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1
SHIMIZU, Takao. "Biologically Active Lipids: From Prostaglandins to Surfactant Lipids". Journal of the Mass Spectrometry Society of Japan 57, nr 3 (2009): 153–55. http://dx.doi.org/10.5702/massspec.57.153.
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Wright, J. R. "Clearance and recycling of pulmonary surfactant". American Journal of Physiology-Lung Cellular and Molecular Physiology 259, nr 2 (1.08.1990): L1—L12. http://dx.doi.org/10.1152/ajplung.1990.259.2.l1.
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In a steady state the rate of secretion of pulmonary surfactant lipids and proteins into the alveolar airspace must be balanced by the rate of removal. Several potential pathways for clearance have been identified including uptake by alveolar type II cells, which also synthesize and secrete surfactant components, uptake by other epithelial cells, and internalization by alveolar macrophages. A small amount of surfactant moves up the airways and through the epithelium-endothelium barrier into the blood. Some of the surfactant lipids and proteins that are cleared from the alveolar airspace appear to be “recycled” in that they appear in the lamellar body, a surfactant secretory granule found in the type II cell. Some surfactant lipids are degraded, probably intracellularly, and the degradation products are reutilized to synthesize new lipids. Several factors have been shown to affect internalization by the type II cell and/or alveolar clearance including the surfactant proteins, lipids, and known stimuli of surfactant secretion. Surfactant proteins may be involved in regulating pool size by modulating both secretion rates and uptake rates, possibly by a receptor-mediated process, although such receptors have not yet been identified or isolated. Clearance of surfactant lipids from the alveolar airspace is more rapid than clearance from the whole lung, and these two processes may be regulated by different factors. Elucidation of the factors that fine tune the balance between synthesis, secretion, and clearance of the lipid and protein components of surfactant awaits further investigation
3
KEOUGH, KEVIN M. W. "Physicochemical properties of surfactant lipids". Biochemical Society Transactions 13, nr 6 (1.12.1985): 1081–84. http://dx.doi.org/10.1042/bst0131081.
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Batenburg, J. J. "Surfactant phospholipids: synthesis and storage". American Journal of Physiology-Lung Cellular and Molecular Physiology 262, nr 4 (1.04.1992): L367—L385. http://dx.doi.org/10.1152/ajplung.1992.262.4.l367.
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Pulmonary surfactant, a complex consisting of 90% lipids and 10% specific proteins, lines the alveoli of the lung and prevents alveolar collapse and transudation by lowering the surface tension at the air-liquid interface. Dipalmitoylphosphatidylcholine constitutes approximately 50% of the surfactant lipids and is primarily responsible for the surface tension-lowering property of the surfactant mixture. This phospholipid, together with the other surfactant phospholipids, is produced at the endoplasmic reticulum of the alveolar type II epithelial cells. The characteristic lamellar bodies in these cells serve as storage depot for the surfactant before this is secreted onto the alveolar surface. This article reviews the pathways via which the surfactant lipids are synthesized, our current knowledge of the regulation of these pathways, and what is known about intracellular traffic of phospholipids from their site of synthesis to the lamellar bodies.
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Casals, Cristina, Belen García-Fojeda, Paula Tenreiro i Carlos M. Minutti. "Surfactant lipids inhibit PI3K-dependent signaling pathways induced by IL-4 in alveolar macrophages". Journal of Immunology 210, nr 1_Supplement (1.05.2023): 72.32. http://dx.doi.org/10.4049/jimmunol.210.supp.72.32.
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Abstract Alveolar macrophages (AMs) are less able to respond to IL-4 in vivo than macrophages from the peritoneal cavity, due to a still-unknown factor of the lung environment. The aim of this study is to investigate whether surfactant lipids, which are continuously endocytosed by AMs, could influence IL-4-mediated alternative activation and proliferation of AMs. To that end, AMs were preincubated with surfactant lipids and stimulated with IL-4 in the presence or absence of surfactant protein SP-A, an amplifier of IL-4 actions. We found that alveolar lipids reduced IL-4- and IL-4+SP-A-dependent arginase activity, the expression of genes associated with alternative activation, and proliferation of AMs. Mechanistically, endocytosed lipids decreased IL-4- and IL-4+SP-A-induced activation of the PI3K-Akt-mTORC1 signaling axis, but not the IL-4-dependent STAT6 axis. Lipid-dependent inhibition of the Akt/mTORC1 signaling axis is consistent with reduced IL-4+SP-A-driven glycolysis and mitochondrial respiration as well as decreased ATP citrate lyase expression and histone acetylation stimulated by IL-4. We conclude that surfactant lipids inhibit PI3K-dependent signaling pathways and suggest that decrease of surfactant lipids in chronic lung diseases might augment IL-4-dependent fibrotic responses. This research is funded by the Spanish Ministry of Science and Innovation through Grant PID2021-123044OB-I00 to C. Casals
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Mudgil, Poonam, i Thomas J. Millar. "Surfactant Properties of Human Meibomian Lipids". Investigative Opthalmology & Visual Science 52, nr 3 (24.03.2011): 1661. http://dx.doi.org/10.1167/iovs.10-5445.
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Van Iwaarden, J. F., H. Shimizu, P. H. M. Van Golde, D. R. Voelker i L. M. G. Van Golde. "Rat surfactant protein D enhances the production of oxygen radicals by rat alveolar macrophages". Biochemical Journal 286, nr 1 (15.08.1992): 5–8. http://dx.doi.org/10.1042/bj2860005.
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Rat surfactant protein D (SP-D) was shown to enhance the production of oxygen radicals by rat alveolar macrophages. This enhancement, which was determined by a lucigenin-dependent chemiluminescence assay, was maximal after 18 min at an SP-D concentration of 0.2 micrograms/ml. Surfactant lipids did not influence the stimulation of alveolar macrophages by SP-D, whereas the oxygen-radical production of these cells induced by surfactant protein A was inhibited by the lipids in a concentration-dependent manner.
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Kremlev, S. G., i D. S. Phelps. "Effect of SP-A and surfactant lipids on expression of cell surface markers in the THP-1 monocytic cell line". American Journal of Physiology-Lung Cellular and Molecular Physiology 272, nr 6 (1.06.1997): L1070—L1077. http://dx.doi.org/10.1152/ajplung.1997.272.6.l1070.
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Pulmonary surfactant and its lipid components inhibit cell proliferation and cytokine expression. Surfactant protein A (SP-A) can stimulate these same functions. We assessed the impact of SP-A and surfactant lipids on the expression of the cell surface markers, CD14, CD54 (intercellular adhesion molecule-1), and CD11b, by the human monocytic cell line THP-1 using fluorescent antibody staining and fluorescence-activated cell sorting. Under basal conditions CD14 and CD54 were undetectable, and CD11b was expressed at low levels. Incubation of the cells in 1,25(OH)2D3 alone, or with low doses of surfactant lipids, increased CD14, CD54, and CD11b. Expression was increased further by SP-A. However, the SP-A-induced increases in cell markers were blocked by simultaneous treatment with lipid. The results suggest that the ability of the macrophage to participate in an inflammatory response is enhanced by SP-A alone or by surfactant containing a higher than normal proportion of SP-A. They further suggest that the addition of lipids results in a phenotype less prone to initiate an inflammatory reaction.
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Soll, Roger F., i Jerold F. Lucey. "Surfactant Replacement Therapy". Pediatrics In Review 12, nr 9 (1.03.1991): 261–67. http://dx.doi.org/10.1542/pir.12.9.261.
