Competition as a means of procuring public services. Lessons for the UK from the US experience.

Competition is now widely used as the means of choosing the providers of essential public services in the USA and the UK. Many different approaches are found in the USA and there are useful lessons for the UK. With particular reference to mental health and substance abuse services, describes the effects of using competitive tendering on users, providers, purchasers and citizens and examines the problems of specification, transaction costs, the use of consultants, supply, the level playing field, trust, innovation, local accessibility and accountability. Ends with discussion of co-operation and collaboration and the emergence of monopolies and integrated delivery systems in the USA and concludes by finding politics and political decision making of overriding importance.

The mechanisms of action of antiprotozoal and anthelmintic drugs in man.

The mechanisms of action of antiprotozoal and anthelmintic drugs are reviewed according to: (1) drugs interfering with metabolic processes; (2) drugs interfering with reproduction and larval physiology; and (3) drugs interfering with neuromuscular physiology of parasites.

Parasitological serendipity: from Schistocephalus to Echinococcus.

Attention is drawn to the situation nowadays, whereby workers are encouraged to undertake research which appears useful or of economic importance, although the History of Science indicates that many major discoveries have been the result of 'serendipity'--'the chance observation falling on the receptive eye'. Some of the more important examples in Medicine and Parasitology are reviewed. The author then relates how he was given a stickleback infected with the plerocercoid of Schistocephalus solidus, an episode which eventually led to the successful in vitro culture of the adult of this species. Attention is also drawn to the largely unrecognized work of the Danish Veterinarian, P. C. Abildgaard, who in 1789 demonstrated that this species completed its life cycle in a bird, thus establishing, for the first time, the transmission of a parasite from one host to another. The in vitro culture of S. solidus led to the development of successful in vitro techniques for Ligula intestinalis and for Echinococcus granulosus and E. multilocularis. The observation that E. granulosus of horse origin failed to grow in vitro led eventually to the concept of physiological 'strains' of E. granulosus, now a subject of much international research.

Hydatidosis: changing concepts in epidemiology and speciation.

Hydatidosis, caused by dog tapeworms of the genus Echinococcus, is one of the most important cestode infections of man. It is widely distributed and recent information points to a spread of the disease into areas previously free of it. This article reviews recent advances in understanding the biology of Echinococcus, relating these developments to the epidemiology of hydatid disease and its control.

Intermediary carbohydrate metabolism in protoscoleces of Echinococcus granulosus (horse and sheep strains) and E. multilocularis.

With few exceptions, the specific activities of the glycolytic enzymes and the steady-state content of glycolytic and associated intermediates in protoscoleces of the horse (E.g.H) and sheep (E.g.S) strains of Echinococcus granulosus and the closely related E. multilocularis (E.m.) are very similar. Phosphorylase, hexokinase, phosphofructokinase and pyruvate kinase catalyse non-equilibrium reactions and the patterns of activity for pyruvate kinase, phosphoenolypyruvate carboxykinase and malic enzyme are similar in the three organisms. The levels of tricarboxylic acid cycle intermediates in E.g.H., E.g.S. and E.m. are of the same order as those reported in tissues with an active cycle. Each has a complete sequence of cycle enzymes but there are substantial differences between the three parasites with regard to the activity of individual enzymes. The activities of NAD and NADP-linked isocitrate dehydrogenases are significantly lower in E.g.H. than in E.g.S. and particularly in E.m. which suggests that the tricarboxylic acid cycle may play a more important role in carbohydrate metabolism and energy production in the latter parasites. Nevertheless, the three organisms utilize fermentative pathways for alternative energy production, fix carbon dioxide via phosphoenolpyruvate carboxykinase and have a partial reversed tricarboxylic acid cycle. It is speculated that in vivo more carbon will be channelled towards oxaloacetate than pyruvate at the phosphonenolpyruvate branch point. The steady state content of ATP and the ATP/AMP ratios are low in the three organisms, suggesting a low rate of ATP utilization in each.

Experience with mebendazole in the treatment of inoperable hydatid disease in England.

Eleven heterogeneous patients with inoperable hydatid disease were treated with high doses of oral mebendazole, up to 200 mg/kg/day for 16 to 48 weeks. Toxicity was not encountered. Despite careful assessment it proved difficult critically to evaluate the efficacy of mebendazole. In four patients chemotherapy appeared to have been at least partially successful and success seems to have correlated with serum levels in excess of 100 ng/ml one to three hours after dosage. The problems of assessment are discussed and the need for controlled trials of mebendazole in hydatid disease are stressed.

Procedures for testing the viability of human hydatid cysts following surgical removal, especially after chemotherapy.

The basic problems involved in assessing the viability of hydatid material following surgical removal from human cases are outlined and the use of enzyme digestion techniques is shown to provide a rapid and relatively simple diagnostic procedure. The method is described in detail and examples of its practicability are cited. Infection in laboratory animals provides a back-up diagnostic procedure but cyst development in them is too slow to be of value for most clinical work.

Echinococcus granulosus and E. multilocularis: in vitro culture of the strobilar stages from protoscoleces.

The techniques for the in vitro culture of Echinococcus granulosus and E. multilocularis are described in detail. The sheep strain of E. granulosus was grown to sexual maturity but fertile eggs were not produced due to the failure to achieve insemination in vitro. The horse strain of E. granulosus grew only slightly in vitro and then ceases to develop, although remaining active for long periods. E. multiloculoris differentiated largely into unsegmented, sexually mature, "monozoic" forms; some organisms developed "pseudo-proglottids" with the interproglottid membrane absent or poorly formed. After prolonged culture, some strobila of E. multilocularis developed an extra scolex.