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PubMedDate not supplied

Effect of aqueous cigarette smoke extract on the chemiluminescence kinetics of polymorphonuclear leukocytes and on their glycolytic and phagocytic activity.

Water-soluble extracts of cigarette smoke are easily formed in some body compartments, such as saliva or fluid lining alveolar spaces, and can act on both cellular and extracellular compartments. In this paper we have analysed the effect of aqueous smoke extract on some metabolic and functional aspects of polymorphonuclear leukocytes. In particular, the following cellular aspects were studied: chemiluminescence, glycolysis, membrane fluidity and microscopic interaction with zymosan particles. While chemiluminescence and glycolytic activity are highly inhibited, no effect of smoke extract on membrane fluidity was observed. Moreover, the response of luminol-dependent chemiluminescence was significantly delayed, while that of lucigenin-dependent chemiluminescence was anticipated. Furthermore, the phagocytic ability of neutrophils pretreated with aqueous smoke extract was also significantly hindered. All these results might indicate that the finely tuned activity of polymorphonuclear leukocytes is somehow hampered by the aqueous extract of cigarette smoke in a way which makes these cells less effective against bacteria and more noxious towards surrounding tissues.

2-Naphthylamine↗
PubMed2001

Preparation, stability, and in vitro performance of vesicles made with diblock copolymers.

Vesicles made completely from diblock copolymers-polymersomes-can be stably prepared by a wide range of techniques common to liposomes. Processes such as film rehydration, sonication, and extrusion can generate many-micron giants as well as monodisperse, approximately 100 nm vesicles of PEO-PEE (polyethyleneoxide-polyethylethylene) or PEO-PBD (polyethyleneoxide-polybutadiene). These thick-walled vesicles of polymer can encapsulate macromolecules just as liposomes can but, unlike many pure liposome systems, these polymersomes exhibit no in-surface thermal transitions and a subpopulation even survive autoclaving. Suspension in blood plasma has no immediate ill-effect on vesicle stability, and neither adhesion nor stimulation of phagocytes are apparent when giant polymersomes are held in direct, protracted contact. Proliferating cells, in addition, are unaffected when cultured for an extended time with an excess of polymersomes. The effects are consistent with the steric stabilization that PEG-lipid can impart to liposomes, but the present single-component polymersomes are far more stable mechanically and are not limited by PEG-driven micellization. The results potentiate a broad new class of technologically useful, polymer-based vesicles.

2-Naphthylamine↗
PubMed2006

Microfluorometry of cell membrane dynamics.

Membranes of living cells are characterized by a combination of conventional and total internal reflection fluorescence microscopy (TIRFM) using the membrane marker laurdan. In the first case, all cellular membranes are assessed simultaneously, whereas in the second case, the plasma membrane is excited selectively by the evanescent electromagnetic field of a laser beam. A spectral shift depending on the phase of membrane lipids is used to characterize membrane stiffness, which decreases with temperature and increases with the amount of cholesterol. Spectral properties are evaluated and displayed as microscopic images.

2-Naphthylamine↗
PubMedDate not supplied

Lead-induced changes in human erythrocytes and lymphocytes.

In the present work we studied, by chemiluminescence measurements, the influence of lead on the production of reactive oxygen species (ROS) in haemolysates obtained from human erythrocytes incubated in the presence of different concentrations of lead acetate. Moreover, we evaluated the modification of proteins and lipids in human erythrocyte and lymphocyte membranes by using the fluorescence probes N-(1-pyrene)maleimide (PM), laurdan and pyrene. No significant changes in chemiluminescence were detected for erythrocytes incubated with 1-10 microM lead acetate for 3 h at 37 degrees C. By increasing the lead acetate concentration in cell suspensions up to 50 microM for the same incubation time, the percentage of chemiluminescence inhibition was ca. 20%. It was shown that, after incorporating fluorescence probes in the membrane lipid bilayer of erythrocytes and lymphocytes treated with 10 and/or 50 microM lead acetate, the total fluorescence intensity and the excimer to monomer intensity ratio of PM decreased and the generalized fluorescence polarization of laurdan decreased by 10-15%. The pyrene excimerization coefficient (kappa(ex)) increased by 20% (in comparison with a magnitude of kappa(ex) for white membranes isolated from intact erythrocytes) with 6-10 microM lead acetate for 3 h at 37 degrees C. The data obtained suggest that the effect of low concentrations of lead acetate does not cause production of ROS in erythrocytes in vitro, but can change the physicochemical state of proteins and lipids in erythrocyte and lymphocyte membranes. This effect is important because it influences the enzymatic activity and the functionality of receptors and channels present at the plasma membrane level, thus modulating the molecular composition of the intracellular space and cell functions.

