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P Claude

Publications and source records attributed to P Claude.

27 records · Page 2Linked to original sources
PubMed1982

Binding, internalization, and retrograde transport of 125I-nerve growth factor in cultured rat sympathetic neurons.

Sympathetic neurons internalize nerve growth factor (NGF) and transport it retrogradely to their cell bodies where it appears to serve a trophic function in maintaining neuronal survival. We have characterized the binding, internalization, and retrograde transport of 125I-NGF by cultured rat sympathetic neurons. After 3 to 4 weeks in culture, sympathetic neurons possessed approximately 2 X 10(7) specific, cell surface NGF binding sites per neuron with an apparent affinity constant of 2 to 5 X 10(9) M. The density of binding sites on the plasma membrane of the neurites approximately twice that on the plasma membrane of the cell bodies. Because of the extensive network of neuronal processes, the neurites probably account for more than 99.5% of the total binding in mature cultures. Using electron microscope autoradiography, we localized the distribution of 125I-NGF in the cell body following a 1-hr exposure to 125I-NGF. The majority of silver grains were associated with lysosomal organelles, including secondary lysosomes, residual bodies, and multivesicular bodies (MVB). The MVB were the most heavily labeled, with a labeling density (L.D.) of 21, while the lysosomes had a L.D. of 3.1. To study the retrograde transport of 125I-NGF, neurons were grown in compartmentalized culture dishes and their distal processes were exposed to 125I-NGF. Radioactive material was transported to the cell bodies at the rate of approximately 3 mm/hr. The transport mechanism was sensitive to colchicine and was saturable with respect to NGF. After 8 hr of transport, when the radioactivity in the cell bodies had reached a steady state, the label again was localized primarily to the MVB (L.D. = 16.8) and the lysosomes (L.D. = 3.8). The nuclei were not labeled significantly and had an overall L.D. of 0.47. We saw no evidence for the accumulation of NGF by the nuclear membrane, the nucleolus, or chromatin.

Animals↗
PubMed1981

Regulation of pituitary growth and prolactin gene expression by estrogen.

We presented evidence that primary cultures of rat pituitary cells respond to estradiol by increased incorporation of precursors into prolactin. The response is specific for estrogenic hormones and is maximal at physiological concentrations of estradiol. The time course and magnitude of the response in cultured cells is in agreement with that observed under in vivo conditions, suggesting that estrogen exerts its effect mainly through a direct action on the pituitary gland. The data presented indicate that estrogen stimulates prolactin synthesis predominantly through increased prolactin mRNA accumulation, and to a lesser extent, through mammotroph cell proliferation. Chronic treatment with DES caused sustained proliferation of pituitary cells leading to prolactin producing pituitary tumors in the Fischer 344 rat, but not in the Holtzman rat. The genetic basis for these differences are currently under investigation.

Animals↗
PubMed1978

Morphological factors influencing transepithelial permeability: a model for the resistance of the zonula occludens.

Epithelial cells are joined at their apical surfaces by zonulae occludentes. Claude and Goodenough (1973) demonstrated a correlation between the structure of the zonula occludens as seen in freeze-fracture preparations and the passive electrical permeability of several simple epithelia. In epithelia with high transepithelial resistance, the zonula occludens consisted of many strands. In epithelia with low transepithelial resistance the zonula occludens was much reduced, sometimes consisting of only one strand. Evidence is reviewed here that indicates that in a number of simple epithelia the structure of the zonula occludens is largely responsible for the magnitude of transepithelial conductance. An equation is derived relating transepithelial junctional resistance to the number of junctional strands: R = RminP-N where R is the transepithelial resistance of the zonula occludens, Rmin is the minimum resistance of the junction (as when there are no strands in the zonula occludens), p is the probability a given strand is "open" and n is the number of strands in the junction. Using published experimental values of R and n for different epithelia, the calculated value of p was found to be as high as 0.4, which suggests that the strands in the zonula occludens are remarkably labile. Other morphological parameters relevant to transepithelial permeability are also considered, such as the width and depth of the intercelllar spaces, and the size of the epithelial cells themselves.

Cell Membrane Permeability↗
PubMed1974

Evidence for cholinergic synapses between dissociated rat sympathetic neurons in cell culture.

Sympathetic principal neurons were dissociated from superior cervical ganglia of new-born rats, and grown in cell culture. In electrophysiological experiments two types of excitatory synapses were found. One, which was relatively rare, was shown to operate by electrical transmission. The other, the predominant type, had several characteristics of chemical transmission, and pharmacological evidence indicated it was cholinergic.

Acetylcholine↗
PubMed1973

Fracture faces of zonulae occludentes from "tight" and "leaky" epithelia.

Epithelia vary with respect to transepithelial permeability. In those that are considered "leaky", a large fraction of the passive transepithelial flux appears to follow the paracellular route, passing across the zonulae occludentes and moving down the intercellular clefts. In "tight" epithelia, the resistance of the paracellular pathway to passive flux is greatly increased. To see whether differences in the morphology of the zonula occludens could contribute to this variability in leakiness among epithelia, replicas of zonulae occludentes in freeze-fractured material from a variety of tight and leaky epithelia were examined. The junctions appear as a branching and anastomosing network of strands or grooves on the A and B membrane fracture faces, respectively. It was found that the zonula occludens from a "very leaky" epithelium, the proximal convoluted tubule of the mouse kidney, is extremely shallow in the apical-basal direction, consisting in most places of only one junctional strand. In contrast, the "very tight" frog urinary bladder exhibits a zonula occludens that is relatively deep (>0.5 microm) in the apical-basal direction, and consists of five or more interconnected junctional strands interposed between luminal and lateral membrane surfaces. Epithelia of intermediate permeabilities exhibited junctions with intermediate or variable morphology. Toad urinary bladder, mouse stomach, jejunum, and distal tubule, rabbit gallbladder, and Necturus kidney and gallbladder were also examined, and the morphological data from these epithelia were compared to physiological data from the literature.

Animals↗
PubMedDate not supplied

Nerve growth factor is a mitogen for cultured chromaffin cells.

Nerve growth factor (NGF) is essential for the survival and differentiation of a number of neural crest derivatives, including sympathetic and sensory neurones. While early studies suggested that NGF might also have a mitogenic effect on these neurones, subsequent work has favoured the interpretation that NGF promotes cell survival or differentiation rather than proliferation. We have addressed the issue of a mitogenic effect of NGF using adrenal chromaffin cells, which are endocrine cells derived from the neural crest, and are closely related to sympathetic neurones. Adrenal chromaffin cells respond to NGF in vitro by expressing neuronal traits. We now report that NGF elicits a mitotic response in cultured chromaffin cells from young rats, and that this response is blocked by an antiserum to 2.5S NGF. The chromaffin cells that divided in response to NGF can subsequently become neuronal in the continued presence of NGF.

Animals↗