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Despite medical and technological advances, respiratory distress syndrome (RDS) remains a major cause of morbidity and mortality in premature infants. Thirty years have passed since Avery and Mead demonstrated that infants dying of RDS were deficient in pulmonary surfactant. In those three decades, advances in our understanding of the composition, function, and metabolism of pulmonary surfactant have finally led to clinical trials of surfactant replacement therapy in thousands of premature infants. This article reviews the current status of surfactant replacement therapy. BACKGROUND Pulmonary surfactant is essential for normal lung function. Surfactant forms a film at the alveolar surface, which prevents the lung from collapsing at the end of expiration. Surfactant may have other functions as well, including the prevention of pulmonary edema, the prevention of infection, and the prevention of lung injury from toxic substances, such as oxygen (Table 1) CHEMICAL MAKEUP The chemical makeup of pulmonary surfactant has been well defined (Table 2). Lipids are the major component, comprising up to 80% to 90% of surfactant by weight. The majority of the lipids in pulmonary surfactant are highly polar phospholipids, predominantly phosphatidylcholine. Three proteins associated with surfactant have been these surfactant proteins may play a critical role in surfactant function by improving the adsorption of surfactant at the alveolar surface and by aiding in surfactant re-uptake and metabolism.
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Kremlev, S. G., T. M. Umstead i D. S. Phelps. "Surfactant protein A regulates cytokine production in the monocytic cell line THP-1". American Journal of Physiology-Lung Cellular and Molecular Physiology 272, nr 5 (1.05.1997): L996—L1004. http://dx.doi.org/10.1152/ajplung.1997.272.5.l996.
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Surfactant lipids inhibit cytokine production by immune cells, and surfactant protein A (SP-A) stimulates it. By enzyme-linked immunosorbent assay and mRNA blotting, we studied proinflammatory cytokine production by the monocytic cell line THP-1. SP-A caused increases in tumor necrosis factor (TNF)-alpha within 1 h, peaking at 4 h and then declining. Interleukin (IL)-1 beta increased and stayed elevated for 24 h. SP-A stimulated IL-8 also, peaking at 4 h, rapidly declining, and peaking again at 24 h. SP-A-dependent changes were detected for IL-6, but at higher SP-A doses. mRNA levels for TNF-alpha and IL-1 beta increased in response to SP-A, peaking within 2 h. The increases in TNF-alpha mRNA and protein induced by SP-A were inhibited by surfactant lipids. For IL-1 beta and IL-8, the lipids either had no inhibitory influence or inhibited less than for TNF-alpha. This suggests that the ability of macrophages to participate in inflammatory reactions is enhanced by SP-A alone or by mixtures of lipids and SP-A containing more SP-A than in normal surfactant, as occurs in many conditions leading to inflammation.
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Johnston, Sonya D., Christopher B. Daniels, David Cenzato, Jeffrey A. Whitsett i Sandra Orgeig. "The pulmonary surfactant system matures upon pipping in the freshwater turtle Chelydra serpentina". Journal of Experimental Biology 205, nr 3 (1.02.2002): 415–25. http://dx.doi.org/10.1242/jeb.205.3.415.
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SUMMARY Pulmonary surfactant (PS), a mixture of phospholipids (PL), neutral lipids and surfactant proteins (SP), lowers surface tension within the lung, which increases lung compliance and improves the removal of fluid at birth. Here, we have examined the expression of thyroid transcription factor-1 (TTF-1) and the surfactant protein SP-B, and also the composition of pulmonary surfactant lipids in the developing lung of the turtle Chelydra serpentina. Lavage and lung tissue were collected from late embryonic, pipped and hatchling turtles. TTF-1, a regulator of gene expression of surfactant proteins and cell differentiation in mammals, was detected using immunohistochemistry in epithelia of the gas-exchange area and conducting airways during late development. Expression declined in hatchlings. SP-B was detected in subsets of cells within the respiratory epithelium at all stages sampled. The same cell types also stained for TTF-1. Turtle surfactant lipids matured toward the end of incubation. Maximal secretion of both total phospholipids and disaturated phospholipid (DSP) occurred at the time of pipping, coincident with the onset of breathing. The DSP/PL ratio increased after pipping, whereas cholesterol levels (Chol) increased prior to pipping. This resulted in a decrease in the Chol/PL and Chol/DSP ratios after pipping. Thus, TTF-1 and SP-B appear to be highly conserved within the vertebrates. Maturation of surfactant phospholipid content occurred with the commencement of pulmonary ventilation.
12
Young, S. L., i R. Silbajoris. "Dexamethasone increases adult rat lung surfactant lipids". Journal of Applied Physiology 60, nr 5 (1.05.1986): 1665–72. http://dx.doi.org/10.1152/jappl.1986.60.5.1665.
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Prenatal administration of glucocorticoids stimulates epithelial cell maturation and induces a precocious development of pulmonary surfactant. The response of the adult lung to steroid administration is less well understood. We administered dexamethasone (2 mg X kg-1 X day-1) to adult male rats for 1 wk by daily subcutaneous injection. After pentobarbital anesthesia we lavaged the lungs and also isolated lamellar bodies from the tissue. Lipid analyses of the extracellular and intracellular surfactant compartments showed two- to fourfold greater amounts of total phospholipids and disaturated phosphatidylcholine compared with control. These changes were not found in kidney nor liver and were not present in plasma membrane, mitochondrial, or microsomal fractions from lungs. Morphometric analyses of the type II cells showed that anatomic measures of the lamellar body pool did not increase. We conclude that glucocorticoids have a significant effect to increase lung surfactant lipid pools of adult rat lungs by changing the phospholipid content of lamellar bodies, without changing lamellar body volume.
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Veldhuizen, Ruud, Kaushik Nag, Sandra Orgeig i Fred Possmayer. "The role of lipids in pulmonary surfactant". Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease 1408, nr 2-3 (listopad 1998): 90–108. http://dx.doi.org/10.1016/s0925-4439(98)00061-1.
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Polańska, Żaneta, Zuzanna Pietralik-Molińska, Daria Wojciechowska, Augustyn Moliński, Marek Weiss, Andrzej Skrzypczak i Maciej Kozak. "The Process of Binding and Releasing of Genetic Material from Lipoplexes Based on Trimeric Surfactants and Phospholipids". International Journal of Molecular Sciences 22, nr 14 (20.07.2021): 7744. http://dx.doi.org/10.3390/ijms22147744.
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Nonviral vectors for gene therapy such as lipoplexes are characterized by low toxicity, high biocompatibility, and good transfection efficiency. Specifically, lipoplexes based on polymeric surfactants and phospholipids have great potential as gene carriers due to the increased ability to bind genetic material (multiplied positive electric charge) while lowering undesirable effects (the presence of lipids makes the system more like natural membranes). This study aimed to test the ability to bind and release genetic material by lipoplexes based on trimeric surfactants and lipid formulations of different compositions and to characterize formed complexes by circular dichroism (CD) spectroscopy and atomic force microscopy (AFM). The cytotoxicity of studied lipoplexes was tested on HeLa cells by the MTT cell viability assay and the dye exclusion test (trypan blue). The presence of lipids in the system lowered the surfactant concentration required for complexation (higher efficiency) and reduced the cytotoxicity of lipoplexes. Surfactant/lipids/DNA complexes were more stable than surfactant/DNA complexes. Surfactant molecules induced the genetic material condensation, but the presence of lipids significantly intensified this process. Systems based on trimeric surfactants and lipid formulations, particularly TRI_N and TRI_IMI systems, could be used as delivery carrier, and have proven to be highly effective, nontoxic, and universal for DNA of various lengths.
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Holm, B. A., i R. H. Notter. "Effects of hemoglobin and cell membrane lipids on pulmonary surfactant activity". Journal of Applied Physiology 63, nr 4 (1.10.1987): 1434–42. http://dx.doi.org/10.1152/jappl.1987.63.4.1434.
