 0.01), discharge not to home (aOR = 2.127, P < 0.01), and 30-day readmission (aOR = 2.427, P < 0.01).

CONCLUSIONS

The mFI-5 is associated with 30-day mortality and complications including stroke, MACE, cardiac complications, pulmonary complications, sepsis, and restenosis. Additionally, elevated mFI-5 scores correlate with an increased likelihood of unplanned operations, extended LOS, discharge to facilities other than home, and 30-day readmissions, all of which could negatively impact long-term prognosis. Therefore, mFI-5 can serve as a concise yet effective metric of frailty in patients undergoing CEA.

Letter re: Misidentification of Transcarotid Artery Revascularization by Current Procedural Terminology

In this letter, we discussed the selection of patients undergoing Transcarotid Artery Revascularization (TCAR) using the Current Procedural Terminology (CPT) codes. We examined a previous study using CPT code 37215 to identify TCAR cases using the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database. As an ACS-NSQIP participating site, we have complete access to the ACS-NSQIP database, and we performed a more in-depth examination of the method. We found significant discrepancies in the method described and conclude that it is methodologically flawed to use CPT code 37215 to differentiate TCAR cases. This study not only re-evaluates the validity of the previous study but also has the potential to prevent other researchers from employing the erroneous methodology for TCAR selection using the CPT code, which is one of the most widely used standardizations of medical communication for surgical procedures. This is particularly pertinent given the recent "TCAR revolution", where significant attention has been focused on TCAR.

Locoregional Anesthesia Has Lower Risks of Cardiac Complications Than General Anesthesia After Prolonged Endovascular Repair of Abdominal Aortic Aneurysms

OBJECTIVES

Although general anesthesia is the primary anesthesia in endovascular aneurysm repair (EVAR), some studies suggest locoregional anesthesia could be a feasible alternative for eligible patients. However, most evidence was from retrospective studies and was subjected to an inherent selection bias that general anesthesia is often chosen for more complex and prolonged cases. To mitigate this selection bias, this study aimed to compare 30-day outcomes of prolonged, nonemergent, intact, infrarenal EVAR in patients undergoing locoregional or general anesthesia. In addition, risk factors associated with prolonged operative time in EVAR were identified.

DESIGN

Retrospective large-scale national registry study.

SETTING

American College of Surgeons National Surgical Quality Improvement Program targeted database from 2012 to 2022.

PARTICIPANTS

A total of 4,075 out of 16,438 patients (24.79%) had prolonged EVAR. Among patients with prolonged EVAR, 324 patients (7.95%) were under locoregional anesthesia. There were 3,751 patients (92.05%) under general anesthesia, and 955 of them were matched to the locoregional anesthesia cohort.

INTERVENTIONS

Patients undergoing infrarenal EVAR were included. Exclusion criteria included age <18 years, emergency cases, ruptured abdominal aortic aneurysm, and acute intraoperative conversion to open. Only cases with prolonged operative times (>157 minutes) were selected. A 1:3 propensity-score matching was used to address demographics, baseline characteristics, aneurysm diameter, distant aneurysm extent, and concomitant procedures between patients under locoregional and general anesthesia. Thirty-day postoperative outcomes were assessed. Moreover, factors associated with prolonged EVAR were identified by multivariate logistic regression.

MEASUREMENTS AND MAIN RESULTS

Except for general anesthesia contraindications, patients undergoing locoregional or general anesthesia exhibited largely similar preoperative characteristics. After propensity-score matching, patients under locoregional and general anesthesia had a lower risk of myocardial infarction (0.93% v 2.83%, p = 0.04), but comparable 30-day mortality (3.72% v 2.72%, p = 0.35) and other complications. Specific concomitant procedures, aneurysm anatomy, and comorbidities associated with prolonged EVAR were identified.

CONCLUSIONS

Locoregional anesthesia can be a safe and effective alternative to general anesthesia, particularly in EVAR cases with anticipated complexity and prolonged operative times, as it offers the potential benefit of reduced cardiac complications. Risk factors associated with prolonged EVAR can aid in preoperative risk stratification and inform the decision-making process regarding anesthesia choice.

