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PubMed2001

Peroxidation of linoleic acid and its relation to aging and age dependent diseases.

Cell proliferation, cell injury and aging are connected with changes in the cell membrane structure. Apparently these changes activate, in mammalian as well as in plant cells, lipases which liberate polyunsaturated fatty acids (PUFAs). PUFAs are the substrates for lipoxygenases which convert them to corresponding hydroperoxides (LOOHs). Lipoxygenases commit suicide by releasing iron ions. LOOHs react with iron ions to generate radicals. Thus, a nonenzymic lipid peroxidation process (LPO) is induced. It is speculated that the change from enzymic to nonenzymic LPO is connected with the switch from apoptosis to necrosis and that LOOHs produced in enzymic reactions are degraded specifically to signal compounds which induce physiological responses, while nonenzymic reactions seem to induce generation of reactive oxygen species, cell death and age related diseases. Enzymic and nonenzymic LPO processes concern all PUFAs not only arachidonic acid. The main PUFA in mammals is linoleic acid. Since these products serve signalling functions, different degradation paths of linoleic-hydroperoxides are described in detail and the physiological properties of LPO products are discussed in relation to aging and age related diseases.

Aging↗
PubMed1988

Lipid-phase structure in epithelial cell membranes: comparison of renal brush border and basolateral membranes.

The lipid-phase structures of brush border membrane vesicles (BBMV) and basolateral membrane vesicles (BLMV) isolated from rabbit renal cortex were compared by steady-state and phase-modulation measurements of diphenylhexatriene (DPH) and trans- and cis-parinaric acid (tPnA and cPnA) fluorescence. A temperature-scanning system was used which gave reproducible temperature profiles of steady-state and dynamic fluorescence parameters with a resolution of 0.1 degrees C. Steady-state anisotropy of DPH showed a triphasic dependence on temperature with slope discontinuities at 22 +/- 4 and 47 +/- 3 degrees C (BBMV) and at 23 +/- 2 and 48 +/- 1 degrees C (BLMV). At all temperatures, DPH anisotropy in BBMV was greater than that in BLMV. Ground-state heterogeneity analysis of tPnA and cPnA fluorescence lifetime data demonstrated the presence of long (greater than 12 ns) and short (less than 5 ns) lifetime components, interpreted in terms of solid-phase and fluid-phase lipid domains. The fraction of solid-phase phospholipid decreased from 0.9 to 0.1 for BBMV and from 0.7 to 0.3 in BLMV with increasing temperature (10-50 degrees C). In both membranes, tryptophan-PnA fluorescence energy-transfer measurements showed that membrane proteins were surrounded by a fluidlike phospholipid phase. These results demonstrate the inadequacy of steady-state DPH anisotropy data in defining the structural characteristics of complex biological membranes. Results obtained with the phase-sensitive parinaric acid probes demonstrate major differences in the phase structure of the two opposing cell membranes in both the bulk lipid and the lipid microenvironment around membrane proteins.

Animals↗
PubMed2003

Nasal polyps and middle turbinates epithelial cells sensitivity to amphotericin B.

HYPOTHESIS: Intranasal application of the antimycotic agent amphotericin B (AmphoB) has been proposed as an effective treatment of chronic rhinosinusitis (CRS) with polyps. AmphoB is a sterol-binding agent known to modify cell membrane structure. The cytotoxic effects of AmphoB were studied on primary human nasal epithelial cells in vitro. METHODS: Human epithelial cells were isolated from nasal polyps and middle turbinates of patients suffering from CRS, and grown on collagen-coated polycarbonate filters with an air liquid-interface. After 15 days of culture, cells were exposed apically to 50 microM AmphoB during 4 h daily for 5 days. Some cells were treated during 4 weeks. The bioelectric properties of cells were then studied in Ussing chambers. Integrity of the cell monolayers was assessed by measurement of the transepithelial resistance (R) and immunofluorescent localization of the tight junction protein occludin. RESULTS: Disruption of the epithelial monolayer integrity was observed in all of the nasal polyps cell cultures, as demonstrated by a 60% drop in R. Immunofluorescence microscopy showed significant loss in cell number and disruption in the distribution of occludin. Turbinate cell cultures elicited no change in R and expression of occludin after AmphoB treatment. However, the transepithelial potential, the basal short-circuit current and the amiloride-sensitive current were reduced by 70%. CONCLUSIONS: AmphoB was cytotoxic for nasal polyp epithelial cells with disruption of the epithelium integrity and loss of tight junctions. In contrast, integrity of turbinate epithelial cells was conserved despite alterations in transepithelial ion transport. These observations may explain the beneficial effect of intranasal application of AmphoB on CRS observed in clinical trials.

