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1
Blöcher, Detlef, Raymund Gutermann, Birgit Henkel, and Klaus Ring. "Physicochemical Characterization of Tetraetherlipids from Thermoplasma acidophilum." Zeitschrift für Naturforschung C 40, no. 9-10 (August 1, 1985): 606–11. http://dx.doi.org/10.1515/znc-1985-9-1003.
Анотація:
Abstract By means of differential thermoanalysis, the miscibility of the main polar tetraether lipid of Thermoplasma acidophilum with two ester lipids, dipalmitoyl phosphatidylcholine and dipalmitoyl phosphatidylglycerol, resp., in the presence of excess water was studied. It is shown that with increasing fraction of tetraether lipid in the mixture, the transition range of dipalmitoyl phosphatidylcholine is broadened and the temperature of the maximum heat flow (Tm) is shifted to lower temperatures; furthermore, the enthaply change (ΔH) of the transition declines. Similar results were obtained with mixtures of tetraether lipid with dipalmitoyl phosphatidylglycerol. It is therefore concluded that the main polar tetraether lipid of Thermoplasma acidophilum , which essentially forms monomolecular layers, is able to form stable common phases with bilayer-forming ester lipids. Miscibility of the tetraether lipid with dipalmitoyl phosphatidylglycerol, which are both monovalent anions at neutral pH, is also observed in the presence of high proton or calcium ion concentrations.
2
Schlame, M., C. Casals, B. Rüstow, H. Rabe, and D. Kunze. "Molecular species of phosphatidylcholine and phosphatidylglycerol in rat lung surfactant and different pools of pneumocytes type II." Biochemical Journal 253, no. 1 (July 1, 1988): 209–15. http://dx.doi.org/10.1042/bj2530209.
Анотація:
It is not yet completely understood how a cell is able to export specific phospholipids, like dipalmitoylphosphatidylcholine (dipalmitoyl-PC), which is secreted by pneumocytes type II, into pulmonary surfactant. The acyl species composition of [3H]PC which was synthesized in type II cells in the presence of [2-3H]glycerol resembled the species composition of PC localized in intracellular pneumocyte membranes. This species pattern was different from the pattern of PC of lamellar bodies, i.e., intracellularly stored surfactant, by a higher proportion of dipalmitoyl-PC mainly at expense of 1-palmitoyl-2-oleoyl-PC. Lamellar body PC in turn showed the same species distribution as surfactant PC. The data suggest that subcellular compartmentation and/or intracellular transfer of PC destined to storage in lamellar bodies, but not secretion of lamellar bodies, involves an enrichment of dipalmitoyl-PC and a depletion of 1-palmitoyl-2-oleoyl-PC. In contrast, the acyl species pattern of phosphatidylglycerol does not seem to undergo gross changes on the path from synthesis to secretion.
3
Girod, S., C. Galabert, D. Pierrot, M. M. Boissonnade, J. M. Zahm, A. Baszkin, and E. Puchelle. "Role of phospholipid lining on respiratory mucus clearance by cough." Journal of Applied Physiology 71, no. 6 (December 1, 1991): 2262–66. http://dx.doi.org/10.1152/jappl.1991.71.6.2262.
Анотація:
Phospholipid lining, present at the respiratory mucus-mucosa interface, may have an important role in the protective function of the airways by its abhesive properties and may also facilitate mucus transport. To mimic respiratory mucus-mucosa interface, monolayers of three different forms of phosphatidylglycerol (PG) have been deposited on glass slides by the Langmuir-Blodgett technique. Mucus adhesion and clearance by cough of mucus on these PG-coated or noncoated surfaces have been analyzed and compared, using frog respiratory mucus as “normal” mucus. Among the three PG types studied, the phosphatidylglycerol distearoyl, which is the phospholipid with the longest saturated fatty acid chain, was found to significantly improve the mucus cough clearance by decreasing the mucus work of adhesion compared with the noncoated surfaces. On the other hand, phosphatidylglycerol dipalmitoyl did not improve mucus cough clearance although it decreased mucus adhesion, and phosphatidylglycerol dioleyl did not improve either mucus cough clearance or mucus adhesion.
4
Kurniawan, Yogi, Keerthi P. Venkataramanan, Mar Piernavieja, Carmen Scholz, and Geoffrey D. Bothun. "Role of Ionic Strength onn-Butanol Partitioning into Anionic Dipalmitoyl Phosphatidylcholine/Phosphatidylglycerol Vesicles." Journal of Physical Chemistry B 117, no. 28 (July 2, 2013): 8484–89. http://dx.doi.org/10.1021/jp403735h.
5
Souza, Adriano L., Lucinéia F. Ceridório, Gustavo F. Paula, Luiz H. C. Mattoso, and Osvaldo N. Oliveira. "Understanding the biocide action of poly(hexamethylene biguanide) using Langmuir monolayers of dipalmitoyl phosphatidylglycerol." Colloids and Surfaces B: Biointerfaces 132 (August 2015): 117–21. http://dx.doi.org/10.1016/j.colsurfb.2015.05.018.
6
Gutberlet, Thomas, Sabine Markwitz, Harald Labischinski, and Hans Bradaczek. "Monolayer investigations on the bacterial amphiphile lipoteichoic acid and on lipoteichoic acid/dipalmitoyl-phosphatidylglycerol mixtures." Makromolekulare Chemie. Macromolecular Symposia 46, no. 1 (June 1991): 283–87. http://dx.doi.org/10.1002/masy.19910460139.
7
Teissié, J. "Interaction of N-phenyl-1-naphthylamine with phospholipid monolayers: a fluorescence investigation." Biochemistry and Cell Biology 68, no. 2 (February 1, 1990): 574–78. http://dx.doi.org/10.1139/o90-082.
Анотація:
Binding isotherms of N-phenyl-1-naphthylamine to different lipid monolayers are obtained by use of fluorescence spectroscopy for different surface pressures. In the case of dipalmitoyl phosphatidylcholine, the affinity is high in the liquid expanded state, but drops in the liquid condensed state. The affinity for the negatively charged dilauryl phosphatidylglycerol is very low. In the case of phosphatidylethanolamine extracted from Escherichia coli, a strong decrease in the affinity is detected about 20 mN/m. This can be explained by an increase of interactions between the molecules of the lipid matrix. These data lead to the conclusion that the packing is not uniform in sonicated vesicles.Key words: monolayer, phospholipid, fluorescence, phase transition.
8
Pabst, Georg, Richard Koschuch, Beatriz Pozo-Navas, Michael Rappolt, Karl Lohner, and Peter Laggner. "Structural analysis of weakly ordered membrane stacks." Journal of Applied Crystallography 36, no. 6 (November 15, 2003): 1378–88. http://dx.doi.org/10.1107/s0021889803017527.
Анотація:
The applicability of full-q-range models to fit low-resolution X-ray diffraction data from multibilayers exhibiting only weak quasi-Bragg peak scattering has been analysed. The models consider different structure factors, accounting for different types of lattice disorder caused by stacking faults or bending fluctuations. Numerical tests of the models, considering instrumental influence of a line-focus collimation system, demonstrated that Bragg peak line shapes given by different lattice disorders cannot be discerned. However, line-shape parameters can be determined for a particular sample, if the type of disorder is knowna priori. This has been verified by comparing the experimental results for the fluctuation parameter of palmitoyl-oleoyl phosphatidylcholine (POPC) as a function of temperature with high-resolution data on the same lipid. Tests further show that the calculation of structural parameters, such as the membrane thickness or the extent of the interbilayer water region, is not obscured by the smearing imposed by the instrument. The model was further applied successfully to experimental data of lipid mixtures composed of sphingomyelin (SM)/POPC/cholesterol and dipalmitoyl phosphatidylethanolamine (DPPE)/dipalmitoyl phosphatidylglycerol (DPPG). The structural parameters determined give valuable insight into the physical state of the membrane system, which is not accessible when quasi-Bragg reflections only are considered.
9
Aoki, P. H. B., W. Caetano, D. Volpati, A. Riul, and C. J. L. Constantino. "Sensor Array Made with Nanostructured Films to Detect a Phenothiazine Compound." Journal of Nanoscience and Nanotechnology 8, no. 9 (September 1, 2008): 4341–48. http://dx.doi.org/10.1166/jnn.2008.297.
