Aberrant soluble epoxide hydrolase and oxylipin levels in a porcine arteriovenous graft stenosis model.

Synthetic arteriovenous grafts (AVGs) used for hemodialysis frequently fail due to the development of neointimal hyperplasia (NH) at the vein-graft anastomosis. Inflammation and smooth-muscle cell (SMC) and myofibroblast proliferation and migration likely play an important role in the pathogenesis of NH. Epoxyeicosatrienoic acids (EETs), the products of the catabolism of arachidonic acid by cytochrome P450 enzymes, possess anti-inflammatory, antiproliferative, antimigratory and vasodilatory properties that should reduce NH. The degradation of vasculoprotective EETs is catalyzed by the enzyme, soluble epoxide hydrolase (sEH). sEH upregulation may thus contribute to NH development by the enhanced removal of vasculoprotective EETs. In this study, sEH, cytochrome P450 and EETs were examined after AVG placement in a porcine model to explore their potential roles in AVG stenosis. Increased sEH protein expression, decreased P450 epoxygenase activity and dysregulation of 5 oxylipin mediators were observed in the graft-venous anastomotic tissues when compared to control veins. Pharmacological inhibitors of sEH decreased the growth factor-induced migration of SMCs and fibroblasts, although they had no significant effect on the proliferation of these cells. These results provide insights on epoxide biology in vascular disorders and a rationale for the development of novel pharmacotherapeutic strategies to prevent AVG failure due to NH and stenosis.

PDGF-induced proliferation in human arterial and venous smooth muscle cells: molecular basis for differential effects of PDGF isoforms.

Platelet-derived growth factor (PDGF) has been implicated in the pathogenesis of arterial atherosclerosis and venous neointimal hyperplasia. We examined the effects of PDGF isoforms on smooth muscle cells (SMCs) from arterial and venous origins in order to further understand the differential responsiveness of these vasculatures to proliferative stimuli. Serum-starved human arterial and venous SMCs exhibited very different proliferative responses to PDGF isoforms. Whereas, proliferation of arterial SMCs was strongly stimulated by PDGF-AA, venous SMCs showed no proliferative response to PDGF-AA, but instead demonstrated a significantly greater proliferative response to PDGF-BB than arterial SMCs. Part of this difference could be attributed to differences in PDGF receptors expression. There was a 2.5-fold higher (P < 0.05) density of PDGF receptor-α (PDGF-Rα) and a 6.6-fold lower (P < 0.05) density of PDGF-Rß expressed on arterial compared to venous SMCs. Concomitant with an increased proliferative response to PDGF-AA in arterial SMCs was a marked PDGF-Rα activation, enhanced phosphorylation of ERK1/2 and Akt, a transient activation of c-Jun NH2-terminal kinase (JNK), and a significant reduction in expression of the cell-cycle inhibitor p27(kip1). This pattern of signaling pathway changes was not observed in venous SMCs. No phosphorylation of PDGF-Rα was detected after venous SMC exposure to PDGF-AA, but there was enhanced phosphorylation of ERK1/2 and Akt in venous SMCs, similar to that seen in the arterial SMCs. PDGF-BB stimulation of venous SMC resulted in PDGF-Rß activation as well as transactivation of epidermal growth factor receptor (EGF-R); transactivation of EGF-R was not observed in arterial SMCs. These results may provide an explanation for the differential susceptibility to proliferative vascular diseases of arteries and veins.

The proteomic signature of NPM/ALK reveals deregulation of multiple cellular pathways.

Constitutive expression of the chimeric NPM/ALK fusion protein encoded by the t(2;5)(p32;q35) is a key oncogenic event in the pathogenesis of most anaplastic large cell lymphomas (ALCLs). The proteomic network alterations produced by this aberration remain largely uncharacterized. Using a mass spectrometry (MS)-driven approach to identify changes in protein expression caused by the NPM/ALK fusion, we identified diverse NPM/ALK-induced changes affecting cell proliferation, ribosome synthesis, survival, apoptosis evasion, angiogenesis, and cytoarchitectural organization. MS-based findings were confirmed using Western blotting and/or immunostaining of NPM/ALK-transfected cells and ALK-deregulated lymphomas. A subset of the proteins distinguished NPM/ALK-positive ALCLs from NPM/ALK-negative ALCLs and Hodgkin lymphoma. The multiple NPM/ALK-deregulated pathways identified by MS analysis also predicted novel biologic effects of NPM/ALK expression. In this regard, we showed loss of cell adhesion as a consequence of NPM/ALK expression in a kinase-dependent manner, and sensitivity of NPM/ALK-positive ALCLs to inhibition of the RAS, p42/44ERK, and FRAP/mTOR signaling pathways. These findings reveal that the NPM/ALK alteration affects diverse cellular pathways, and provide novel insights into NPM/ALK-positive ALCL pathobiology. Our studies carry important implications for the use of MS-driven approaches for the elucidation of neoplastic pathobiology, the identification of novel diagnostic biomarkers, and pathogenetically relevant therapeutic targets.

