Michelle C. Martin

Gene Expression of Pro-Inflammatory Cytokines and Neuropeptides in Diabetic Wound Healing

The interaction between neuropeptides and cytokines and its role in cutaneous wound healing is becoming evident. The goal of the present study is to investigate the impact of diabetes on peripheral cytokine and neuropeptide expression and its role in diabetic wound healing. To achieve this goal, the effect of diabetes on wound healing, along with the role of inflammatory cytokines such as interleukin-6 (IL-6) and interleukin-8 (IL-8) secreted in the wound microenvironment, and neuropeptides such as substance P (SP) and neuropeptide Y (NPY), secreted from peripheral nerves is monitored in non-diabetic and diabetic rabbits. Rabbits in the diabetic group received alloxan monohydrate (100mg/kg i.v.). Ten days after diabetic induction, four full thickness circular wounds were created in both ears using a 6mm punch biopsy. Wound healing was monitored over 10 d and gene expression of cytokines and neuropeptides was assessed in the wounds. Compared with the non-diabetic rabbits, wounds of diabetic rabbits heal significantly slower. Diabetic rabbits show significantly increased baseline gene expression of IL-6 and IL-8, their receptors, CXCR1, CXCR2, GP-130, and a decrease of prepro tachykinin-A (PP-TA), the precursor of SP, whereas the expression of prepro-NPY (PP-NPY), the precursor of NPY is not different. Similarly, baseline protein expression of CXCR1 is higher in diabetic rabbit skin. Post-injury, the increase over baseline gene expression of IL-6, IL-8, CXCR1, CXCR2, and GP-130 is significantly less in diabetic wounds compared with non-diabetic wounds. Although there is no difference in PP-TA gene expression between non-diabetic and diabetic rabbits post-injury, the gene expression of PP-NPY is reduced in diabetic rabbits. In conclusion, diabetes causes dysregulation in the neuropeptide expression in the skin along with a suppressed focused inflammatory response to injury. This suggests that the chronic inflammation in the skin of diabetic rabbits inhibits the acute inflammation much needed for wound healing.

MARCKS silencing differentially affects human vascular smooth muscle and endothelial cell phenotypes to inhibit neointimal hyperplasia in saphenous vein

Intimal hyperplasia (IH) limits the patency of all cardiovascular vein bypass grafts. We previously found the myristoylated alanine‐rich C kinase substrate (MARCKS), a key protein kinase C (PKC) substrate, to be up‐regulated in canine models of IH. Here, we further characterize the role of MARCKS in IH and examine the phenotypic consequences of MARCKS silencing by small interfering RNA (siRNA) transfection in human vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) in vitro and use a rapid 10‐min nonviral siRNA transfection technique to determine the effects of MARCKS silencing in human saphenous vein cultured ex vivo. We demonstrate MARCKS silencing attenuates VSMC migration and arrests VSMC proliferation in part through the up‐regulation of the cyclin‐dependent kinase inhibitor p27kip1. Conversely, MARCKS silencing had little or no effect on EC migration or proliferation. These phenotypic changes culminated in reduced neointimal formation in cultured human saphenous vein. These data identify MARCKS as a pathogenic contributor to IH and indicate therapeutic MARCKS silencing could selectively suppress the “atherogenic,” proliferative phenotype of VSMCs without collateral harm to the endothelium. This approach could be readily translated to the clinic to silence MARCKS in vein bypass grafts prior to implantation.— Monahan, T. S., Andersen, N. D., Martin, M. C, Malek, J. Y., Shrikhande, G. V., Pradhan, L., Ferran, C, LoGerfo, F. W. MARCKS silencing differentially affects human vascular smooth muscle and endothelial cell phenotypes to inhibit neointimal hyperplasia in saphenous vein. FASEB J. 23, 557–564 (2009)

Routine use of ultrasound-guided access reduces access site-related complications after lower extremity percutaneous revascularization