Amphotericin B↗
PubMed1996

Mechanism of action of NIM-76: a novel vaginal contraceptive from neem oil.

The present study was undertaken to elucidate the mechanism of spermicidal action of NIM-76, a fraction isolated from neem oil. The spermicidal activity of NIM-76 was confirmed using a fluorescent staining technique. NIM-76 was found to affect the motility of the sperm in a dose-dependent manner. Supplementation of pentoxifylline, which is known to enhance the motility of the sperm, could not prevent the spermicidal action of NIM-76. There was a gradual leakage of cytosolic LDH from the sperm in the presence of NIM-76. Electron microscopic studies revealed the formation of pores and vesicles over the sperm head, indicating the damage to the cell membrane. Membrane fluidization studies did not reveal any significant change in the fluidity of sperm cell membrane structure.

Animals↗
PubMed1978

Role of cell-cell interactions in mitogenic stimulation of lymphocytes. I. Dissociation on concanavalin A-inducible lymphocyte activation and agglutination.

The aim of the study was to decide whether the delayed agglutination of lymphocytes following mitogenic doses of concanavalin A (Con A) is a prerequisite of the activation process. It was shown that both phenomena can be greatly dissociated; suitable doses of cytochalasin B (CB) completely block agglutination, while the capacity to respond (by [14C]thymidine incorporation) to Con A-induced stimulation is retained. It was concluded that agglutinability is acquired in the early phase of the activation process, concomitant with induced changes in the cell membrane structure; the manifestation (i.e. agglutination) of this capacity is not necessary for the activation of the cell nucleus to take place, and it depends on the cells' chances of being brought together, either by active movement or by external forces.

Agglutination↗
PubMed1982

Inactivation of Kell blood group antigens by 2-aminoethylisothiouronium bromide.

Human red cells incubated with a solution containing 6% 2-aminoethylisothiouronium bromide (AET) lose activity of antigens that are part of, or related to, the Kell blood group system. However, Kx antigen is not inactivated. Studies on a wide range of other blood-group antigens show no other evidence of changes and AET appears to react specifically with red-cell membrane structures that have Kell activity. The AET procedure produces an artificial K0 red cell that can be used in blood group serology, and allows easy recognition of antibodies that are associated with the Kell system. AET has been used by other workers to produce a red cell that has many serological and biochemical characteristics of a PNH cell. Our studies on red cells from PNH patients have not shown any changes in Kell blood-group antigens.

Blood Group Antigens↗
PubMed1989

[The distribution of chlorine e6 and its derivatives in HeLa cells studied using luminescence microscopy].

The influence of the chemical structure of porphyrin pigments on their accumulation and localization in HeLa cells has been examined by the scanning fluorescence microphotometry. It has been found that the replacement of carboxyl groups of chlorine e6 for methyl and amino groups has no influence on the pigment distributions in cells. All the pigments are bound by cell membrane structures. The chemical modification of chlorine e6 structure is essential for the ability of pigment to be accumulated by cells that can be used to increase the efficiency of cancer phototherapy. The charge and hydrophobic properties of pigment molecules are of great importance for accumulating porphyrin sensitizers by cells.