Effects of exercise on hematological parameters, circulating side population cells, and cytokines.

OBJECTIVE: To determine the effects of exercise and/or training on hematologic indices, circulating side population (SP) cells, and cytokines. Specifically hemoglobin (Hgb), hematocrit (Hct), white blood cell (WBC) and platelet (Plt) numbers, SP cells and plasma vascular endothelial growth factor (VEGF) and interleukin-6 (IL-6) levels were analyzed before and following exercise to maximal fatigue. MATERIALS AND METHODS: Thirty-seven nonsmoking subjects, aged 19 to 35 years, free of cardiopulmonary disease were enrolled and characterized as "trained" or "untrained." Standard hematologic indices were measured. Blood cells were stained with Hoechst 33342 vital dye and analyzed using flow cytometry for enumeration of SP cells. The levels of IL-6 and VEGF were determined by enzyme-linked immunosorbent assay. RESULTS: Trained individuals had higher oxygen utilization and significantly longer exercise times than untrained individuals. Following exercise, significant increases were observed in Hgb, Hct, Plt, SP cell numbers, and IL-6 levels. These changes occurred in both trained and untrained individuals of both genders. No significant change in WBC numbers or VEGF levels was observed. Although circulating SP cell numbers were significantly increased, the "quality" of SP cells, defined by the ratio of lower SP to upper SP cells, was unchanged. Increases in SP cells did not correlate with cytokine levels. CONCLUSION: Exercise increased Hgb, Hct, and Plt numbers, circulating SP cell numbers and IL-6 levels in young, healthy individuals of both genders and all fitness levels. These changes in hematologic, hematopoietic, and cytokine parameters, suggest that exercise can have a physiologic impact by potentially mobilizing stem cells and thereby enhancing tissue repair mechanisms.

Bronchodilator responsiveness in swine veterinarians.

OBJECTIVE: Swine veterinarians are known to be at risk for respiratory symptoms and airflow obstruction. The present study reassessed the prevalence of respiratory complaints and pulmonary function abnormalities in swine veterinarians and sought to characterize their response to bronchodilators. METHODS: A cross-sectional study was conducted during the American Association of Swine Veterinarians annual meeting. Subjects completed a respiratory symptom and workplace exposure history questionnaire and spirometry. Subjects with airflow obstruction were assessed for a post-bronchodilator response with beta2 agonist administration. RESULTS: Participants included 58 veterinarians (mean age, 45.5 years). Work-related symptoms assessed by questionnaire included rhinitis symptoms (60.3%), cough and chest tightness (55.2%), and wheezing (35.1%). Airflow obstruction was detected in 11/58 (19%) of subjects by spirometry. Only 2/9 (22.2%) met American Thoracic Society criteria for reversibility with bronchodilator administration. CONCLUSIONS: Respiratory symptoms and airway obstruction remain common findings in swine veterinarians. Airflow obstruction was not consistently reversible with beta agonists, suggesting that swine barn exposure may be a risk factor for irreversible airflow obstruction.

Regulation of COX-2 transcription in a colon cancer cell line by Pontin52/TIP49a.

Cyclooxygenase-2 (COX-2) is expressed early in colon carcinogenesis and is known to play a crucial role in the progress of the disease. Here we show that the regulation of the expression of this enzyme in a colon cancer cell line, and in patients, is associated with overexpression of the Wnt pathway-associated proteins, Pontin52/TIP49a and LEF-1. Recently shown to be essential for transformation via the c-Myc pathway, Pontin52/TIP49a promotes COX-2 expression in tissue culture and is overexpressed in colon cancer tissue, co-localizing with COX-2 expression in transformed tissue, relative to paired normal tissue.