Анотація:
The detection of trace amounts of phenothiazines with fast, direct methods is important for medical applications and the pharmaceutical industry. In this paper we explore the concept of an electronic tongue to detect methylene blue (MB), with a sensor array comprising 6 units. These units were a bare Pt electrode, and Pt electrodes coated with 1-layer LB films of dipalmitoyl phosphatidylcholine (DPPC) and dipalmitoyl phosphatidylglycerol (DPPG), a 5-layer LB film of stearic acid, and 10 nm PVD films of bis benzimidazo perylene (AzoPTCD) and iron phthalocyanine (FePc). The electrical response obtained with impedance spectroscopy varied with the sensing unit, in spite of the small film thickness, thus indicating good cross-sensitivity. Upon treating the capacitance data at 1 kHz with Principal Component Analysis (PCA), the sensor array was capable of distinguishing MB solutions from ultrapure water down to 1 nM. This unprecedented high sensitivity was probably due to strong interactions between MB and DPPC and DPPG, as the sensing units of these phospholipids gave the most important contributions to the PCA plots. Such strong interaction was not manifested in the surface pressure–area isotherms of co-spread monolayers of MB and DPPC or DPPG, which emphasizes the high sensitivity of the electrical measurements in ultrathin films in contact with liquids, now widely exploited in electronic tongues.
10
Schlame, M., B. Rüstow, D. Kunze, H. Rabe, and G. Reichmann. "Phosphatidylglycerol of rat lung Intracellular sites of formation de novo and acyl species pattern in mitochondria, microsomes and surfactant." Biochemical Journal 240, no. 1 (November 15, 1986): 247–52. http://dx.doi.org/10.1042/bj2400247.
Анотація:
The subcellular site of phosphatidylglycerol (PG) formation for lung surfactant has not been convincingly clarified. To approach this problem we analysed the acyl species pattern of lung PG in mitochondria, microsomes and surfactant by h.p.l.c. separation of its 1,2-diacyl-3-naphthylurethane derivatives. Both mitochondrial and microsomal PG proved identical with surfactant PG, containing the major species 1-palmitoyl-2-oleoyl-PG and 1,2-dipalmitoyl-PG. The fatty acid composition of mitochondrial PG differs markedly from that of diphosphatidylglycerol. This may be taken as an indication that mitochondrial PG is synthesized on purpose to form surfactant, rather than being only the precursor of diphosphatidylglycerol. In vitro, sn-[U-14C]glycerol 3-phosphate incorporation into PG of mitochondria or microsomes occurs in the presence of CTP, ATP and CoA but independently of the supply of exogenous lipoidic precursors. Although the rate in vitro of autonomous PG synthesis, and the endogenous PG content, are higher in mitochondria than in microsomes, it is assumed that both subcellular fractions are involved in PG formation for surfactant.
11
Adachi, H., H. Hayashi, H. Sato, K. Dempo, and T. Akino. "Characterization of phospholipids accumulated in pulmonary-surfactant compartments of rats intratracheally exposed to silica." Biochemical Journal 262, no. 3 (September 15, 1989): 781–86. http://dx.doi.org/10.1042/bj2620781.
Анотація:
Phospholipids in the lung fractions, i.e. alveolar free cells, extracellular pulmonary surfactant, intracellular pulmonary surfactant (lamellar bodies) and microsomal fractions, of rats were examined 28 days after intratracheal injection of silica (40 mg/kg). Significant accumulations of phospholipids were observed in the extracellular- and intracellular-surfactant fractions of rats exposed to silica. The prominent phospholipid accumulated was phosphatidylcholine (PC), consisting mainly of the dipalmitoyl species. However, a compositional change in acidic phospholipids of surfactant fractions was produced by the silica treatment. The percentage of phosphatidylglycerol (PG) was significantly decreased; in contrast, that of phosphatidylinositol (PI) was increased. Thus the ratio PG/PI in the surfactant fractions was markedly decreased in response to silica. This compositional change in both acidic phospholipids occurred even in the early stages, i.e. before appreciable accumulations of alveolar phospholipids were noticed. The molecular-species profiles of both acidic phospholipids in the surfactant fractions were distinctly different from each other. The dipalmitoyl species accounted for more than 30% of PG and less than 6% of PI, respectively. These species patterns of PG and PI were similar in control and silica-treated rats. These findings suggest two possibilities that (1) PG and PI destined for pulmonary surfactant are synthesized from each specific CDP-diacylglycerol (DG) pool having different molecular species in the lung, or (2) individual enzymes responsible for synthesis of surfactant PG and PI have substrate specificities for molecular species of CDP-DG, thereby producing PG and PI having different molecular species in surfactant compartments.
12
Schreiner, Mark E., and Bernhard J. Eikmanns. "Pyruvate:Quinone Oxidoreductase from Corynebacterium glutamicum: Purification and Biochemical Characterization." Journal of Bacteriology 187, no. 3 (February 1, 2005): 862–71. http://dx.doi.org/10.1128/jb.187.3.862-871.2005.
Анотація:
ABSTRACT Pyruvate:quinone oxidoreductase catalyzes the oxidative decarboxylation of pyruvate to acetate and CO2 with a quinone as the physiological electron acceptor. So far, this enzyme activity has been found only in Escherichia coli. Using 2,6-dichloroindophenol as an artificial electron acceptor, we detected pyruvate:quinone oxidoreductase activity in cell extracts of the amino acid producer Corynebacterium glutamicum. The activity was highest (0.055 ± 0.005 U/mg of protein) in cells grown on complex medium and about threefold lower when the cells were grown on medium containing glucose, pyruvate, or acetate as the carbon source. From wild-type C. glutamicum, the pyruvate:quinone oxidoreductase was purified about 180-fold to homogeneity in four steps and subjected to biochemical analysis. The enzyme is a flavoprotein, has a molecular mass of about 232 kDa, and consists of four identical subunits of about 62 kDa. It was activated by Triton X-100, phosphatidylglycerol, and dipalmitoyl-phosphatidylglycerol, and the substrates were pyruvate (k cat = 37.8 ± 3 s−1; Km = 30 ± 3 mM) and 2-oxobutyrate (k cat = 33.2 ± 3 s−1; Km = 90 ± 8 mM). Thiamine pyrophosphate (Km = 1 μM) and certain divalent metal ions such as Mg2+ (Km = 29 μM), Mn2+ (Km = 2 μM), and Co2+ (Km = 11 μM) served as cofactors. In addition to several dyes (2,6-dichloroindophenol, p-iodonitrotetrazolium violet, and nitroblue tetrazolium), menadione (Km = 106 μM) was efficiently reduced by the purified pyruvate:quinone oxidoreductase, indicating that a naphthoquinone may be the physiological electron acceptor of this enzyme in C. glutamicum.
13
Casals, C., E. Miguel, and J. Perez-Gil. "Tryptophan fluorescence study on the interaction of pulmonary surfactant protein A with phospholipid vesicles." Biochemical Journal 296, no. 3 (December 15, 1993): 585–93. http://dx.doi.org/10.1042/bj2960585.
Анотація:
The fluorescence characteristics of surfactant protein A (SP-A) from porcine and human bronchoalveolar lavage were determined in the presence and absence of lipids. After excitation at either 275 or 295 nm, the fluorescence emission spectrum of both proteins was characterized by two maxima at about 326 and 337 nm, indicating heterogeneity in the emission of the two tryptophan residues of SP-A, and also revealing a partially buried character for these fluorophores. Interaction of both human and porcine SP-A with various phospholipid vesicles resulted in an increase in the fluorescence emission of tryptophan without any shift in the emission wavelength maxima. This change in intrinsic fluorescence was found to be more pronounced in the presence of dipalmitoyl phosphatidylcholine (DPPC) than with dipalmitoyl phosphatidylglycerol (DPPG), DPPC/DPPG (7:3, w/w) and 1-palmitoyl-sn-glycerol-3-phosphocholine (LPC). Intrinsic fluorescence of SP-A was almost completely unaffected in the presence of egg phosphatidylcholine (egg-PC). In addition, we demonstrated a shielding of the tryptophan fluorescence from quenching by acrylamide on interaction of porcine SP-A with DPPC, DPPG or LPC. This shielding was most pronounced in the presence of DPPC. In the case of human SP-A, shielding was only observed on interaction with DPPC. From the intrinsic fluorescence measurements as well as from the quenching experiments, we concluded that the interaction of some phospholipid vesicles with SP-A produces a conformational change on the protein molecule and that the interaction of SP-A with DPPC is stronger than with other phospholipids. This interaction appeared to be independent of Ca2+ ions. Physiological ionic strength was found to be required for the interaction of SP-A with negatively charged vesicles of either DPPG or DPPC/DPPG (7:3, w/w). Intrinsic fluorescence of SP-A was sensitive to the physical state of the DPPC vesicles. The increase in intrinsic fluorescence of SP-A in the presence of DPPC vesicles was much stronger when the vesicles were in the gel state than when they were in the liquid-crystalline state. The effect produced by SP-A on the lipid vesicles was also dependent on temperature. The aggregation of DPPC, DPPC/DPPG (7:3, w/w) or dimyristoyl phosphatidylglycerol (DMPG) was many times higher below the phase-transition temperature of the corresponding phospholipids. These results strongly indicate that the interaction of SP-A with phospholipid vesicles requires the lipids to be in the gel phase.
