Effects of L-arginine on fibroblast growth factor 2-induced angiogenesis in a model of endothelial dysfunction.

BACKGROUND: Nitric oxide availability, which is decreased in advanced coronary artery disease associated with endothelial dysfunction, is an important mediator of fibroblast growth factor-2 (FGF-2)-induced angiogenesis. This could explain the disappointing results of FGF-2 therapy in clinical trials despite promising preclinical studies. We examined the influence of L-arginine supplementation to FGF-2 therapy on myocardial microvascular reactivity and perfusion in a porcine model of endothelial dysfunction. METHODS AND RESULTS: Eighteen pigs were fed either a normal (NORM, n=6) or high cholesterol diet, with (HICHOL-ARG, n=6) or without (HICHOL, n=6) L-arginine. All pigs underwent ameroid placement on the circumflex artery and 3 weeks later received surgical FGF-2 treatment. Four weeks after treatment, endothelial-dependent coronary microvascular responses and lateral myocardial perfusion were assessed. Endothelial cell density was determined by immunohistochemistry. FGF-2, fibroblast growth receptor-1, endothelial-derived nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS), and syndecan-4 levels were determined by immunoblotting. Pigs from the HICHOL group showed endothelial dysfunction in the circumflex territory, which was normalized by L-arginine supplementation. FGF-2 treatment was ineffective in the HICHOL group (circumflex/left anterior descending blood flow ratios: 1.01 (rest) and 1.01 (pace), after and before treatment). Addition of L-arginine improved myocardial perfusion in response to FGF-2 at rest (ratio 1.13, P=0.02 versus HICHOL) but not during pacing (ratio 0.94, P=NS), and was associated with increased protein levels of iNOS and eNOS. CONCLUSIONS: L-arginine supplementation can partially restore the normal response to endothelium-dependent vasorelaxants and myocardial perfusion in response to FGF-2 treatment in a swine model of hypercholesterolemia-induced endothelial dysfunction. These findings suggest a role for L-arginine in combination with FGF-2 therapy for end-stage coronary artery disease.

Normalization of coronary microvascular reactivity and improvement in myocardial perfusion by surgical vascular endothelial growth factor therapy combined with oral supplementation of l-arginine in a porcine model of endothelial dysfunction.

OBJECTIVE: Vascular endothelial growth factor acts in part through nitric oxide release, the availability of which is decreased in endothelial dysfunction associated with advanced coronary artery disease. This could explain the relatively disappointing results of vascular endothelial growth factor therapy in clinical studies compared with animal studies. We examined the influence of L-arginine supplementation to vascular endothelial growth factor therapy on myocardial microvascular reactivity and perfusion in a porcine model of endothelial dysfunction. METHODS: Twenty-four pigs were fed either a normal (NORM, n = 8) or high-cholesterol diet with (CHOL-ARG, n = 8) or without (CHOL, n = 8) L-arginine. All pigs underwent ameroid placement on the circumflex artery and then 3 weeks later received surgical vascular endothelial growth factor treatment. Four weeks after treatment, endothelial-dependent coronary microvascular responses and lateral myocardial perfusion were assessed. Endothelial cell density was determined by means of immunohistochemistry. Vascular endothelial growth factor, endothelial nitric oxide synthase, and Akt levels were determined by means of immunoblotting. RESULTS: Pigs from the CHOL group showed endothelial dysfunction in the circumflex territory, which was normalized by L-arginine supplementation. Vascular endothelial growth factor treatment was ineffective in the CHOL group (circumflex/left anterior descending coronary artery blood flow ratios: 0.95 [rest] and 0.74 [pace] before-after treatment; P < .05 compared with the NORM group). Addition of L-arginine restored the angiogenic effect of vascular endothelial growth factor (ratios: 1.13 [rest] and 1.20 [pace]; P < .05) and was associated with increased endothelial cell density, as well as vascular endothelial growth factor, endothelial nitric oxide synthase, and Akt protein levels in the ischemic territory. CONCLUSIONS: L-Arginine supplementation can restore normal endothelium-dependent vasorelaxation and angiogenic response to vascular endothelial growth factor in a swine model of chronic myocardial ischemia with hypercholesterolemia-induced endothelial dysfunction. These findings suggest a putative role for L-arginine in combination with vascular endothelial growth factor therapy for end-stage coronary artery disease.

