The peritoneal cavity is a distinct compartment of angiogenic molecular mediators.

OBJECTIVE: This study was designed to analyze porcine plasma and peritoneal fluid for concentration differences of angiogenic molecular mediators and to determine local peritoneal sites of production of these molecules. BACKGROUND: The peritoneum is now recognized as a dynamic cellular membrane with important functions, including antigen presentation; transport and movement of fluid, solutes, and particulate matter across serosal cavities; and secretion of glycosaminoglycans, extracellular matrix proteins, proinflammatory cytokines, and growth factors. The mechanisms of the peritoneal response to injury and the factors that determine the outcome of the reactive or reparative processes of the peritoneum remain poorly defined. METHODS: Domestic swine (n = 12) underwent percutaneous diagnostic peritoneal lavage to obtain preincision peritoneal fluid for biochemical analysis. Open biopsy samples of parietal peritoneum and omentum were obtained for immunochemical and molecular analysis. Vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) levels were quantitated by enzyme-linked immunosorbent assay, and nitrite/nitrate (NOx) measured by nonenzymatic assay. Sections of formalin-fixed tissue were stained for immunoreactivity to VEGF, bFGF, and nitric oxide synthase (NOS). Frozen homogenized peritoneum and omentum were prepared for isolation of protein and RNA. An endothelial growth assay was created using human umbilical vein endothelial cells cultured with peritoneal fluid with or without anti-VEGF or anti-bFGF antibodies. RESULTS: The mean plasma concentrations of VEGF, bFGF, and NOx were 20 +/- 5 pg/mL, 35 +/- 9 pg/mL, and 4.5 +/- 1.3 microm, compared with mean peritoneal fluid concentrations of 395 +/- 75 pg/mL, 486 +/- 72 pg/mL, and 35.0 +/- 8.8 mum respectively (P < 0.05 for each molecule). Immunochemistry demonstrated VEGF, bFGF, and NOS protein in mesothelium, submesothelium, and omentum. The use of Western blotting and reverse transcription polymerase chain reaction confirmed peritoneal and omental presence of VEGF and NOS-2. The use of endothelial bioassay documented peritoneal fluid angiogenic activity, which was inhibited by addition of neutralizing antibody to VEGF or bFGF. CONCLUSION: Peritoneal compartmentalization of angiogenic mediators important in wound healing, inflammation, and tumor growth suggests that the plasma concentrations of these mediators do not reflect their tissue concentrations or local biological activity.

Local arginine supplementation results in sustained wound nitric oxide production and reductions in vascular endothelial growth factor expression and granulation tissue formation.

OBJECTIVE: The goal of this work was to test the functional role of L-arginine in promotion of nitric oxide (NO) production and the vigorous granulation tissue formation characteristic of this wound model. BACKGROUND: Therapeutic use of supplemental arginine has been proposed as a safe and efficacious method to produce NO from nitric oxide synthase (NOS) and to produce proline and polyamines from arginase to improve wound healing. Although NO appears to be necessary to promote wound healing, the preferential metabolism of arginine to NO via NOS 2 may be detrimental if maintained beyond the initial days of healing. METHODS: A ventral hernia, surgically created in the abdominal wall of 12 swine, was repaired with silicone sheeting and skin closure. Osmotic infusion pumps, inserted in remote subcutaneous pockets, continuously delivered saline (n = 6) or L-arginine (n = 6) into the wound environment. Granulation tissue thickness was determined by ultrasonography. Fluid was aspirated serially from the wound compartment for measurements of nitrite/nitrate (NOx), vascular endothelial growth factor (VEGF), transforming growth factor-beta1 (TGF-beta1), and amino acid concentrations. On day 14, the animals were sacrificed and the abdominal wall was harvested for immunohistochemical and molecular analysis. RESULTS: In animals receiving saline, a nearly linear four-fold increase in granulation tissue thickness was measured during the 14-day interval. In contrast, quantitative ultrasound analysis detected significant reductions in L-arginine infused granulation tissue thickness compared with controls between days 4 and 14 (P < 0.05). Wound vessel count and luminal vascular surface area estimates derived from image analysis of histological sections were two- to three-fold lower in the L-arginine animals compared with controls (P < 0.05). Significant and sustained increases in wound fluid NOx levels were noted in L-arginine animals compared to saline controls (230 microM versus 75 microM at day 14, P < 0.05). Conversely, late VEGF levels (days 11 to 14) were reduced in the L-arginine animals compared to controls (7500 pg/ml versus 10,000 pg/ml at day 11, P < 0.05; 7250 pg/ml versus 11,101 pg/ml at day 14, P < 0.05). Arginine concentrations remained two- to four-fold greater in L-arginine treated animals compared with controls over the entire time course (P < 0.05). There were no significant differences in concentrations of ornithine, citrulline, or proline noted between groups over the 14-day period. Finally, TGF-beta1 levels were unaffected by L-arginine treatment. CONCLUSION: Although NO appears to be necessary for granulation tissue formation, early supplemental arginine may disturb the reciprocal regulation of NOS 2 and arginase, leading to the preferential metabolism of arginine to excess NO rather than ornithine, with consequent reductions in angiogenesis and granulation tissue formation.

Survey of physician experience, trends and outcomes with atrial fibrillation ablation.

OBJECTIVE: We evaluated the prevalence, trends, outcomes and the general experience of physicians performing atrial fibrillation ablation (AF-ABL) in the United States (US). BACKGROUND: AF-ABL is a non-pharmacological and potentially curative therapy for AF. Success rates for AF-ABL have been reported to be between 80 and 90%. Although there are numerous clinical trial addressing this therapy little is known about the general status of AF-ABL in clinical practice. METHODS: We administered a mailed survey to the physician members of a professional arrhythmia society (Heart Rhythm Society, formerly known as the North American Society of Pacing and Electrophysiology) who practiced in the US (n = 1843). RESULTS: There were 304 responses, 66% (n = 204) performed ABL and 30% (n = 92) performed AF-ABL. The study group performed a total of 5,592 AF-ABL from 2000 to 2003, out of 72,575 total ABL procedures during the same time period. There was a four-fold increase in the number of AF-ABL between 2000 and 2003 (2000: 628 vs. 2003: 2,575). In the same period, the self-reported short and long-term success rates of AF-ABL improved an average of 18 +/- 4% (p < or = 0.001). In 2003 the average self-reported one-month, one-year, and two-year success rates were: 71 +/- 4%, 66 +/- 5%, 63 +/- 6% respectively. The predicted five-year success was 60 +/- 4%. The average procedure took 4.5 +/- 0.4 hours. Physicians reported that approximately 29 +/- 4% of their patents were potential candidates for AF-ABL. CONCLUSIONS: AF-ABL is becoming a much more common procedure in the US. Over the last four years the perceived short and long term success rates of AF-ABL have improved. Success rates in this survey are 10 to 20% lower than those reported in the recent clinical trials.