Classical and Alternative Activation of Cyanobacterium Oscillatoria sp. Lipopolysaccharide-Treated Rat Microglia in vitro.

The purpose of this investigation was to test the hypothesis that an in vitro exposure to cyanobacterium Oscillatoria sp. Lipopolysaccharide (LPS) might result in classical and alternative activation of rat neonatal microglia. Using Escherichia coli LPS-primed microglia as a positive control, this study revealed that treatment of rat microglia with Oscillatoria sp. LPS for 17 h in vitro resulted in both classical and alternative activation as well as concomitant pro-inflammatory and anti-inflammatory mediator release, in a concentration-dependent manner: (1) treatment with 0.1-10 000 ng/ml Oscillatoria sp. LPS resulted in minimal lactic dehydrogenase (LDH) release, induced concentration-dependent and statistically significant O2 (-) generation, matrix metalloproteinase-9 (MMP-9) release, generation of the cytokines tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), and the chemokines macrophage inflammatory protein-2 (MIP-2/CXCL2), interferon γ-induced protein 10 kDa (IP-10/CXCL-10), (MIP-1α/CCL3), monocyte chemotactic protein-1 (MCP-1/CCL2), regulated on activation, normal T cell expressed and secreted (RANTES/CCL5), and the alternative activation cytokine IL-10; (3) in contrast, treatment with 100 000 ng/ml Oscillatoria sp. LPS appeared to damage the microglia cell membrane, because it resulted in minimal O2 (-) generation, statistically significant LDH release, and a decrease in the generation of all the cytokines and chemokines investigated, with the exception of IL-1α and cytokine-induced neutrophil chemoattractant 1 (CINC-1/CXCL1) generation, which was increased. Thus, our results provide experimental support for our working hypothesis, namely that Oscillatoria sp. LPS induces classical and alternative activation of rat brain microglia in vitro in a concentration-dependent manner, namely 0.1-10 000 ng/ml Oscillatoria sp. LPS, when microglia cells were shown to be viable. Furthermore, should cyanobacterium Oscillatoria sp. LPS gain entry into the CNS, our findings suggest that classical and alternative activation of rat brain microglia in vivo, might lead to concomitant mediator release that could result in an interplay between neuroinflammation and neural repair in a concentration-dependent manner.

A novel mesh electrode catheter for mapping and radiofrequency delivery at the left atrium-pulmonary vein junction: a single-catheter approach to pulmonary vein antrum isolation.

BACKGROUND: Electrical isolation of pulmonary veins (PV) by radiofrequency (RF) ablation is often performed in patients with atrial fibrillation (AF). Current catheter technology usually requires the use of a multielectrode catheter for mapping in addition to the ablation catheter. PURPOSE: We evaluated the feasibility and safety of using a single, expandable electrode catheter (MESH) to map and to electrically isolate the PV. METHODS AND RESULTS: Nineteen closed-chest mongrel dogs, weighing 23-35 kg, were studied under general anesthesia. Intracardiac echocardiography (ICE) was used to guide transseptal puncture and to assess PV dimensions and contact of the MESH with PV ostia. ICE and angiography of RSPV were obtained before and after ablation, and prior to sacrifice at 7-99 days. An 11.5 Fr steerable MESH was advanced and deployed at the ostium of the RSPV. Recordings were obtained via the 36 electrodes comprising the MESH. For circumferential ablation, RF current was delivered at a target temperature of 62-65 degrees C (4 thermocouples) and maximum power of 70-100 W for 180 to 300 seconds. Each animal received 1-4 RF applications. Entrance conduction block was obtained in 13/19 treated RSPVs. Pathological examination confirmed circumferential and transmural lesions in 13 of 19 RSPV. LA mural thrombus was present in 3 animals. There was no significant PV stenosis. CONCLUSION: Based on this canine model, a new expandable MESH catheter may safely be used for mapping and for PV antrum isolation. This approach may decrease procedure time without compromising success rate in patients undergoing AF ablation.

Testing of a new T-wave subtraction algorithm as an aid to localizing ectopic atrial beats.

BACKGROUND: Identifying the timing and morphology of an ectopic P wave from the surface electrogram can aid in the diagnosis and localization of atrial arrhythmias. Given the relatively short coupling interval of atrial ectopic beats, the P wave is often obscured by the larger amplitude QRS-T wave complex. A method to uncover such "buried" P waves using a standard 12-lead surface ECG would be clinically useful and could potentially be a noninvasive guide to catheter ablation of focal atrial tachycardia. METHODS: We developed an automated computerized program (BARD DUO LAB SYSTEM trade mark ) designed to subtract the QRS-T wave complex from the surface electrogram and uncover a previously obscured P wave. The purpose of the present study was to validate this program. The surface ECG from 21 patients undergoing atrial pacing during electrophysiologic study (group I) and 10 patients with atrial tachycardia (group II) were analyzed and the derived P-wave morphology assessed using correlation waveform analysis (CWA) and visual grading by three reviewers. RESULTS: The algorithm successfully uncovered the P wave in each surface ECG. For the 21 patients in group I, average CWA comparing the derived P wave with the previous paced P wave was 83%. Average CWA for group II was 82%. Visual grading of the match between derived P waves and paced P waves revealed a 21/21 match in group I patients and a 12/12 match in 9/10 of group II patients. CONCLUSIONS: An ectopic atrial P wave obscured by a coincident QRS-T wave complex can be accurately uncovered using this new algorithm. Addition of this technique to existing methods may improve the diagnosis of atrial arrhythmias and aid in the localization and ablation of ectopic atrial foci.