14
Yanez, Aladino M., Mark Wallace, Rodney Ho, Danny Shen, and Tony L. Yaksh. "Touch-evoked Agitation Produced by Spinally Administered Phospholipid Emulsion and Liposomes in Rats." Anesthesiology 82, no. 5 (May 1, 1995): 1189–98. http://dx.doi.org/10.1097/00000542-199505000-00014.
Анотація:
Background Phospholipid-based liposomes can alter the kinetics of spinally administered agents. We have observed that spinal delivery of these preparations results in an unexpected touch-evoked agitation, a state in which light touch evokes vocalization by the rat. In the current study we characterized this agitated state induced by various liposome preparations. Methods Rats prepared with lumbar intrathecal catheters received a variety of phospholipids delivered spinally as emulsions or as liposomes. Before and after injection, the animal's hot-plate latency (52.5 degrees C surface), spontaneous mobility, and spontaneous and evoked pain behavior were assessed. Results Spinal delivery of L-alpha-phosphatidylcholine of egg yolk (L-EPC) and the phospholipase hydrolysis product (lyso-L-alpha-phosphatidylcholine [lyso-L-EPC]) produced dose-dependent touch-evoked agitation; the order of potency and rapidity of onset was lyso-L-EPC > L-EPC, with no difference in activity whether administered as an emulsion or as a liposome preparation. Examination of the activity of a series of pure phospholipids revealed the ordering of touch-evoked agitation potency (where PC = phosphatidylcholine) to be L-monopalmitoyl-PC (lyso product of L-dipalmitoyl-PC) > L-dipalmitoyl-PC > L-distearoyl-PC, L-dioleoyl-PC > L-dilauroyl-PC > L-dimyristoyl-PC; D-dipalmitoyl-PC = 0. The effect of unsaturation on touch-evoked agitation cannot be predicted because dioleoyl-PC and dioleoyl phosphatidylglycerol produced touch-evoked agitation but dipalmitoleoyl-PC did not. Substitution of glycerol for choline as the head group had no influence on touch-evoked agitation. Spinal treatment with an inhibitor of phospholipase (mepacrine) or a cyclooxygenase (ketorolac) blocked the touch-evoked agitation of L-EPC but not that of lyso-L-EPC. Conclusions These results emphasize that certain L-isomeric phospholipids with their gel-transition temperatures near body temperature can produce prominent touch-evoked agitation after spinal delivery, an effect likely mediated by a phospholipase hydrolysis product. This touch-evoked agitation, which is consistent with neurotoxicity reported in the early literature on lysophospholipids, suggests that the choice of lipids for the formulation of liposomes intended for spinal drug delivery should be carefully considered.
15
Pérez-Gil, Jesus, Jacqueline Tucker, Gary Simatos, and Kevin M. W. Keough. "Interfacial adsorption of simple lipid mixtures combined with hydrophobic surfactant protein from pig lung." Biochemistry and Cell Biology 70, no. 5 (May 1, 1992): 332–38. http://dx.doi.org/10.1139/o92-051.
Анотація:
Hydrophobic pulmonary surfactant protein enriched in SP-C has been mixed in amounts up to 10% by weight with various phospholipids. The lipids used were dipalmitoyl phosphatidylcholine (DPPC), or DPPC plus unsaturated phosphatidylglycerol (PG), or phosphatidylinositol (PI) in molar ratios of 9:1 and 7:3. The protein enhanced the rate and extent of adsorption of each lipid preparation into the air–water interface, and its respreading after compression on a surface balance. Maximum surface pressures attained on compression of monolayers of mixtures of lipids were slightly higher in the presence of protein. The effects on rate and extent of adsorption were proportional to the amount of protein present. Mixtures containing 30 mol% PG or PI adsorbed more readily into the interface than those containing 10% acidic lipid or DPPC alone. Mixtures containing 30% PI were slightly more rapidly adsorbed than those containing 30% PG. The results suggest that mixtures of DPPC with either acidic lipid in the presence of surfactant protein could be effective in artificial surfactants.Key words: pulmonary surfactant, monolayer formation, adsorption, synthetic surfactant, proteolipids.
16
Kinkaid, A., and D. C. Wilton. "Comparison of the catalytic properties of phospholipase A2 from pancreas and venom using a continuous fluorescence displacement assay." Biochemical Journal 278, no. 3 (September 15, 1991): 843–48. http://dx.doi.org/10.1042/bj2780843.
Анотація:
Phospholipases A2 from pig pancreas and the venoms from bee, Naja naja and Crotalus atrox have been studied by using a new continuous fluorescence displacement assay that utilizes normal phospholipid substrates [Wilton (1990) Biochem. J. 266, 435-439]. With limiting amounts of substrate, the assay demonstrated stoichiometric conversion into products with both pancreatic and venom enzymes, and thus would allow phospholipid determination at concentrations down to about 0.1 microM. The substrate specificity of the enzyme was determined for the four enzymes in terms of both phospholipid head group and fatty acid selectivity. None of the enzymes demonstrated a preference for arachidonic acid-containing phospholipid under the conditions of this assay. No lag was observed with any enzyme with either phosphatidylcholine or phosphatidylglycerol as substrate. With dipalmitoyl-phosphatidylcholine as substrate, the assay clearly highlighted the different membrane-penetrating properties of the pancreatic and Naja naja enzymes and demonstrated maximal activity for the pancreatic enzyme in the region of the phase-transition temperature of this substrate, at about 35 degrees C.
17
Nair, Andrew, Shahidan Radiman, and Mamot Said. "Simple Thermodynamically-Derived Model for Predicting the Hydrolase and Transferase Activity of Phospholipase D in the Synthesis of Phosphatidylglycerol." Lipid Insights 5 (January 2012): LPI.S8376. http://dx.doi.org/10.4137/lpi.s8376.
Анотація:
Preparation of a single and pure phospholipid via transphosphatidylation has been a much sought after endeavor in the pharmaceutical and nonmedical industries. For this reason, phosphatidylglycerol, a lung surfactant, was produced from phosphatidylcholine with defined fatty acids, ie, dipalmitoyl phosphatidylcholine. Substrate type and concentration, enzyme source, and reaction temperature were investigated. Phospholipase D from two sources, ie, savoy cabbage, was purified in the authors’ laboratory and a commercially available Streptomyces species was used for this study. The substrates used were glycerol, a polyhydric alcohol, and solketal, a monohydric form of glycerol. The progress of the reaction was monitored using thin layer chromatography, and synthesis with solketal, an unusual form of glycerol, was confirmed by liquid chromatography mass spectrometry. Surface response methodology used on four combinations of enzyme and substrate at various temperatures (30 °C–60 °C) and concentration (0.25–1 mM) revealed that yield and selectivity was temperature-driven and predictable. To validate further the thermodynamic attributes, a modified version of the Eyring equation was derived from selectivity and the Arhenius equation. These equations provide some useful insights into the difference in activation of enthalpy change(ΔΔH++) and difference in activation of entropy change(ΔΔS++). Plots of ln[PG]/[PA] versus 1/T gave good linear fits for these four combinations. In addition, a new thermodynamic parameter known as T PG = PA has emerged as a theoretical temperature for equivalent transferase and hydrolase activity.
18
Banerjee, R., and Jayesh R. Bellare. "Scoring of surface parameters of physiological relevance to surfactant therapy in respiratory distress syndrome." Journal of Applied Physiology 90, no. 4 (April 1, 2001): 1447–54. http://dx.doi.org/10.1152/jappl.2001.90.4.1447.
Анотація:
The Wilhelmy balance was used for in vitro testing of surface parameters of surfactants used for respiratory distress syndrome therapy. Two commercial protein-free surfactants, ALEC and Exosurf, were compared with pure forms of the three main phospholipids in natural surfactants, dipalmitoyl phosphatidylcholine (PC), phosphatidylglycerol (PG), and phosphatidylethanolamine (PE), and their binary mixtures, PC with PE and PG each in the ratio 2:3. Surface excess films (15 Å2/molecule) were compressed at 1.2 cycles/min past collapse to a compression ratio of 4:1. The maximum surface pressure, spreading time, compressibility, respreading ratio, recruitment index, and hysteresis area were compared. A consolidated list of criteria for selection of suitable surfactants was compiled from the literature. A relative scoring system was devised for comparison based on these criteria. PC/PG (2:3) performed the best as it fulfilled all the criteria and obtained the highest relative score. Exosurf also performed well, except on the respreading criterion. ALEC and PC/PE were equivalent in their performance and performed well, except on two criteria: hysteresis area and recruitment index. Thus the scoring system proposed here proved valuable to rate the overall efficacy as well as relative merits of surfactant formulations.