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These experiments characterize the effects of hemoglobin and erythrocyte membrane lipids on the dynamic surface activity and adsorption facility of whole lung surfactant (LS) and a calf lung surfactant extract (CLSE) used clinically in surfactant replacement therapy for the neonatal respiratory distress syndrome (RDS). The results show that, at concentrations from 25 to 200 mg/ml, hemoglobin (Hb) increased the minimum dynamic surface tension of LS or CLSE mixtures (0.5 and 1.0 mumol/ml) from less than 1 to 25 dyn/cm on an oscillating bubble apparatus at 37 degrees C. Similarly, erythrocyte membrane lipids (0.5–3 mumol/ml) also prevented LS and CLSE suspensions (0.5–2.0 mumol/ml) from lowering surface tension below 19 dyn/cm under dynamic compression on the bubble. Surface pressure-time adsorption isotherms for LS suspensions (0.084 and 0.168 mumol phospholipid/ml) were also adversely affected by Hb (0.3–2.5 mg/ml), having a slower adsorption rate and magnitude. Significantly, these inhibitory effects of Hb and membrane lipids could be abolished if LS and CLSE concentrations were raised to high levels. In complementary physiological experiments, instillation of Hb, membrane lipids, or albumin into excised rat lungs was shown to cause a decrease in pressure-volume compliance. This decreased compliance was most prominent in lungs made partially surfactant deficient before inhibitor delivery and could be reversed by supplementation with active exogenous surfactant. Taken together, these data show that molecular components in hemorrhagic pulmonary edema can biophysically inactivate endogenous LS and adversely affect lung mechanics. Moreover, exogenous surfactant replacement can reverse this process even in the continued presence of inhibitor molecules and thus has potential utility in therapy for adult as well as neonatal RDS.
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Kobayashi, T., W. Z. Li, K. Tashiro, R. Takahashi, Y. Waseda, K. Yamamoto i Y. Suzuki. "Disparity between tidal and static volumes of immature lungs treated with reconstituted surfactants". Journal of Applied Physiology 80, nr 1 (1.01.1996): 62–68. http://dx.doi.org/10.1152/jappl.1996.80.1.62.
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We biologically assessed functions of several reconstituted surfactants with the same minimum surface tension (2-3 mN/m) as “complete” porcine pulmonary surfactant (natural surfactant) but with longer surface adsorption times. Administration of natural surfactant (adsorption time 0.29 s) into the lungs of surfactant-deficient immature rabbits brought a tidal volume of 16.1 +/- 4.4 (SD) ml/kg during mechanical ventilation with 40 breaths/min and 20 cmH2O insufflation pressure. In static pressure-volume recordings, these animals showed a lung volume of 62.4 +/- 9.7 ml/kg at 30 cmH2O airway pressure and maintained 55% of this volume when the pressure decreased to 5 cmH2O. With two reconstituted surfactants consisting of synthetic lipids or isolated lipids from porcine lungs plus surfactant-associated hydrophobic proteins (adsorption times 0.57 and 0.78 s, respectively), tidal volumes were < 38% of that with natural surfactant (P < 0.05), but static pressure-volume recordings were not different. Care is therefore needed in estimating the in vivo function of surfactant preparations from minimum surface tension or static pressure-volume measurements.
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Walther, Frans J., Monik Gupta, Larry M. Gordon i Alan J. Waring. "An oxidation-resistant peptide mimic of surfactant protein B (B-YL) forms an amphipathic helix-hairpin in liposomes with high surface activity". Gates Open Research 2 (26.02.2018): 13. http://dx.doi.org/10.12688/gatesopenres.12799.1.
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Background: Animal-derived surfactants containing surfactant proteins B (SP-B) and C (SP-C) are used to treat respiratory distress syndrome (RDS) in preterm infants. SP-B (79 residues) plays a pivotal role in lung function and the design of synthetic lung surfactant. Super Mini-B (SMB), a 41-residue peptide based on the N- and C-domains of SP-B joined with a turn and two disulfides, folds as an α-helix hairpin mimicking the properties of these domains in SP-B. Here, we studied ‘B-YL’, a 41-residue oxidation-resistant SMB variant that has its four Cys and two Met residues replaced by Tyr and Leu, respectively, to test whether these hydrophobic substitutions produce a surface-active, α-helix hairpin. Methods: Structure and function of B-YL and SMB in surfactant lipids were compared with CD and FTIR spectroscopy and molecular dynamic (MD) simulations, and surface activity with captive bubble surfactometry and in lavaged, surfactant-deficient adult rabbits. Results: CD and FTIR spectroscopy of B-YL in surfactant lipids showed secondary structures compatible with peptide folding as an α-helix hairpin, similar to SMB in lipids. MD simulations confirmed that B-YL maintained its α-helix hairpin in a lipid bilayer, matching the hairpin obtained from MD of SMB. Unlike the disulfide-reinforced helix-turn of SMB, the B-YL fold was stabilized by a core of clustered Tyr linking the N- and C-helices through noncovalent interactions involving aromatic rings. B-YL in surfactant lipids demonstrated excellent in vitro surface activity and good oxygenation and dynamic compliance in lavaged, surfactant-deficient adult rabbits. Conclusions: ‘Sulfur-free’ and ‘oxidation-resistant’ B-YL forms an amphipathic helix-hairpin in surfactant liposomes with high surface activity and is functionally similar to SMB and native SP-B. B-YL’s resistance against free oxygen radical damage provides an extra edge over oxidized SMB in the treatment of respiratory failure in preterm infants with RDS and children and adults with acute lung injury.
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Walther, Frans J., Monik Gupta, Larry M. Gordon i Alan J. Waring. "A sulfur-free peptide mimic of surfactant protein B (B-YL) exhibits high in vitro and in vivo surface activities". Gates Open Research 2 (10.07.2018): 13. http://dx.doi.org/10.12688/gatesopenres.12799.2.
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Background: Animal-derived surfactants containing surfactant proteins B (SP-B) and C (SP-C) are used to treat respiratory distress syndrome (RDS) in preterm infants. SP-B (79 residues) plays a pivotal role in lung function and the design of synthetic lung surfactant. Super Mini-B (SMB), a 41-residue peptide based on the N- and C-domains of SP-B covalently joined with a turn and two disulfides, folds as an α-helix hairpin mimicking the properties of these domains in SP-B. Here, we studied ‘B-YL’, a 41-residue SMB variant that has its four cysteine and two methionine residues replaced by tyrosine and leucine, respectively, to test whether these hydrophobic substitutions produce a surface-active, α-helix hairpin. Methods: Structure and function of B-YL and SMB in surfactant lipids were compared with CD and FTIR spectroscopy, and surface activity with captive bubble surfactometry and in lavaged, surfactant-deficient adult rabbits. Results: CD and FTIR spectroscopy of B-YL in surfactant lipids showed secondary structures compatible with peptide folding as an α-helix hairpin, similar to SMB in lipids. B-YL in surfactant lipids demonstrated excellent in vitro surface activity and good oxygenation and dynamic compliance in lavaged, surfactant-deficient adult rabbits, suggesting that the four tyrosine substitutions are an effective replacement for the disulfide-reinforced helix-turn of SMB. Here, the B-YL fold may be stabilized by a core of clustered tyrosines linking the N- and C-helices through non-covalent interactions involving aromatic rings. Conclusions: ‘Sulfur-free’ B-YL forms an amphipathic helix-hairpin in surfactant liposomes with high surface activity and is functionally similar to SMB and native SP-B. The removal of the cysteines makes B-YL more feasible to scale up production for clinical application. B-YL’s possible resistance against free oxygen radical damage to methionines by substitutions with leucine provides an extra edge over SMB in the treatment of respiratory failure in preterm infants with RDS.
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Frey, Shelli L., Luka Pocivavsek, Alan J. Waring, Frans J. Walther, Jose M. Hernandez-Juviel, Piotr Ruchala i Ka Yee C. Lee. "Functional importance of the NH2-terminal insertion sequence of lung surfactant protein B". American Journal of Physiology-Lung Cellular and Molecular Physiology 298, nr 3 (marzec 2010): L335—L347. http://dx.doi.org/10.1152/ajplung.00190.2009.
