Copper-based LECs with a maximum efficacy of 3.0 cd A−1 (luminance = 145 cd m−2) or with lifetimes >80 h have been achieved.

Atrial arrhythmias, and specifically atrial fibrillation (AF), induce rapid and irregular activation patterns that appear on the torso surface as abnormal P-waves in electrocardiograms and body surface potential maps (BSPM). In recent years both P-waves and the BSPM have been used to identify the mechanisms underlying AF, such as localizing ectopic foci or high-frequency rotors. However, the relationship between the activation of the different areas of the atria and the characteristics of the BSPM and P-wave signals are still far from being completely understood. In this work we developed a multi-scale framework, which combines a highly-detailed 3D atrial model and a torso model to study the relationship between atrial activation and surface signals in sinus rhythm. Using this multi scale model, it was revealed that the best places for recording P-waves are the frontal upper right and the frontal and rear left quadrants of the torso. Our results also suggest that only nine regions (of the twenty-one structures in which the atrial surface was divided) make a significant contribution to the BSPM and determine the main P-wave characteristics.

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BackgroundHeart failure is operationally defined as the inability of the heart to maintain blood flow to meet the needs of the body and it is the final common pathway of various cardiac pathologies. Electrophysiological remodeling, intercellular uncoupling and a pro-fibrotic response have been identified as major arrhythmogenic factors in heart failure.ObjectiveIn this study we investigate vulnerability to reentry under heart failure conditions by incorporating established electrophysiological and anatomical remodeling using computer simulations.MethodsThe electrical activity of human transmural ventricular tissue (5 cm×5 cm) was simulated using the human ventricular action potential model Grandi et al. under control and heart failure conditions. The MacCannell et al. model was used to model fibroblast electrical activity, and their electrotonic interactions with myocytes. Selected degrees of diffuse fibrosis and variations in intercellular coupling were considered and the vulnerable window (VW) for reentry was evaluated following cross-field stimulation.ResultsNo reentry was observed in normal conditions or in the presence of HF ionic remodeling. However, defined amount of fibrosis and/or cellular uncoupling were sufficient to elicit reentrant activity. Under conditions where reentry was generated, HF electrophysiological remodeling did not alter the width of the VW. However, intermediate fibrosis and cellular uncoupling significantly widened the VW. In addition, biphasic behavior was observed, as very high fibrotic content or very low tissue conductivity hampered the development of reentry. Detailed phase analysis of reentry dynamics revealed an increase of phase singularities with progressive fibrotic components.ConclusionStructural remodeling is a key factor in the genesis of vulnerability to reentry. A range of intermediate levels of fibrosis and intercellular uncoupling can combine to favor reentrant activity.

The rapid increase in CIPNS E. coli causing bacteraemia was closely related to the increase in resistance to amoxicillin/clavulanic acid, production of ESBLs and resistance to aminoglycosides. Community use of fluoroquinolones (mainly moxifloxacin and levofloxacin) and of amoxicillin/clavulanic acid represents a significant driver in the progression of fluoroquinolone resistance in bacteraemic E. coli.

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Two hundred fifty isolates of Mycobacterium tuberculosis were evaluated for susceptibility to ciprofloxacin, ofloxacin, levofloxacin, grepafloxacin, trovafloxacin, and gemifloxacin (SB-265805). Levofloxacin, ciprofloxacin, and grepafloxacin showed the greatest activity (MIC for 90% of strains tested [MIC 90 ] 1 g/ml), although ofloxacin also showed good activity, with an MIC 90 of 2 g/ml. Trovafloxacin and gemifloxacin showed lower in vitro activity, with MIC 90 s of 64 and 8 g/ml, respectively.The increase in drug-resistant Mycobacterium tuberculosis isolates during recent years presents a therapeutic challenge to physicians selecting antimicrobial agents (2,3,4,10,12). Fluoroquinolones may have a useful role in the treatment of these infections not only because some of their derivatives, e.g., ofloxacin (11), have already been used for the treatment of pulmonary tuberculosis but also because newer derivatives are continually being developed. However, comparative in vitro susceptibility data for classic and new agents of this class against a representative number of M. tuberculosis isolates are scarce (5,13,14).In our study, we compared the activities of the fluoroquinolones ciprofloxacin, ofloxacin, levofloxacin, grepafloxacin, trovafloxacin, and the novel compound gemifloxacin (SB-265805) against 250 clinical isolates of M. tuberculosis with different levels of susceptibility to first-line antituberculosis drugs.(Part of this study was presented as a poster at the 39th Interscience Conference on Antimicrobial Agents and Chemotherapy, 1999.) The active substances of the assayed antimycobacterial agents were kindly provided as reference powders by SmithKline Beecham (Worthing, United Kingdom). Ofloxacin was obtained from Sigma Chemical Co. (St. Louis, Mo.). Agent corrections were made for purity of antimicrobials. Stock solutions of all of the fluoroquinolones were prepared at 10,000 g/ml in distilled water by adding a 0.1 M NaOH solution for dilution when necessary. Aliquots of the antituberculosis agents were frozen at Ϫ70°C until use. Staphylococcus aureus strain ATCC 29213 was used for quality control to ensure the potency of the fluoroquinolones tested.Two hundred fifty clinical isolates of M. tuberculosis from 250 tuberculosis patients were selected from our laboratory collection (1988 to 1999). Of the samples tested, 197 were of respiratory origin and 53 were of nonrespiratory origin. Testing of susceptibility to first-line antituberculosis drugs (isoniazid, rifampin, ethambutol, and streptomycin) was performed by the agar proportion method in a reference laboratory. Of the strains tested, 44 (18%) were resistant to at least one first-line antituberculosis drug (R-MTB group; 24 monodrug-resistant and 20 multidrug-resistant strains) while the rest were fully susceptible (S-MTB group). The agar proportion method was performed as recommended by the National Committee for Clinical Laboratory Standards (9). Briefly, 7H10 agar medium (Difco) was prepared from a dehydrated base as recommended by the manufact...

A versatile remotely controlled fast reciprocating Langmuir probe has been developed for the TJ-II stellarator. The main components of the system are a removable head, containing the measurement tips, and a displacement system that enables the probe to be displaced in vacuum. The probe displacement system has two different components: a slow one ͑course lengthр0.8 m͒ to set the probe at the initial measurement position, and a fast one ͑run lengthϭ0.1 m͒ to obtain the desired measurements within an adjustable time interval during the plasma discharge. The radial movement of the probe is controlled remotely by means of a programmable logical control system, with a radial resolution of better than 1 mm. The fast displacement of the probe ͑up to 1.7 m/s͒ is achieved by using a pneumatic system. Its position as a function of time is monitored by means of the on-line response of a linear resistor attached to the fast displacement system.