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Biomedical subjects

C Tamponnet

Publications and source records attributed to C Tamponnet.

13 recordsLinked to original sources
PubMed1999

Water recovery in space.

In the absence of recycling, water represents over 90% of the life-support consumables for a manned spacecraft. In addition, over 90% of the waste water generated can be classified as moderately or slightly contaminated (e.g. shower water, condensate from the air-conditioning system, etc.). The ability to recover potable water from moderately contaminated waste water hence enables significant savings to be made in resupply costs. A development model of such a water-recovery system, based on membrane technology has been produced and tested using "real waste water" based on used shower water Results indicate some 95% recovery of potable water meeting ESA standards, with total elimination of microbial contaminants such as bacteria, spores and viruses.

Ecological Systems, Closed↗
PubMed1994

Biological life support for manned missions by ESA.

The anticipated evolution of life support technologies for ESA, considering both the complementary life support system requirements and the missions' characteristics, is presented. Based on these results, promising biological life support technologies for manned space missions have been selected by ESA either for their intrinsic ability and performance in effecting specific tasks for atmosphere-, water-, waste-management versus physico-chemical alternatives and/or for longer-term application to a more ecological concept (CES) focusing ultimately on food production. Actual status and plan for terrestrial and space testing of biological life support presented focusing on the "task specific" decontamination technology of the Biological Air Filter (BAF), and on food reprocessing technologies from biodegradable wastes with the MELISSA microbial ecosystem.

Air Conditioning↗
PubMed1994

Spirulina acceptability trials in rats. A study for the "MELISSA" life-support system.

Groups of five rats were fed for sixteen weeks a slightly deficient diet, supplemented with 0-40% of a dried preparation of the blue-green alga Spirulina as a protein source. Control groups were fed a normal rat diet. No significant differences between groups were found in food intake, growth rate or carbon dioxide production. All animals remained apparently healthy, and had similar organ weights. The study suggests that Spirulina may be used as a protein source in rat diets.

Animals↗
PubMed1993

Bioencapsulation: a biotechnological tool for biological life support for manned missions by the European Space Agency.

ESA (European Space Agency) decision in 1987 to acquire the capability needed to support man living and working in space, was the trigger for initiating the development of space life support technologies in Europe. The discipline of life support covers basically all the techniques that ensure the biological autonomy of man when isolated from his original biosphere. Biological life support technologies are presently under development at ESA either for their intrinsic ability to better achieve specific tasks than the currently available physico-chemical processes, or because only they can achieve these tasks. Moreover, a global integration of these biotechnologies leads us to the important notion of closed ecological life support system (CELSS). Indeed, a CELSS is the ultimate form of life support system we currently foresee for long-term space missions (over 2 years). Among those biotechnologies, immobilisation processes such as bioencapsulation are considered as potentially potent tools. They are detailed and presented in their life support context as they are currently standing along with their possible future time course in the ESA life support space program.

Ammonia↗
PubMed1993

Alginate immobilized mammalian neurons: a potential tool to isolate new neuronal ligands.

We developed improved immobilization conditions which permitted (i) to immobilize neuroblastoma cells (N18) in calcium-alginate gel beads, (ii) to test the function of ionic channels using patch-clamp electrophysiological techniques and (iii) to quantitatively analyze ligand interactions with voltage-dependent sodium channels in neurons inside the beads. These results qualify this immobilization technique for the isolation and/or purification of ligands specific for neuronal cells.

Alginates↗
PubMed1993

Implementation of biological elements in life support systems: rationale and development milestones.

To ensure the complete autonomy of man in space, biological life support technologies must be developed. A survey of today's knowledge in biotechnology has been performed and technologies suited to long-duration manned missions in space have been identified. Regardless of whether they are to be used in a space vehicle or at a lunar or planetary base, most of those technologies require development times of 20 to 30 years. It is therefore essential to start development now to ensure that the life support system is ready when development of Moon or Mars bases begins.

Air Conditioning↗
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↗
PubMed1990

Entrainment and Phase-Shifting of the Circadian Rhythm of Cell Division by Calcium in Synchronous Cultures of the Wild-Type Z Strain and of the ZC Achlorophyllous Mutant of Euglena gracilis.

Cell division in exponentially increasing populations of the wild-type, photosynthetic Z strain of Euglena gracilis Klebs cultured autotrophically on an aerated, magnetically stirred, minimal mineral medium (pH 7.0) in constant light (LL) or in a light-dark 1 hour:1 hour cycle (LD:1,1) at 25 degrees C could be synchronized by a 10-hour:10-hour low (2 micromolar):normal (200 micromolar) cycle in the concentration of external calcium. Similar results were obtained with the photosynthesis-deficient, achlorophyllous ZC mutant cultured in darkness at 16 degrees C on mineral medium supplemented with 0.1% ethanol as a carbon source; even a single low-Ca(2+) (2 micromolar) pulse was effective in eliciting synchrony. In contrast, whereas the 20-hour entrained rhythm of cell division in ZC then free-ran with a circadian period (tau = 26 hours) for many cycles after the imposed calcium regimen was discontinued, division rhythmicity did not persist in the Z strain in LL. The rhythm in wild-type cultures (free-running in LD:1,1) could be phase-shifted by a single 2-hour increase (from 200 micromolar to 10 millimolar; HiCa) or decrease (from 200-2 micromolar; LoCa) in external Ca(2+) concentration (varied by the addition of CaCl(2) or EDTA, respectively, to the medium). Pulses were terminated by returning the cells to medium containing 200 micromolar Ca(2+) (the normal concentration), and the steady-state phase-shifts engendered (if any) after transients had subsided were calculated with reference to an unperturbed culture. For both HiCa and LoCa pulses given at different circadian times, strong (type 0) phase-response curves (PRCs) were obtained, but although the LoCa PRC was the same as that obtained for light signals, the HiCa PRC was the opposite (a mirror image). These results implicate calcium in clock function, although it is likely that only a small portion of the total intracellular Ca(2+) ion is playing a role since the period of the division rhythm in cultures grown in the continuous presence of excess Ca(2+) or under LoCa was not altered significantly.

Journal Article↗
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↗