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4282. Postsympathectomy pain and changes in sensory neuropeptides: towards an animal model.
Postsympathectomy limb pain, postsympathectomy parotid pain, and Raeder's paratrigeminal syndrome are pain states associated with the loss of sympathetic fibres and in particular with postganglionic sympathetic lesions. There is a characteristic interval of about 10 days between surgical sympathectomy and onset of pain. It is proposed that this pain in man is correlated with the delayed rise in sensory neuropeptides seen in rodents after sympathectomy. These chemical changes probably reflect the sprouting of sensory fibres and may result from the greater availability of nerve growth factor after sympathectomy. The balance between the sensory and sympathetic innervations of a peripheral organ may be determined by competition for a limited supply of nerve growth factor.
4286. Towards an aetiological classification of schizophrenia.
The genetic contribution to schizophrenia is widely accepted, yet none of the proposed models of transmission has been convincing. Schizophrenia is generally viewed as aetiologically homogeneous with the exception of supposedly rare "phenocopies" associated with organic brain lesions and without a family history. However, up to one-third of schizophrenics have enlarged cerebral ventricles, and this appears to be a consequence of environmental damage. Although the aetiology of schizophrenia comprises genetic and environmental components acting in variable proportions, a simple division into familial and sporadic cases would facilitate research. Families with several ill members will be most valuable for molecular genetic studies, while the new brain imaging techniques should be particularly directed towards sporadic cases.
4295. Outcome for infants of very low birthweight: survey of world literature.
Reports from developed countries world wide describing the outcome for infants of very low birthweight (VLBW, less than or equal to 1500 g) born since 1946 show that, in general, mortality rates and the prevalence of major handicap in survivors were high until 1960. Since then the chances of healthy survival have trebled, whereas the handicap-rate has remained stable and relatively low at 6--8% of VLBW live births.
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