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Lung surfactant protein B (SP-B) is required for proper surface activity of pulmonary surfactant. In model lung surfactant lipid systems composed of saturated and unsaturated lipids, the unsaturated lipids are removed from the film at high compression. It is thought that SP-B helps anchor these lipids closely to the monolayer in three-dimensional cylindrical structures termed “nanosilos” seen by atomic force microscopy imaging of deposited monolayers at high surface pressures. Here we explore the role of the SP-B NH2 terminus in the formation and stability of these cylindrical structures, specifically the distribution of lipid stack height, width, and density with four SP-B truncation peptides: SP-B 1–25, SP-B 9–25, SP-B 11–25, and SP-B 1–25Nflex (prolines 2 and 4 substituted with alanine). The first nine amino acids, termed the insertion sequence and the interface seeking tryptophan residue 9, are shown to stabilize the formation of nanosilos while an increase in the insertion sequence flexibility (SP-B 1–25Nflex) may improve peptide functionality. This provides a functional understanding of the insertion sequence beyond anchoring the protein to the two-dimensional membrane lining the lung, as it also stabilizes formation of nanosilos, creating reversible repositories for fluid lipids at high compression. In lavaged, surfactant-deficient rats, instillation of a mixture of SP-B 1–25 (as a monomer or dimer) and synthetic lung lavage lipids quickly improved oxygenation and dynamic compliance, whereas SP-B 11–25 surfactants showed oxygenation and dynamic compliance values similar to that of lipids alone, demonstrating a positive correlation between formation of stable, but reversible, nanosilos and in vivo efficacy.
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Wright, J. R., i D. C. Youmans. "Degradation of surfactant lipids and surfactant protein A by alveolar macrophages in vitro". American Journal of Physiology-Lung Cellular and Molecular Physiology 268, nr 5 (1.05.1995): L772—L780. http://dx.doi.org/10.1152/ajplung.1995.268.5.l772.
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Pulmonary surfactant is synthesized and secreted into the airspaces by the alveolar type II cell. After it is secreted, surfactant undergoes a series of poorly understood transformations resulting in formation of a surface tension-reducing surface at the air-liquid interface. The by-products of the surface film and/or other products of surfactant metabolism are eventually cleared from the alveolar space. Both the alveolar type II cell and the macrophage are thought to be involved in surfactant clearance and have been shown to internalize surfactant lipid in vitro. The goal of the current investigation was to characterize further and to quantitate the role of the macrophage in surfactant clearance by investigating the uptake and metabolism of surfactant lipids and surfactant protein A (SP-A) by macrophages in vitro. SP-A enhanced the uptake of lipids by macrophages in a time-, temperature-, and concentration-dependent manner. In contrast, neither of the collagen-like proteins SP-D or C1q enhanced the uptake. Phosphatidylcholine was rapidly degraded by macrophages and the degradation occurred both in the presence and absence of SP-A. In addition, macrophages degrade SP-A by a process that is time- and temperature-dependent. These results and calculations of uptake and degradation rates suggest that macrophages may contribute significantly to the process of surfactant clearance.
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Thakur, N. R., M. Tesan, N. E. Tyler i J. E. Bleasdale. "Altered lipid synthesis in type II pneumonocytes exposed to lung surfactant". Biochemical Journal 240, nr 3 (15.12.1986): 679–90. http://dx.doi.org/10.1042/bj2400679.
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When type II pneumonocytes were exposed to purified lung surfactant that contained 1-palmitoyl-2-[3H]palmitoyl-glycero-3-phosphocholine, radiolabelled surfactant was apparently taken up by the cells since it could not be removed by either repeated washing or exchange with non-radiolabelled surfactant, but was released when the cells were lysed. After 4 h of exposure to [3H]surfactant, more than half of the 3H within cells remained in disaturated phosphatidylcholine. Incorporation of [3H]choline, [14C]palmitate and [14C]acetate into glycerophospholipids was decreased in type II cells exposed to surfactant and this inhibition, like surfactant uptake, was half-maximal when the extracellular concentration of surfactant was approx. 0.1 mumol of lipid P/ml. Inhibition of incorporation of radiolabelled precursors by surfactant occurred rapidly and reversibly and was not due solely to dilution of the specific radioactivity of intracellular precursors. Activity of dihydroxyacetone-phosphate acyltransferase, but not glycerol-3-phosphate acyltransferase, was decreased in type II cells exposed to surfactant and this was reflected by a decrease in the 14C/3H ratio of total lipids synthesized when cells incubated with [U-14C]glycerol and [2-3H]glycerol were exposed to surfactant. Phosphatidylcholine, phosphatidylglycerol and cholesterol, either individually or mixed in the molar ratio found in surfactant, did not mimic purified surfactant in the inhibition of glycerophospholipid synthesis. In contrast, an apoprotein fraction isolated from surfactant inhibited greatly the incorporation of [3H]choline into lipids and this inhibitory activity was labile to heat and to trypsin. It is concluded that the apparent uptake of surfactant by type II cells in vitro is accompanied by an inhibition of glycerophospholipid synthesis via a mechanism that involves a surfactant apoprotein.
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Rüdiger, Mario, Angelika Tölle, Wolfgang Meier i Bernd Rüstow. "Naturally derived commercial surfactants differ in composition of surfactant lipids and in surface viscosity". American Journal of Physiology-Lung Cellular and Molecular Physiology 288, nr 2 (luty 2005): L379—L383. http://dx.doi.org/10.1152/ajplung.00176.2004.
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Pulmonary surfactant biophysical properties are best described by surface tension and surface viscosity. Besides lecithin, surfactant contains a variety of minor lipids, such as plasmalogens, polyunsaturated fatty acid-containing phospholipids (PUFA-PL), and cholesterol. Plasmalogens and cholesterol improve surface properties of lipid mixtures significantly. High PUFA-PL and plasmalogen content in tracheal aspirate of preterm infants reduces the risk of developing chronic lung disease. Different preparations are available for exogenous surfactant substitution; however, little is known about lipid composition and surface viscosity. Thus lipid composition and surface properties (measured by oscillating drop surfactometer) of three commercial surfactant preparations (Alveofact, Curosurf, Survanta) were compared. Lipid composition exhibited strong differences: Survanta had the highest proportion of disaturated PL and total neutral lipids and the lowest proportion of PUFA-PL. Highest plasmalogen and PUFA-PL concentrations were found in Curosurf (3.8 ± 0.1 vs. 26 ± 1 mol%) compared with Alveofact (0.9 ± 0.3 vs. 11 ± 1) and Survanta (1.5 ± 0.2 vs. 6 ± 1). In Survanta samples, viscosity increased >8 × 10−6 kg/s at surface tension of 30 mN/m. Curosurf showed only slightly increased surface viscosity below surface tensions of 25 mN/m, and viscosity did not reach 5 × 10−6 kg/s. By adding defined PL to Survanta, we obtained a Curosurf-like lipid mixture (without plasmalogens) that exhibited biophysical properties like Curosurf. Different lipid compositions could explain some of the differences in surface viscosity. Therefore, PL pattern and minor surfactant lipids are important for biophysical activity and should be considered when designing synthetic surfactant preparations.
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Haddad, I. Y., H. Ischiropoulos, B. A. Holm, J. S. Beckman, J. R. Baker i S. Matalon. "Mechanisms of peroxynitrite-induced injury to pulmonary surfactants". American Journal of Physiology-Lung Cellular and Molecular Physiology 265, nr 6 (1.12.1993): L555—L564. http://dx.doi.org/10.1152/ajplung.1993.265.6.l555.
