To know the lethal mechanism of microorganisms under pulsed electric field treatment, the relationship between the inactivation of Saccharomyces cerevisiae (CICC1308) cell and the permeability and ...fluidity changes of its cell membrane treated by pulsed electric field (0-25 kV x cm(-1), 0-266 ms) was investigated. With 1,6-diphenyl-1,3,5-hexatriene (DPH) used as a probe, the cell membrane fluidity of Saccharomyces cerevisiae treated by pulsed electric field was expressed by fluorescence polarization. Results showed that the cell membrane fluidity decreases when the electric flied strength is up to 5 kV x cm(-1), and decreases with the increase in electric field strength and treatment time. The plate counting method and ultraviolet spectrophotometer were used to determine the cell viability and to investigate the cell membrane permeability, respectively, treated by pulsed electric field. Results showed that the lethal ratio and the content of protein and nucleic acid leaked from intracellular plasma increased w
Studies with multidrug resistance modifiers indicate that perturbations of the cell membrane structure may influence P-glycoprotein (P-gp)-mediated drug transport. We describe studies of plasma ...membrane order using electron-paramagnetic resonance (EPR) in resistant (CHRC5) and sensitive (AUXB1) chinese hamster ovary cells treated with R-verapamil and bile salts. Cell growth rates were determined in presence of doxorubicin mitomycin and cisplatin. The plasma membrane order in untreated resistant cells was higher than in the sensitive cells. Both the bile salt taurochenodeoxycholate (TCDC; 0.2–1.6 mM) and R-verapamil (1–3 μM) lowered the membrane order in the CHRC5 cells to that in the sensitive cells and reversed the resistance to doxorubicin and mitomycin. The bile salt tauroursodeoxycholate (TUDC; 0.2–3 mM) did not lower membrane order and did not sensitise CHRC5 cells. Neither R-verapamil, TCDC nor TUDC reduced the membrane order of the sensitive cells AUXB1 cells. These results support the view that changes in multidrug resistance in Chinese hamster ovary cells and P-gp function are associated with alterations in the fluidity of the plasma membrane.
In the light of a novel mode of action, the antiproliferative effects of green tea catechins were studied with relating to their membrane lipid interactions. Mouse myeloma cells and liposomes ...consisting of phospholipids and cholesterol were treated with structurally-different catechins of 10 and 100 μM for 0.5-48 hr. The induced changes in membrane fluidity were comparatively determined by measuring fluorescence polarization with different probes to characterize the membrane-acting sites. (－)-Epicatechin-3-gallate (ECG) and (－)-epigallocatechin-3-gallate (EGCG) showed the growth-inhibitory effects on tumor cells with the potency increasing in this order, but neither (－)-epicatechin (EC) nor (＋)-catechin (C). Simultaneously with inhibiting the cell growth, both catechin gallates rigidified tumor cell membranes by acting on their hydrophilic and hydrophobic regions. The most antiproliferative EGCG predominantly affected the centers of celn membranes and its acting site was deeper with increasing the culture time. Correlating to the comparative effects on tumor cells, EGCG reduced the fluidity of liposomal membranes more intensively than ECG, whereas EC and C were essentially ineffective. The antiproliferative effects of green tea catechins are associated with their structure-dependent interactions with lipid bilayers to modify cell membrane fluidity.
When cell is exposed to short electric pulses with
high amplitudes its membrane is transiently permeabilised.
Characteristics of the cell play important role in this process.
In the present study the ...effect of cell membrane fluidity on
electroporation was investigated. To obtain significant differences
in cell membrane fluidity cell suspension was exposed to
different temperatures for five minutes before and during the
pulse application. To exclude the effect of the temperature on
cell membrane resealing only a small droplet of cell suspension
was used for cell membrane permeabilization assay as it
reached room temperature in few seconds after it was removed
from electroporated sample. It was found that the decrease in
cell membrane fluidity caused by exposure of cells to low temperature
during electric pulse application significantly reduces
electroporation effectiveness of the cell line V79.
