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Biomedical subjects

J Teissie

Publications and source records attributed to J Teissie.

33 records · Page 2Linked to original sources
PubMed1987

Lateral proton conduction at a lipid/water interface. Effect of lipid nature and ionic content of the aqueous phase.

Fast lateral proton conduction was observed along the lipid/water interface using a fluorescence technique. This conduction can be detected for a large number of lipids, both phospholipids and glycolipids. The efficiency of the proton transfer is dependent on the molecular packing of the host lipid at a given surface pressure. The proton conduction which is present in the liquid expanded state is abolished by the transition to the liquid condensed state. The proton transfer is affected slightly by the ionic content of the aqueous subphase except in the case of calcium which can inhibit the conduction along phosphatidylglyceroethanolamine. We suggest that the transfer of the protons occurs along a bidimensional hydrogen-bond network formed from the polar head groups, their water molecules of hydration and the water molecules which are intercalated between the lipid molecules.

Anions↗
PubMed1986

Fusion of mammalian cells in culture is obtained by creating the contact between cells after their electropermeabilization.

Electropermeabilization of chinese hamster ovary cells (CHO) is a long lived process but is nevertheless fully reversible. Electrofusion can be obtained by centrifuging the cells several minutes after the pulsation and then by incubating the pellet. These results show that fusion is not directly created by the field but is due to the existence of a peculiar state of the plasma membrane. The permeabilized patches are local on the cell surface and do not spread or diffuse on it.

Animals↗
PubMed1984

A study of the structure and dynamics of complexes between polymyxin B and phosphatidylglycerol in monolayers by fluorescence.

Interactions between the antibiotic polymyxin B and monolayers of dipalmitoylglycerophosphoglycerol have been reinvestigated through a study of the structure and dynamics of the complexes by means of an interface fluorimeter of our fabrication. A fluorescence technique has been developed where the use of linearly polarized incident beams gives the simultaneous determination of the orientation and the lateral diffusion rate of a fluorescent probe inserted in the film. The present investigation was carried out with 12-(9-anthroyloxy)-stearic acid, a fluorescent compound which forms non-fluorescent photodimers upon illumination. Orientation of the probe was studied by computing the ratio of the two dimerization constants KD and the ratio of the fluorescence intensities obtained with crossed linearly polarized incident lights. The lateral diffusion rate of the probe was obtained by measuring fluorescence recovery after photobleaching (photodimerization) of the probe. Control experiments, carried out with dimyristoylglycerophosphocholine, a lipid which does not interact with polymyxin B, show that the antibiotic does not significantly modify the behaviour of the probe. Both in terms of orientation and dynamics, with respect to dipalmitoylglycerophosphoglycerol, when the antibiotic is present in the subphase (1 microM, saturating conditions), data indicate that the lipid remains in a liquid-expanded state. This is true even at a high surface pressure (pi approximately equal to 37 mN X m-1), above the apparent 'transition' which can be observed at 30-35 mN X m-1 on its compression isotherm. Computation of the contribution of polymyxin B to the film expansion to the conclusion that this 'transition' would be a structural transition between two models of interaction: one, below the 'transition', where the polypeptide ring penetrates between the film-forming lipid molecules and another one, above the 'transition', were the antibiotic is adsorbed at the lipid-water interface with only its hydrocarbon chain penetrating the film.

Dimyristoylphosphatidylcholine↗
PubMed1983

Induction of calcium-dependent, localized cortical granule breakdown in sea-urchin eggs by voltage pulsation.

A technique that employs a high-voltage pulses to produce pores in cell membranes (Kinosita and Tsong (1977) Proc. Natl. Acad. Sci. U.S.A. 74, 1923) has been used to investigate the role of Ca2+ in the early events of activation of sea-urchin eggs. Exposure of eggs to a voltage pulse of 1 kV/cm for 100 microseconds resulted in localized exocytosis of the contents of cortical granules and development of a partial fertilization envelope. This effect was triggered by entrance of Ca2+ through the voltage-induced pores. In a medium containing 100 microM Ca2+ and 45Ca2+ tracer, the voltage-treated eggs admitted 3.6 +/- 0.3 fmol Ca2+/egg within a few seconds. Untreated eggs took up only 1.0 +/- 0.2 fmol/egg after minutes of incubation. Furthermore, depletion of Ca2+ or the presence of EGTA in the external medium prevented elevation of the fertilization envelope by the voltage pulsation. Delay in Ca2+ addition after the voltage pulsation reduced the fraction of eggs that developed partial fertilization envelope. Loss of essential cytoplasmic components during the delay period is judged unlikely, since these eggs were viable, could form partial fertilization envelopes if re-pulsed in the presence of Ca2+, and could develop to normal blastula stage embryos upon fertilization with sperm. Thus, we interpret this effect as due to a resealing of pores; the half-life of pores being 20 s. The elevation of partial fertilization envelopes occurred only at the loci facing the anode, and multiple pulses with mixing resulted in the formation of multiple fertilization envelopes. These envelopes were stable for up to several hours; further propagation (wave spreading) was not observed. The above results indicate that a primary reaction in the sequence of steps in fertilization envelope formation involves Ca2+ to trigger cortical granule breakdown and formation of the fertilization envelope.