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Activated alveolar macrophages secrete both nitric oxide and superoxide in the alveolar lining fluid which combine rapidly to form peroxynitrite, a potent oxidizing agent capable of damaging lipids and proteins in biological membranes. Peroxynitrite (1 mM) plus 100 microM Fe3+EDTA inhibited calf lung surfactant extract (CLSE) from reaching a minimum surface tension below 10 mN/m on dynamic compression. Peroxynitrite and its by-products reacted with the unsaturated lipid components of CLSE, as evidenced by the appearance of conjugated dienes and thiobarbituric acid products, and damaged all surfactant proteins. A mixture of the hydrophobic proteins [surfactant protein B (SP-B) and surfactant protein C (SP-C)] exposed to peroxynitrite became incapable of lowering phospholipid minimum surface tension on dynamic compression. Exposure of SP-A to peroxynitrite decreased its ability to cause lipid aggregation and to act synergistically with SP-B and SP-C in lowering surface tension of surfactant lipids. Western blot analysis of SP-A exposed to peroxynitrite was consistent with fragmentation and polymerization of the 28- to 36-kDa triplet band, and amino acid analysis revealed the presence of significant levels of 3-nitro-L-tyrosine. We conclude that peroxynitrite and its reactive intermediates inhibit pulmonary surfactant function by lipid peroxidation and damaging surfactant proteins.
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Van Golde, L. M. G. "Synthesis of Surfactant Lipids in the Adult Lung". Annual Review of Physiology 47, nr 1 (październik 1985): 765–74. http://dx.doi.org/10.1146/annurev.ph.47.030185.004001.
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Fisher, A. B., i A. Chander. "Intracellular Processing of Surfactant Lipids in the Lung". Annual Review of Physiology 47, nr 1 (październik 1985): 789–802. http://dx.doi.org/10.1146/annurev.ph.47.030185.004041.
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Quintero, Omar A., i Jo Rae Wright. "Metabolism of phosphatidylglycerol by alveolar macrophages in vitro". American Journal of Physiology-Lung Cellular and Molecular Physiology 279, nr 2 (1.08.2000): L399—L407. http://dx.doi.org/10.1152/ajplung.2000.279.2.l399.
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In whole animal studies, it has been shown that turnover of surfactant dipalmitoylphosphatidylglycerol (DPPG) is faster than that of dipalmitoylphosphatidylcholine (DPPC). The goal of this investigation was to characterize the metabolism of DPPG by alveolar macrophages and to determine whether they contribute to the faster alveolar clearance of DPPG. Isolated rat alveolar macrophages were incubated with liposomes colabeled with [3H]DPPG and [14C]DPPC. Macrophages internalized both lipids in a time- and temperature-dependent manner. The uptake of both lipids was increased by surfactant protein (SP) A and by adherence of the macrophages to plastic slides. The isotope ratio of DPPC to DPPG internalized by macrophages in suspension in the absence of SP-A was significantly lower than the isotope ratio in liposomes, suggesting that macrophages preferentially internalize DPPG when SP-A is absent. Phospholipase activity in macrophage homogenate was higher toward sn-2-labeled DPPG than toward sn-2-labeled DPPC. These studies show that alveolar macrophages play an important role in catabolizing surfactant lipids and may be partially responsible for the relatively faster clearance of DPPG from the lung.
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Haddad, I. Y., S. Zhu, H. Ischiropoulos i S. Matalon. "Nitration of surfactant protein A results in decreased ability to aggregate lipids". American Journal of Physiology-Lung Cellular and Molecular Physiology 270, nr 2 (1.02.1996): L281—L288. http://dx.doi.org/10.1152/ajplung.1996.270.2.l281.
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We assessed the extent to which nitration of surfactant protein (SP) A, isolated from the bronchoalveolar lavage of patients with alveolar proteinosis, alters its ability to enhance lipid aggregation, bind lipids, and act synergistically with surfactant apoproteins B and C (SP-B, SP-C) in lowering the surface activity of surfactant lipids. SP-A was treated with various concentrations of tetranitromethane (TNM) at pH 6, 7.4, 8, or 10. Depending on the pH, TNM acts either as a nitrating (pH > or = 7.4) or an oxidizing agent (pH < or = 6). Exposure of SP-A to TNM (0.1-1 mM) at pH 7.4 or 8 for 30 min resulted in dose-and pH-dependent increases in nitrotyrosine, detected by Western blotting, enzyme-linked immunosorbent assay, and direct amino acid analysis. Treatment of SP-A with 0.5 mM TNM decreased its ability to aggregate lipids by 30% at pH 7.4, and 90% at pH 8, but had no effect on the disulfide-dependent oligomeric state of SP-A. In contrast, SP-A exposed to 1 mM TNM at pH 6 had background levels of nitrotyrosine and exhibited normal lipid aggregation properties. TNM, but not a hydroxyl radical-generating system, resulted in a pH-dependent loss of SP-A fluorescence, suggesting that tryptophan also may have been nitrated. Nitration of SP-A did not affect its ability to bind lipids. In addition, SP-A (1-3% by weight), treated with 0.25-0.5 mM TNM at pH 8, restored the surface-active properties of calf lung surfactant extract, previously damaged by exposure to peroxynitrite. We conclude that tyrosine nitration selectively inhibits the SP-A-mediated lipid aggregation without affecting its ability to bind lipids.
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Kremlev, S. G., T. M. Umstead i D. S. Phelps. "Effects of surfactant protein A and surfactant lipids on lymphocyte proliferation in vitro". American Journal of Physiology-Lung Cellular and Molecular Physiology 267, nr 4 (1.10.1994): L357—L364. http://dx.doi.org/10.1152/ajplung.1994.267.4.l357.
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We studied the effects of dipalmitoyl L-alpha-phosphatidylcholine (DPPC), Survanta, surfactant protein A (SP-A), and mixtures of these substances on mitogen-induced lymphocyte proliferation using concanavalin A as a mitogen. A concentration-dependent suppression of proliferation was observed with 50-250 micrograms/ml of DPPC or Survanta. However, when SP-A was added to cultures, proliferation was stimulated. The inhibitory effects of DPPC and Survanta were altered in mixtures that contained SP-A. When added to 50 micrograms/ml of Survanta, SP-A reversed the inhibitory influence of Survanta and caused increased proliferation. These findings suggest that surfactant phospholipids cause a suppression of mitogen-induced lymphocyte proliferation, which is reversed somewhat by addition of SP-A. We hypothesize that immune cell function in the lung varies with changes in the relative amounts of surfactant components. Changes in surfactant composition may occur during pulmonary inflammation or infection or with surfactant replacement therapy and may influence immune and inflammatory processes in the lung.
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Liau, Deng F., i Stephen F. Ryan. "Purification of surfactant protein A from dog lung by reconstitution with surfactant lipids". Chemistry and Physics of Lipids 59, nr 1 (sierpień 1991): 29–38. http://dx.doi.org/10.1016/0009-3084(91)90060-o.
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Palaniyar, Nades, Ross A. Ridsdale, Stephen A. Hearn, Fred Possmayer i George Harauz. "Formation of membrane lattice structures and their specific interactions with surfactant protein A". American Journal of Physiology-Lung Cellular and Molecular Physiology 276, nr 4 (1.04.1999): L642—L649. http://dx.doi.org/10.1152/ajplung.1999.276.4.l642.
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Biological membranes exist in many forms, one of which is known as tubular myelin (TM). This pulmonary surfactant membranous structure contains elongated tubes that form square lattices. To understand the interaction of surfactant protein (SP) A and various lipids commonly found in TM, we undertook a series of transmission-electron-microscopic studies using purified SP-A and lipid vesicles made in vitro and also native surfactant from bovine lung. Specimens from in vitro experiments were negatively stained with 2% uranyl acetate, whereas fixed native surfactant was delipidated, embedded, and sectioned. We found that dipalmitoylphosphatidylcholine-egg phosphatidylcholine (1:1 wt/wt) bilayers formed corrugations, folds, and predominantly 47-nm-square latticelike structures. SP-A specifically interacted with these lipid bilayers and folds. We visualized other proteolipid structures that could act as intermediates for reorganizing lipids and SP-As. Such a reorganization could lead to the localization of SP-A in the lattice corners and could explain, in part, the formation of TM-like structures in vivo.