Chlorophyllides↗
PubMedDate not supplied

Glycoproteins in disease.

The class of carbohydrate macromolecules known as glycoproteins exhibits great structural diversity. Their key role in the function of biological systems includes determination of cell membrane structure and function as well as antigenic determinants. In the recent decade, the detection of inborn errors of metabolism of these macromolecules as well as changes in their composition following mutagenesis and oncogenesis have highlighted the key role they play in the biology of man. The application of analytic techniques for their quantitation and structural characterization has resulted in their increasing utility in diagnostic medicine. They may be used not only as markers of active and inactive disease, but they also have become important in the diagnosis of congenital defects and tumors.

ABO Blood-Group System↗
PubMed1994

Glutathione treatment of dyspermia: effect on the lipoperoxidation process.

We recently introduced reduced glutathione into the therapeutic protocols in some selected cases of dyspermia. This therapy improved semen quality both in a pilot follow-up study and in a double-blind cross-over trial. This improvement was seen in patients with varicocele and germ-free genital tract inflammation, two pathologies in which production of reactive oxygen species or other toxic compounds could have a pathogenic role. Polyunsaturated fatty acids of phospholipids play a major role in membrane constitution and function and are one of the main targets of the lipoperoxidative process. Therefore, to understand the therapeutic action of reduced glutathione, we selected infertile patients and studied the modifications produced by the therapy in seminal parameters, biochemical sperm membrane parameters, and the pattern of fatty acids of phospholipids from blood serum and red blood cell membranes (a model widely accepted as representative of general cell membrane status). The results showed an improvement in both sperm parameters and cell membrane characteristics. This study suggests that biochemical modifications in membrane constitution could explain the seminal results of glutathione therapy. On the other hand, it seems likely that only subjects with systemic membrane disturbances associated with andrological pathologies express this membrane damage in spermatozoa, resulting in dyspermia. This sperm alteration can be partially reversed by glutathione therapy if the structural cell membrane damage is not too severe.

Adult↗
PubMed2000

Scavenger receptor BI transfers major lipoprotein-associated phospholipids into the cells.

The phospholipids of lipoproteins can be transferred to cells by an endocytosis-independent uptake pathway. We analyzed the role of scavenger receptor BI (SR-BI) for the selective cellular phospholipid import. Human monocytes rapidly acquired the pyrene (py)-labeled phospholipids sphingomyelin (SM), phosphatidylcholine, and phosphatidylethanolamine from different donors (low and high density lipoproteins (LDL, HDL), lipid vesicles). The anti-SR-BI antibody directed against the extracellular loop of the membrane protein lowered the cellular import of the phospholipids by 40-80%. The phospholipid transfer from the lipid vesicles into the monocytes was suppressed by LDL, HDL, and apoprotein AI. Transfection of BHK cells with the cDNA for human SR-BI enhanced the cellular import of the vesicle-derived py-phospholipids by 5-6-fold. In the case of the LDL donors, transfer of py-SM to the transfected cells was stimulated to a greater extent than the uptake of the other py-phospholipids. Similar differences were not observed when the vesicles and HDL were used as phospholipid donors. The concentration of LDL required for the half-maximal phospholipid import was close to the previously reported apparent dissociation constant for LDL binding to SR-BI. The low activation energy of the SR-BI-mediated py-phospholipid import indicated that the transfer occurs entirely in a hydrophobic environment. Disruption of cell membrane caveolae by cyclodextrin treatment reduced the SR-BI-catalyzed incorporation of py-SM, suggesting that intact caveolae are necessary for the phospholipid uptake. In conclusion, SR-BI mediates the selective import of the major lipoprotein-associated phospholipids into the cells, the transfer efficiency being dependent on the structure of the donor lipoprotein.

Animals↗
PubMed1977

[Effect of polyenic antibiotics on the activity of alkaline phosphatase from Candida albicans].