19
Shen, Jie, Zili Chen, Feng Yue, Yanfei Li, Zhiqin Xu, and Xinjun Xu. "Simultaneous Quantification of DPPG, DEPC and Cholesterol in Propofol Liposome by HPLC-ELSD Using Alkaline Hydrolysis." Journal of Chromatographic Science 58, no. 1 (December 23, 2019): 53–59. http://dx.doi.org/10.1093/chromsci/bmz109.
Анотація:
Abstract A high-performance liquid chromatography method with evaporative light-scattering detection (ELSD) was performed for simultaneous determination of dipalmitoyl phosphatidylglycerol (DPPG), dierucoyl phosphatidylcholine (DEPC) and cholesterol in propofol liposome by the pretreatment of alkaline hydrolysis (temperature, concentration of KOH anhydrous ethanol solution and reaction time were 90°C, 1 mol · L−1 and 10 min, respectively). The analysis was carried out on an Agilent TC-C18 column (4.6 mm × 250 mm, 5 μm) with isocratic elution of methanol and 0.1% acetic acid aqueous solution (95:5, v/v) at a flow rate of 1.0 mL · min−1. The column temperature was 30°C. The drift tube temperature of the ELSD system was set at 30°C, and the pressure of carrier gas was 350 KPa. The regression equation revealed a good linear relationship (r = 0.9990–0.9993) during the test ranges. The RSD of stability and repeatability (n = 6) was found to be less than 1.96 and 1.46%, respectively. The average recoveries ranged from 97.90 to 101.00%. The proposed method was validated and showed good precision, stability, repeatability and recovery, which indicated that the method could be readily utilized as a quality evaluation method for the determination of DPPG, DEPC and cholesterol in propofol liposome.
20
Spragg, R. G., R. M. Smith, K. Harris, J. Lewis, D. Häfner, and P. Germann. "Effect of recombinant SP-C surfactant in a porcine lavage model of acute lung injury." Journal of Applied Physiology 88, no. 2 (February 1, 2000): 674–81. http://dx.doi.org/10.1152/jappl.2000.88.2.674.
Анотація:
Synthetic surfactants allow examination of the effects of specific components of natural surfactant. To determine whether surfactant containing apoprotein C, dipalmitoyl-phosphatidylcholine, phosphatidylglycerol, and palmitic acid restores gas-exchanging function in acute lung injury (ALI), we administered such surfactant (in doses of 50 or 100 mg/kg and in volumes from 1 to 6 ml/kg) or phospholipid (PL) alone, by intratracheal instillation, to pigs with ALI induced by massive saline lavage. Animals ventilated with 100% O2 and receiving 1, 2, 4, or 6 ml/kg of 50 mg/kg recombinant surfactant apoprotein C (rSP-C) surfactant or 2 ml/kg of 50 mg/kg PL (control) had mean arterial[Formula: see text] values, 4 h after treatment, of 230, 332, 130, 142, or 86 Torr, respectively. Animals receiving 1, 2, or 4 ml/kg of 100 mg/kg rSP-C surfactant or 2 ml/kg of 100 mg/kg PL (control) had mean arterial[Formula: see text] values of 197, 214, 148, or 88 Torr, respectively. Surfactant PL distribution was homogeneous. Hyaline membrane formation was reduced in treated animals. Thus, in this model of ALI, rSP-C with PL has the capacity to improve gas exchange and possibly modify lung injury.
21
Kumashiro, Munehiro, Ryoga Tsuji, Shoma Suenaga та Koichi Matsuo. "Formation of β-Strand Oligomers of Antimicrobial Peptide Magainin 2 Contributes to Disruption of Phospholipid Membrane". Membranes 12, № 2 (21 січня 2022): 131. http://dx.doi.org/10.3390/membranes12020131.
Анотація:
The antimicrobial peptide magainin 2 (M2) interacts with and induces structural damage in bacterial cell membranes. Although extensive biophysical studies have revealed the interaction mechanism between M2 and membranes, the mechanism of membrane-mediated oligomerization of M2 is controversial. Here, we measured the synchrotron-radiation circular dichroism and linear dichroism (LD) spectra of M2 in dipalmitoyl-phosphatidylglycerol lipid membranes in lipid-to-peptide (L/P) molar ratios from 0–26 to characterize the conformation and orientation of M2 on the membrane. The results showed that M2 changed from random coil to α-helix structures via an intermediate state with increasing L/P ratio. Singular value decomposition analysis supported the presence of the intermediate state, and global fitting analysis revealed that M2 monomers with an α-helix structure assembled and transformed into M2 oligomers with a β-strand-rich structure in the intermediate state. In addition, LD spectra showed the presence of β-strand structures in the intermediate state, disclosing their orientations on the membrane surface. Furthermore, fluorescence spectroscopy showed that the formation of β-strand oligomers destabilized the membrane structure and induced the leakage of calcein molecules entrapped in the membrane. These results suggest that the formation of β-strand oligomers of M2 plays a crucial role in the disruption of the cell membrane.
22
Rüstow, B., Y. Nakagawa, H. Rabe, K. Waku, and D. Kunze. "Species pattern of phosphatidylinositol from lung surfactant and a comparison of the species pattern of phosphatidylinositol and phosphatidylglycerol synthesized de novo in lung microsomal fractions." Biochemical Journal 254, no. 1 (August 15, 1988): 67–71. http://dx.doi.org/10.1042/bj2540067.
Анотація:
1. Phosphatidylinositol (PI) is a minor component of lung surfactant which may be able to replace the functionally important phosphatidylglycerol (PG) [Beppu, Clements & Goerke (1983) J. Appl. Physiol. 55, 496-502] without disturbing lung function. The dipalmitoyl species is one of the main species for both PI (14.4%) and PG (16.9%). Besides the C16:0--C16:0 species, the C16:0--C18:0, C16:0--C18:1, C16:0--C18:2 and C18:0--C18:1 species showed comparable proportions in the PG and PI fractions. These similarities of the species patterns and the acidic character of both phospholipids could explain why surfactant PG may be replaced by PI. 2. PI and PG were radiolabelled by incubation of microsomal fractions with [14C]glycerol 3-phosphate (Gro3P). For 11 out of 14 molecular species of PI and PG we measured comparable proportions of radioactivity. The radioactivity of these 11 species accounted together for more than 80% of the total. The addition of inositol to the incubation system decreased the incorporation in vitro of Gro3P into PG and CDP-DG (diacylglycerol) of lung microsomes (microsomal fractions), but did not change the distribution of radioactivity among the molecular species of PG. These results supported the idea that both acidic surfactant phospholipids may be synthesized de novo from a common CDP-DG pool in lung microsomes.
23
Fisher, A. B., C. Dodia, and A. Chander. "Degradation and reutilization of alveolar phosphatidylcholine by rat lungs." Journal of Applied Physiology 62, no. 6 (June 1, 1987): 2295–99. http://dx.doi.org/10.1152/jappl.1987.62.6.2295.
Анотація:
We have shown previously that phospholipids instilled through the trachea are removed from the air spaces in isolated rat lungs by a process that is stimulated by beta-adrenergic agonists. In this study, we evaluated the fate of radiolabeled lipid vesicles [50% [3H]dipalmitoyl phosphatidylcholine (DPPC), 25% phosphatidylcholine (PC), 15% cholesterol, and 10% phosphatidylglycerol (PG)]. Vesicles were instilled through the trachea of anesthetized rats, and the lungs removed for perfusion. The percent of instilled 3H that could not be removed from lungs by extensive lung lavage increased progressively; at 3 h this fraction was 25.8 +/- 0.63% (mean +/- SE; n = 8). The percent of dpm in the lung homogenate accounted for by PC decreased progressively while dpm in lyso-PC, unsaturated PC, and aqueous soluble metabolites [choline, choline phosphate, glycerophosphorycholine, and cytidine 5′-diphosphate (CDP) choline (CDP-choline) increased. The dpm in microsomal and lamellar body fractions isolated from lung homogenates also increased progressively with time of perfusion. The presence of 8-bromoadenosine 3′,5′-cyclic monophosphate (8-BrcAMP) significantly stimulated both uptake of DPPC and the appearance of radioactivity in metabolites and subcellular organelles. This effect of 8-BrcAMP was not due to stimulation of phospholipase A activity. These results indicate that exogenous phospholipids instilled into the air spaces of rat lungs are internalized and degraded by a process that is stimulated by cAMP.(ABSTRACT TRUNCATED AT 250 WORDS)
24
PALMBLAD, Marie, Jan JOHANSSON, Bengt ROBERTSON, and Tore CURSTEDT. "Biophysical activity of an artificial surfactant containing an analogue of surfactant protein (SP)-C and native SP-B." Biochemical Journal 339, no. 2 (April 8, 1999): 381–86. http://dx.doi.org/10.1042/bj3390381.
