Secretion of a potential virulence factor, a fungal ribonucleotoxin, during human aspergillosis infections

We show by cloning and nucleotide sequence analysis that the 18kDa antigen found in the urine of patients suffering from aspergillosis is related to the fungal protein toxins restrictocin and mitogillin. These are inhibitors of translation which act by catalytic inactivation of eukaryotic ribosomes; they may be implicated in the pathogenesis of the disease.     

Segmentation and the development of the vertebrate nervous system

1. Recent experiments on the development of neural segmentation in chick embryos are reviewed. 2. Segmentation of the spinal peripheral nerves is governed by a subdivision of the somite-derived sclerotome into anterior and posterior halves. Migrating neural crest cells and outgrowing motor axons are confined to the anterior sclerotome as a result, in part, of inhibitory interactions with posterior sclerotome cells. 3. The sclerotomal distribution of certain molecules known to influence growing nerve cells in vitro, namely laminin, fibronectin, N-CAM, N-Cadherin and J1/tenascin/cytotactin, suggest that these molecules play no critical role in determining the preference of nerve cells for anterior sclerotome. 4. Peanut agglutinin (PNA) recognises cell surface-associated components on posterior cells which, when incorporated into liposomes, cause the abrupt collapse of sensory growth cones in vitro. The PNA receptor(s) may be inhibitory for nerve cells in vivo. 5. The chick hindbrain epithelium is segmented early in its development. Each branchiomotor nucleus in the series of cranial nerves V, VII and IX derives from a pair of segments lying in register with an adjacent branchial arch. Neurogenesis of motor and reticular axons begins in alternate segments, suggesting parallels with insect pattern formation.     

Rabies control and management.

Since the 1950s rabies has become a familiar threat in southern Canada. Periodic outbreaks remind us how slight our control over it is. Although new vaccines such as human diploid-cell rabies vaccine have greatly improved the management of rabies in humans, true control must be sought through knowledge of the disease in or wildlife. A guide to rabies prophylaxis in humans is presented, courtesy of the National Advisory Committee on Immunization.