Transauricular embolization of the rabbit coronary artery for experimental myocardial infarction: comparison of a minimally invasive closed-chest model with open-chest surgery

<p>Abstract</p> <p>Introduction</p> <p>To date, most animal studies of myocardial ischemia have used open-chest models with direct surgical coronary artery ligation. We aimed to develop a novel, percutaneous, minimally-invasive, closed-chest model of experimental myocardial infarction (EMI) in the New Zealand White rabbit and compare it with the standard open-chest surgical model in order to minimize local and systemic side-effects of major surgery.</p> <p>Methods</p> <p>New Zealand White rabbits were handled in conformity with the "Guide for the Care and Use of Laboratory Animals" and underwent EMI under intravenous anesthesia. Group A underwent EMI with an open-chest method involving surgical tracheostomy, a mini median sternotomy incision and left anterior descending (LAD) coronary artery ligation with a plain suture, whereas Group B underwent EMI with a closed-chest method involving fluoroscopy-guided percutaneous transauricular intra-arterial access, superselective LAD catheterization and distal coronary embolization with a micro-coil. Electrocardiography (ECG), cardiac enzymes and transcatheter left ventricular end-diastolic pressure (LVEDP) measurements were recorded. Surviving animals were euthanized after 4 weeks and the hearts were harvested for Hematoxylin-eosin and Masson-trichrome staining.</p> <p>Results</p> <p>In total, 38 subjects underwent EMI with a surgical (n = 17) or endovascular (n = 21) approach. ST-segment elevation (1.90 ± 0.71 mm) occurred sharply after surgical LAD ligation compared to progressive ST elevation (2.01 ± 0.84 mm;p = 0.68) within 15-20 min after LAD micro-coil embolization. Increase of troponin and other cardiac enzymes, abnormal ischemic Q waves and LVEDP changes were recorded in both groups without any significant differences (p > 0.05). Infarct area was similar in both models (0.86 ± 0.35 cm in the surgical group vs. 0.92 ± 0.54 cm in the percutaneous group;p = 0.68).</p> <p>Conclusion</p> <p>The proposed model of transauricular coronary coil embolization avoids thoracotomy and major surgery and may be an equally reliable and reproducible platform for the experimental study of myocardial ischemia.</p

Inhibition of Ion Channels and Heart Beat in Drosophila by Selective COX-2 Inhibitor SC-791

Recent findings suggest that modulation of ion channels might be implicated in some of the clinical effects of coxibs, selective inhibitors of cyclooxygenase-2 (COX-2). Celecoxib and its inactive analog 2,5-dimethyl-celecoxib, but not rofecoxib, can suppress or augment ionic currents and alter functioning of neurons and myocytes. To better understand these unexpected effects, we have recently investigated the mechanism of inhibition of human Kv2.1 channels by a highly selective COX-2 inhibitor SC-791. In this study we have further explored the SC-791 action on ion channels and heartbeat in Drosophila, which lacks cyclooxygenases and thus can serve as a convenient model to study COX-2-independent mechanisms of coxibs. Using intracellular recordings in combination with a pharmacological approach and utilizing available Drosophila mutants, we found that SC-791 inhibited voltage-activated K+ and L-type Ca2+ channels in larval body-wall muscles and reduced heart rate in a concentration-dependent manner. Unlike celecoxib and several other K+ channel blockers, SC-791 did not induce arrhythmia. Instead, application of SC-791 resulted in a dramatic slowing of contractions and, at higher concentrations, in progressively weaker contractions with gradual cessation of heartbeat. Isradipine, a selective blocker of L-type Ca2+ channels, showed a similar pattern of heart arrest, though no prolongation of contractions was observed. Ryanodine was the only channel modulating compound of those tested additionally that was capable of slowing contractions. Like SC-791, ryanodine reduced heart rate without arrhythmia. However, it could not stop heartbeat completely even at 500 µM, the highest concentration used. The magnitude of heart rate reduction, when SC-791 and ryanodine were applied together, was smaller than expected for independent mechanisms, raising the possibility that SC-791 might be interfering with excitation-contraction coupling in Drosophila heart

Celecoxib and acetylbritannilactone interact synergistically to suppress breast cancer cell growth via COX-2-dependent and -independent mechanisms

The use of celecoxib is associated with a significant decrease in breast cancer risk. However, the long-term use of high-dose celecoxib might be limited owing to cardiovascular side effects. In this study, we found that acetylbritannilactone (ABL), extract from a Chinese medicinal herb, could reduce celecoxib dose and potentiate the growth-inhibitory effect in breast cancer cells. ABL enhanced the apoptotic effect of celecoxib in COX-2-expressing cells, but had little effect in COX-2-negative cells. The apoptosis induced by the combination treatment disappeared when COX-2 was knocked down, whereas the lack of apoptotic effects in COX-2-negative cells was reversed after COX-2 transfection. However, the combination treatment induced a G0/G1 phase arrest independent of whether or not the cells expressed COX-2. The G0/G1 arrest was attributed to a decreased expression of cyclinD1, cyclinE, CDK2 and CDK6, especially the upregulation of p21. In addition, inhibition of Akt and p38 signaling pathways was required by the synergism, as the constitutively active Akt and p38 protected cells against apoptosis and cell cycle arrest induced by the combination treatment. In vivo, administration of celecoxib and ABL were more effective than the individual agents against xenograft tumor growth. Thus, our data suggested that the combinatorial approach of celecoxib and ABL might be helpful for breast cancer treatment