OBJECTIVE We sought to elucidate the risks for access site-related complications (ASCs) after percutaneous lower extremity revascularization and to evaluate the benefit of routine ultrasound-guided access (RUS) in decreasing ASCs. METHODS We reviewed all consecutive percutaneous revascularizations (percutaneous transluminal angioplasty or stent) performed for lower extremity atherosclerosis at our institution from 2002 to 2012. RUS began in September 2007. Primary outcome was any ASC (bleeding, groin or retroperitoneal hematoma, vessel rupture, or thrombosis). Multivariable logistic regression was used to determine predictors of ASC. RESULTS A total of 1371 punctures were performed on 877 patients (43% women; median age, 69 [interquartile range, 60-78] years) for claudication (29%), critical limb ischemia (59%), or bypass graft stenosis (12%) with 4F to 8F sheaths. There were 72 ASCs (5%): 52 instances of bleeding or groin hematoma, nine pseudoaneurysms, eight retroperitoneal hematomas, two artery lacerations, and one thrombosis. ASCs were less frequent when RUS was used (4% vs 7%; P = .02). Multivariable predictors of ASC were age >75 years (odds ratio [OR], 2.0; 95% confidence interval [CI], 1.1-3.7; P = .03), congestive heart failure (OR, 1.9; 95% CI, 1.1-1.3; P = .02), preoperative warfarin use (OR, 2.0; 95% CI, 1.1-3.5; P = .02), and RUS (OR, 0.4; 95% CI, 0.2-0.7; P < .01). Vascular closure devices (VCDs) were not associated with lower rates of ASCs (OR, 1.1; 95% CI, 0.6-1.9; P = .79). RUS lowered ASCs in those >75 years (5% vs 12%; P < .01) but not in those taking warfarin preoperatively (10% vs 13%; P = .47). RUS did not decrease VCD failure (6% vs 4%; P = .79). CONCLUSIONS We were able to decrease the rate of ASCs during lower extremity revascularization with the implementation of RUS. VCDs did not affect ASCs. Particular care should be taken with patients >75 years old, those with congestive heart failure, and those taking warfarin.

National Outcomes after Open Repair of Abdominal Aortic Aneurysms with Visceral or Renal Bypass

BACKGROUND We evaluated national outcomes after open repair of abdominal aortic aneurysms (AAAs) with visceral or renal bypass (VRB). METHODS Using the National Inpatient Sample database from 1993 through 2006, AAA repairs were identified by ICD9 codes for diagnosis of intact AAA combined with a procedure of open AAA repair. VRB patients also had an aortorenal and/or mesenteric bypass or mesenteric endarterectomy. Dissections as well as thoracic and thoracoabdominal aneurysms were excluded. Demographics and comorbidities were noted. Mortality and complications were compared to infrarenal AAA (IRA) repairs without VRB. Predictors of perioperative mortality were analyzed by multivariate logistic regression. RESULTS A total of 41,166 VRB and 362,808 IRA repairs were identified. VRB repair volume decreased by 58% and IRA volume decreased by 59% from 1993 to 2006. VRB patients had higher mortality (5.8% vs. 4.4%, p < 0.001) and more complications including acute renal failure (9.5% vs. 6.0%, p < 0.001), acute mesenteric ischemia (2.0% vs. 1.2%), and bowel resection (1.1% vs. 0.8%, p < 0.01). Patients requiring a bowel resection or with acute renal failure were 10 times more likely to die within the hospital stay regardless of repair type. Independent preoperative predictors of mortality were VRB (odds ratio [OR] = 1.3, 95% confidence interval [CI] 1.2-1.5), age (OR = 1.4 per decade, 95% CI 1.4-1.5), chronic renal failure (OR = 5.5, 95% CI 4.9-6.3), congestive heart failure (OR = 7.5, 95% CI 6.1-9.3), and pulmonary disease (OR = 1.2, 95% CI 1.1-1.2). CONCLUSION VRB repair volume decreased per year similarly to open IRA repair volume and may be related to increasing use of endovascular therapy. Mortality after VRB is high and dependent upon age, renal failure, and congestive heart failure. Overall, VRB repair was associated with worsened outcomes; however, this study cannot conclude that avoiding such a repair will improve outcomes. This should be factored into surgical decision making for these patients.