Анотація:
Natural surfactant preparations containing phospholipids and the hydrophobic surfactant proteins B and C (SP-B and SP-C) are effective in the treatment of respiratory distress syndrome in premature infants. The limited supply, and the risk of infectious agents and immunological reactions have promoted the evaluation of synthetic peptides in surfactant preparations. However, the folding of synthetic SP-C into an α-helix is inefficient and α-helical SP-C analogues with Val → Leu substitutions form oligomers. In order to circumvent these problems we have synthesized an SP-C analogue, named SP-C(LKS), which differs from SP-C mainly by the exchange of most of the Val residues in positions 16–28 with Leu residues to promote an α-helical conformation, and by the introduction of Lys residues at positions 17, 22 and 27 in order to locate positive charges around the helical circumference and thereby avoid self polymerization. CD spectroscopy showed a spectrum typical for α-helical peptides and SDS/PAGE disclosed a single band. The biophysical activity of artificial surfactant preparations containing SP-C(LKS) and phospholipids, with and without native SP-B, was measured using a Wilhelmy balance and a pulsating bubble surfactometer. SP-C(LKS) (3%, w/w) in a mixture of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)/phosphatidylglycerol/palmitic acid (68:22:9, by wt.) suspended in 150 mM NaCl, showed rapid spreading at the air-liquid interface and produced a surface tension of < 1 mN/m at minimum bubble size (γmin) and 42 mN/m at maximum bubble size (γmax) in the pulsating bubble surfactometer. The addition of 2% (w/w) SP-B to the preparation reduced the maximum surface tension to 33–35 mN/m, i.e. both γmin and γmax values were similar to those of natural surfactant preparations. Optimal in vitro characteristics were also obtained from a preparation containing SP-C(LKS), SP-B, DPPC and phosphatidylglycerol, i.e. when palmitic acid was omitted from the lipid mixture. SP-B containing surfactant preparations made up in Hepes buffer at pH 6.9, instead of in 150 mM NaCl, had similar biophysical activity provided that palmitic acid was omitted, but decreased activity in the presence of palmitic acid.
25
Rüdiger, M., I. Kolleck, G. Putz, R. R. Wauer, P. Stevens, and B. Rüstow. "Plasmalogens effectively reduce the surface tension of surfactant-like phospholipid mixtures." American Journal of Physiology-Lung Cellular and Molecular Physiology 274, no. 1 (January 1, 1998): L143—L148. http://dx.doi.org/10.1152/ajplung.1998.274.1.l143.
Анотація:
The alkenyl-acyl subclass of phosphatidylethanolamine (PtdEtn) and phosphatidylcholine (plasmalogens) are minor components of alveolar surfactant. Plasmalogens promote and stabilize hexagonal structures of phospholipids. In another study (W. R. Perkins, R. B. Dause, R. A. Parente, S. R. Michey, K. C. Neuman, S. M. Gruner, T. F. Taraschi, and A. S. Janoff. Science 273: 330–332, 1996), it was shown that polymorphic phase behavior may have an important role in the effective functioning of pulmonary surfactant. Therefore, we hypothesized that surface properties of phospholipid mixtures that contain plasmalogens are superior to plasmalogen-free mixtures. The effect of plasmalogens on surface tension of surfactant-like phospholipid mixtures (70 mol% dipalmitoyl phosphatidylcholine, 10 mol% phosphatidylglycerol, and 20 mol% PtdEtn) was measured. Using the pulsating bubble surfactometer, we show that an increasing amount of ethanolamine plasmalogens [plasmenylethanolamine (PlsEtn)] results in reduction of surface tension (0 mol% PlsEtn 44.7 ± 1.7, 2 mol% 33.5 ± 1.7, 4 mol% 36 ± 3.1, 6 mol% 26.2 ± 2.9, and 8 mol% 22.2 ± 0.3 mN/m). By means of the captive bubble surfactometer, minimal surface tension reached with 8 mol% PlsEtn was even lower (3.8 ± 0.7 mN/m). With regard to morphological studies (B. Fringes, K. Gorgas, and A. Reith. Eur. J. Cell Biol. 46: 136–143, 1988), clofibrate treatment of rats might increase the plasmalogen content of alveolar surfactant. However, in the present study, we could not show that synthesis and secretion of plasmalogens are affected by clofibrate treatment.
26
Fisher, A. B., C. Dodia, A. Chander, and M. Jain. "A competitive inhibitor of phospholipase A2 decreases surfactant phosphatidylcholine degradation by the rat lung." Biochemical Journal 288, no. 2 (December 1, 1992): 407–11. http://dx.doi.org/10.1042/bj2880407.
Анотація:
We have shown previously that radiolabelled phosphatidylcholine (PC) in liposomes or natural surfactant is removed from the alveolar space and metabolically recycled in a process that is stimulated by cyclic AMP (cAMP). In this study, we evaluated the effect of a transition-state phospholipid analogue (MJ33; 1-hexadecyl-3-trifluoroethylglycero-sn-2-phosphomethanol) that competitively inhibited acidic phospholipase A2 (PLA2) activity (pH 4.0) of lung homogenate by more than 97%, but had no effect on PLA2 activity at pH 8.5. MJ33 incorporated into unilamellar liposomes (dipalmitoyl PC/egg PC/cholesterol/phosphatidylglycerol, molar proportions 10:5:3:2) or co-sonicated with biosynthesized natural surfactant was instilled into the trachea of the anaesthetized rat; lungs were then removed for 2 h perfusion in the absence or presence of 0.1 mM-8-bromo cAMP. Total uptake for phospholipid was unchanged in the presence of the inhibitor MJ33. Degradation of labelled PC during 2 h perfusion in the absence of MJ33 was approx. 26% of that instilled for choline-labelled liposomal PC, 16% for liposomal PC labelled in the second fatty-acyl position, and 33% for choline-labelled natural surfactant. Degradation of PC was decreased by approx. 25-40% for each substrate in the presence of MJ33. Inhibition of lipid degradation depended on the mole fraction of MJ33 in the liposomes and was maximal at 1 mol%. These studies demonstrate a significant role for acidic Ca(2+)-independent PLA2 in the degradation of internalized alveolar PC, but further indicate that this enzyme accounts for a minor fraction of total lung PC metabolism.
27
Veldhuizen, R. A., S. A. Hearn, J. F. Lewis, and F. Possmayer. "Surface-area cycling of different surfactant preparations: SP-A and SP-B are essential for large-aggregate integrity." Biochemical Journal 300, no. 2 (June 1, 1994): 519–24. http://dx.doi.org/10.1042/bj3000519.
Анотація:
Surface-area cycling is an in vitro procedure for the conversion of large into small surfactant aggregates. In this procedure a tube containing a surfactant suspension is rotated end-over-end at 37 degrees C so that the surface area of the suspension changes twice each cycle. We have utilized this method to study the mechanisms involved in aggregate conversion. Several different surfactant preparations were analysed: (1) bovine natural surfactant, a sucrose-gradient-purified material containing surfactant phospholipid and surfactant-associated proteins (SP-) SP-A, SP-B and SP-C; (2) bovine lipid-extract surfactant, which contains the surfactant phospholipids and SP-B and SP-C; (3) mixtures of dipalmitoyl phosphatidylcholine and phosphatidylglycerol (7:3, w/w) reconstituted with one or more surfactant proteins. Aggregate conversion was measured by phosphorus analysis of a 40,000 g supernatant (small aggregate) and pellet (large aggregates) before and after surface-area cycling. Surface-area cycling of lipid extract surfactant or lipids plus SP-B or SP-C resulted in rapid aggregate conversion. Lipids alone were not converted. Only a small percentage of purified natural surfactant was converted into small aggregates. Addition of SP-A to lipid extract surfactant could inhibit aggregate conversion of this material, but this was only observed when an additional 1% (w/w) of SP-B was added to the lipid extract. It is concluded that SP-A is important for large-aggregate integrity. It appears that SP-A acts in conjunction with SP-B. The presence of SP-B and/or SP-C is required for aggregate conversion; it is proposed that this reflects the necessity for lipid adsorption in aggregate conversion.
28
Chen, Yi, John R. Burke, and Brian A. Hills. "Semipermeability Imparted by Surface-Active Phospholipid in Peritoneal Dialysis." Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis 22, no. 3 (May 2002): 380–85. http://dx.doi.org/10.1177/089686080202200313.
