Biomedical subjects

R Heumann

Publications and source records attributed to R Heumann.

75 records · Page 5Linked to original sources

PubMed1975

Intracisternal A and C particles in mouse neurons: a thin-section study of normal trigeminal ganglion and C1300 neuroblastoma.

Trigerminal ganglia of 4 adult albino mice of the NMRI outbred stock were examined by electron microscopy. In all animals, about 10% of the neurons contained intracisternal A particles. Isolated structures resembling intracisternal A particles could be detected in atleast 50% of the nerve cells and in a few Schwann cells. Budding at the cell surface and/or extracellular type-C particles were not observed. An intracerebrally transplanted mouse C1300 neuroblastoma was likewise studied. Most tumor cells exhibited large numbers of intracisternal A particles having the same ultrastructure as the particles in trigeminal neurons. In addition, budding and extracellular type-C particles were occasionally observed.

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PubMedDate not supplied

Timing and site of nerve growth factor synthesis in developing skin in relation to innervation and expression of the receptor.

We show that nerve growth factor (NGF) synthesis in developing skin begins with sensory innervation and that sensory neurons do not express NGF receptors until their fibres reach their cutaneous targets. Both cutaneous epithelium and mesenchyme synthesize NGF, the concentration of messenger RNA for NGF being higher in the more densely innervated epithelium.

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PubMedDate not supplied

Interleukin-1 regulates synthesis of nerve growth factor in non-neuronal cells of rat sciatic nerve.

The Schwann cells and fibroblast-like cells of the intact sciatic nerve of adult rats synthesize very little nerve growth factor (NGF). After lesion, however, there is a dramatic increase in the amounts of both NGF-mRNA and NGF protein synthesized by the sciatic non-neuronal cells. This local increase in NGF synthesis partially replaces the interrupted NGF supply from the periphery to the NGF-responsive sensory and sympathetic neurons, whose axons run within the sciatic nerve. Macrophages, known to invade the site of nerve lesion during wallerian degeneration, are important in the regulation of NGF synthesis. Here we demonstrate that the effect of macrophages on NGF-mRNA levels in cultured explants of sciatic nerve can be mimicked by conditioned media of activated macrophages, and that interleukin-1 is the responsible agent.

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