Biomedical subjects
Publications and source records attributed to R Dawkins.
The presence of autoantibodies to Extractable Nuclear Antigens (ENA) in myasthenia gravis (MG) was evaluated. These antibodies represent a subset of antinuclear antibodies (ANA), with ENA consisting of RNA and nucleoprotein. ENA autoantibodies had a prevalence of 44% in MG when tested by an
An enzyme linked immunosorbent assay (ELISA) has been developed to detect antinuclear antibodies to extractable nuclear antigens (ENA)--a rabbit thymus nuclear derivative. A second ELISA has also been developed (ENA RNA-ase ELISA) to analyse the relative contribution of the components of ENA (nucleoprotein and RNA antigens) to antibody binding as detected by the ELISA assays. Both ELISA assays provide a rapid screening method for antibodies to soluble, diffusable nuclear antigens that could otherwise go undetected by immunodiffusion or the indirect immunofluorescent method that uses unfixed frozen sections of rat liver. The considerable improvement that these ELISA assays offer in efficiency and both diagnostic and serological sensitivity over the traditional immunodiffusion method used for specificity characterisation of ENA autoantibodies is discussed.
Horner's syndrome is a recognized complication of head and neck wounds. However, the case described of an air-rifle wound is most unusual in that a traumatic unilateral sympathectomy was the only lesion that resulted from the incident. Although a rare occurrence, the surgeon should be a ware of the possibility of this complication when dealing with injuries in this area. The eventual total recovery of the nerve in the young patient would seem to indicate that the original lesion was due to localized bruising rather than direct trauma.
In recent years a considerable body of evidence has accumulated to demonstrate autoimmune mechanisms in myasthenia gravis. This evidence has important implications for the aetiology, diagnosis and management of the disease. The primary abnormality in myasthenia gravis is related to the presence of antibody which reacts with the acetylcholine receptor. Measurement of this IgG antibody in the serum has become the most reliable diagnostic adjunct to the edrophonium test, and in an individual patient, the level of the serum antibody relates closely to the clinical indices. In cases of myasthenia where control with anticholinesterase drugs is unsatisfactory, methods to lower the antiacetylcholine receptor antibody are indicated: these may include thymectomy, immunosuppressive therapy of plasmapheresis. Two patients with very severe disease are described in whom all types of therapy were used and in whom survival depended ultimately on the use of plasmapheresis. These patients illustrate the importance of receptor antibody in the clinical manifestations of myasthenia gravis and in its management.
An adaptation in one lineage (e.g. predators) may change the selection pressure on another lineage (e.g. prey), giving rise to a counter-adaptation. If this occurs reciprocally, an unstable runaway escalation or 'arms race' may result. We discuss various factors which might give one side an advantage in an arms race. For example, a lineage under strong selection may out-evolve a weakly selected one (' the life-dinner principle'). We then classify arms races in two independent ways. They may be symmetric or asymmetric, and they may be interspecific or intraspecific. Our example of an asymmetric interspecific arms race is that between brood parasites and their hosts. The arms race concept may help to reduce the mystery of why cuckoo hosts are so good at detecting cuckoo eggs, but so bad at detecting cuckoo nestlings. The evolutionary contest between queen and worker ants over relative parental investment is a good example of an intraspecific asymmetric arms race. Such cases raise special problems because the participants share the same gene pool. Interspecific symmetric arms races are unlikely to be important, because competitors tend to diverge rather than escalate competitive adaptations. Intraspecific symmetric arms races, exemplified by adaptations for male-male competition, may underlie Cope's Rule and even the extinction of lineages. Finally we consider ways in which arms races can end. One lineage may drive the other to extinction; one may reach an optimum, thereby preventing the other from doing so; a particularly interesting possibility, exemplified by flower-bee coevolution, is that both sides may reach a mutual local optimum; lastly, arms races may have no stable and but may cycle continuously. We do not wish necessarily to suggest that all, or even most, evolutionary change results from arms races, but we do suggest that the arms race concept may help to resolve three long-standing questions in evolutionary theory.
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Explore the source record for details and available documents.