Counteraction of drug resistance is a major challenge in cancer therapy, particularly in adhanced stages. The main mechanism of multidrug resistance is related to an increased drug efflux. In the ...present study we examined the effect of modifying cell membrane lipid fluidity on uptake of adriamycin (ADR) in cells of AKR lymphoma malignancy variants. Modification of cell membrane fluidity, either by lecithin or by lecithin-cholesterol mixtures, induced in a high proportion of cells of all variants a higher capacity to accumulate ADR. The chemosensitizing effect, for lecithin in particular, was proportional to the vegree of malignancy of the lymphoma variants. The increased ADR uptake was up to 1.4-fold in the variant of lowest malignancy and up to 5-fold in the one of highest aggressiveness. This tenvency correlates with our previous studies and is of particular value since highly-malignant tumors are often drug resistant. The cholesterol-lecithin mixture, induced, however, in part of the variants the appearance of a small subpopulation with very low ADR permeability. Cell membrane rigidification is of value for exposing tumor cell cryptic antigens but may be veleterious when used in conjunction with chemotherapy.
The influence of daunorubicin (DNR) on survival of human normal (S-126) and trisomic, with respect to chromosome 21 (T-164; S-240), skin fibroblasts and some parameters related to it, such as ...intracellular drug accumulation, distribution and interaction with cell membrane, were studied. The in vitro growth-inhibition assay indicated that DNR was less cytotoxic for trisomic than for normal cells. Comparison of kinetic parameters and intracellular distribution of this compound showed that the uptake and the amount of intracellular free DNR were greater in normal than in trisomic cells. Contrary to this, there were no significant differences between the amount of DNA-bound drug in both types of cells. TMA-DPH and 12-AS fluorescence anisotropy measurements demonstrated that DNR decreased lipid fluidity in the inner hydrophobic region of plasma membrane in both cell types, but did not influence the fluidity of the outer surface of membrane. We conclude that fibroblasts derived from individuals affected with Down's syndrome are better protected from the damage induced by DNR than normal cells.
With metal phthalocyanine used as the photosensitizer, the cell membrane fluidity under the conditions of different irradiation time in photodynamic therapy was investigated by fluorescence ...polarization. Results show that with the photosensitizer phthalocyanine excited, the fluorescence polarization of the fluorophose was increased and the cancer cell membrane fluidity was decreased due to the photodynamic therapy. Cell proliferation was also studied by MTT. Results show that cell membrane fluidity and cell proliferation are influenced to the same extent, suggesting that cell membrane is one of the binding sites in PDT.
Carotenoids in mollusca: approaching the functions Vershinin, Alexander
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology,
1996, 1996-1-00, Letnik:
113, Številka:
1
Journal Article
Recenzirano
Carotenoids in eight species of freshwater and sea mollusks were investigated. In the nonreproductive organs of all species, only all-trans C
40-xanthophylls were found. Carotenes are limited to ...hepatopancreas. No carotenoid derivatives or carotenoids with < 10 conjugated double bonds were detected. Carotenoids in molluskan cells are present in all subcellular fractions; the major part of them is located in plasma membrane. There are no special carotenoid-containing pigmented granules (“cytosomes” “carotenoxysomes”) in molluskan cells. Comparison of both Raman and absorption spectra of carotenoids
in situ with those in CHCI
3 suggests that pigments are dissolved in lipid matrix of membranes and not bound to proteins. No changes of carotenoid content or carotenoid pattern in
Dreissena polymorpha, Unio pictorum and
Viviparus contectus were observed during 10 days of starvation. There were no changes in isolated gills within 2 days as well. In the freshwater species with the exception of
D. polymorpha, carotenoid content changes after the fast water temperature changes: with elevation of temperature, the carotenoid content in organs increases and
vice versa, without any change in carotenoid composition. This phenomenon is shown to be due to rearrangement of pigments between the hepatopancreas and other organs. The results suggest that the role of carotenoids in molluskan tissues is not connected with their chemical transformations. The most probable function of carotenoids in mollusks is the stabilisation of cell membranes' fluidity.