The 5-Factor Modified Frailty Index is a succinct yet effective predictor of adverse outcomes in patients undergoing open surgery for abdominal aortic aneurysm

BACKGROUND

Frailty is an age-related, clinically recognizable state marked by increased susceptibility. The 5-item Modified Frailty Index (mFI-5) offers a concise assessment of frailty and has demonstrated its efficacy in various surgical fields. While the mFI-5 has been validated for Endovascular Aneurysm Repair (EVAR) for Abdominal Aortic Aneurysm (AAA), its applicability in open surgical repair (OSR) for AAA remains largely unexplored. This study sought to evaluate the utility of mFI-5 in predicting 30-day outcomes following OSR for AAA.

METHODS

Patients underwent OSR for AAA were identified in ACS-NSQIP targeted database from 2012-2021. Patients were stratified into three cohorts: mFI-5 score of 0 (control), 1, and 2+. Multivariable logistic regression was used to compare 30-day perioperative outcomes between frail patients and controls adjusting preoperative variables with p-value<0.1.

RESULTS

Of the 5,249 patients who underwent OSR for AAA, 1,043 were controls, 2,938 had an mFI-5 score of 1, and 1,268 had an mFI-5 score of 2+. When compared to the control group, patients with an mFI-5=1 were more likely to have pulmonary events (aOR=1.452, p<0.01), bleeding events (aOR=1.33, p<0.01), wound complications (aOR=2.214, p<0.01), ischemic colitis (aOR=1.616, p=0.01), and unplanned reoperation (aOR=1.292, p=0.04). Those with an mFI-5=2+ demonstrated higher risks of mortality (aOR=1.709, p<0.01), MACE (aOR=1.347, p=0.04), pulmonary events (aOR=2.045, p<0.01), renal dysfunction (aOR=1.568, p<0.01), sepsis (aOR=1.587, p=0.01), bleeding events (aOR=1.429, p<0.01), wound complications (aOR=2.338, p<0.01), ischemic colitis (aOR=1.775, p=0.01), unplanned reoperation (aOR=1.445, p=0.01), operation over 4 hours (aOR=1.34, p<0.01), length of stay over 7 days (aOR=1.324, <0.01), discharge not to home (aOR=1.547, p<0.01), 30-day readmission (aOR=1.657, p=0.01).

CONCLUSION

The mFI-5 emerges as a succinct yet effective indicator of frailty for patients undergoing OSR for AAA. Especially, a mFI-5 score of 2+ is linked with increased 30-day mortality and complications. As such, mFI-5 can be used as a valuable screening tool for frailty in patients undergoing OSR for AAA.

Development of a comorbidity index for patients undergoing abdominal aortic aneurysm repair

BACKGROUND

Endovascular aneurysm repair (EVAR) and open surgical repair (OSR) are two modalities to treat patients with abdominal aortic aneurysm (AAA). Alternative to individual comorbidity adjustment, a summary comorbidity index is a weighted composite score of all comorbidities that can be used as standard metric to control for comorbidity burden in clinical studies. This study aimed to develop summary comorbidity indices for patients who underwent AAA repair.

METHODS

Patients who went under EVAR or OSR were identified in National Inpatient Sample (NIS) between the last quarter of 2015 to 2020. In each group, patients were randomly sampled into experimental (2/3) and validation (1/3) groups. The weights of Elixhauser comorbidities were determined from a multivariable logistic regression and single comorbidity indices were developed for EVAR and OAR groups, respectively.