Polyenic antibiotics (levorin, amphotericin B, nistatin) inhibit in vivo and in vitro the activity of membrane alkaline phosphatase from sensitive Candida albicans strain, and their inhibitory effect is twice lower on the enzyme from the resistant strain. A correlation is observed between the antibiotic concentration and the inhibitory effect on alkaline phosphatase activity. Nistatin is found to be the least efficient inhibitor (among the antibiotics studied) of alkaline phosphatase. The treatment of membranes with polyenic antibiotics does not result in solubilization of membrane proteins nad alkaline phosphatase. The data obtained are considered with respect to the effect of polyenic antibiotics on cell membrane structure.

Alkaline Phosphatase↗
PubMed1992

Evidence for a membrane defect in Alzheimer disease brain.

To determine whether neurodegeneration in Alzheimer disease brain is associated with degradation of structural cell membrane molecules, we measured tissue levels of the major membrane phospholipids and their metabolites in three cortical areas from postmortem brains of Alzheimer disease patients and matched controls. Among phospholipids, there was a significant (P less than 0.05) decrease in phosphatidylcholine and phosphatidylethanolamine. There were significant (P less than 0.05) decreases in the initial phospholipid precursors choline and ethanolamine and increases in the phospholipid deacylation product glycerophosphocholine. The ratios of glycerophosphocholine to choline and glycerophosphoethanolamine to ethanolamine were significantly increased in all examined Alzheimer disease brain regions. The activity of the glycerophosphocholine-degrading enzyme glycerophosphocholine choline-phosphodiesterase was normal in Alzheimer disease brain. There was a near stoichiometric relationship between the decrease in phospholipids and the increase of phospholipid catabolites. These data are consistent with increased membrane phospholipid degradation in Alzheimer disease brain. Similar phospholipid abnormalities were not detected in brains of patients with Huntington disease, Parkinson disease, or Down syndrome. We conclude that the phospholipid abnormalities described here are not an epiphenomenon of neurodegeneration and that they may be specific for the pathomechanism of Alzheimer disease.

Aged↗
PubMed1992

Involvement of membrane carbohydrates of HeLa cells in the E. coli HB101 (pRI203) invasive pathway.

The recombinant plasmid pRI203 carries a Yersinia pseudotuberculosis chromosomal gene that makes E. coli K-12 HB101 strain able to synthetize an outer membrane protein, invasin, which interacts with integrin receptors of eukaryotic cells, enabling this microorganism to penetrate human cultured animal cells. In this study we evaluated the involvement of HeLa cell membrane structural components in the early phases of the invasive pathway of E. coli HB101 (pRI203). When HeLa cell monolayers were treated with several enzymes we showed that trypsin-, proteinase K- and neuraminidase-sensitive components are required for bacterial invasion. Comparison of the ability of simple and complex carbohydrates to inhibit bacterial invasion indicated that N-acetyl neuraminic acid, N-acetyl glucosamine and mucin were the most effective competitive inhibitors. Among glycolipids, gangliosides enhanced bacterial entry in HeLa cells. The results obtained suggest that N-acetyl neuraminic acid and N-acetyl glucosamine-containing glycoproteins and/or glycolipids participate as putative HeLa cell binding sites for the penetration process of E. coli HB101 (pRI203).

Acetylglucosamine↗
PubMed1996

Constrained diffusion or immobile fraction on cell surfaces: a new interpretation.