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Wright, J. R. "Immunomodulatory functions of surfactant". Physiological Reviews 77, nr 4 (1.10.1997): 931–62. http://dx.doi.org/10.1152/physrev.1997.77.4.931.
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The possibility that the lipoprotein complex of lung surfactant functions in pulmonary host defense as well as lowering surface tension at the air-liquid interface has been the subject of renewed interest in light of the finding that surfactant proteins A and D (SP-A and SP-D) are members of a family of proteins known as collectins. The collectins, so named because they have in common an NH2-terminal collagen-like domain and a COOH-terminal lectin (carbohydrate binding) domain, are found in both lung and serum and participate in "innate" immunity, acting before induction of an antibody-mediated response. In vitro, many of the collectins stimulate phagocytosis, chemotaxis, and production of reactive oxygen and regulate cytokine release by immune cells. It has been known for several years that surfactant lipids suppress a variety of immune cell functions, most notably lymphocyte proliferation, which, conversely, is augmented by SP-A. Thus surfactant lipids and proteins may be counterregulatory, and changes in lipid-to-protein ratios may be important in regulating the immune status of the lung. That these ratios change in disease states is clear, but it is not known whether the alterations are a cause or an effect. Important future studies with mice in which the SP-A and SP-D genes have been ablated will help clarify the role of surfactant in immune function.
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Veldhuizen, R. A., S. A. Hearn, J. F. Lewis i F. Possmayer. "Surface-area cycling of different surfactant preparations: SP-A and SP-B are essential for large-aggregate integrity". Biochemical Journal 300, nr 2 (1.06.1994): 519–24. http://dx.doi.org/10.1042/bj3000519.
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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.
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Walker, S. R., M. C. Williams i B. Benson. "Immunocytochemical localization of the major surfactant apoproteins in type II cells, Clara cells, and alveolar macrophages of rat lung." Journal of Histochemistry & Cytochemistry 34, nr 9 (wrzesień 1986): 1137–48. http://dx.doi.org/10.1177/34.9.2426341.
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The adsorptive properties of phospholipids of pulmonary surfactant are markedly influenced by the presence of three related proteins (26-38 KD, reduced) found in purified surfactant. Whether these proteins are pre-assembled with lipids before secretion is uncertain but would be expected for a lipoprotein secretion. We performed indirect immunocytochemistry on frozen thin sections of rat lung to identify cells and intracellular organelles that contain these proteins. The three proteins, purified from lavaged surfactant, were used to generate antisera in rabbits. Immunoblotting of rat surfactant showed that the IgG reacted with the three proteins and a 55-60 KD band which may be a polymer of the lower MW species. Specific gold labeling occurred over alveolar type II cells, bronchiolar Clara cells, alveolar macrophages, and tubular myelin. In type II cells labeling occurred in synthetic organelles and lamellar bodies, which contain surfactant lipids. Lamellar body labeling was increased fivefold by pre-treating tissue sections with a detergent. Multivesicular bodies and some small apical vesicles in type II cells were also labeled. Secondary lysosomes of alveolar macrophages were immunoreactive. Labeling in Clara cells exceeded that of type II cells, with prominent labeling in secretory granules, Golgi apparatus, and endoplasmic reticulum. These observations clarify the organelles and pathways utilized in the elaboration of surfactant. After synthesis, the proteins move, probably via multivesicular bodies, to lamellar bodies. Both lipids and proteins are present in tubular myelin. Immunologically identical or closely similar proteins are synthesized by Clara cells and secreted from granules which appear not to contain lipid. The role of these proteins in bronchiolar function is unknown.
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Walther, Frans J., Monik Gupta, Michael M. Lipp, Holly Chan, John Krzewick, Larry M. Gordon i Alan J. Waring. "Aerosol delivery of dry powder synthetic lung surfactant to surfactant-deficient rabbits and preterm lambs on non-invasive respiratory support". Gates Open Research 3 (14.01.2019): 6. http://dx.doi.org/10.12688/gatesopenres.12899.1.
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Background: The development of synthetic lung surfactant for preterm infants has focused on peptide analogues of native surfactant proteins B and C (SP-B and SP-C). Non-invasive respiratory support with nasal continuous positive airway pressure (nCPAP) may benefit from synthetic surfactant for aerosol delivery. Methods: A total of three dry powder (DP) surfactants, consisting of phospholipids and the SP-B analogue Super Mini-B (SMB), and one negative control DP surfactant without SMB, were produced with the Acorda Therapeutics ARCUS® Pulmonary Dry Powder Technology. Structure of the DP surfactants was compared with FTIR spectroscopy, in vitro surface activity with captive bubble surfactometry, and in vivo activity in surfactant-deficient adult rabbits and preterm lambs. In the animal experiments, intratracheal (IT) aerosol delivery was compared with surfactant aerosolization during nCPAP support. Surfactant dosage was 100 mg/kg of lipids and aerosolization was performed using a low flow inhaler. Results: FTIR spectra of the three DP surfactants each showed secondary structures compatible with peptide folding as an α-helix hairpin, similar to that previously noted for surface-active SMB in other lipids. The DP surfactants with SMB demonstrated in vitro surface activity <1 mN/m. Oxygenation and lung function increased quickly after IT aerosolization of DP surfactant in both surfactant-deficient rabbits and preterm lambs, similar to improvements seen with clinical surfactant. The response to nCPAP aerosol delivery of DP surfactant was about 50% of IT aerosol delivery, but could be boosted with a second dose in the preterm lambs. Conclusions: Aerosol delivery of active DP synthetic surfactant during non-invasive respiratory support with nCPAP significantly improved oxygenation and lung function in surfactant-deficient animals and this response could be enhanced by giving a second dose. Aerosol delivery of DP synthetic lung surfactant has potential for clinical applications.
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Walther, Frans J., Monik Gupta, Michael M. Lipp, Holly Chan, John Krzewick, Larry M. Gordon i Alan J. Waring. "Aerosol delivery of dry powder synthetic lung surfactant to surfactant-deficient rabbits and preterm lambs on non-invasive respiratory support". Gates Open Research 3 (14.03.2019): 6. http://dx.doi.org/10.12688/gatesopenres.12899.2.
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Background: The development of synthetic lung surfactant for preterm infants has focused on peptide analogues of native surfactant proteins B and C (SP-B and SP-C). Non-invasive respiratory support with nasal continuous positive airway pressure (nCPAP) may benefit from synthetic surfactant for aerosol delivery. Methods: A total of three dry powder (DP) surfactants, consisting of phospholipids and the SP-B analogue Super Mini-B (SMB), and one negative control DP surfactant without SMB, were produced with the Acorda Therapeutics ARCUS® Pulmonary Dry Powder Technology. Structure of the DP surfactants was compared with FTIR spectroscopy, in vitro surface activity with captive bubble surfactometry, and in vivo activity in surfactant-deficient adult rabbits and preterm lambs. In the animal experiments, intratracheal (IT) aerosol delivery was compared with surfactant aerosolization during nCPAP support. Surfactant dosage was 100 mg/kg of lipids and aerosolization was performed using a low flow inhaler. Results: FTIR spectra of the three DP surfactants each showed secondary structures compatible with peptide folding as an α-helix hairpin, similar to that previously noted for surface-active SMB in other lipids. The DP surfactants with SMB demonstrated in vitro surface activity <1 mN/m. Oxygenation and lung function increased quickly after IT aerosolization of DP surfactant in both surfactant-deficient rabbits and preterm lambs, similar to improvements seen with clinical surfactant. The response to nCPAP aerosol delivery of DP surfactant was about 50% of IT aerosol delivery, but could be boosted with a second dose in the preterm lambs. Conclusions: Aerosol delivery of DP synthetic surfactant during non-invasive respiratory support with nCPAP significantly improved oxygenation and lung function in surfactant-deficient animals and this response could be enhanced by giving a second dose. Aerosol delivery of DP synthetic lung surfactant has potential for clinical applications.
