Use of Intracardiac Echocardiography in Interventional Electrophysiology

Intracardiac echocardiography is emerging as a potentially useful tool during RF ablation procedures. There are a number of potential benefits of direct endocardial visualization during RF ablation including: (1) precise anatomical localization of the ablation catheter tip in relation to important endocardial structures, which cannot be visualized with fluoroscopy; (2) reduction in fluoroscopy time; (3) evaluation of catheter tip tissue contact; (4) confirmation of lesion formation and identification of lesion size and continuity; (5) immediate identification of complications; and (6) as a research tool to help in understanding the critical role played by specific endocardial structures in arrhythmogenesis. This article will review existing data and speculate as to possible future roles for intracardiac echocardiography in interventional electrophysiology.     

THE EFFECT OF GLYCEROL ON THE PERCUTANEOUS ABSORPTION OF METHYL NICOTINATE

Summary.— The effect of glycerol on the rate of percutaneous absorption of methyl nicotinate from aqueous vehicles was investigated. The partition coefficients of methyl nicotinate between isopropyl myristate and aqueous solutions of glycerol were determined. The diffusivity of methyl nicotinate in various aqueous solutions of glycerol was also studied. It was shown that addition of glycerol in concentrations above 60% delayed the onset of erythema in human skin. The results suggest that this effect is related to the partition coefficient and diffusivity of methyl nicotinate in the aqueous vehicle. The osmotic effects of glycerol are negligible.     

Exposure to passive smoking among bar staff

The median saliva cotinine concentration in 42 non-smoking bar staff in central London and Birmingham was 7.95 ng/ml, indicating a nicotine intake of about 0.6 mg per day. Pubs appear to give rise to exceptionally heavy exposure to environmental tobacco smoke. Passive smoking in pubs is of concern for its impact both on customers and on those for whom the pub is a place of work.     

Modelling the macrophage invasion of tumours: Effects on growth and composition

E-mail: owen{at}maths.warwick.ac.uk E-mail: jas{at}maths.warwick.ac.uk Even in the early stages of their development, tumours are notsimply a homogeneous grouping of mutant cells; rather, theydevelop in tandem with normal tissue cells, and also recruitother cell types including lymphatic cells and the endothelialcells required for the development of a blood supply. It hasbeen repeatedly seen that macrophages form a significant proportionof the tumour mass, and that they can have a variety of effectsupon the tumour, leading to a delicate balance between growthpromotion and inhibition. This paper develops a model for theearly, avascular growth of a tumour, concentrating on the inhibitoryeffect of macrophages due to their cytolytic activity. It isshown that such an immune response is not sufficient to preventgrowth, due to it being a second-order process with respectto the density of the tumour cells present However, the presenceof macrophages does have important effects on the tumour composition,and the authors perform a detailed bifurcation analysis of theirmodel to clarify this. An extended model is also consideredwhich incorporates addition of exogenous chemical regulators.In this case, the model admits the possibility of tumour regression,and the therapeutic implications of this are discussed.     

Effects of Smoking and Smoking Deprivation on the Articulatory Loop of Working Memory

This study examined the effects of smoking and smoking deprivation on the articulatory loop of working memory. Forty subjects (20 smokers and 20 non-smokers) performed tasks involving serial recall of letters on two occasions 1 week apart. In each test one part was conducted with articulatory suppression and the other without it. The smokers completed one test following 12 h of smoking deprivation, and the other after smoking a cigarette. The order of suppression/non-suppression conditions and the order of smoking and smoking deprivation were balanced across subjects. The results showed that deprived smokers performed significantly worse than both smoking smokers and non-smokers in the task without suppression. Although all the subjects performed significantly worse whilst under articulatory suppression, smoking status was not found to influence performance here. These results imply that smoking has the effect of returning the smoker to a comparable level of performance to that seen in non-smokers, and suggest that smoking abstinence has a negative effect when performance involves the articulatory loop. © 1997 John Wiley & Sons, Ltd.