RESULTS

There were 34,668 patients underwent EVAR (2.19% mortality) and 4792 underwent OSR (10.98% mortality). Both comorbidity indices had moderate discriminative power (EVAR c-statistic, 0.641; 95% confidence interval [CI], 0.616-0.665; OSR c-statistic, 0.600; 95% CI, 0.563-0.630) and good calibration (EVAR Brier score, 0.021; OSR Brier score, 0.096). The indices had significantly better discriminative power (DeLong P <.001) than the Elixhauser Comorbidity Index (ECI) (EVAR c-statistic, 0.572; 95% CI, 0.546-0.597; OSR c-statistic, 0.502; 95% CI, 0.472-0.533). For internal validation, both indices had similar performance compared with individual comorbidity adjustment (EVAR DeLong P = .650; OSR DeLong P = .431). These indices demonstrated good external validation, exhibiting comparable performance to their respective validation groups (EVAR DeLong P = .891; OSR DeLong P = .757).

CONCLUSIONS

ECI, the comorbidity index formulated for the general population, exhibited suboptimal performance in patients who underwent AAA repair. In response, we developed summary comorbidity indices for both EVAR and OSR for AAA repair, which were internally and externally validated. The EVAR and OSR comorbidity indices outperformed the ECI in discriminating in-hospital mortality rates. They can standardize comorbidity measurement for clinical studies in AAA repair, especially for studies with small samples such as single-institute data sources to facilitate replication and comparison of results across studies.

Acute Intraoperative Conversion from Endovascular to Open vs Planned Open Operation for Abdominal Aortic Aneurysm: A Propensity-Score Matched Study from the American College of Surgeons NSQIP Targeted Database

BACKGROUND

Evaluating outcomes for acute intraoperative conversion to open surgery during endovascular aneurysm repair (EVAR) for abdominal aortic aneurysm (AAA) was difficult due to low incidence. This study aimed to compare 30-day outcomes between patients with acute intraoperative conversion during EVAR and planned open surgery, and to identify risk factors associated with acute conversion.

METHODS

Patients underwent EVAR or planned open AAA repair were identified in ACS-NSQIP targeted databases 2012-2021. Patients with acute intraoperative conversion during EVAR were selected. A 1:3 propensity-score matching was used to match demographics, baseline characteristics, surgical indications, aneurysm size and extent, and emergency cases between the conversion open and planned open groups. Thirty-day postoperative outcomes were assessed.

RESULTS

Out of 20,566 EVAR, 177 (0.86%) had acute intraoperative conversion to open surgery. The conversion open group was matched to 504 out of 5,249 planned open patients. Conversion open and planned open groups had comparable 30-day mortality (23.43% vs 17.46%, p=0.09) and organ system complications including MACE (14.86% vs 10.71%, p=0.17), pulmonary complications (17.71% vs 24.01%, p=0.09), and renal complications (8.57% vs 11.11%, p=0.39). The conversion open group had lower bleeding requiring transfusion (48.57% vs 75.60%, p<0.01), shorter operation time (p<0.01), and shorter length of stay (p<0.01). Other postoperative outcomes did not differ. Risk factors associated with acute intraoperative conversion included ruptured aneurysm with or without hypotension. Protective factors included hypertension and aortic distal aneurysm extent.

CONCLUSION

While this study does not endorse a universal "EVAR first" strategy for all patients with AAA, EVAR can be attempted first in eligible AAA patients. Even when EVAR is unsuccessful, intraoperative conversion to open surgery still appears to be safe compared to planned open repair.

AI-Powered Chatbots in Medical Education: Potential Applications and Implications

Artificial intelligence (AI) is anticipated to have a considerable impact on the routine practice of medicine, spanning from medical education to clinical practice across specialties and, ultimately, patient care. With the imminent widespread adoption of AI in medical practice, it is imperative that medical schools adapt to the use of these advanced technologies in their curriculum to produce future healthcare professionals who can seamlessly integrate these tools into practice. Chatbots, AI systems programmed to process and generate human language, are currently being evaluated for various tasks in medical education. This paper explores the potential applications and implications of chatbots in medical education, specifically in learning and research. With their capability to summarize, simplify complex concepts, automate the creation of memory aids, and serve as an interactive tutor and point-of-care medical reference, chatbots have the potential to enhance students' comprehension, retention, and application of medical knowledge in real-time. While the integration of AI-powered chatbots in medical education presents numerous advantages, it is crucial for students to use these tools as assistive tools rather than relying on them entirely. Chatbots should be programmed to reference evidence-based medical resources and produce precise and trustworthy content that adheres to medical science standards, scientific writing guidelines, and ethical considerations.

