Hedgehog (Hh) signal transduction is directly required in zebrafish DRG precursors for proper development of DRG neurons. Zebrafish mutations in the Hh signaling pathway result in the absence of DRG neurons and the loss of expression of neurogenin1 (ngn1), a gene required for determination of DRG precursors. Cell transplantation experiments demonstrate that Hh acts directly on DRG neuron precur...

Precursors and near misses are well known for providing a major source of useful information for safety risk management. They are more frequent events than accidents and their causes may potentially result in an accident under slightly different circumstances. Despite the importance of this type of feedback, there is little knowledge on the characteristics of precursors and near misses, and on ...

Monoclonal antibodies were used to examine the immunoglobulin isotypes expressed by B lymphocyte precursors of IgM, IgG, IgA, and IgA2 plasma cells. Plasma-cell differentiation was induced by the addition of pokeweed mitogen to cultures of blood mononuclear cells. Anti-mu, -gamma, -alpha, and -alpha 1 antibodies were used in some experiments to inhibit differentiation of B lymphocytes bearing t...

Although it is usually assumed that all those who commit suicide give some prior indication of their intention to take their own life, there is growing evidence that a small but significant proportion of suicides occur without clear, explicit indicators. It is proposed that these suicides emerge from similar pathways to other suicides but the despair is not expressed so clearly, often being kep...