2-Naphthylamine↗
PubMed1991

Regulation of neuronal differentiation in neuron-enriched primary cultures from embryonic rat cerebra by platelet activating factor and the structurally related glycerol ether lipid, dodecylglycerol.

Primary cultures enriched in neurons dissociated from embryonic rat cerebra were used to demonstrate that platelet activating factor and the structurally related ether glycerolipid, dodecylglycerol, are readily taken up in small amounts by neurons and that they stimulate the differentiation of neurons. The stimulation of neuronal differentiation was observed as a precocious development of axon-like extensions which correlated with a concentration-dependent increase in neuronal-specific enzyme activities. This stimulation of morphological and neurochemical factors by either platelet activating factor or dodecylglycerol was almost completely abolished by triazolam, a known inhibitor of platelet activating factor function. Neither platelet activating factor nor dodecylglycerol at the concentrations used to achieve stimulation of neuronal differentiation compromised the plasma membrane, as indicated by the lack of leakage of cytoplasmic lactic acid dehydrogenase.

Acetylcholinesterase↗
PubMed1988

Preparation and characterization of disodium fluorescein powders in association with lauric and capric acids.

Hygroscopic growth of pharmaceutical aerosol powders is a factor governing their deposition, absorption, and pharmacologic effect in the respiratory tract. Surface association of hydrophobic molecules may reduce this effect. Disodium fluorescein was coated with the hydrophobic materials lauric and capric acids. The nature and extent of the association was investigated by a variety of techniques, with the notable use of X-ray photoelectron spectroscopy to examine the powder surface directly. It was concluded that the fatty acids associate at the phenol--sodium bond of the disodium fluorescein, and that the extent of the bulk interaction was governed by a fatty acid-, solute-, and concentration-dependent expanded surface area effect which resulted in much higher surface concentrations than might be expected by simple adsorption.

Caproates↗
PubMed1995

beta-Cryptoxanthin selectively increases in human chylomicrons upon ingestion of tangerine concentrate rich in beta-cryptoxanthin esters.

beta-Cryptoxanthin is a major source of vitamin A, often second only to beta-carotene, and is present in fruits such as oranges, tangerines, and papayas. Here, we studied the uptake of this carotenoid upon ingestion of tangerine juice concentrate, rich in beta-cryptoxanthin esters. Increasing amounts of free beta-cryptoxanthin were detected in chylomicrons and serum. Peak levels in chylomicrons were reached at t = 6 h, and the concentration returned toward basal levels at t = 9 h. No beta-cryptoxanthin esters were detected in chylomicrons or serum, indicating efficient cleavage in the intestine before the carotenoid is incorporated into lipoproteins by the liver. Other xanthophyll esters, e.g., of zeaxanthin and lutein, were present in low amounts in the tangerine concentrate. As with beta-cryptoxanthin, no esters appeared in serum or chylomicrons, suggesting that the cleavage of carotenoid esters prior to release into the lymphatic circulation occurs generally in human oxocarotenoid biokinetics.

Absorption↗
PubMed1999

Phase properties of liquid-crystalline Phosphatidylcholine/Phosphatidylethanolamine bilayers revealed by fluorescent probes.

The mixing properties of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) were examined in liquid-crystalline phase using fluorescent probes incorporated into lipid bilayers. The excimer to monomer (E/M) fluorescence ratio of 1-hexadecanoyl-2-(1-pyrenedecanoyl)-sn-glycero-3-phosphocholine (PPC) versus PPC concentration was higher for binary mixtures containing phosphatidylcholine (PC)/phosphatidylethanolamine (PE) (1:1) compared to PC matrix. When POPC was gradually replaced with POPE, the E/M ratio also increased suggesting the enhanced lateral mobility or the lateral enrichment of PPC into domains or both. Evidences for the PE-induced domain formation were further provided by resonance energy transfer between 2-(4, 4-difluoro-5-methyl-4-boro-3a, 4a-diaza-s-indacene-3-dodecanoyl)-1-hexadecanoyl-sn-glycero- 3-phospho choline and PPC, which was enhanced as a function of PE concentration, and by the polarization of 1,6-diphenyl-1,3, 5-hexatriene. In addition, PE reduced free volume and polarity of lipid bilayers as measured by the emission fluorescence of 1,2-bis PPC and 6-lauroyl-2-dimethylaminonaphthalene. When POPE analogs with a methylated head group instead of normal POPE were used, the diminished effect on the domain formation was shown in the order N-methyl PE > N,N-dimethyl PE. The results suggest that the mixing properties of POPE and POPC are not random but that lipid domains of phospholipids are formed.