Effects of L-arginine on the endogenous angiogenic response in a model of hypercholesterolemia.

BACKGROUND: The angiogenic properties of vascular endothelial growth factor and fibroblast growth factor-2 are mediated in part through nitric oxide release, whose availability is decreased in endothelial dysfunction associated with advanced coronary artery disease. We examined the influence of L-arginine supplementation on the endogenous angiogenic response to ischemia in a porcine model of hypercholesterolemia. METHODS: Eighteen Yucatan pigs were fed either a normal (NORM, n=6) or a high-cholesterol diet, with (CHOL-ARG, n=6) or without (CHOL, n=6) L-arginine (100 mg/kg/day), throughout the experiment. All pigs underwent ameroid constrictor placement on the circumflex artery (LCx). Seven weeks later, endothelium-dependent coronary microvascular responses to fibroblast growth factor-2 and vascular endothelial growth factor were assessed by videomicroscopy. Perfusion was assessed with radioactive microspheres; angiogenesis was evaluated by platelet-endothelial cell adhesion molecule-1 (CD-31) staining. Regional myocardial function was assessed by sonomicrometry. Expression of endothelial nitric oxide synthase and inducible nitric oxide synthase was measured by Western blot analyses. RESULTS: Pigs from the CHOL group showed significant endothelial dysfunction in the LCx territory. The dysfunction was normalized partially by L-arginine supplementation, which restored the response in the LCx territory to the level of the nonischemic anterior wall. L-arginine supplementation resulted in increases of perfusion, density of capillary endothelial, and level of endothelial nitric oxide synthase in the ischemic region. Despite these findings, no improvement in myocardial regional function was found. CONCLUSIONS: L-arginine supplementation can partially restore endothelium-dependent vasorelaxation and improve myocardial perfusion in a swine model of chronic myocardial ischemia with hypercholesterolemia-induced endothelial dysfunction. These findings suggest a putative role for L-arginine in combination with growth factor therapy for end-stage coronary artery disease.

A novel approach using liquid embolic agent for the treatment of pancreatic-cutaneous fistulas: Report of a case.

Pancreatic fistula formation remains one of the most dreadful complications after pancreaticoduodenectomies, resulting in extended hospital stays, increased healthcare costs, along with significantly increased morbidity and mortality. Little is mentioned in the literature about the use of percutaneous techniques to resolve this complication when conservative treatments fail. Thus, we developed a novel technique for treating pancreatic-cutaneous fistulas that develop post-pancreaticoduodenectomy. This work describes a novel approach of using a liquid embolic agent to treat a high-output pancreatic-cutaneous fistula after a Whipple procedure, which to the best of our knowledge after extensive literature searches, has not been performed before.

A Randomized 2x2 Factorial Clinical Trial of Renal Transplantation: Steroid-Free Maintenance Immunosuppression with Calcineurin Inhibitor Withdrawal after Six Months Associates with Improved Renal Function and Reduced Chronic Histopathology.

INTRODUCTION: The two most significant impediments to renal allograft survival are rejection and the direct nephrotoxicity of the immunosuppressant drugs required to prevent it. Calcineurin inhibitors (CNI), a mainstay of most immunosuppression regimens, are particularly nephrotoxic. Until less toxic antirejection agents become available, the only option is to optimize our use of those at hand. AIM: To determine whether intensive rabbit anti-thymocyte globulin (rATG) induction followed by CNI withdrawal would individually or combined improve graft function and reduce graft chronic histopathology-surrogates for graft and, therefore, patient survival. As previously reported, a single large rATG dose over 24 hours was well-tolerated and associated with better renal function, fewer infections, and improved patient survival. Here we report testing whether complete CNI discontinuation would improve renal function and decrease graft pathology. METHODS: Between April 20, 2004 and 4-14-2009 we conducted a prospective, randomized, non-blinded renal transplantation trial of two rATG dosing protocols (single dose, 6 mg/kg vs. divided doses, 1.5 mg/kg every other day x 4; target enrollment = 180). Subsequent maintenance immunosuppression consisted of tacrolimus, a CNI, and sirolimus, a mammalian target of rapamycin inhibitor. We report here the outcome of converting patients after six months either to minimized tacrolimus/sirolimus or mycophenolate mofetil/sirolimus. Primary endpoints were graft function and chronic histopathology from protocol kidney biopsies at 12 and 24 months. RESULTS: CNI withdrawal (on-treatment analysis) associated with better graft function (p <0.001) and lower chronic histopathology composite scores in protocol biopsies at 12 (p = 0.003) and 24 (p = 0.013) months, without affecting patient (p = 0.81) or graft (p = 0.93) survival, or rejection rate (p = 0.17). CONCLUSION: CNI (tacrolimus) withdrawal at six months may provide a strategy for decreased nephrotoxicity and improved long-term function in steroid-free low immunological risk renal transplant patients. TRIAL REGISTRATION: ClinicalTrials.gov NCT00556933.