Animals↗
PubMed1982

Electric pulse-induced fusion of 3T3 cells in monolayer culture.

Swiss mouse 3T3-C2 fibroblasts, grown to confluence in monolayer culture, are shown to fuse when exposed to electric fields. Exposure to five repetitive electric pulses of about 1 kilovolt per centimeter with a duration of 50 microseconds caused approximately 20 percent of the cells to become fused (multinucleate) when 1 millimolar magnesium was present in the medium. The effects of minimum thresholds of field strength, pulse duration, and number of pulses were determined. Cell disruption was observed when the electric field exceeded 2.0 kilovolts per centimeter or the pulse was of longer duration than 120 microseconds.

Animals↗
PubMed1981

Electric field induced transient pores in phospholipid bilayer vesicles.

A study of the voltage induction of transient pores in phospholipid bilayer vesicles is reported. Unilamellar vesicles (dipalmitoylphosphatidylcholine), with a size distribution of 100 +/- 30 nm, were prepared by the method of Enoch & Strittmatter [Enoch, H., & Strittmatter, P. (1979) Proc. Natl. Acad. Sci. U.S.A. 76, 145]. The vesicles loaded with [14C]sucrose and suspended in a mixture of 150 mM NaCl and 272 mM sucrose (both are the isotonic solvent for erythrocytes) were exposed to an intense electric field in the range of 20--40 kV/cm, with a field decay time of 5--15 micro second. A transient leakage of sucrose label was detected when the field strength exceeded 30 kV/cm. After the field was removed, no slow leakage of the tracer molecules occurred during a 65-h incubation period at the room temperature (23 +/- 2 degrees C). The leakage is attributed to the field-induced transmembrane potential, but not other effects such as the Joule heating or the shock wave associated with the voltage discharge. When the potential exceeded a threshold value of 200 mV, corresponding to an applied field strength of 30 kV/cm, there was a dielectric breakdown of the bilayer structure. Pores which allowed passage of sucrose were formed, transiently. Experiments show that these pores were fully reversible, and no global and permanent damages to the vesicle bilayer were detected. The implication of this membrane potential triggered conducting state of lipid bilayers to biological functions of cells is discussed.

Chemical Phenomena↗
PubMed1981

Interaction of cytochrome c with phospholipid monolayers. Orientation and penetration of protein as functions of the packing density of film, nature of the phospholipids, and ionic content of the aqueous phase.

Energy-transfer fluorescence quenching has been used to observe the binding of cytochrome c to a lipid assembly. The probe (donor), dansylphosphatidylethanolamine, was dispersed either in dipalmitoylphosphatidylcholine, in phosphatidic acid, or in a mixture of the two lipids. The heme of the protein was the acceptor. When the phospholipids were spread in monolayer at the air-water interface, orientation and penetration parameters of the protein relative to the membrane were obtained. The cytochrome is bound with an orientation such that its heme crevice is fully accessible to the aqueous space. It penetration in the lipid layer is dependent on the ionic content of the subphase and the initial packing of the film. The perturbation induced in the lipid matrix by the binding appear very localized. The same results were obtained with lipid microvesicles. The type of binding of cytochrome c to phospholipids observed here implies that there are specific areas on the protein which appear to be different from those involved in its interaction with cytochrome oxidase and other cytochromes. These conclusions are relevant to the existence of different classes of binding sites for cytochrome c in the mitochondrial membrane.

Cytochrome c Group↗
PubMed1981

Synthesis of adenosine triphosphate in respiration-inhibited submitochondrial particles induced by microsecond electric pulses.