2-Naphthylamine↗
PubMed2000

Effects of Al(3+) and related metals on membrane phase state and hydration: correlation with lipid oxidation.

The aim of the present study was to further understand how changes in membrane organization can lead to higher rates of lipid oxidation. We previously demonstrated that Al(3+), Sc(3+), Ga(3+), Be(2+), Y(3+), and La(3+) promote lipid packing and lateral phase separation. Using the probe Laurdan, we evaluated in liposomes if the higher rigidity of the membrane caused by Al(3+) can alter membrane phase state and/or hydration, and the relation of this effect to Al(3+)-stimulated lipid oxidation. In liposomes of dimyristoyl phosphatidylcholine and dimyristoyl phosphatidylserine, Al(3+) (10-100 microM) induced phase coexistence and displacement of T(m). In contrast, in liposomes of brain phosphatidylcholine and brain phosphatidylserine, Al(3+) (10-200 microM) did not affect membrane phase state but increased Laurdan generalized polarization (GP = -0. 04 and 0.09 in the absence and presence of 200 microM Al(3+), respectively). Sc(3+), Ga(3+), Be(2+), Y(3+), and La(3+) also increased GP values, with an effect equivalent to a decrease in membrane temperature between 10 and 20 degrees C. GP values in the presence of the cations were significantly correlated (r(2) = 0.98, P < 0.001) with their capacity to stimulate Fe(2+)-initiated lipid oxidation. Metal-promoted membrane dehydration did not correlate with ability to enhance lipid oxidation, indicating that dehydration of the phospholipid polar headgroup is not a mechanism involved in cation-mediated enhancement of Fe(2+)-initiated lipid oxidation. Results indicate that changes in membrane phospholipid phase state favoring the displacement to gel state can facilitate the propagation of lipid oxidation.

2-Naphthylamine↗
PubMed2000

Lipid-protein interactions in rat renal subcellular membranes: a biophysical and biochemical study.

The phase behavior of plasma membrane (PM), endoplasmic reticulum (ER), and nuclear membranes (NM) isolated from adult rat papillary cells was studied using the molecular probe Laurdan. The steady-state fluorescence data analysis was correlated with the lipid composition obtained by biochemical assays. The comparison between intact membranes and protein-free reconstituted vesicles using the whole lipid extract shows the essential role of proteins on the temperature response of natural membranes. The phospholipid (PL) and cholesterol (Cho) content was measured in the three membrane fractions, the PL/Cho molar ratio being between 1.5 and 1.9. However, Laurdan's parameters in NM show a fluid phase state pattern even at low temperature (5 degrees C), with a restricted dipole relaxation in comparison with that displayed in liquid crystalline phase state lipid model membranes. PM and ER are in a gel-like state at temperatures below 20 degrees C, showing increasing dipole relaxation with temperature. The curved fits obtained are characteristic of cholesterol-enriched membranes. The distinctive phase behavior of nuclear membranes vanishes when proteins are extracted. However, relaxation is still faster in this fraction, which correlates with the native lipid composition. NM has the lowest percentage of phosphatidylinositol and sphingomyelin-the latter being a highly saturated phospholipid- and the highest percentage of phosphatidylcholine and phosphatidylethanolamine (PE), nuclear PE being enriched in arachidonic acid. All these changes agree with the higher fluidity of NM compared with ER or PM in the conditions assayed.

2-Naphthylamine↗
PubMed1996

Vitamin D3-binding protein as a precursor for macrophage activating factor in the inflammation-primed macrophage activation cascade in rats.