Implication of Tissue Factor Bearing Microvesicles in Hypercoagulable State in Acute Promyelocytic Leukemia

4788 Introduction Thrombosis is a common complication of patients with malignancies. Patients with hematological malignancy have a 28 fold increase risk to develop venous thromboembolism (VTE). A population-based cohort was used to determine the incidence and risk factors associated with development of venous thromboembolism (VTE) among Californians diagnosed with acute leukemia between 1993 to 1999. Principal outcomes were deep vein thrombosis in the lower and upper extremities, pulmonary embolism, and mortality. Among 5,394 cases with acute myelogenous leukemia (AML), the 2-year cumulative incidence of VTE was 281 (5.2%). Sixty-four% of the VTE events occurred within 3 months of AML diagnosis. The induction of hypercoagulable state mechanisms is not fully understood to date. Multifactorial aspects such as physic immobility, chemotherapy adverse effects or the overexpression of several procoagulant substances (cytokines, cysteine protease and tissue factor) by cancer cells are often provoked. Several studies strongly suggest that microvesicles (MVs) harboring tissue factor activity may have a primary role in VTE. MVs are small membrane vesicles shed from normal and/or tumor cells following activation or apoptosis. MVs may present TF and negatively charged phospholipids (PL) such as phosphatidylserine on their membrane. These elements are thought to be implicated in the procoagulant activity (PCA). Objectives The aim of this study was to assess the capacity of untreated acute promyelocytic leukemia cells to shed procoagulant MVs. Methods Acute promyelocytic leukemia (APL) cells lines (NB4 and HL-60) were cultured 48h in medium at 600,000 cells/mL. Cells and MVs were separated by filtrations (0.1–0.22–0.45–0.65μm). The PCA was assessed by thrombin generation assay. Alternatively, MVs were incubated with anti-TF antibodies (10μg/mL) or with annexin V (0,5μM to assess the contribution of TF and phospholipids to the PCA. Moreover HL-60 cells were incubated with HgCl2 which promote di-S bond formation (activation of TF). Results NB4 cells and HL-60 cells can stimulate thrombin generation. HL60 cells reduced the lagtime 3.9-fold and increased the peak 1.6-fold in comparison to CTL and NB4 cells decreased the lagtime 10.9-fold and increased the peak 6.7-fold in comparison to CTL. No PCA was observed in HL-60 filtered with 0.65 μm membrane (no statistical difference in lagtime peak and ETP). By contrast, NB4 cells can support thrombin generation activity when filtered at different sizes. MVs of sizes <0.65 and <0.45 μm decreased the lagtime 4.2- and 3.8-fold, respectively and increased the peak of thrombin 4.6- and 4.1-fold, respectively. MVs of sizes lower than 0.22 and <0.1 μm reduced the lagtime 2.4- and 1.6-fold, respectively and increased the peak 2.3- and 1.4-fold, respectively. Thrombin generation activity of MVs of size <0.65 μm derived from NB4 cells wass abolished when anti-TF antibodies or annexin V were preincubated Discussion NB4 cells and HL-60 cells have different PCA. NB4 cells have a higher procoagulant activity and most of the PCA is linked to MVs of size under 0.45 μm. NB4 cells spontaneously release different sized MVs which can support thrombin generation. By using an anti-TF function-blocking antibody (HTF-1) and annexin V which binds phosphatidylserine, we confirmed that the PCA of MVs is related to the expression of active TF and PL. HL-60 cells have a weaker procoagulant activity because TF is mostly present in an inactive form (activation of TF by reduction agent such as HgCl2 increased the PCA of HL-60 cells of +/− 35%). Moreover HL-60 cells do not produce MVs<0.65 μm associated with PCA. Conclusions APL NB4 cells and HL-60 cells can stimulate thrombin generation. NB4 cells release MVs (of size <0.65 μm) whose procoagulant activity is mediated by TF and PL. These MVs could have a prognostic value for VTE in patient with APL. Disclosures No relevant conflicts of interest to declare

Recruitment and activation of circulating neutrophils after sinus surgery

Objective: After failure of pharmacological treatment, sinus surgery is the recommended alternative treatment for chronic sinusitis with or without nasal polyps. During post-operative healing, adequate local neutrophil activation plays an important role in the repair process. This pilot study aimed to systematically explore the participation of circulating neutrophils in early-phase wound repair of the nasal and paranasal mucosa after sinus surgery, with a special focus on neutrophil recruitment and activation patterns. Methodology: We conducted a single-center outcome study of patients undergoing sinus surgery. Whole blood samples were collected from eleven patients before surgery and at post-surgical time points of 1 hour and 1,7,14, and 30 days. Hematological analysis was conducted to count circulating neutrophils and evaluate their overall activation status. Using flow cytometry, neutrophil expression of membrane CD11b, CD11c, and CD15 was also measured, and oxidative burst analysis was performed. Results: After sinus surgery, neutrophilia increased by 1 hour after surgery, reached a maximum at Day 1, and showed a gradual return toward baseline by Day 30. The oxidative burst initially decreased during the first hours after surgery, increased at Day 14, and returned toward normal by Day 30. Lewis X factor and the expression of CD11b and CD11c exhibited a bimodal change over time, in an inverted phase compared to the oxidative reaction. Conclusions: Circulating neutrophils are involved in the first phase of wound healing after sinus surgery as indicated by increased abundance, early membrane changes, and the modulation of their oxidative capacities