Arterial, but Not Venous, Reconstruction Increases 30-Day Morbidity and Mortality in Pancreaticoduodenectomy

BACKGROUND

Vascular reconstruction during pancreaticoduodenectomy is increasingly utilized to improve pancreatic cancer resectability. However, few multi-institutional studies have evaluated the morbidity and mortality of arterial and venous reconstruction during this procedure.

METHODS

A retrospective analysis was performed utilizing the targeted pancreas module of the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) for pancreaticoduodenectomy from 2014 to 2015. Demographics, comorbidities, and 30-day outcomes for patients who underwent venous or arterial reconstruction and both were compared to no reconstruction.

RESULTS

A total of 3002 patients were included in our study: 384 with venous reconstruction, 52 with arterial, 81 with both, and 2566 without. Compared to patients without reconstruction, those who underwent venous reconstruction had more congestive heart failure (1.8% vs 0.2%, P < 0.01), those with arterial reconstruction had higher rates of pulmonary disease (11.5% vs. 4.5%, P = 0.02), and neoadjuvant chemotherapy was more common in both venous (34% vs 12%, P < 0.01) and arterial reconstruction (21% vs 12%, P = 0.04). In multivariable analysis, there was no increase in morbidity or mortality following venous reconstruction. However, arterial reconstruction was associated with increased 30-day mortality with an odds ratio (OR): 6.7, 95%; confidence interval (CI): 1.8-25. Morbidity was increased as represented with return to the operating room (OR: 4.5, 95%; CI: 1.5-15), pancreatic fistula (OR: 4.4, 95%; CI: 1.7-11), and reintubation (OR: 3.9, 95%; CI: 1.1-14).

CONCLUSIONS

Venous reconstruction during pancreaticoduodenectomy does not increase perioperative morbidity or mortality and should be considered for patients previously considered to be unresectable or those where R0 resection would otherwise not be possible due to venous involvement. Careful consideration should be made prior to arterial reconstruction given the significant increase in perioperative complications and death within 30 days.

Preservation of renal perfusion by hepatorenal and splenorenal bypasses before explantation of an infected abdominal aortic endograft

We report the case of an 82-year-old patient with an infected abdominal aortic endograft who presented with a right psoas abscess and lumbar osteomyelitis. The psoas abscess was drained percutaneously. Fluid obtained grew Fusobacterium nucleatum. The patient, an active and highly functional individual, wished to pursue definitive management. The infected endograft was surgically removed, and the aorta was ligated above the renal arteries after staged axillary-bifemoral, hepatorenal, and splenorenal bypasses.

Abstract 139: PARP-1 Silencing Upregulates FOSL1 Transcription, Enhances Angiogenesis and Accelerates Ischemic-Diabetic Wound Healing

Objective: People with combined ischemic and diabetic wounds of the lower extremities have the highest risk for limb loss, especially for those without surgical revascularization options. We have demonstrated that Poly-ADP-Ribose polymerase (PARP-1) is hyperactivated in hyperglycemic/hypoxic cells and in ischemic/diabetic murine wounds. This study elucidates the molecular mechanisms of PARP-1 mediated impairment of angiogenesis in diabetic/ischemic wounds.

Methods: A model of dorsal bipedicle flap-ischemic wounds on diabetic mice was used. The wounds were treated topically with nanoparticle-encapsulated siPARP-1 or vehicle. Wound closure rate and perfusion was analyzed using digital photography and Laser Doppler scanning, respectively. Angiogenetic markers in the tissues were measured by immunohistochemistry. In-vitro endothelial tube formation assay was performed using HUVECs cultured under hyperglycemic and hypoxic conditions.

