Biomedical subjects

P Cau

Publications and source records attributed to P Cau.

48 records · Page 3Linked to original sources

PubMed1987

Early appearance of cells bearing Na+ channels in developing mouse brain. A quantitative analysis using light microscopic autoradiography.

125I-alpha-Scorpion toxin (alpha-ScTx) binds to a component of the voltage-sensitive Na+ channel. We have previously shown that receptor capacity on dissociated mouse brain cells increases between days 12 and 19 of fetal life as does the expression of neurotoxin-sensitive 22Na+ influx. In the present study we have investigated the distribution of Na+ channels at the cellular level. Quantitative analysis by light-microscopic autoradiography was carried out on dissociated brain cells labeled with 125I-alpha-ScTx at 13, 15 and 18 fetal days. We have shown that at day 13 a large population of cells (39% of total) is alpha-ScTx-labeled, providing direct confirmation for a wide-spread presence of Na+ channels at an early stage of mouse brain development. The subsequent increase in receptor number with age is due both to an increase in alpha-ScTx-labeled cells (to 53% and 97% at days 15 and 18, respectively) and to an increase in the receptor density on these cells (10.9, 12.7 and 34.5 silver grains/1000 microns2 of cell surface for the 3 stages studied).

Animals↗

PubMed1986

Early alterations at the plasma membrane of breast cancer cell lines in response to estradiol and hydroxytamoxifen.

The time course of the early stage of estradiol-17 beta (E2) and hydroxytamoxifen (OHTAM) action at the plasma membrane of hormone-responsive MCF-7 and non-responsive MDA-MB-231 (MDA) breast cancer cell lines was investigated using scanning electron microscopy (SEM), electron probe X-ray microanalysis and microelectrophysiology analysis. SEM showed a marked increase in the density and the length of microvilli (MV) on MCF-7 cells treated with 1 nM estradiol for 1 min. This membrane response disappeared at 5 min. No early effect was obtained with OHTAM, but both compounds produced a similar surge of heterogeneous MV at 15 min of treatment. The morphological change induced by E2 subsided at 60 min, whereas that of OHTAM persisted. X-ray microanalysis and computer determination of peak/background ratios permitted the demonstration that these morphological alterations were concomitant with a rise in the intracellular level of potassium. Microelectrophysiology analysis showed a sharp transitory decrease in the membrane potential of MCF-7 cells in response to estradiol. In the estrogen-insensitive MDA cells, the hormone did not modify the membrane potential and K levels decreased at 1 and 5 min before rising again to control levels at minute 15 when MV appeared. With OHTAM, potassium decreased significantly at 60 min of treatment. These initial and transitory changes in surface morphology paralleled by alterations in potassium level may be consistent with the occurrence of estrogen membrane receptors on target cells, a new aspect of steroid hormone action.

Breast Neoplasms↗

PubMed1985

Extracellular material secreted by human colonic adenocarcinoma cell lines promotes spreading in serum-free medium and induces neurite outgrowth of PC-12 cells.

A completely defined medium has been designed to promote cell proliferation of 2 colonic adenocarcinoma cell lines of epithelial origin (HT 29 and HRT 18). The spreading of both cell types, especially of HT 29 cells, was not possible in a serum-free medium supplemented with growth factors. Spreading was obtained in a defined medium (a 1/1 mixture of DMEM and F12 media supplemented with 5 micrograms/ml transferrin, 5 ng/ml EGF, 10 ng/ml selenite and 15 mM HEPES pH 7.3) with an extracellular matrix-like material (ECM) secreted by the cells themselves. The properties of the ECM have been studied: ECM secreted by the 2 cell lines induced very quick spreading of HT 29 and HRT 18 cells (1 to 2 hr vs. 12 to 24 hr in serum-supplemented medium). ECM induced morphological differentiation of a rat pheochromocytoma cell line (PC 12). PC-12 cells grown under these conditions began to develop neurite extensions as early as 2 hr after seeding.

Adenocarcinoma↗

PubMed1985

Ultrastructural localization of voltage-sensitive sodium channels using [125I]alpha scorpion toxin.

