A new method for the preparation of liposomes is described that avoids the use of pharmaceutically unacceptable solvents and energy-expensive procedures such as sonication. The method is based on the initial formation of a proliposome mixture containing lipid, ethanol and water, which is converted to lipsomes by a simple dilution step. Measurements using 6-carboxyfluorescein as a marker indicate that water-soluble drugs can be trapped with extremely high efficiency (65-80% depending on lipid composition). The structural organization of the proliposome mixture and the final liposomes were characterized using electron microscopy and 31P-NMR.

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An extensive assessment was made of nine common similarity measures on the basis of their discriminative ability and bias in weighting of different types of variation in species abundance between samples, by using sets of river macroinvertebrate samples. Seven agglomerative hierarchical clustering methods were applied to these measures. Successful site discrimination is defined as grouping of all replicate samples from a particular site. Major differences existed in the discriminative ability between the similarity measures. The measures overweight some types of variation and underweight the others to varying extents, which is closely related to their discriminative ability. A new dissimilarity-similarity measure was devised to respond to all types of variation with minimum bias. This measure yielded a higher percentage of correct site discrimination than the others tested. Use of an extra data set confirmed the superior performance of the new measure and also indicated that it could discriminate between sites of different water quality. Water Environ. Res., 69, 95 (1997).

The responses of macroinvertebrate communities to pollution by sewage effluent in the River Trent system (UK) were investigated using a variety of multivariate approaches, biotic indices and diversity indices. It was found that multivariate analyses clearly illuminated the change of community structure along the pollution gradient. CY Dissimilarity Measure (CYD)-based Non-Metric Multidimensional Scaling (NMDS) appeared to perform better than DCA and clustering. Species richness, the BMWP, BMWP-ASPT, the Chandler Score, Chandler-ASPT could detect the effects of major pollution. However, these indices showed varying sensitivity to different ranges of pollution, for example, Chandler-ASPT and BMWP-ASPT are more sensitive to the change in clean/slightly polluted range than in the moderate/very polluted range. The diversity indices were the least informative. The advantages and disadvantages of the various approaches were discussed.

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