The molecular cues regulating the migratory process of LHRH neurons from the olfactory placode into the brain are not well known, but gradients of chemotropic and chemorepellent factors secreted by the targets are likely to play a key role in guidance mechanisms. Hepatocyte growth factor/scatter factor (HGF/SF) is a pleiotropic cytokine inducing cell migration. It is involved in a variety of developmental processes through interaction with its receptor c-Met. Here we show that c-Met-antibody labels LHRH migrating neurons in the olfactory mesenchyme of E12 mouse and analyze the potential chemotropic effect of HGF/SF on two immortalized LHRH cell lines, GT1-7 and GN11, isolated from tumors developed in the hypothalamus and in the olfactory bulb, respectively. By RT-PCR analysis, Western blotting, and immunocytochemistry, we provide evidence for a high level of c-Met expression in GN11, but not in GT1-7, cells. In addition, HGF/SF treatment promotes specific migratory activity of GN11 cells, as demonstrated by collagen gel assay, time-lapse video microscopy, and Boyden's chamber experiments. Such promotion is inhibited by the neutralizing antibody. The data reported here represent the first direct evidence of a chemotactic effect of HGF/SF on immortalized LHRH neurons.
Two young brothers were bilaterally affected by pigmentary glaucoma and extensive symmetrical changes of the retinal pigment epithelium (RPE). Fundus changes consisted in widespread salt-and-pepper RPE mottling and pigment clumping, sparing only the peripapillary and foveal areas. During the course of 4 years, one of the two patients suffered multiple, recurrent, exudative and hemorrhagic detachments of the RPE that involved the midperiphery and posterior pole. No exudative lesions appeared in the brother. The medical history and systemic laboratory tests were noncontributory in both patients. The ERG was normal and the EOG subnormal. Dark adaptation was delayed and showed an elevation of the scotopic threshold. These cases seem to support the hypothesis that the RPE is also involved in the pigmentary dispersion syndrome. An inherited defect could affect the pigment epithelium in both the anterior and posterior segments of the eye. The multifocal subretinal exudative pattern that occurred in one of our patients has not been previously observed in hereditary disorders of the RPE.
Dermal electrodes allowed the recording of retinal oscillatory potentials with similar shape and timing as tracings obtained with conventional corneal electrodes. Normative data is presented. We concluded that dermal electrodes were a reproducible and more comfortable method of testing.
The human gamma oscillatory response mediating in cortical visual information processing further proved independent of the VEPs. It can contribute to VEP waveform distortion, and its observation in substitution of VEPs should be regarded as an indication of impaired visual pathway function.
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