Анотація:
Objective It has previously been demonstrated that a lining of surface-active phospholipid (SAPL) is reversibly bound (adsorbed) to normal peritoneal mesothelium. The lining acts as a boundary lubricant and release (anti-stick) agent preserving mechanical integrity of the epithelial surface. In a review of clinical trials on the use of SAPL (akin to “surfactant”) to restore ultrafiltration (UF) in patients on peritoneal dialysis (PD), speculation is that, by adsorption, the SAPL lining might also be imparting the semipermeability vital for UF. Design To evaluate the hypothesis, SAPL harvested from the spent dialysate of 5 patients with normal UF was deposited onto a porous, inert medium, and the resulting 7 “membranes” were clamped in an Ussing chamber used as an osmometer. Results With every “membrane,” a clinical concentration of glucose (2.5%) was able to induce a statistically significant osmotic pressure when dialyzed against saline. We also demonstrated how synthetic SAPL—in the form of dipalmitoyl phosphatidylcholine (DPPC) and an admixture of DPPC with phosphatidylglycerol (PG) called artificial lung-expanding compound (ALEC)—imparts greater osmotic pressure in proportion to an increasing glucose gradient. Our findings prove that human peritoneal SAPL has the physical capability to impart semipermeability when adsorbed to a surface. Comment As a lipid lining, adsorbed SAPL could also explain the high permeability of the natural membrane to lipophilic substances in PD. Administered as a very fine powder or as a solution in a lipid solvent, ALEC offers a potential treatment for restoring UF, if applied during the interdialytic interval. In various physical forms, ALEC and DPPC have both been widely used for two decades with complete safety in the treatment of respiratory distress syndrome in newborns. The question of formulation of exogenous SAPL in restoring UF is discussed as a complex physicochemical compromise between the higher surface activity of saturated phosphatidylcholine and its lower solubility in water.
29
Banerjee, R., and R. R. Puniyani. "Effect of Eucalyptus Oil Added Surfactants on the Rheology of Mucus Gel Simulants." Applied Rheology 9, no. 6 (December 1, 1999): 254–61. http://dx.doi.org/10.1515/arh-2009-0017.
Анотація:
Abstract Eucalyptus oil is a commonly used remedy for common colds. For a substance to be effective therapy in obstructive airway diseases, it must reduce the viscosity of respiratory mucus. The present study evaluates the effectiveness of eucalytpus oil added phospholipid mixtures as possible substitute therapies in diseases of altered mucus viscosity by studying their effect on the viscosity of mucus gel simulants in vitro. Test formulations of surfactants consisting of phospholipid-eucalyptus oil mixtures in the ratio of 1 part of oil to 9 parts of phospholipid were prepared. The phospholipids used were dipalmitoyl phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylglycerol (PG). The effects of these phospholipid-eucalyptus oil mixtures on the viscosity of Mucus Gel Simulant (MGS – a polymeric gel consisting mainly of gum tragacanth and simulating respiratory mucus) was studied by application of steady shear rates ranging from 0.512 to 51.2 s−1 in a concentric cylinder viscometer at 37°C. The change in MGS viscosity, after incubation with surfactants, with application of shear rates was found to have a Non-Newtonian flow and to follow the power law model with R2 values > 0.8. The addition of eucalyptus oil-phospholipid mixtures caused a decrease in the MGS viscosity when compared with the effect of the phospholipid alone at both low and high shear rates. The combination of PG with eucalyptus oil and of PG with eucalyptus oil and calcium caused ratios of change in MGS viscosity < 1, i.e. they caused a decrease in the MGS viscosity. Thus, the addition of eucalyptus oil improved the ability of the phospholipids to alter MGS viscosity. The combinations of PG with eucalyptus oil and PG with eucalyptus oil in the presence of calcium were even capable of lowering mucus gel viscosity and should be further researched as possible substitute therapies for diseases of altered mucus viscosity.
30
Johansson, J., G. Nilsson, R. Strömberg, B. Robertson, H. Jörnvall, and T. Curstedt. "Secondary structure and biophysical activity of synthetic analogues of the pulmonary surfactant polypeptide SP-C." Biochemical Journal 307, no. 2 (April 15, 1995): 535–41. http://dx.doi.org/10.1042/bj3070535.
Анотація:
Native pulmonary-surfactant-associated lipopolypeptide SP-C, its chemically depalmitoylated form and several synthetic analogues lacking the palmitoylcysteine residues were analysed for secondary structure in phospholipid micelles and for biophysical activity in 1,2-dipalmitoyl-sn-glycero-3- phosphocholine/phosphatidylglycerol/palmitic acid (68:22:9, by wt.). Compared with the native molecule, with the entire poly-valyl part in a known alpha-helical conformation, depalmitoylated SP-C was found to be still mainly alpha-helical, but with an approx. 20% decrease in the helical content. A synthetic hybrid polypeptide where the entire poly-valyl alpha-helical part of native SP-C had been replaced with the amino acid sequence of a transmembrane helix of bacteriorhodopsin is also predominantly alpha-helical. In contrast, synthetic SP-C analogues lacking only the palmitoyl groups, by replacement of the palmitoylcysteine residues with cysteine, phenylalanine or serine, or lacking the positively charged amino acids by replacement with alanine, are considerably less alpha-helical than both native and depalmitoylated SP-C. The data indicate that the SP-C palmitoyl groups are important for maintenance of the alpha-helical conformation in parts of the polypeptide, and that the poly-valyl alpha-helical conformation is not fully formed in synthetic SP-C polypeptides. Furthermore, the helical structure of both native and depalmitoylated SP-C in dodecylphosphocholine micelles is very resistant to thermal denaturation, exhibiting ordered structure at 90 degrees C. The alpha-helical content grossly parallels the peptide-induced acceleration of the spreading of phospholipids at an air/water interface and the increase of surface pressure. The data suggest that the alpha-helical conformation itself, rather than just the covalent structure, is of prime importance for the biological function of synthetic pulmonary-surfactant peptides.
31
Johansson, Jan, Margareta Some, Britt-Marie Linderholm, Andreas Almlén, Tore Curstedt, and Bengt Robertson. "A synthetic surfactant based on a poly-Leu SP-C analog and phospholipids: effects on tidal volumes and lung gas volumes in ventilated immature newborn rabbits." Journal of Applied Physiology 95, no. 5 (November 2003): 2055–63. http://dx.doi.org/10.1152/japplphysiol.00153.2003.
Анотація:
Available surfactants for treatment of respiratory distress syndrome in newborn infants are derived from animal lungs, which limits supply and poses a danger of propagating infectious material. Poly-Val→poly-Leu analogs of surfactant protein (SP)-C can be synthesized in large quantities and exhibit surface activity similar to SP-C. Here, activity of synthetic surfactants containing a poly-Leu SP-C analog (SP-C33) was evaluated in ventilated premature newborn rabbits. Treatment with 2.5 ml/kg body wt of 2% (wt/wt) SP-C33 in 1,2-dipalmitoyl- sn-3-glycero phosphoryl choline (DPPC)-1-palmitoyl-2-oleoyl- sn-3-glycero phosphoryl choline (POPC)-1-palmitoyl-2-oleoyl- sn-3-glycero phosphoryl glycerol (POPG), 68:0:31, 68:11:20, or 68:16:15 (wt/wt/wt) suspended at 80 mg/ml gave tidal volumes (Vt) of 20-25 ml/kg body wt, with an insufflation pressure of 25 cmH2O and no positive end-expiratory pressure (PEEP), comparable to the Vt for animals treated with the porcine surfactant Curosurf. Nontreated littermates had a Vt of ∼2 ml/kg body wt. The Vt for SP-C33 in DPPC-egg phosphatidylglycerol-palmitic acid [68:22:9 (wt/wt/wt)], DPPC-POPG-palmitic acid [68:22:9 (wt/wt/wt)], and DPPC-POPC-POPG [6:2:2 (wt/wt/wt)] was 15-20 ml/kg body wt. Histological examination of lungs from animals treated with SP-C33-based surfactants showed incomplete, usually patchy air expansion of alveolar spaces associated with only mild airway epithelial damage. Lung gas volume after 30 min of mechanical ventilation were more than threefold larger in animals treated with Curosurf than in those receiving SP-C33 in DPPC-POPC-POPG, 68:11:20. This difference could be largely counterbalanced by ventilation with PEEP (3-4 cmH2O). An artificial surfactant based on SP-C33 improves Vt in immature newborn animals ventilated with standardized peak pressure but requires PEEP to build up adequate lung gas volumes.
32
PLASENCIA, Inés, Antonio CRUZ, Cristina CASALS, and Jesús PÉREZ-GIL. "Superficial disposition of the N-terminal region of the surfactant protein SP-C and the absence of specific SP-B–SP-C interactions in phospholipid bilayers." Biochemical Journal 359, no. 3 (October 25, 2001): 651–59. http://dx.doi.org/10.1042/bj3590651.