Phosphorylation of ADP to ATP was induced in nonrespiring submitochondrial particles (SMP) from rat liver by the application of electric pulses with field strengths of 10-35 kV/cm and a decay time of 60 mus. In all cases respiration was inhibited completely by using cyanide or rotenone. Newly formed ATP was measured by two independent methods, (i) the luciferase/luciferin bioluminescence assay and (ii) synthesis of [(32)P]ATP from ADP and (32)P(i). Both methods gave consistent and essentially identical results. Above 10 kV/cm the amount of ATP synthesized increased with increasing field strength, and at 30 kV/cm, approximately 40 pmol of ATP was synthesized per mg of SMP protein per pulse. ATP synthesis was shown to be related to the field-induced transmembrane potential, not to Joule heating of the suspension. Synthesis was abolished by the uncouplers carbonyl cyanide p-trifluoromethoxyphenylhydrazone, carbonyl cyanide m-chlorophenylhydrazone, and 2,4-dinitrophenol. The ionophores valinomycin and A23187 reduced the level of synthesis by 75% and 50%, respectively. ATP synthesis was also blocked by inhibitors of the F(0)F(1) ATPase complex, oligomycin, N,N'-dicyclohexyl carbodiimide, venturicidin, and aurovertin. The activities of the adenine nucleotide translocator and adenylate kinase, as well as release of bound nucleotides, could be excluded as sources of the new ATP. The data indicate that the minimal applied field at which ATP synthesis could be detected is approximately 8 kV/cm, corresponding to a maximal induced membrane potential of 60 mV in SMP. The maximal synthesis occurred at around 30 kV/cm, or an induced transmembrane potential of 200 mV. The duration of the applied pulse was also found to be critical, with 8 mus being the minimal triggering time for the synthesis. The induction of ATP synthesis in nonrespiring SMP by an externally applied electrical field is a direct demonstration of the transformation, by the mitochondrial inner membrane, of electrical energy into the chemical bond energy of ATP.

Adenosine Triphosphate↗
PubMed1981

Voltage modulation of Na+/K+ transport in human erythrocytes.

For a cell to perform certain functions it presumably must maintain a steady-state transmembrane potential. This potential differential can take several forms, e.g. a proton gradient, an ionic concentration gradient, or an asymmetric distribution of charges in membraneous proteins and lipids. We report here a study which indicates that an externally applied electric field can induce opening/closing of membrane channels, including Na+/K+ ATPase channels. The method utilizes a continuous AC stimulation of cell suspensions. Reversible channel opening/closing of human erythrocytes in an isotonic suspension can be demonstrated by directly measuring the conductivity of the bulk suspension. Channel opening occurs at a field intensity of 10 V/cm, which corresponds to a maximum transmembrane potential of about 6 mV, when the frequency of AC field is maintained below 1 kHZ. The apparent half-time of the channel opening decreases with an increase in the stimulating voltage, and reaches a plateau value of 2 sec beyond 24 V/cm (15 mV of transmembrane potential). When the AC field is removed, these channels close with a half-time of 10.2 sec. Of the channels opened, roughly 20% belongs to the Na+/K+ ATPase, as this fraction of conductance signals can be quantitatively blocked by a specific inhibitor ouabain in a low ionic medium. The AC field appears to stimulate active Na+/K+ transport against a concentration gradient in erythrocytes. At a field strength of 24 V/cm, the net transport against a controlled sample is about 1 mM 42K+ ion per hour under our experimental condition. This translates into a rate of 60 K+ ions per channel per second. The AC field also increases the K+/Na+ ratio of cytoplasmic concentration in the stimulated sample, indicating an active extrusion of Na+ ion from the cells. Higher consumption of ATP is not detected in the stimulated cells as compared with unstimulated cells. As expected, an addition of ouabain in the external medium abolishes the above effects. Experiments described here would demonstrate that the phenomena observed are due to the effect of the field-induced transmembrane potential. The significance of these observations are discussed in the light of the recent discovery that transmembrane potential is an important driving force for certain cellular functions.

Adult↗
PubMed1980

Evidence of voltage-induced channel opening in Na/K ATPase of human erythrocyte membrane.