The distribution of alpha scorpion toxin (alpha-ScTx) receptors was examined in differentiated mouse neuroblastoma cell cultures (N IE 115 clone) by electron microscope autoradiography using [125I]alpha-ScTx. This neurotoxin binds specifically to voltage-sensitive sodium channels, slowing down the inactivation of the sodium permeability. Quantitative analysis demonstrated that only plasma membranes were labelled. The alpha-ScTx receptors seemed to be randomly dispersed on both cell bodies and cell processes. Microvilli protruding from the cell bodies carried more sodium channels than other parts of the membrane. The specific binding site density for alpha-ScTx varied from 4 (cell body membrane) to 13 (cell process membrane) per square micrometer.

Animals↗

PubMed1985

Ultrastructural visualization of Na+-channel associated [125I]alpha-scorpion toxin binding sites on fetal mouse nerve cells in culture.

Purified neurotoxin II from the scorpion Androctonus australis Hector (alpha-ScTx) has previously been shown to bind specifically to the voltage-sensitive Na+ channels of excitable cells. Recent studies, using high specific activity 125I-labeled alpha-ScTx, demonstrated specific binding to neuronal cells derived from fetal mouse brains. In the present study, 125I-labeled alpha-ScTx was used to localize the voltage-sensitive Na+ channels in cultured fetal mouse brain cells. By quantitative electron microscope autoradiography we demonstrate that specific alpha-ScTx binding sites are selectively located at the plasma membrane. Estimates of their density revealed that neurites at 13 days in vitro carry at least 6 X more specific alpha-ScTx sites than cell body membrane.

Animals↗

PubMed1983

Voltage-sensitive Na+ channels in the neurohypophysis of the rat as demonstrated by 125I-labelled scorpion toxin.

Fresh rat neural lobe slices were incubated in the presence of [125I] alpha-scorpion toxin (ScTX), a specific marker of Na+ channels. Quantitative electron microscope autoradiography revealed preferential, irregularly spaced labeling of the axolemma of neurosecretory axons, with a significantly higher crude specific activity than any other neuronal or non-neuronal compartment. The number of specific binding sites at the neural lobe surface was calculated to be about 23 per microns2 of axolemma.

Animals↗

PubMed1979

Autoimmune alterations in the neurohypophysis of rabbits immunized against vasopressin.

Rabbits immunized against vasopressin developed clinical signs of diabetes insipidus persisting for up to two months after the last boost. Ultrastructural and immunocytochemical studies of the neurohypophysis demonstrated autoimmune alterations: infiltration by immune cells and extracellular deposits of immunoglobulins. No alterations were observed in the hypothalamic nuclei synthesizing vasopressin nor in hormone-target cells of the kidney. Immunization against vasopressin may provide the first example of an autoimmune disease in the hypothalamo-neurohypophysial system.

Animals↗

PubMed1978

Evolution of vasopressin levels in the hypothalamo-posthypophysial system of the rat during rehydration following water deprivation. Correlation with ultrastructural aspects in the posterior lobe.

Evolution of the (arginine)-vasopressin (AVP) content of the supraoptic (SON), paraventricular (PVN) and suprachiasmatic nuclei (SchN) and of the posterior lobe of the hypophysis (PLH) has been studied in rats at successive stages of rehydration after 4 days deprivation of drinking water. Particular attention has been focussed on short periods of rehydration. Evolution of the AVP content of the hypothalamo-posthypophysial system (HHS), the blood serum AVP concentration and osmolalities of serum and urine were compared. Variations of the AVP content in the different hypothalamo-hypophysial structures, are parallel. A marked depletion of AVP is observed after 2 and 4 days of dehydration. The AVP content of the PLH and of the hypothalamic nuclei shows two dramatic and short increases 15 min and 3 h after the onset of rehydration; these results are discussed in relation to the known physiological regulation mechanism of the HHS. In the PLH depleted by dehydration, reloading with neurosecretory granules (NSG) begins to be noticeable only after 24 h of rehydration, so that it does not seem to account for elevations of the AVP content occurring earlier. These could be related to a marked increase of the smooth endoplasmic reticulum (SER) network taking place in axons and nerve endings before the NSG reloading.

Animals↗

PubMed1978