Dans l’industrie agro-alimentaire, l’adhésion de micro-organismes altérants ou pathogènes sur les surfaces induit des effets néfastes à la fois en termes de qualité, d’hygiène et de santé publique. ...Les vêtements professionnels constituent un des vecteurs de contamination par le personnel. Ce travail de thèse concerne l’évaluation de l’activité antimicrobienne de textiles antimicrobiens développés pour le secteur hospitalier et le secteur agro-alimentaire et rentre dans le cadre du projet collaboratif Actiprotex. Trois méthodologies ont été employées pour le dépôt d’agents antimicrobiens sur les textiles : méthodologie plasma (PVD/PECVD) ou sol-gel pour le dépôt d’argent, foulardage avec une solution contenant du laurylsulfate et du Poly Hexaméthylène Biguanide (PHMB) pour provoquer une co-précipitation du PHMB. Les activités antimicrobiennes de chaque textile ont été évaluées après 24 h de contact (suivant la norme ISO 20743-2005). Les quantités d’agent antimicrobien à la surface des textiles ont été évaluées par 2 techniques d’analyses de surface : la spectroscopie photoélectronique par rayons X (XPS) et la spectrométrie de masse d’ions secondaires (ToF-SIMS). Les textiles traités par plasma à l’argent se sont avérés être efficaces vis-à-vis de Listeria innocua LRGIA 01. Pour le traitement sol-gel, les textiles testés étaient également très actifs vis-à-vis de L. innocua LRGIA 01 et d’Escherichia coli XL1 blue. Cependant, E. coli XL1 blue est apparue plus sensible à l’argent que L. innocua LRGIA 01. Les textiles traités au PHMB se sont également avérés être très actifs vis-à-vis de L. innocua LRGIA 01 et de Staphylococcus aureus méthi-R nosoco 3011 cependant des cellules viables mais non cultivables (VNC) ont également été mises en évidence après contact de ces 2 souches avec le textile traité au PHMB. Pseudomonas aeruginosa ATCC 15742 s’est quant à elle avérée être plus résistante que ces 2 souches. La tenue aux lavages industriels ou ménagers des dépôts plasma d’argent et de PHMB par foulardage a également été évaluée. Les dépôts plasma d’argent résistent mal au lavage alors que le dépôt PHMB par foulardage s’est avéré résister à 10 lavages industriels. Pour mieux comprendre le mécanisme d’action du PHMB vis-à-vis de L. innocua LRGIA 01 en milieu liquide, trois approches ont été mises en oeuvre : la microscopie à épifluorescence en présence de marqueurs fluorescents pour évaluer l’état de la membrane des cellules, la spectrofluorimétrie en présence de sondes fluorescentes (DPH et TMA-DPH) pour évaluer la fluidité de la membrane des cellules et enfin la spectroscopie infrarouge à transformée de Fourier (IRTF) pour évaluer les changements de conformation de la membrane. Les résultats obtenus par ces 3 méthodes permettent de proposer un mode d’action du PHMB de type « carpet », c’est à dire une fixation de l’agent antimicrobien en surface puis une désorganisation de la membrane conduisant à des changements de sa conformation puis à la formation de pores et à la mort cellulaire
Adhesion of pathogenic or spoilage microorganisms on the surfaces present in food industry can lead to contaminations of foods. Besides the economical impact for this industrial sector, these contaminations might alleviate food quality and hygiene and affect public health. Professional clothes constitute one of the vectors of contamination by the staff of food-processing industry. This work is a part of a collaborative project (Actiprotex) and concerns the evaluation of the antimicrobial activity of antimicrobial textiles developed for the hospital sector and the food-processing industry. Three methodologies were employed to obtain deposits of antimicrobial agents on textiles surfaces: plasma (PVD / PECVD) or sol-gel methodologies for the silver deposit and spin coating with a solution containing laurylsulfate and PolyHexamethylene Biguanide (PHMB). The antimicrobial activities