Results: Wounds treated with topical siPARP-1 significantly accelerated wound healing compared to vehicle (from 25% ± 5% to 40%± 8% ( n =7, p < .05) by day 6 and from 50% ± 15% to 75%± 3% ( n =7, p < .05) by day 12, and also exhibited improved tissue perfusion (50%± 5% increase in perfusion units over control on day 6, n =47 p <0.05). Improved capillary density was also observed in the siPARP-1 treated wounds detected by immunohistochemistry for SMA (250%±35% increase in mean fluorescence intensity over control on day 12, n =4, p <0.05) and CD31 (125% ± 15% increase in mean fluorescence intensity over control on day 12, n =4, p <0.05). In-vitro angiogenesis assay showed that PARP-1-silencing significantly enhanced endothelial tube formation of hyperglycemic/hypoxic HUVECs (15± 4 complete polygons as compared to 0 in untreated, n =4, p <0.05). Human angiogenesis PCR-array analysis of pro-angiogenic factors revealed that PARP-1 silencing upregulated FOSL1 transcription by 5-fold ( n =4, p <0.05). Interestingly, co-silencing of FOSL1 in PARP-1 silenced HUVECs resulted in loss of endothelial tube formation.

Conclusions: PARP-1 silencing is an effective strategy to promote ischemic-diabetic wound healing. Our data suggest that PARP-1-FOSL1 is a potential novel axis in angiogenesis and PARP-1 could be a promising therapeutic target for improving angiogenesis in these wounds.

Establishing patient-specific criteria for selecting the optimal upper extremity vascular access procedure

OBJECTIVE

The Kidney Disease Outcome Quality Initiative and Fistula First Breakthrough Initiative call for the indiscriminate creation of arteriovenous fistulas (AVFs) over arteriovenous grafts (AVGs) without providing patient-specific criteria for vascular access selection. Although the U.S. AVF rate has increased dramatically, several reports have found that this singular focus on increasing AVFs has resulted in increased AVF nonmaturation/early failure and a high prevalence of catheter dependence. The objective of this study was to determine the appropriateness of vascular access procedures in clinical scenarios constructed with combinations of relevant factors potentially influencing outcomes.

METHODS

The RAND/UCLA Appropriateness Method was used. Accordingly, a comprehensive literature search was performed and a synthesis of results compiled. The RAND/UCLA Appropriateness Method was applied to 2088 AVF and 1728 AVG clinical scenarios with varying patient characteristics. Eleven international vascular access experts rated the appropriateness of each scenario in two rounds. On the basis of the distribution of the panelists' scores, each scenario was determined to be appropriate, inappropriate, or indeterminate.

RESULTS

Panelists achieved agreement in 2964 (77.7%) scenarios; 860 (41%) AVF and 588 (34%) AVG scenarios were scored appropriate, 686 (33%) AVF and 480 (28%) AVG scenarios were scored inappropriate, and 542 (26%) AVF and 660 (38%) AVG scenarios were indeterminate. Younger age, larger outflow vein diameter, normal or obese body mass index (vs morbidly obese), larger inflow artery diameter, and higher patient functional status were associated with appropriateness of AVF creation. Older age, dialysis dependence, and smaller vein size were associated with appropriateness of AVG creation. Gender, diabetes, and coronary artery disease were not associated with AVF or AVG appropriateness. Dialysis status was not associated with AVF appropriateness. Body mass index and functional status were not associated with AVG appropriateness. To simulate the surgeon's decision-making, scenarios were combined to create situations with the same patient characteristics and both AVF and AVG options for access. Of these 864 clinical situations, 311 (36%) were rated appropriate for AVG but inappropriate or indeterminate for AVF.

CONCLUSIONS

The results of this study indicate that patient-specific situations exist wherein AVG is as appropriate as or more appropriate than AVF. These results provide patient-specific recommendations for clinicians to optimize vascular access selection criteria, to standardize care, and to inform payers and policy. Indeterminate scenarios will guide future research.

