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C Ferrand

Publications and source records attributed to C Ferrand.

9 recordsLinked to original sources
PubMed1991

A continuous-flow model for phonatory reaction time.

The purpose of this study was to validate a proposed continuous-flow model of phonatory reaction time by investigating the temporal order of selected laryngeal and neurophysiological events involved in a phonatory reaction time task. Ten normal speakers participated in a phonatory reaction time task. Laryngeal positioning movements prior to vocal fold closure (laryngeal shift) and onset of vocal fold vibration (acoustic onset) were recorded with an electroglottograph. P300 brain potentials were collected simultaneously, and they served as an index of a central process underlying reaction time. The obtained temporal ordering of laryngeal shift, P300, and acoustic onset supported a continuous-flow model of phonatory reaction time. Use of this model might yield information that is more accurate in explaining physiological function and more precise in describing temporal patterning than the serial model.

Adult↗
PubMed1987

Comparison of the effects of elevated K+ ions and muscle-conditioned medium on the neurotransmitter phenotype of cultured sympathetic neurons.

Neuronal depolarization and culture media conditioned by certain nonneuronal cells (CM) are known to exert opposite effects on the expression of cholinergic and noradrenergic traits in cultured rat sympathetic neurons. We have compared their effects on the developments of choline acetyltransferase (CAT), tyrosine hydroxylase (TOH), dopa decarboxylase (AADC) and acetylcholinesterase (AcChE) in these cultures. A macromolecular factor which was partially purified from CM increased CAT development in a dose-dependent manner and depressed the development of TOH and AADC by 5- to 10-fold. In the presence of intermediate concentrations of this partially purified factor, both CAT and catecholamine synthesizing enzymes developed to high levels, whereas high concentrations caused a long-lasting, but not total, impairment of TOH development. The effects of CM on both CAT and AADC activities resulted from variations in the number of immunotitratable enzyme molecules. Conversely, K+ ions (30-40 mM) depressed the development of CAT by 90% and stimulated TOH development 2.5-fold. Cultures grown with CM in high K+ medium had similar CAT and TOH activities as compared to those cultures grown without CM in low K+ medium suggesting that CM and K+ ions had antagonistic effects on the expression of these enzymes. However, K+ ions did not affect the development of AADC in these cultures. CM suppressed in a reversible manner the development of the 16 S form of AcChE. In the presence of 40 mM K+, the rate of development of AcChE was reduced. In particular, the development of 16 S AcChE was strikingly impaired, although not totally suppressed. The effect of elevated K+ ions on the percentage of 16 S AcChE was rapidly reversible. It is concluded that CM and elevated K+ ions have antagonistic effects on CAT and TOH, but not on AADC development; AcChE, in particular its asymmetric 16 S form, is regulated independently of the cholinergic/noradrenergic status of sympathetic neurons.

Acetylcholinesterase↗
PubMed1986

Cellular localization of the molecular forms of acetylcholinesterase in primary cultures of rat sympathetic neurons and analysis of the secreted enzyme.

The secretion and cellular localization of the molecular forms of acetylcholinesterase (AChE) were studied in primary cultures of rat sympathetic neurons. When cultured under conditions favoring a noradrenergic phenotype, these neurons synthesized and secreted large quantities of the tetrameric G4, and the dodecameric A12 forms, and minor amounts of the G1 and G2 forms. When these neurons adopted the cholinergic phenotype, i.e., in the presence of muscle-conditioned medium, the development of the cellular A12 form was completely inhibited. These neurons secreted only globular, mainly G4, AChE. Both cellular and secreted A12 AChE in adrenergic cultures aggregated at an ionic strength similar to that of the culture medium, raising the hypothesis that this form was associated with a polyanionic component of basal lamina. In noradrenergic neurons, 60-80% of the catalytic sites were exposed at the cell surface. In particular, 80% of G4 form, but only 60% of the A12 form, was external, demonstrating for the A12 form a sizeable intracellular pool. The hydrophobic character of the molecular forms was studied in relation to their cellular localization. As in muscle cells, most of the G4 form was membrane-bound. Whereas 76% of the cell surface A12 form was solubilized in the aqueous phase by high salt concentrations, only 50% of the intracellular A12 form was solubilized under these conditions. The rest of intracellular A12 could be solubilized by detergents and was thus either membrane-bound or entrapped in vesicles originating from, e.g., the Golgi apparatus.

Acetylcholinesterase↗
PubMed1985

Changes in plasma fibronectin levels after cardiac and pulmonary surgery: role of cardiopulmonary bypass.

The changes in immunoassayable plasma fibronectin were studied during seven days after cardiac surgery with cardiopulmonary bypass (group A, 19 patients) or lung surgery without bypass (group B, 11 patients). In group A the fibronectin showed a series of rapid changes during the 24 perioperative hours. Simultaneous assessment of other plasma proteins (albumin, fibrinogen and immunoglobulin G) suggested that these changes mainly reflected hemodilution and hemoconcentration processes following the cardiopulmonary bypass, being influenced by the necessarily large transfusions of plasma. The fibronectin level decreased after day 1, with maximum depletion (averaging -32% of preoperative value) on day 3. Despite subsequent progressive rise, full restoration had not been reached by day 7. Group B did not show the initial rapid changes, but progressive fall in fibronectin level to a nadir on day 2 (-20% of preoperative) was followed by gradual return to outset value on days 4-5. The study demonstrated 1) that cardiac or lung surgery induces transient fibronectin depletion on days 2 to 3 postoperatively, and 2) that in surgery with cardiopulmonary bypass the decrease is significantly greater and more prolonged. It is proposed that this supplementary decrease is due to the large amounts of particulates of various origin entering the blood during the bypass.

Blood Proteins↗
PubMed1985

The role of extracellular signals in the differentiation of cholinergic neurons from the CNS and PNS in culture.

Rat skeletal muscle cells release in culture a macromolecule which stimulates by 25-100 fold the development of choline acetyltransferase (CAT) in cultures of new-born rat sympathetic neurons. This "cholinergic factor" impaired the development of three norepinephrine synthesizing enzymes and of acetylcholinesterase (AChE) in these cultures. The 16S form of AChE failed to develop in cultures grown with the factor, but amounted to 30-40% in 3-week old cultures grown in its absence. Using the development of CAT activity in sympathetic neuron cultures as an assay, the cholinergic factor has been partially purified in 6 steps, and its hydrodynamic parameters determined. The effects of this factor on sympathetic neurotransmitter choice were qualitatively reproduced by 1-10 mM Na butyrate. The cholinergic factor increased CAT activity and decreased AChE in neuron cultures from new-born rat nodose ganglia. The factor also stimulated CAT activity in rat embryo (E14) spinal cord cultures, but stimulated the development of AChE in these cultures.

Animals↗