of functionalized textiles were estimated after 24 hours of contact (according to the standard ISO 20743- 2005). The quantities of antimicrobial agent at the extreme surface of the textiles were estimated by two techniques of analyses of surface: the photoelectronic spectroscopy by X-rays (XPS) and the mass spectrometry of secondary ions (ToF-SIMS). Textiles functionalized by plasma methodology with silver were effective against Listeria innocua LRGIA 01. For the textiles functionalized by sol-gel methodology, the tested textiles were also very active towards L. innocua LRGIA 01 and Escherichia coli XL1 blue. However, E. coli XL1 blue seemed to be more sensitive to the silver on textiles than the L. innocua LRGIA 01 strain. Textiles treated with the PHMB also turned out to be very active towards L. innocua LRGIA 01 and Staphylococcus aureus methi-R nosoco 3011, however viable but not cultivable cell (VNC) were also revealed after contact of these 2 strains with the PHMB treated textile. Pseudomonas aeruginosa ATCC 15742 was more resistant to PHMB than these 2 strains. The washing resistance of silver- or PHMB-deposits was also estimated. Most of the silver deposit following plasma treatment was washed out while the PHMB deposit turned out to resist to 10 industrial washes. To understand the mechanism of action of the PHMB against L. innocua LRGIA 01, three approaches were considered: the epifluorescence microscopy in the presence of fluorescent dyes to estimate the state of the membrane cells, spectrofluorimetry in the presence of fluorescent probes (DPH and TMA-DPH) to estimate the membrane fluidity of cells and finally the infrared transformed Fourier spectroscopy (IRTF) to estimate the changes of conformation of the membrane
Biochemical disturbances of the reactive oxygen species metabolism revealed in subjects with Down's syndrome (DS), and the findings indicating that heat-induced cell alterations have been, at least, ...partly mediated by reactive oxygen species, made the elucidation of the response of trisomic cells to elevated temperatures of special interest. Kinetic analysis of cell-survival curves, accompanied by the flow cytometry and the scanning electron microscopy (SEM) examinations, and their relationship with the cell membrane fluidity, were undertaken. At each temperature (48–54°C),
D
q parameters, representing the ability to accumulate sublethal damages, were similar for both cell groups.
D
0 parameters (inverse leakage rates;
D
0=1/
k) were greater for DS cells at each temperature below 54°C. The haemolysis sensitivity ratio (HSR) showed that DS erythrocytes were, in average, 1.60 times more resistant to heat injury than those from normal subjects. Activation energies of haemolysis, calculated according to the Arrhenius equation, were similar both for normal (290.8±6.5 kJ/mol) and DS erythrocytes (288.0±5.5 kJ/mol). Flow cytometry studies showed that the scattering properties of intact DS erythrocytes (reflecting size, volume, shape and cell membrane surface morphology) were different than those of normal cells. Scanning electron micrographs and scattering diagrams obtained for cells submitted to heat stress (51°C) confirmed that DS erythrocytes were more resistant, to a certain extent, to heat-induced disruption than normal cells. The steady-state fluorescence anisotropy of TMA-DPH (1-(4-trimethyl-ammoniumphenyl)-6-phenyl-1,3,5-hexatriene) showed that untreated DS erythrocytes had substantially lower fluidity (
r=0.356±0.008) of the outer monolayer of cell membranes as compared to normal cells (
r=0.324±0.011). The increase of the cell membrane fluidity during exposure to heat was observed. The greatest elevation of cell membrane fluidity occurred during the preleakage period, immediately upon the heat treatment and was considered as a rate-limiting step of heat-induced haemolysis.
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