Fluorescence microscopy imaging is an important technique for studying lipid membranes and is increasingly being used for examining lipid bilayer membranes, especially those showing macroscopic coexisting domains. Lipid phase coexistence is a phenomenon of potential biological significance. The identification of lipid membrane heterogeneity by fluorescence microscopy relies on membrane markers with well-defined partitioning behavior. While the partitioning of fluorophores between gel and liquid-disordered phases has been extensively characterized, the same is not true for coexisting liquid phases. We have used fluorescence microscopy imaging to examine a large variety of lipid membrane markers for their liquid phase partitioning in membranes with various lipid compositions. Most fluorescent lipid analogs are found to partition strongly into the liquid-disordered (L(d)) phase. In contrast, some fluorescent polycyclic aromatic hydrocarbons with a flat ring system were found to partition equally, but others partition preferentially into liquid-ordered (L(o)) phases. We have found these fluorescent markers effective for identification of coexisting macroscopic membrane phases in ternary lipid systems composed of phospholipids and cholesterol.

No abstract

No abstract

The National Health Service is heavily dependent on overseas workers at all levels. Some 33 per cent of all doctors and 20 per cent of student nurses now working in Britain were born overseas. The traditional justification for this situation is that it constitutes a form of British 'aid' to the third world, training health workers who then go back to their own countries. However a closer examination reveals that in reality these workers provide a crucial source of cheap labour and their utilisation has always been an important component both in keeping down costs and in rationalising the labour process in health care. Moreover, many do not return home and for those who do, the training they have received in Britain may well have very little relevance to the health needs of their own countries. Against the background of the epidemic of national chauvinism being fostered by the Conservative government, this article examines the vital role played by overseas workers in sustaining a major social service. We wish to acknowledge the important role of Frances Gee and Imogen Pennell in producing the material on which much of this article is based.

No abstract