Анотація:
A dansylated form of porcine surfactant-associated protein C (Dns-SP-C), bearing a single dansyl group at its N-terminal end, has been used to characterize the lipid–protein and protein–protein interactions of SP-C reconstituted in phospholipid bilayers, using fluorescence spectroscopy. The fluorescence emission spectrum of Dns-SP-C in phospholipid bilayers is similar to the spectrum of dansyl-phosphatidylethanolamine, and indicates that the N-terminal end of the protein is located at the surface of the membranes and is exposed to the aqueous environment. In membranes containing phosphatidylglycerol (PG), the fluorescence of Dns-SP-C shows a 3-fold increase with respect to the fluorescence of phosphatidylcholine (PC), suggesting that electrostatic lipid–protein interactions induce important effects on the structure and disposition of the N-terminal segment of the protein in these membranes. This effect saturates above 20% PG molar content in the bilayers. The parameters for the interaction of Dns-SP-C with PC or PG have been estimated from the changes induced in the fluorescence emission spectrum of the protein. The protein had similar Kd values for its interaction with the different phospholipids tested, of the order of a few micromolar. Cooling of Dns-SP-C-containing dipalmitoyl PC bilayers to temperatures below the phase transition of the phospholipid produced a progressive blue-shift of the fluorescence emission of the protein. This effect is interpreted as a consequence of the transfer of the N-terminal segment of the protein into less polar environments that originate during protein lateral segregation. This suggests that conformation and interactions of the N-terminal segment of SP-C could be important in regulating the lateral distribution of the protein in surfactant bilayers and monolayers. Potential SP-B–SP-C interactions have been explored by analysing fluorescence resonance energy transfer (RET) from the single tryptophan in porcine SP-B to dansyl in Dns-SP-C. RET has been detected in samples where native SP-B and Dns-SP-C were concurrently reconstituted in PC or PG bilayers. However, the analysis of the dependence of RET on the protein density excluded specific SP-B–Dns-SP-C associations.
33
Notter, Robert H., Rohun Gupta, Adrian L. Schwan, Zhengdong Wang, Mohanad Gh Shkoor, and Frans J. Walther. "Synthetic lung surfactants containing SP-B and SP-C peptides plus novel phospholipase-resistant lipids or glycerophospholipids." PeerJ 4 (October 27, 2016): e2635. http://dx.doi.org/10.7717/peerj.2635.
Анотація:
BackgroundThis study examines the biophysical and preclinical pulmonary activity of synthetic lung surfactants containing novel phospholipase-resistant phosphonolipids or synthetic glycerophospholipids combined with Super Mini-B (S-MB) DATK and/or SP-Css ion-lock 1 peptides that replicate the functional biophysics of surfactant proteins (SP)-B and SP-C. Phospholipase-resistant phosphonolipids used in synthetic surfactants are DEPN-8 and PG-1, molecular analogs of dipalmitoyl phosphatidylcholine (DPPC) and palmitoyl-oleoyl phosphatidylglycerol (POPG), while glycerophospholipids used are active lipid components of native surfactant (DPPC:POPC:POPG 5:3:2 by weight). The objective of the work is to test whether these novel lipid/peptide synthetic surfactants have favorable preclinical activity (biophysical, pulmonary) for therapeutic use in reversing surfactant deficiency or dysfunction in lung disease or injury.MethodsSurface activity of synthetic lipid/peptide surfactants was assessedin vitroat 37 °C by measuring adsorption in a stirred subphase apparatus and dynamic surface tension lowering in pulsating and captive bubble surfactometers. Shear viscosity was measured as a function of shear rate on a Wells-Brookfield micro-viscometer.In vivopulmonary activity was determined by measuring lung function (arterial oxygenation, dynamic lung compliance) in ventilated rats and rabbits with surfactant deficiency/dysfunction induced by saline lavage to lower arterial PO2to <100 mmHg, consistent with clinical acute respiratory distress syndrome (ARDS).ResultsSynthetic surfactants containing 5:3:2 DPPC:POPC:POPG or 9:1 DEPN-8:PG-1 combined with 3% (by wt) of S-MB DATK, 3% SP-Css ion-lock 1, or 1.5% each of both peptides all adsorbed rapidly to low equilibrium surface tensions and also reduced surface tension to ≤1 mN/m under dynamic compression at 37 °C. However, dual-peptide surfactants containing 1.5% S-MB DATK + 1.5% SP-Css ion-lock 1 combined with 9:1 DEPN-8:PG-1 or 5:3:2 DPPC:POPC:POPG had the greatestin vivoactivity in improving arterial oxygenation and dynamic lung compliance in ventilated animals with ARDS. Saline dispersions of these dual-peptide synthetic surfactants were also found to have shear viscosities comparable to or below those of current animal-derived surfactant drugs, supporting their potential ease of deliverability by instillation in future clinical applications.DiscussionOur findings support the potential of dual-peptide synthetic lipid/peptide surfactants containing S-MB DATK + SP-Css ion-lock 1 for treating diseases of surfactant deficiency or dysfunction. Moreover, phospholipase-resistant dual-peptide surfactants containing DEPN-8/PG-1 may have particular applications in treating direct forms of ARDS where endogenous phospholipases are present in the lungs.
34
Wahlmüller, Felix, Margareta Furtmüller, Barbora Sokolikova, Bernd R. Binder, and Margarethe Geiger. "Phosphoinositides and Other Glycerophospholipids Interact with Protein C Inhibitor (PCI) and Modify Its Activity towards Activated Protein C (APC)." Blood 114, no. 22 (November 20, 2009): 2122. http://dx.doi.org/10.1182/blood.v114.22.2122.2122.
Анотація:
Abstract Abstract 2122 Poster Board II-99 Protein C Inhibitor (PCI, SERPINA5, PAI3) is a non-specific, secreted serine protease inhibitor (serpin) which circulates at low levels (5μg/mL or 90nM) in blood plasma (review: Geiger 2007, Suzuki 2008). First described as an inhibitor of activated protein C (APC) an anticoagulant serine protease in human plasma, it has been shown that PCI inactivates a variety of other proteases and has a wide tissue distribution. Some compounds like glycosaminoglycans (e.g. heparin, heparan sulfate) and certain phospholipids can modify PCI activity. Recently it was shown that single-stranded DNA aptamers stimulates the inhibitory activity of PCI towards APC in a glycosaminoglycan-like fashion (Müller 2009). In 2007 Malleier et al. analyzed the interaction of PCI with phosphatidylserine (PS), oxidized PS (OxPS) and oxidized phosphatidylethanolamin (OxPE). PS, OxPS and OxPE bind to PCI and enhance the stimulation of APC-inhibition 130 to 190-fold. In addition, PE supports the internalization of PCI by cells, and internalized PCI promotes phagocytosis of bacteria (Baumgärtner et al. 2007). JFC1 (synaptotagmin-like protein 1) was identified by our group as a new intracellular interaction partner of PCI and colocalization of PCI and CSN6, a subunit of the COP9 signalosome could be observed in lymphocytes. Here, we analyzed the interaction of PCI with phosphatidic acid (PA), phosphatidylglycerol (PG), cardiolipin (CL), phosphoinositides and derived second messengers like inositol-1,4,5-trisphosphate (IP3) and diacylglycerol (DAG). To identify lipid-regions which are important for PCI binding we were focusing on differences in fatty acid composition and headgroup phosphorylation. The binding was studied by native PAGE, protein overlay assays (dot blot analysis) or ELISA. The stimulation of PCI activity towards APC was analyzed in functional assays using a low molecular weight substrate (S-2366). IP3 and inositol-1,3,4,5-tetrakisphosphate (IP4) did neither interact with PCI nor stimulate its activity towards APC. PCI bound to saturated, unsaturated and oxidized PA. The oxidized form of 1-palmitoyl-2-arachidonoyl-phosphatidic acid (OxPAPA) exhibited lower binding to PCI, but higher stimulatory activity on APC inhibition, as compared to unoxidized PAPA. Saturated dipalmitoyl-PA did not modulate PCI activity. From all studied lipids 1-palmitoyl-2-arachidonoyl-PG (PAPG) had the strongest stimulatory effect on APC-inhibition similar to 0.1μM low molecular weight heparin. Oxidation of PAPG led to a slight decrease and saturation to a complete loss in stimulatory activity. Also tetra-oleoyl-CL bound to PCI with high affinity and had a similar effect as oxidized PAPG and OxPAPA. All mono- and diphosphorylated phosphoinositides as well as phosphatidylinositol-3,4,5-triphosphate (PI3,4,5P3) bound to PCI as judged from binding assays. A mobility shift of PCI antigen on native PAGE was observed when PCI was incubated with phosphatidylinositol-3,5-diphosphate and phosphatidylinositol-4,5-diphosphate (PI4,5P2). Therefore different phospholipids modulate the activity of PCI, but on the other hand PCI may as well effect lipid signaling. As PI4,5P2 plays an important role as substrate for PI3-kinase we will take a closer look at the effect of PCI on the PI3K/PTEN system and on the activation of AKT (PKB) by PDK1. We will also study the influence of PCI on the generation of IP3 and DAG and its possible role in calcium signaling and protein kinase activation. So far we conclude that phosphoinositides and other glycerophospholipids may function as additional intracellular interaction partners of PCI. Disclosures: No relevant conflicts of interest to declare.