A randomized 2×2 factorial trial, part 1: single-dose rabbit antithymocyte globulin induction may improve renal transplantation outcomes.

BACKGROUND: We conducted a randomized and unblinded 2 × 2 sequential-factorial trial, composed of an induction arm (part 1) comparing single-dose (SD) versus divided-dose rabbit antithymocyte globulin (rATG), and a maintenance arm (part 2) comparing tacrolimus minimization versus withdrawal. We report the long-term safety and efficacy of SD-rATG induction in the context of early steroid withdrawal and tacrolimus minimization or withdrawal. METHODS: Patients (n=180) received 6 mg/kg rATG, SD or four alternate-day doses (1.5 mg/kg/dose), with early steroid withdrawal and tacrolimus or sirolimus maintenance. After 6 months targeted maintenance levels were tacrolimus, 2 to 4 ng/mL and sirolimus, 4 to 6 ng/mL or, if calcineurin inhibitor-withdrawn, sirolimus 8 to 12 ng/mL with mycophenolate mofetil 2 g two times per day. Primary endpoints were renal function (abbreviated modification of diet in renal disease) and chronic graft histopathology (Banff). Secondary endpoints included patient survival, graft survival, biopsy-proven rejection, and infectious or noninfectious complications. RESULTS: Follow-up averaged longer than 4 years. Tacrolimus or sirolimus and mycophenolate mofetil exposure was identical between groups. The SD-rATG associated with improved renal function (2-36 months; P<0.001) in deceased donor recipients. The SD-rATG associated with quicker lymphocyte, CD4 T cell, and CD4-CD8 recovery and fewer infections. Cox multivariate hazard modeling showed divided-dose-rATG (P=0.019), deceased donor (P=0.003), serious infection (P=0.0.018), and lower lymphocyte count (P=0.001) associated with increased mortality. Patients with all four covariates showed a 27-fold increased likelihood of death (P=0.00002). Chronic graft histopathology, rejection rates, and death-censored graft survival were not significantly different between groups. CONCLUSION: The SD-rATG induction improves the 3-year renal function in recipients of deceased donor kidneys. This benefit, along with possibly improved patient survival and fewer infections suggest that how rATG is administered may impact its efficacy and safety.

Inhibition of the cardiac angiogenic response to exogenous vascular endothelial growth factor.

BACKGROUND: The angiogenic effects of vascular endothelial growth factor (VEGF) are mediated by the stimulation of endothelial nitric oxide synthase (eNOS) and nitric oxide release. Nitric oxide availability is decreased in patients with coronary disease, a possible explanation for the humble results of VEGF in clinical trials. We sought to examine the effects of exogenous VEGF in a model of endothelial dysfunction. METHODS: Miniswine fed either a regular (N = 6, group NORM) or hypercholesterolemic diet (N = 6, HICHOL) underwent ameroid placement on the circumflex artery. Three weeks later, baseline myocardial perfusion was assessed by microsphere injections, and all pigs were treated with VEGF. Four weeks later, microsphere injections were repeated and the hearts harvested. Endothelial-dependent coronary microvascular reactivity, and VEGF and eNOS expression were assessed. RESULTS: HICHOL pigs showed significant endothelial dysfunction in the ischemic territory. Post-treatment myocardial blood flow in the circumflex territory was significantly higher in the NORM compared to the HICHOL group. VEGF and eNOS levels were increased in the ischemic territory in the NORM group but decreased in the HICHOL group. CONCLUSIONS: The cardiac angiogenic response to VEGF was markedly inhibited in a hypercholesterolemia-induced porcine model of endothelial dysfunction. Coronary endothelial dysfunction could be an obstacle to the efficacy of clinical angiogenesis protocols and a putative therapeutic target.