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C Tamponnet

Publications and source records attributed to C Tamponnet.

5 recordsLinked to original sources
PubMed1992

Rabbit articular chondrocytes in alginate gel: characterisation of immobilized preparations and potential applications.

Primary cultivated rabbit articular chondrocytes were immobilized in calcium alginate beads. Both free and entrapped cells were allowed to grow under normal conditions. After long-term immobilization, the cells still exhibited metabolic activities, patterns of division, synthesis and secretion of extracellular matrix macromolecules such as type II collagen and proteoglycans. After 38 days, immobilized rabbit articular chondrocytes predominantly expressed type II but not type I collagen. Thus, they maintained their cartilage pheno-type. After bead lysis, harvested cells showed normal growth patterns when resuspended in culture medium. On the basis of these results, long-duration storage and large-scale production of extracellular matrix components are being investigated.

Alginates↗
PubMed1992

The role of ions and second messengers in circadian clock function.

The fact that single cells can exhibit circadian rhythmicity simultaneously in quite different processes, such as those of photosynthesis, bioluminescence, and cell division, suggests that membrane-bound compartmentalization is important for temporal organization. Since these rhythms, as well as others, are known to be affected by changes in the ionic environment and are probably membrane-bound systems, it is not surprising that transmembrane ion transport or flux has been proposed to be a key feature of the underlying circadian oscillator(s). Likewise, signal transduction along the entrainment pathway leading to the clock, among the elements, or "gears," of the timing loop itself, and within the output pathway between the oscillator and its "hands" likely is mediated by ions and second messengers. In this overview, we examine the theoretical and experimental evidence supporting the possible roles of intracellular free calcium and cyclic AMP in these capacities, particularly in view of the fact that oscillations in the concentrations of both species have been proposed to form the basis of pacemaker activity and other biological rhythms.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1990

Storage and growth of neuroblastoma cells immobilized in calcium-alginate beads.

Mouse neuroblastoma cells (N18) were immobilized in calcium-alginate gel beads. Under standard culture conditions (37 degrees C; 5% CO2), cell growth was observed inside the beads. The number of cells increased threefold during 7 days of culture with cell division and differentiation visualized by electron microscopy. Cell properties maintained after short-term storage (2-3 days at 4 degrees C) included: (i) properties of voltage-dependent ionic channels tested by patch-clamp electrophysiological techniques; (ii) expression of cell-adhesion membrane proteins tested by immunohistochemistry (iii) morphological differentiation obtained by depletion of foetal calf serum in culture medium. The advantages of such an immobilization technique as applied to neurone cells are discussed.

Alginates↗
PubMed1988

A quick preparative method for electron microscopy observations of delicate objects using alginate embedding medium.

A quick, safe method has been devised for embedding small or fragile specimens and keeping delicate structures intact. Cells or organisms to be embedded are placed in a viscous sodium alginate solution (1-2%), which is then polymerized in 100 mM calcium chloride. The resulting gel is easily dehydrated, embedded in resin and sectioned for electron microscopy. This method, the alginate gel portion of which was originally developed for the immobilization of Euglena, allows direct observation of each element of the specimens in micrographs. If desired, the alginate can be removed after sectioning by sequestration of calcium in a 20 mM solution of sodium citrate or a 10 mM solution of EGTA. Cells and organelles in the sections respond normally to standard staining procedures.

Alginates↗