When rat peritoneal nonadherent cells were treated with inflammatory lipid metabolites and cultured with adherent cells in 1% fetal calf serum (FCS) supplemented medium RPMI 1640 (FCS medium) for 3 hr, markedly enhanced phagocytic and superoxide generating capacities of macrophages were observed. Stepwise preparation of conditioned medium of lysophosphatidylcholine (lyso-Pc)-treated B cells and untreated T cells in FCS medium generated a potent macrophage activating factor whereas cultivation of lyso-Pc-treated B cells alone in a 1% adult rat serum supplemented medium efficiently generated the macrophage activating factor. Generation of macrophage activating factor requires a precursor protein, serum vitamin D3-binding protein (DBP), as well as participation of lymphocyte glycosidases. The lyso-Pc-inducible beta-galactosidase of B lymphocytes and the Neu-1 sialidase of T lymphocytes modified bovine DBP (bDBP) to yield the macrophage activating factor, a protein with N-acetylgalactosamine as the remaining sugar. In contrast, lyso-Pc-inducible beta-galactosidase of B cells alone modified rat DBP (rDBP) to yield the macrophage activating factor, a protein with N-acetylgalactosamine as the remaining sugar. Thus, we conclude that bDBP carries a trisaccharide composed of N-acetylgalactosamine, galactose, and sialic acid while rDBP carries a disaccharide composed of N-acetylgalactosamine and galactose.

Animals↗
PubMed1984

Synthetic surfactants: a new approach to the development of shark repellents.

The toxic and shark repellent secretion of Pardachirus marmoratus (PMC) and a series of 15 surfactants and industrial detergents were assayed for their lethality to fish, termination of shark's tonic immobility and feeding inhibition of aggressive, hungry lemon sharks. Sodium and lithium lauryl sulfate salts were more potent than PMC in all three bioassays. Graduated activity, from mildly repellent to inactive, was demonstrated by several other surfactants. The abundance, versatility, chemical stability, modifiability, and low price of detergents justify their use in further development of effective shark repellents.

Animals↗
PubMed1984

Inhibition of peptidoglycan synthesis of Streptococcus faecium ATCC 9790 and Streptococcus mutans BHT by the antibacterial agent dodecyl glycerol.

Dodecyl glycerol inhibits the synthesis of the peptidoglycans of Streptococcus faecium ATCC 9790 and Streptococcus mutans BHT. This metabolic regulation represents the second known mode by which dodecyl glycerol expresses antibacterial activity. The first mode of action of dodecyl glycerol was shown to stimulate autolysin activity which degrades cell-wall peptidoglycan (Ved HS, Gustow E, Mahadevan V and Pieringer RA, 1984, J. Biol. Chem. 259, 8115-8121).

Carbon Radioisotopes↗
PubMed1994

Participation of serum proteins in the inflammation-primed activation of macrophages.

Inflamed lesions release degradation products of membrane lipids, lysophospholipids, and inflamed tumor tissues release alkylglycerols. Macrophages were activated by administration of lysophosphatidylcholine (lyso-Pc) or dodecylglycerol (DDG) to mice. In vitro treatment of mouse peritoneal cells (mixture of nonadherent and adherent cells) with lyso-Pc or DDG in fetal calf serum supplemented medium for 30 min, followed by 3-h cultivation of adherent cells (macrophages) alone, resulted in greatly enhanced Fc-receptor mediated phagocytic activity and superoxide generating capacity of macrophages. The tumor lipid metabolite, DDG, is far more potent (400-fold) than lyso-Pc in terms of doses required for the maximal levels of macrophage activation. The inflammation-primed macrophage activation required a serum factor, vitamin D binding protein, as a precursor for the macrophage activating factor. Treatment of mouse peritoneal cells with 1 microgram lyso-Pc/ml or 50 ng DDG/ml in a serum-free 0.1% egg albumin supplemented medium for 30 min, followed by 3-h cultivation of the treated peritoneal cells in a medium supplemented with a very small amount (0.0005-0.05%) of ammonium sulfate [20-50% saturated (NH4)2SO4] precipitable protein fraction of FCS, resulted in greatly enhanced superoxide generating capacity of macrophages. The ammonium sulfate precipitable fraction was found to contain vitamin D binding protein.

Ammonium Sulfate↗
PubMed1975

Compartmentalization of amino acids in surfactant aggregates. Partitioning between water and aqueous micellar sodium deodecanoate and between hexane and dodecylammonium propionate trapped water in hexane.