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Minoo, P., R. J. King i J. J. Coalson. "Surfactant proteins and lipids are regulated independently during hyperoxia". American Journal of Physiology-Lung Cellular and Molecular Physiology 263, nr 2 (1.08.1992): L291—L298. http://dx.doi.org/10.1152/ajplung.1992.263.2.l291.
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Adult hamsters were exposed to 100% oxygen for up to 8 days. At time of death lung tissue was analyzed for the expression of surfactant protein (SP) genes, and surfactant was isolated from alveolar lavage fluid. Surfactant was analyzed for the composition of proteins and phospholipids and for its surface properties. We found, over the 8 days of exposure, that an alveolitis composed of polymorphonuclear leukocytes (PMNs) and alveolar macrophages, accompanied by exudation of edema fluid, appeared in the alveolar spaces. The steady-state levels of SP mRNAs declined after 8 days of exposure to 100% oxygen, but the patterns indicated individual genetic control. SP-A was elevated early in the course of the hyperoxic exposure but decreased significantly by day 8; SP-B decreased continuously; SP-C was unchanged (or slightly elevated) through day 2 and then declined. The amounts of recoverable lavage surfactant increased by greater than threefold, and the phospholipid composition showed increasing percentages of disaturated phosphatidylcholine. All surfactants lowered surface tension to less than 10 dyn/cm, but the adsorption rates decreased as exposure progressed. The results indicate that lung injury induced by 100% oxygen is accompanied by altered patterns of surfactant metabolism, possibly because of a changing type II cell phenotype or alterations in Clara cell-derived surfactant. These changes may result in perturbed physiological function contributing to decreased lung compliance.
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Dietl, Paul, i Manfred Frick. "Channels and Transporters of the Pulmonary Lamellar Body in Health and Disease". Cells 11, nr 1 (24.12.2021): 45. http://dx.doi.org/10.3390/cells11010045.
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The lamellar body (LB) of the alveolar type II (ATII) cell is a lysosome-related organelle (LRO) that contains surfactant, a complex mix of mainly lipids and specific surfactant proteins. The major function of surfactant in the lung is the reduction of surface tension and stabilization of alveoli during respiration. Its lack or deficiency may cause various forms of respiratory distress syndrome (RDS). Surfactant is also part of the innate immune system in the lung, defending the organism against air-borne pathogens. The limiting (organelle) membrane that encloses the LB contains various transporters that are in part responsible for translocating lipids and other organic material into the LB. On the other hand, this membrane contains ion transporters and channels that maintain a specific internal ion composition including the acidic pH of about 5. Furthermore, P2X4 receptors, ligand gated ion channels of the danger signal ATP, are expressed in the limiting LB membrane. They play a role in boosting surfactant secretion and fluid clearance. In this review, we discuss the functions of these transporting pathways of the LB, including possible roles in disease and as therapeutic targets, including viral infections such as SARS-CoV-2.
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López, O., M. Cócera, R. Pons, H. Amenitsch, J. Caelles, J. L. Parra, L. Coderch i A. de la Maza. "Use of Synchrotron Radiation SAXS to Study the First Steps of the Interaction between Sodium Dodecyl Sulfate and Charged Liposomes". Spectroscopy 16, nr 3-4 (2002): 343–50. http://dx.doi.org/10.1155/2002/714548.
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The technique of time resolved small angle X–ray scattering (SAXS) using a synchrotron radiation source was used to study the structural transformations as well as the kinetic associated with the first steps of the solubilization of liposomes induced by the anionic surfactant sodium dodecyl sulfate (SDS). Neutral and electrically charged (anionic and cationic) liposomes were used to investigate the effect of the electrostatic charges on these initial steps. The mechanism that induces the solubilization process consisted in an adsorption of surfactant on the bilayers and a desorption of mixed micelles from the liposomes surface to the aqueous medium. Regardless of the type of charge of the liposome the time needed for the desorption of the first mixed micelles was shorter than that for the complete adsorption of the surfactant on the liposomes surface. The present work demonstrates that the adsorption of the SDS molecules on liposomes was slower when the charges of surfactant and lipids were the same. As for the release of mixed micelles from the surface of these liposomes, this process was slower when the charges of surfactant and lipids were opposite.
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Kremlev, S. G., i D. S. Phelps. "Surfactant protein A stimulation of inflammatory cytokine and immunoglobulin production". American Journal of Physiology-Lung Cellular and Molecular Physiology 267, nr 6 (1.12.1994): L712—L719. http://dx.doi.org/10.1152/ajplung.1994.267.6.l712.
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Pulmonary surfactant plays a variety of roles related to the regulation of immune function in the lung. Of particular interest in this regard is surfactant protein A (SP-A), a calcium-dependent lectin. We have reported previously that SP-A enhances concanavalin A-induced proliferation, and in this study we examined the secretion of tumor necrosis factor-alpha (TNF-alpha), interleukins 1 alpha, 1 beta, and 6, and interferon-gamma by human peripheral blood mononuclear cells. Levels of all of the cytokines except interferon-gamma were increased by SP-A. In rat peripheral blood cells, splenocytes, and alveolar macrophages we found a similar enhancement of TNF-alpha release by SP-A. In combinations of SP-A and surfactant lipids, the increased levels of TNF-alpha resulting from SP-A treatment decreased as the lipids increased. At higher relative concentrations of SP-A, the lipids had little or no effect. SP-A also enhanced the production of immunoglobulins A, G, and M by rat splenocytes. Levels of each isotype were increased severalfold over control levels. These data demonstrate that SP-A is capable of modulating immune cell function in the lung by regulating cytokine production and immunoglobulin secretion.
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Quintero, Omar A., i Jo Rae Wright. "Clearance of surfactant lipids by neutrophils and macrophages isolated from the acutely inflamed lung". American Journal of Physiology-Lung Cellular and Molecular Physiology 282, nr 2 (1.02.2002): L330—L339. http://dx.doi.org/10.1152/ajplung.00190.2001.
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Pulmonary surfactant reduces surface tension at the lung air-liquid interface and defends the host against infection. Several lines of evidence show that surfactant levels are altered in animal models and patients with inflammatory or infectious lung diseases. We tested the hypothesis that cells responding to lung injury alter surfactant levels through increased phospholipid clearance. Acute lung injury was induced by intratracheal administration of lipopolysaccharide (LPS; Escherichia coli026:B6) into rats. LPS exposure resulted in a 12-fold increase in the number of cells isolated by lavage, the majority of which were neutrophils. Isolated macrophages and neutrophils from LPS-treated lungs internalized and degraded lipids in vitro, and LPS injury stimulated uptake by macrophages twofold. We estimate that lipid clearance by lavage cells in LPS-treated lungs could be enhanced 6- to 13-fold with both activated macrophages and increased numbers of neutrophils contributing to the process. These data show that the increased number of cells in the alveolar space after acute lung injury may lead to alterations in surfactant pools via enhanced clearance and degradation of lipids.
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Pérez-Gil, Jesus, Jacqueline Tucker, Gary Simatos i Kevin M. W. Keough. "Interfacial adsorption of simple lipid mixtures combined with hydrophobic surfactant protein from pig lung". Biochemistry and Cell Biology 70, nr 5 (1.05.1992): 332–38. http://dx.doi.org/10.1139/o92-051.
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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.
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Rustow, B., R. Haupt, P. A. Stevens i D. Kunze. "Type II pneumocytes secrete vitamin E together with surfactant lipids". American Journal of Physiology-Lung Cellular and Molecular Physiology 265, nr 2 (1.08.1993): L133—L139. http://dx.doi.org/10.1152/ajplung.1993.265.2.l133.