Previous studies have shown that human erythrocytes when subjected to a high voltage pulsation, in the microsecond time range, lysed in an isotonic medium. The hemolysis was the result of the colloid osmotic swelling, which, in turn, was caused by the voltage perforation of the red cell membranes. In this work we demonstrate that in a low ionic medium at least 35% of the pores was related to the opening of Na+/K4 ATPase channels. The membrane conductance generated by the externally applied electric field could be partially blocked by a specific inhibitor, ouabain, or by a specific cross-linkin g reagent, Cu++-phenanthroline, of the ATPase. The effect of ouabain was saturable and had a mid-point of saturation at 0.15 microM. This value agrees with the physiological inhibition constant of the drug. K+ ion in the external medium suppressed the effect of ouabain, as has also been demonstrated n physiological studies. Experiment presented in this communicaton also suggests that the Na+/K+ ATPase was not perforable in a high ionic medium, and that a large fraction of the voltage-induced pores occurred at as yet unidentified sites.

Erythrocyte Membrane↗
PubMed1979

Fluorescence temperature jump relaxations of dansylphosphatidylethanolamine in aqueous dispersions of dipalmitoylphosphatidylcholine during the gel to liquid-crystal transition.

The change of fluorescence of the probe dansylphosphatidylethanolamine embedded in multilamellar liposomes of dipalmitoylphosphatidylcholine was used to investigate the dynamics of the thermotropic gel to liquid-crystalline phase transition by use of the temperature-jump technique. The results are discussed and compared to published observations on the same system in which the phenomenon was reported by turbidity changes.

Dansyl Compounds↗
PubMed1979

A fluorescence study with polarised incident light of the compression of phospholipid monolayers spread at the air/water interface: orientation processes in the glycerol region.

Monolayers of phospholipids spread at the air/water interface were studied by means of fluorescence measurements. Using linearly polarised incident light and following the behaviour of a fluorescent covalently-labelled phospholipid (dansylphosphatidylethanolamine) embedded in the monolayer, it was possible to obtain information about the orientation changes at the glycerol level of the phospholipid. When using dipalmitoylphosphatidylcholine as phospholipid, the main orientation of the probe appears unchanged during the phase transition process. On the other hand, the standard deviation of the distribution function of orientation is larger in the liquid-expanded state relative to the condensed state. When using phosphatidic acid or a mixture of dipalmitoylphosphatidylcholine and phosphatidic acid as phospholipids, the same orientation of the probe is observed as with pure dipalmitoylphosphatidylcholine. This orientation stays the same whatever the ionic content of the subphase, i.e. the ionisation state of the polar head. The glycerol region of a phospholipid spread in monolayer at the air/water interface appears unaffected structurally either by the nature of the polar moiety, by its ionisation state, or by the physical state of the hydrocarbon chains.

Air↗
PubMed1978

A fluorescence approach of the determination of translational diffusion coefficients of lipids in phospholipid monolayer at the air-water interface.

In the present work, it is shown that the photobleaching technique as well as experimentation based on fluorescence recovery after bleaching can be extended to monolayers spread at the air-water interface. A mathematical model is derived which allows the determination of translational diffusion coefficients of species diffusing in such a system. Using 12-(9-anthroyl)stearic acid (anthroylstearate) as a fluorescent probe, dispersed either in dipalmitoylphosphatidylcholine or in dipalmitoylphosphatidylglycerol in various conditions of subphase ionic composition and surface pressure of the monolayer, including phase transition domains, we are led to the following conclusions: 1. Anthroylstearate molecules seem to aggregate in 'microdomains' where their fluorescence properties remain unchanged regardless of the compression states of the host monolayer. 2. In any case, a break in the diffusion constants appears on compressing films of both dipalmitoylphosphatidylcholine and dipalmitoylphosphatidylglycerol. In particular, this break coincides with the liquid expanded to gel phase transition of these lipids when it occurs. 3. Diffusion of anthroylstearate in dipalmitoylphosphatidylglycerol depends strongly on the subphase ionic strength and on the nature of cations: Na+, Mg2+, Ca2+.

Diffusion↗
PubMedDate not supplied

[New applications of electricity in clinical practice].

The living matter is sensitive to electric field impulses, and in particular the membrane structure of cells can be transiently modified under calibrated impulses. This, combined with permeabilization, gives access to the cytoplasmic volume. Moreover, fusion of cells by contact or insertion of receptors is made possible. These acquisitions of fundamental research on electricity-living matter interactions has recently led to practical achievements.

Cell Fusion↗