Cationic amino acids, arginine and lysine partition differentially from water into aqueous micellar sodium dodecanoate. Conversely, partitioning of serine, glycine, aspartic acid, glutamic acid, threonine, alanine, proline, valine, leucine, phenylalanine and isoleucine do not vary appreciably. Partitioning from neat hexane into dodecylammonium propionate trapped water in hexane is, however, dependent upon both electrostatic and hydrophobic interactions. These results imply that the interior of dedecylammonium propionate aggregates is negatively charged and is capable of hydrogen bonding in addition to providing a hydrophobic enviroment. The solubilities of amino acids in neat hexane substantiate the previously derived amino acid hydrophobicity scale. Relevance of partitioning in these systems to the postulated selective amino acid compartmentalization is discussed.

Alanine↗
PubMed1990

Synergism between penicillin G and the antimicrobial ether lipid, rac-1-dodecylglycerol, acting below its critical micelle concentration.

rac-1-Dodecylglycerol (DDG) and penicillin G (Pen G) act synergistically to dramatically lower the minimum inhibitory concentration (MIC) of each other in four Gram-positive bacteria studied. At one-half its MIC, DDG ether lowered the MIC of Pen G 10- to 80-fold. Under the same conditions, Pen G lowered the MIC of DDG 4- to 7.5-fold. The critical micelle concentration of DDG was determined to be 7.93 mg/ml (0.0305 mM), which is approximately two-fold greater than the minimum inhibitory concentration of DDG determined in the presence of a protein-free chemically defined medium. This finding suggests that DDG is not killing bacteria through its detergent action. Pen G also did not alter the critical micelle concentration of DDG, which indicates that the synergism between these two agents is not related to micelle formation.

Anti-Bacterial Agents↗
PubMedDate not supplied

Dodecylglycerol provides partial protection against glutamate toxicity in neuronal cultures derived from different regions of embryonic rat brain.

Primary cultures enriched in neurons dissociated from embryonic rat cerebral cortex, cerebellum, or hippocampus were treated in a chemically defined serum-free media with either vehicle, dodecylglycerol (DDG, 3 microM), or glutamate (75 microM), or preincubated with DDG for 4 or 24 h, and further incubated with glutamate. Their morphological and biochemical assessments (lactate dehydrogenase [LDH] release in the culture media, neuronal viability and intracellular Ca2+ mobilization) were made. Neurotoxic effects of glutamate and glutamate-mediated increases in intracellular Ca2+ were maximal in neurons from cerebellum and minimal in neurons from cortex. Cotreatment of cells with DDG and glutamate failed to provide significant neuronal protection against glutamate in the three brain regions. Pretreatment of cells with DDG for 4 or 24 h prior to glutamate treatment provided significant neuroprotection as judged by morphological changes and a decrease in LDH activity. Neuroprotection of approximately 15-35% was observed following 4 h of DDG pretreatment, increasing to 60-85% protection after 24 h of DDG pretreatment. Although the mechanism of DDG's neuroprotective action remains to be elucidated, these results demonstrate that both glutamate and DDG have differential specificity for anatomical regions of the brain.

Animals↗
PubMed2006

Membrane physical state as key parameter for the resistance of the gram-negative Bradyrhizobium japonicum to hyperosmotic treatments.

The survival of Bradyrhizobium japonicum under hyperosmotic treatments achieved at various temperatures was investigated. The bacterial viability was measured at a combination of different levels of osmotic pressure (1.4-49.2 MPa) in glycerol solutions and temperature (4-28 degrees C). Viability was dependent on these two variables, with low temperatures (10 and 4 degrees C) exhibiting a protective effect against exposure to high levels of osmotic pressure. To understand these results, the relation between membrane physical state and structure of whole cells and osmotic shock tolerance of B. japonicum was studied. Membrane physical changes were evaluated by using 1,3-diphenyl-1,3,5-hexatriene (DPH) and Laurdan (6-dodecanoil-2-dimethylaminonaphtelene) as probes. The results showed that the membrane of B. japonicum was subjected to a progressive phase transition from the liquid-crystalline to the gel phase during cooling between 28 and 4 degrees C. Accordingly, under isotonic conditions, the Laurdan GP spectra showed that, in the range 12-28 degrees C, membrane lipids were in the liquid-crystalline phase, and in a gel phase at 4 degrees C. The study of the variation in anisotropy of DPH revealed that cooling cells before the hyperosmotic treatment could induce opposite effects to the fluidizing effect of the hyperosmotic shock. Cell resistance was finally related to modifications of the membrane structure depending on combined effects of cooling and dehydration.

2-Naphthylamine↗