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Lung surfactant is exposed to strongly oxidizing conditions. We examined the hypothesis that in lung, lipophilic antioxidants are secreted together with surfactant to counteract the peroxidation of surfactant constituents. Lung lavage and the subfractions of the alveolar surfactant contain the lipophilic antioxidants vitamin E, vitamin A, and plasmalogens. The specific radioactivity of vitamin E isolated from serum, lung homogenate, lamellar bodies, and lung lavage increased linearly up to 3 h after intraperitoneal application of [3H]tocopherol. [3H]tocopherol was secreted in situ together with [14C]palmitic acid-labeled phospholipid in response to isoproterenol. Type II cells cultured in presence of [3H]tocopherol or of [3H]cholecalciferol and [14C]palmitic acid responded to isoproterenol by a time-dependent increase in secretion of [3H]tocopherol and of 14C-labeled phospholipids but not of [3H]cholecalciferol. The isoproterenol-stimulated secretion of [3H]tocopherol and of 14C-labeled phospholipids by type II cells is inhibited by surfactant protein A. We conclude that the alveolar surfactant contains lipophilic antioxidants as integral constituents. [3H]tocopherol seems to be secreted together with surfactant.
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Stachowicz-Kuśnierz, A., L. Cwiklik, J. Korchowiec, E. Rogalska i B. Korchowiec. "The impact of lipid oxidation on the functioning of a lung surfactant model". Physical Chemistry Chemical Physics 20, nr 38 (2018): 24968–78. http://dx.doi.org/10.1039/c8cp04496a.
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Rochman, M. Fatchur, Aditya Darmawan i Pramudya Wardhana. "Nanostructured Lipid Carriers System Solid Lipid Poloxamer and Stearic Acid with Liquid Lipid Soybean Oil". Jurnal Ilmiah Medicamento 8, nr 1 (29.03.2022): 1–7. http://dx.doi.org/10.36733/medicamento.v8i1.3161.
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Nanostructured Lipid Carriers (NLC) are lipid-based carrier system that use a matrix combination in the form of solid and liquid which are stabilized with the addition of surfactant. This NLC was developed to facilitate the dispersion of hydrophobic bioactive compound in a hydrophilic system. This research aims to get the right formulation and can develop stable characterization, using solid lipids Poloxamer and Stearic Acid with liquid lipids Soybeans Oil using surfactant Tween 80 and co-surfactant Propyleneglycol.. The to make the formulation of NLC with a ratio of poloxamer and stearic acid as solid lipid: soybeans oil asliquid lipid is 3:3, 4:2, 5:1 ,surfactant tween 80 and co surfactant propyleneglycol. Test the NLC characterization including PH value, viscosity, particle size, and polydispersity index. Data analysis used to evaluate the characteristics of the obtained NLC using descriptive. The result of the research showed that NLC had good characteistics at a solid lipid poloxamer and stearic acid with Soybean oil liquid lipid ,pH in the range 4-6; good viscosity; good particles have a range of 1000nm; and polydispersity index which shows the results of monodispersion. Nanostructured Llipid Carriers with solid lipid poloxamer and stearic acid and liquid lipid soybean oil obtained good characteristics.
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Shamsieva, Elena V., Svetlana A. Lukina i Marina R. Timofeeva. "The effect of the imbalance of the neurotransmitter systems of the dorsal hippocampus on the activity of alveolar macrophages and lung surfactant". Journal of Ural Medical Academic Science 19, nr 4 (2022): 412–20. http://dx.doi.org/10.22138/2500-0918-2022-19-4-412-420.
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The purpose of the study. The paper analyzes the metabolism of surfactant lipids and phagocytic activity of alveolar macrophages with an imbalance of the neurotransmitter systems of the dorsal hippocampus. Materials and methods. Male rats were microinjected with L-glutamate and GABA into the dorsal hippocampus bilaterally by stereotactic coordinates. Studies included determination of surfactant lipid fractions (thin-layer chromatography method), total phospholipids and their surface-active properties (Wilhelmi method), phospholipase activity, evaluation of endopulmonary cytogram, phagocytic index, and phagocytic number. Results. It was found that the introduction of L-glutamate was accompanied by an increase in phospholipids in the surfactant due to «inert» fractions of phosphatidylserine, phosphatidylinositol, and a low-active fraction of phosphatidylethanolamine against the background of a decrease in the intensity of phospholipase hydrolysis and the ability of macrophages to phagocytosis. The introduction of GABA led to redistribution of phospholipid fractions toward a decrease in phosphatidylcholine surfactant and an increase in the proportion of lysophosphatidylcholine under conditions of phospholipase activation and macrophage phagocytic activity. Conclusions The imbalance of the glutamate and GABAergic systems of the hippocampus has a multidirectional effect on the composition of surfactant lipids, the ability of alveolar macrophages to phagocytosis, and is characterized by the deterioration of the surface-active properties of the lungs.
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Hidayat, Nur, i Luqman Nur Chandra. "Selection of Pseudomonas sp. for Lipid and Detergent Degradation". Agroindustrial Journal 3, nr 1 (16.05.2017): 121. http://dx.doi.org/10.22146/aij.v3i1.25027.
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The objective of the research was to identify which Pseudomonas species has the ability to alter lipids and surfactants simultaneously. This research was conducted by using three Pseudomonas species, vegetable oil, and commercial detergent which contains Linear Alkyl Sulfonate LAS. The result shows that Pseudomonas aeruginosa is able to reduce lipids and surfactant 80.53% and 61.22% respectively.
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Rider, Evelyn D., Machiko Ikegami, Kent E. Pinkerton, Janice L. Peake i Alan H. Jobe. "Lysosomes from rabbit type II cells catabolize surfactant lipids". American Journal of Physiology-Lung Cellular and Molecular Physiology 278, nr 1 (1.01.2000): L68—L74. http://dx.doi.org/10.1152/ajplung.2000.278.1.l68.
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The role of a lysosome fraction from rabbit type II cells in surfactant dipalmitoylphosphatidylcholine (DPPC) catabolism was investigated in vivo using radiolabeled DPPC and dihexadecylphosphatidylcholine (1,2-dihexadecyl- sn-glycero-3-phosphocholine; DEPC), a phospholipase A1- and A2-resistant analog of DPPC. Freshly isolated type II cells were gently disrupted by shearing, and lysosomes were isolated with Percoll density gradients (density range 1.0591–1.1457 g/ml). The lysosome fractions were relatively free of contaminating organelles as determined by electron microscopy and organelle marker enzymes. After intratracheal injection of rabbits with [3H]DPPC and [14C]DEPC associated with a trace amount of natural rabbit surfactant, the degradation-resistant DEPC accumulated 16-fold compared with DPPC in lysosome fractions at 15 h. Lysosomes can be isolated from freshly isolated type II cells, and lysosomes from type II cells are the primary catabolic organelle for alveolar surfactant DPPC following reuptake by type II cells in vivo.
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LODEN, M., i A. C. ANDERSSON. "Effect of topically applied lipids on surfactant-irritated skin". British Journal of Dermatology 134, nr 2 (luty 1996): 215–20. http://dx.doi.org/10.1046/j.1365-2133.1996.978714.x.
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LODEN, M., i A. C. ANDERSSON. "Effect of topically applied lipids on surfactant-irritated skin". British Journal of Dermatology 134, nr 2 (luty 1996): 215–20. http://dx.doi.org/10.1111/j.1365-2133.1996.tb07604.x.
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Tyman, John H. P., i Ian E. Bruce. "Surfactant properties and biodegradation of polyethoxylates from phenolic lipids". Journal of Surfactants and Detergents 7, nr 2 (kwiecień 2004): 169–73. http://dx.doi.org/10.1007/s11743-004-0300-3.
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