35
Bernhard, Wolfgang, Marco Raith, Christopher J. Pynn, Christian Gille, Guido Stichtenoth, Dieter Stoll, Erwin Schleicher, and Christian F. Poets. "Increased palmitoyl-myristoyl-phosphatidylcholine in neonatal rat surfactant is lung specific and correlates with oral myristic acid supply." Journal of Applied Physiology 111, no. 2 (August 2011): 449–57. http://dx.doi.org/10.1152/japplphysiol.00766.2010.
Анотація:
Surfactant predominantly comprises phosphatidylcholine (PC) species, together with phosphatidylglycerols, phosphatidylinositols, neutral lipids, and surfactant proteins-A to -D. Together, dipalmitoyl-PC (PC16:0/16:0), palmitoyl-myristoyl-PC (PC16:0/14:0), and palmitoyl-palmitoleoyl-PC (PC16:0/16:1) make up 75–80% of mammalian surfactant PC, the proportions of which vary during development and in chronic lung diseases. PC16:0/14:0, which exerts specific effects on macrophage differentiation in vitro, increases in surfactant during alveolarization (at the expense of PC16:0/16:0), a prenatal event in humans but postnatal in rats. The mechanisms responsible and the significance of this reversible increase are, however, not understood. We hypothesized that, in rats, myristic acid (C14:0) enriched milk is key to lung-specific PC16:0/14:0 increases in surfactant. We found that surfactant PC16:0/14:0 in suckling rats correlates with C14:0 concentration in plasma chylomicrons and lung tissue triglycerides, and that PC16:0/14:0 fractions reflect exogenous C14:0 supply. Significantly, C14:0 was increased neither in plasma PC, nor in liver triglycerides, free fatty acids, or PC. Lauric acid was also abundant in triglycerides, but was not incorporated into surfactant PC. Comparing a C14:0-rich milk diet with a C14:0-poor carbohydrate diet revealed increased C14:0 and decreased C16:0 in plasma and lung triglycerides, respectively. PC16:0/14:0 enrichment at the expense of PC16:0/16:0 did not impair surfactant surface tension function. However, the PC profile of the alveolar macrophages from the milk-fed animals changed from PC16:0/16:0 rich to PC16:0/14:0 rich. This was accompanied by reduced reactive oxygen species production. We propose that nutritional supply with C14:0 and its lung-specific enrichment may contribute to decreased reactive oxygen species production during alveolarization.
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Pynn, Christopher J., M. Victoria Picardi, Tim Nicholson, Dorothee Wistuba, Christian F. Poets, Erwin Schleicher, Jesus Perez-Gil, and Wolfgang Bernhard. "Myristate is selectively incorporated into surfactant and decreases dipalmitoylphosphatidylcholine without functional impairment." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 299, no. 5 (November 2010): R1306—R1316. http://dx.doi.org/10.1152/ajpregu.00380.2010.
Анотація:
Lung surfactant mainly comprises phosphatidylcholines (PC), together with phosphatidylglycerols and surfactant proteins SP-A to SP-D. Dipalmitoyl-PC (PC16:0/16:0), palmitoylmyristoyl-PC (PC16:0/14:0), and palmitoylpalmitoleoyl-PC (PC16:0/16:1) together comprise 75–80% of surfactant PC. During alveolarization, which occurs postnatally in the rat, PC16:0/14:0 reversibly increases at the expense of PC16:0/16:0. As lipoproteins modify surfactant metabolism, we postulated an extrapulmonary origin of PC16:0/14:0 enrichment in surfactant. We, therefore, fed rats (d19–26) with trilaurin (C12:03), trimyristin (C14:03), tripalmitin (C16:03), triolein (C18:13) or trilinolein (C18:23) vs. carbohydrate diet to assess their effects on surfactant PC composition and surface tension function using a captive bubble surfactometer. Metabolism was assessed with deuterated C12:0 (ω-d3-C12:0) and ω-d3-C14:0. C14:03 increased PC16:0/14:0 in surfactant from 12 ± 1 to 45 ± 3% and decreased PC16:0/16:0 from 47 ± 1 to 29 ± 2%, with no impairment of surface tension function. Combined phospholipase A2 assay and mass spectrometry revealed that 50% of the PC16:0/14:0 peak comprised its isomer 1-myristoyl-2-palmitoyl-PC (PC14:0/16:0). While C12:03 was excluded from incorporation into PC, it increased PC16:0/14:0 as well. C16:03, C18:13, and C18:23 had no significant effect on PC16:0/16:0 or PC16:0/14:0. d3-C14:0 was enriched in lung PC, either via direct supply or via d3-C12:0 elongation. Enrichment of d3-C14:0 in surfactant PC contrasted its rapid turnover in plasma and liver PC, where its elongation product d3-C16:0 surmounted d3-C14:0. In summary, high surfactant PC16:0/14:0 during lung development correlates with C14:0 and C12:0 supply via specific C14:0 enrichment into lung PC. Surfactant that is high in PC16:0/14:0 but low in PC16:0/16:0 is compatible with normal respiration and surfactant function in vitro.
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Katsai, Oleksii, and Olena Ruban. "PREPARATION AND CHARACTERIZATION OF LIPOSOMAL DELIVERY SYSTEM OF NATURAL HEME PROTEIN." International Journal of Applied Pharmaceutics, June 1, 2019, 418–25. http://dx.doi.org/10.22159/ijap.2019v11i4.32080.
Анотація:
Objective: The objective of the present study was to develop and optimize the methods for preparation and characterization of the liposomal delivery system of natural heme protein.
Methods: Cytochrome C containing liposomes (Cyt-LS) were prepared by high-pressure homogenization technique using phosphatidylcholine (PC) and dipalmitoyl phosphatidylglycerol (DPPG). Nanoparticles were characterized by using: dynamic light scattering, zeta potential measurements, scanning electron microscopy and HPLC. The specific activity was studied in vitro.
Results: The study of homogenization regimes for obtaining unilamellar Cyt-LS was carried out. The selected temperature regime of homogenization was kept within 38–44 °С with optimal homogenization pressure of 800 bar. The obtained Cyt-LS were characterized by the main physicochemical parameters showed: Encapsulation efficiency 95.8±2.0%, Zeta potential-57±1.0 mV, pH-6.95±0.05. Phospholipid impurities had the following content: lysophosphatidylcholine-0.60±0.05% and free fatty acids-0.4±0.05%. The average particle diameter was 156±2 nm. Also, the size of Cyt-LS particles was confirmed by the ability of emulsion subjected to the sterilizing filtration with the preservation of its main physicochemical properties. Cyt-LS exhibit specific activity, similar to non-liposomal Cyt-C solution.
Conclusion: The formulation of the liposomal delivery system of heme protein was successfully prepared using natural components and evaluated for different parameters.
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Milowska, Katarzyna, Aleksandra Rodacka, Sophie Melikishvili, Adam Buczkowski, Bartlomiej Pałecz, Iveta Waczulikova, Tibor Hianik, Jean Pierre Majoral, Maksim Ionov, and Maria Bryszewska. "Dendrimeric HIV-peptide delivery nanosystem affects lipid membranes structure." Scientific Reports 11, no. 1 (August 19, 2021). http://dx.doi.org/10.1038/s41598-021-96194-x.
Анотація:
AbstractThe aim of this study was to evaluate the nature and mechanisms of interaction between HIV peptide/dendrimer complexes (dendriplex) and artificial lipid membranes, such as large unilayered vesicles (LUV) and lipid monolayers in the air–water interface. Dendriplexes were combined as one of three HIV-derived peptides (Gp160, P24 and Nef) and one of two cationic phosphorus dendrimers (CPD-G3 and CPD-G4). LUVs were formed of 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC) or of a mixture of DMPC and dipalmitoyl-phosphatidylglycerol (DPPG). Interactions between dendriplexes and vesicles were characterized by dynamic light scattering (DLS), fluorescence anisotropy, differential scanning calorimetry (DSC) and Langmuir–Blodgett methods. The morphology of formed systems was examined by transmission electron microscopy (TEM). The results suggest that dendriplexes interact with both hydrophobic and hydrophilic regions of lipid bilayers. The interactions between dendriplexes and negatively charged lipids (DMPC–DPPG) were stronger than those between dendriplexes and liposomes composed of zwitterionic lipids (DMPC). The former were primarily of electrostatic nature due to the positive charge of dendriplexes and the negative charge of the membrane, whereas the latter can be attributed to disturbances in the hydrophobic domain of the membrane. Obtained results provide new information about mechanisms of interaction between lipid membranes and nanocomplexes formed with HIV-derived peptides and phosphorus dendrimers. These data could be important for the choosing the appropriate antigen delivery vehicle in the new vaccines against HIV infection.