Protein lateral mobility in cell membranes is generally measured using fluorescence photobleaching recovery (FPR). Since the development of this technique, the data have been interpreted by assuming free Brownian diffusion of cell surface receptors in two dimensions, an interpretation that requires that a subset of the diffusing species remains immobile. The origin of this so-called immobile fraction remains a mystery. In FPR, the motions of thousands of particles are inherently averaged, inevitably masking the details of individual motions. Recently, tracking of individual cell surface receptors has identified several distinct types of motion (Gross and Webb, 1988; Ghosh and Webb, 1988, 1990, 1994; Kusumi et al. 1993; Qian et al. 1991; Slattery, 1995), thereby calling into question the classical interpretation of FPR data as free Brownian motion of a limited mobile fraction. We have measured the motion of fluorescently labeled immunoglobulin E complexed to high affinity receptors (Fc epsilon RI) on rat basophilic leukemia cells using both single particle tracking and FPR. As in previous studies, our tracking results show that individual receptors may diffuse freely, or may exhibit restricted, time-dependent (anomalous) diffusion. Accordingly, we have analyzed FPR data by a new model to take this varied motion into account, and we show that the immobile fraction may be due to particles moving with the anomalous subdiffusion associated with restricted lateral mobility. Anomalous subdiffusion denotes random molecular motion in which the mean square displacements grow as a power law in time with a fractional positive exponent less than one. These findings call for a new model of cell membrane structure.

Animals↗
PubMed1988

T4 cell receptor distortion in acquired immune deficiency syndrome.

Among the possible affects of the HIV virus on T-cells in Acquired Immune Deficiency Syndrome is the cell membrane distortion of the T4 cell protein receptor for Genetically Related Macrophage Factor (GRF). The integrity of this specific T-cell receptor takes on profound significance due to its relationship to soluble antigen. Alpha-tocopheral has been shown to assist in the maintenance of cell membrane structure and may have application in a strategy of membrane restoration. Adoptive Transfer, a method of immune cell alteration applicable in anti-tumor therapy, may play a role in the mechanics of such a strategy.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Hormone regulation of cardiac energy metabolism. I. Creatine transport across cell membranes of euthyroid and hyperthyroid rat heart.

Hyperthyroid rat heart was studied with the purpose of identifying the mechanism for the significant decrease in total creatine (free creatine plus phosphocreatine) observed in this pathology and its consequences on heart function. Administration of L-thyroxine in doses of 50-100 micrograms/100 g of body weight during a week resulted in a reversible decrease of the total creatine by 40-50%. Simultaneously, remarkable changes in the creatine transport system across the cardiac cell membranes were observed: both the maximal rate of its active uptake and its passive movement along its concentration gradient were enhanced. In euthyroid hearts, the parameters of creatine uptake (Km approximately or equal to 0.05 mM, Vmax = 20 nmole/min/g dry weight) were similar to those for skeletal muscle and the passive movement of creatine was negligible. In hyperthyroid hearts the latter rate was enhanced to 0.4 mumole min/g dry weight, this showing reversible damages in the cell membrane structure induced by L-thyroxine. This conclusion is consistent with observed penetration of colloidal lanthanum into the cells of hyperthyroid hearts. Perfusion of hyperthyroid rat hearts with 50 mM creatine significantly restored creatine content in the cells, Hyperthyroid hearts with decreased creatine content were found to develop ischemic contracture more rapidly and in higher extent than the euthyroid hearts. Increased sensitivity to ischemic damage may be related to decreased efficiency of energy channeling via phosphocreatine pathway.

Animals↗
PubMed2003

[Principles of changes of structural organization of cell membranes and functional properties of erythrocytes in neurotic disorders].

Investigation into structural, metabolic, and functional conditions of red blood cells was performed in 24 patients with a neurosis (neurasthenia, disturbance of asaptation) with the aid of electrophoretic division of proteins of the erythrocyte membrane, thin-layer chromatography, fluorescent probing of membranes, evaluation of peroxidative oxidation process, scanning and transmission electron microscopy, laser diphractometry, photometry. The patients with neurotic disorders at the early period after the influence of psychogenic factors (up to 3 months) revealed disorganization of lipid and protein composition of the red cell membrane, increase in microviscosity of its lipid phase, impairment of surface architectonics and ultrastructure of red cells, decrease of a deformation ability and increase of aggregate properties of erythrocytes. The authors treat stability of erythrocytes' homeostasis under the long-term influence of psychogenic factors from a viewpoint of adaptive changes in organism under the influence of neurogenic factors.

Adult↗