Poly-ADP-ribose polymerase inhibition enhances ischemic and diabetic wound healing by promoting angiogenesis

OBJECTIVE

Chronic nonhealing wounds are a major health problem for patients in the United States and worldwide. Diabetes and ischemia are two major risk factors behind impaired healing of chronic lower extremity wounds. Poly-ADP-ribose polymerase (PARP) is found to be overactivated with both ischemic and diabetic conditions. This study seeks a better understanding of the role of PARP in ischemic and diabetic wound healing, with a specific focus on angiogenesis and vasculogenesis.

METHODS

Ischemic and diabetic wounds were created in FVB/NJ mice and an in vitro scratch wound model. PARP inhibitor PJ34 was delivered to the animals at 10 mg/kg/d through implanted osmotic pumps or added to the culture medium, respectively. Animal wound healing was assessed by daily digital photographs. Animal wound tissues, peripheral blood, and bone marrow cells were collected at different time points for further analysis with Western blot and flow cytometry. Scratch wound migration and invasion angiogenesis assays were performed using human umbilical vein endothelial cells (HUVECs). Measurements were reported as mean ± standard deviation. Continuous measurements were compared by t-test. P < .05 was considered statistically significant.

RESULTS

A significant increase in PARP activity was observed under ischemic and diabetic conditions that correlated with delayed wound healing and slower HUVEC migration. The beneficial effect of PARP inhibition with PJ34 on ischemic and diabetic wound healing was observed in both animal and in vitro models. In the animal model, the percentage of wound healing was significantly enhanced from 43% ± 6% to 71% ± 9% (P < .05) by day 7 with the addition of PJ34. PARP inhibition promoted angiogenesis at the ischemic and diabetic wound beds as evidenced by significantly higher levels of endothelial cell markers (vascular endothelial growth factor receptor 2 [VEGFR2] and endothelial nitric oxide synthase) in mice treated with PJ34 compared with controls. Flow cytometry analysis of peripheral blood mononuclear cells showed that PARP inhibition increased mobilization of endothelial progenitor cells (VEGFR2⁺/CD133⁺ and VEGFR2⁺/CD34⁺) into the systemic circulation. Furthermore, under in vitro hyperglycemia and hypoxia conditions, PARP inhibition enhanced HUVEC migration and invasion in Boyden chamber assays by 80% and 180% (P < .05), respectively.

CONCLUSIONS

Delayed healing in ischemic and diabetic wounds is caused by PARP hyperactivity, and PARP inhibition significantly enhanced ischemic and diabetic wound healing by promoting angiogenesis.

Disruption of transforming growth factor-beta signaling through beta-spectrin ELF leads to hepatocellular cancer through cyclin D1 activation

Transforming growth factor-beta (TGF-beta) signaling members, TGF-beta receptor type II (TBRII), Smad2, Smad4 and Smad adaptor, embryonic liver fodrin (ELF), are prominent tumor suppressors in gastrointestinal cancers. Here, we show that 40% of elf(+/-) mice spontaneously develop hepatocellular cancer (HCC) with markedly increased cyclin D1, cyclin-dependent kinase 4 (Cdk4), c-Myc and MDM2 expression. Reduced ELF but not TBRII, or Smad4 was observed in 8 of 9 human HCCs (P<0.017). ELF and TBRII are also markedly decreased in human HCC cell lines SNU-398 and SNU-475. Restoration of ELF and TBRII in SNU-398 cells markedly decreases cyclin D1 as well as hyperphosphorylated-retinoblastoma (hyperphosphorylated-pRb). Thus, we show that TGF-beta signaling and Smad adaptor ELF suppress human hepatocarcinogenesis, potentially through cyclin D1 deregulation. Loss of ELF could serve as a primary event in progression toward a fully transformed phenotype and could hold promise for new therapeutic approaches in human HCCs.

RING finger-dependent ubiquitination by PRAJA is dependent on TGF-beta and potentially defines the functional status of the tumor suppressor ELF

In gastrointestinal cells, biological signals for transforming growth factor-beta (TGF-beta) are transduced through transmembrane serine/threonine kinase receptors that signal to Smad proteins. Smad4, a tumor suppressor, is often mutated in human gastrointestinal cancers. The mechanism of Smad4 inactivation, however, remains uncertain and could be through E3-mediated ubiquitination of Smad4/adaptor protein complexes. Disruption of ELF (embryonic liver fodrin), a Smad4 adaptor protein, modulates TGF-beta signaling. We have found that PRAJA, a RING-H2 protein, interacts with ELF in a TGF-beta-dependent manner, with a fivefold increase of PRAJA expression and a subsequent decrease in ELF and Smad4 expression, in gastrointestinal cancer cell lines (P < 0.05). Strikingly, PRAJA manifests substantial E3-dependent ubiquitination of ELF and Smad3, but not Smad4. Delta-PRAJA, which has a deleted RING finger domain at the C terminus, abolishes ubiquitination of ELF. A stable cell line that overexpresses PRAJA exhibits low levels of ELF in comparison to a Delta-PRAJA stable cell line, where ELF expression is high compared to normal controls. The alteration of ELF and/or Smad4 expression and/or function in the TGF-beta signaling pathway may be induced by enhancement of ELF degradation, which is mediated by a high-level expression of PRAJA in gastrointestinal cancers. In hepatocytes, half-life (t(1/2)) and rate constant for degradation (k(D)) of ELF is 1.91 h and 21.72 min(-1) when coupled with ectopic expression of PRAJA in cells stimulated by TGF-beta, compared to PRAJA-transfected unstimulated cells (t(1/2) = 4.33 h and k(D) = 9.6 min(-1)). These studies reveal a mechanism for tumorigenesis whereby defects in adaptor proteins for Smads, such as ELF, can undergo degradation by PRAJA, through the ubiquitin-mediated pathway.

Role of insulin-like growth factor-I (IGF-I) receptor, IGF-I, and IGF binding protein-2 in human colorectal cancers

The identification of novel autocrine/paracrine signaling pathways and possible markers represents an important component in the understanding of tumor growth control. In this study, we assessed the potential role of insulin-like growth factor-I (IGF-I), the IGF-I receptor (IGF-IR) and IGF binding protein-2 (IGFBP-2) in human colorectal cancer. Initial studies demonstrating increased IGF-I binding and IGF-IR density in human colon cancer tissue revealed that a component of iodinated (3-[125-I]iodotyrosyl) IGF-I (125I-ICGF-I) binding was not attributable to IGF-IR. Binding studies and Western blot analysis suggested that this second component of 125I-IGF-I binding could be due to IGFBP-2. Further analysis by a specific solution hybridization/RNase protection assay for IGF-IR mRNA levels, IGFBP-2 mRNA levels and in situ hybridization for IGFBP-2 localization, was carried out in nine patients with colon cancer. IGF-IR mRNA levels by RNAse protection assays were unchanged, whereas IGFBP-2 mRNA levels were increased 4-8-fold in patients with colon cancer compared to controls. Three patients with Dukes stage C disease had the highest levels of IGFBP-2 mRNA. In situ hybridization studies localized IGFBP-2 mRNA to malignant cells and not to the surrounding stromal cells, suggesting an autocrine role for IGFBP-2. The discrepancy between increased IGF-I binding, IGF-IR density, IGFBP-2 mRNA and the minimal modulation of the IGF-IR mRNA implies post-transcriptional regulation of IGF-IRs. Our results suggest that IGFBP-2 may be implicated in colon cancer metastases and prognosis. Its usefulness as a potential tumor marker should be further investigated.

A modified directional atherectomy catheter for resection of calcified atherosclerotic plaques

BACKGROUND

The purpose of this study was to determine the feasibility of resecting calcified atherosclerotic plaques in human cadaveric vessels by using a modified directional coronary atherectomy catheter and to correlate these results with bench tests using an in-vitro sea coral model.

METHODS

The conventional directional coronary atherectomy catheter was modified by changing the cutter blade to a tungsten carbide material and by increasing the torsional strength of the drive cable. The performance of the modified directional coronary atherectomy (DCA) catheter was compared with the conventional catheter using a sea coral model to simulate calcified material. Then, 10 human ex-vivo arteries (eight with calcification) were treated with both conventional and modified catheters, and the results studied with intravascular ultrasound and confirmed by histologic examination.

RESULTS

Using the modified directional coronary atherectomy catheter it was possible to perform effective and consistent longitudinal cutting, and to resect a significantly larger amount of coral (1.0 +/- 0.1 mm2 versus 0.2 +/- 0.1 mm2 with conventional cutter, P < 0.0001). In heavily calcified ex-vivo arteries, the modified catheter was more effective in removing calcified plaques (13 +/- 11 mg versus 3.7 +/- 1.4 mg with conventional cutter, P = 0.07). Intravascular ultrasound confirmed the effective atherectomy (residual area stenosis 28 +/- 16% versus 47 +/- 10% with the conventional device, P < 0.05), and histologic examination showed calcified nodules in the atherectomy samples obtained with the modified cutter (area of calcium 1.43 +/- 0.89 mm2 versus 0.93 +/- 0.83 mm2 with the conventional cutter).

CONCLUSIONS

The modified directional coronary atherectomy catheter effectively removed both non-calcified and calcified plaques in the ex-vivo human cadaveric arteries, thus demonstrating the feasibility of directional coronary atherectomy of calcified plaques. This modified device shows promise for treating calcified coronary lesions, especially in larger vessels.

Surgical management of subclavian and axillary vein thrombosis in patients with a functioning arteriovenous fistula

Until recently, secondary thrombosis of the deep veins of the upper extremity was rarely encountered. The expanding use of the subclavian vein as a route to the central circulation has increased its occurrence, but symptoms are uncommon. Patients on hemodialysis with a functioning arteriovenous fistula become symptomatic with venous hypertension and swelling. Treatment becomes necessary, and fistula ligation is usually recommended; however, this renders the extremity unsuitable for a future life-sustaining access. Patency of grafts in the venous system has been accomplished with a temporary arteriovenous fistula. In six patients with chronic renal failure and a functioning arteriovenous fistula, a polytetrafluoroethylene graft was used to replace or bypass the obstructed vein. Symptoms resolved, and the fistula was preserved in three of the six patients for 1 to 3 years.

A new method for the prediction of peripheral vascular resistance from the preoperative angiogram

The preoperative angiogram is widely used to estimate runoff prior to infrainguinal bypass grafting, but the traditional method of angiographic scoring (0, 1, 2, or 3 based on the number of patent tibial vessels) correlates poorly with measurements of peripheral vascular resistance. We assigned a score of 0, 1, or 2 to each of four parameters (anterior and posterior tibial arteries [AT and PT], peroneal artery [PER], and plantar arch [ARCH]) on the preoperative angiograms of 39 patients admitted for elective femoral bypass grafting. These scores were then examined for their ability to correlate with the peripheral vascular resistance measured in each patient at the time of surgery. Multiple linear regression suggested that the scores assigned to the AT, PT, and ARCH were significantly correlated with observed resistance, but the PER subscore was not. Multiple linear regression of the AT, PT, and ARCH subscores suggested that resistance could be predicted from the equation: In (Resistance [mm Hg/ml/min]) = 0.786 - 0.268(AT) - 0.25(PT) - 0.358(ARCH), for which r = 0.78 and p less than 0.001. The ability of this relationship to predict resistance was tested by a division of the patient population into two roughly equal groups based on their observed resistance at surgery. When tested in this fashion, this equation had a sensitivity of 88% and a specificity of 82%. These findings suggest that the preoperative angiogram can be graded in a simple, yet unambiguous way, which allows a reasonable prediction of peripheral vascular resistance.