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Abstract
Evidence is reviewed that demonstrates how the mesothelial cell in the normal peritoneum and comparable serosal cavities secretes surface-active phospholipid (SAPL) as a means of protecting itself and the membrane it forms with its neighbors. It is shown how SAPL, if adsorbed (reversibly bound) to mesothelium, can impart excellent lubricity, antiwear and release (antistick) properties, while impeding surgical adhesion formation. More-speculative benefits include acting as a deterrent to fibrosis and as a barrier to both protein leakage and pathogen invasion by spanning cell junctions. Such spanning would also “pin down” cell corners, impeding peeling as the first step in exfoliation encountered in prolonged continuous ambulatory peritoneal dialysis (CAPD). The molecular mechanism underlying each of these possible functions is adsorption. Morphological and hydrophobicity studies are discussed as validation for such an adsorbed lining and how it can be fortified by administering exogenous SAPL.Any role for SAPL in ultrafiltration is much more controversial. However, a surfactant lining can explain the very high permeability of the membrane to lipid-soluble drugs, implying that it is a barrier to water-soluble solutes. The clinical and animal evidence is conflicting but would seem to be best explained by a role for the barrier in promoting semipermeability, and hence the osmotic driving force for water transmission. Thus, adsorption of exogenous SAPL in CAPD patients with low ultrafiltration seems to restore this barrier function. The future direction for surfactant in CAPD would seem to rest with the physical chemists in producing formulations that optimize adsorption, probably involving a compromise between water solubility and surface activity of the phospholipids selected. It might even warrant using the interdialytic interval for re-adsorbing SAPL without the problem of dilution by a large volume of dialysate.
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Affiliation(s)
- Brian A. Hills
- Paediatric Respiratory Research Centre, Mater Children's Hospital, and Department of Medicine, The University of Queensland, Brisbane, Australia
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Hills BA, Burke JR, Thomas K. Surfactant Barrier Lining Peritoneal Mesothelium: Lubricant and Release Agent. Perit Dial Int 2020. [DOI: 10.1177/089686089801800203] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Objective Five studies are described to determine whether there is an outermost lining of surface-active phospholipid (SAPL) adsorbed to the peritoneum and to quantify its ability to act as a release (antistick) agent and boundary lubricant by standard tests. Methods Using a hydrophobic probe (phosphin E), epifluorescence microscopy was used to demonstrate an outermost lining of oligolamellar SAPL by spectral analysis of the emitted light, a finding consistent with the appreciable hydrophobicity demonstrated on canine peritoneal mesothelium and its virtual elimination by incubation with bile salt. Good release and excellent lubricating capabilities of human peritoneal SAPL have been quantified as the release factor and coefficient of friction, respectively, by standard tests from the physical sciences. Results A well-defined outermost layer was clearly visible on peritoneal mesothelium whose color spectrum was identical to that produced by pure phosphatidylcholine ultrasonicated into its oligolamellar state. Further evidence for a SAPL lining was demonstrated by a parietal contact angle of 43° (47° visceral) on this surface and its virtual elimination by incubation with dilute bile salt. Human SAPL from continuous ambulatory peritoneal dialysis (CAPD) effluent proved an effective release agent, reducing adhesion by 67%, and an excellent lubricant as quantified by a coefficient of friction of 0.091 under load (1.9 kg/cm2). Conclusions The good release and excellent lubricating properties of SAPL adsorbed to mesothelial surfaces are highly desirable in reducing wear and exfoliation of epithelial cells. In spanning epithelial cells, the same lining might also serve to render tight junctions tight and reduce macromolecular escape while compatible with many aspects of CAPD, including lipid permeability and conflicting results obtained from administering exogenous SAPL.
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Affiliation(s)
- Brian A. Hills
- Paediatric Respiratory Research Centre, Mater Children's Hospital; Brisbane, Australia
| | - John R. Burke
- The Renal Unit, Princess Alexandra Hospital, Brisbane, Australia
| | - Kristen Thomas
- Paediatric Respiratory Research Centre, Mater Children's Hospital; Brisbane, Australia
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Ajebli M, Eddouks M. The Promising Role of Plant Tannins as Bioactive Antidiabetic Agents. Curr Med Chem 2019; 26:4852-4884. [PMID: 29874989 DOI: 10.2174/0929867325666180605124256] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 05/16/2018] [Accepted: 05/30/2018] [Indexed: 01/12/2023]
Abstract
BACKGROUND Plant tannins are polyphenolic substances with various molecular weights and a variable complexity. Due to the beneficial effects for controlling chronic disorders particularly diabetes mellitus, this class of secondary metabolites has gained more interest in the recent years. OBJECTIVE We aimed through this review to collect, analyze and discuss all available information related to the antidiabetic effect of isolated tannins (including both condensed and hydrolysable varieties) and tannin-rich plants as well as the possible mechanisms of action involved in this antidiabetic activity. METHODS AND RESULTS Our bibliographic research was conducted to gather more than 41 medicinal plants containing tannins and 19 isolated tannins and tannin-rich crud extracts which were revealed to possess glucose lowering effect according to pharmacological studies. CONCLUSION Hence, according to findings of the present review, tannins could be useful for prevention and management of diabetes mellitus and its associated complications and these natural products could be promising compounds for the discovery of new hypoglycemic agents.
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Affiliation(s)
- Mohammed Ajebli
- Faculty of Sciences and Techniques Errachidia, Moulay Ismail University, BP 509, Boutalamine, Errachidia, 52000, Morocco
| | - Mohamed Eddouks
- Faculty of Sciences and Techniques Errachidia, Moulay Ismail University, BP 509, Boutalamine, Errachidia, 52000, Morocco
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Vermeer MA, Mulder TPJ, Molhuizen HOF. Theaflavins from black tea, especially theaflavin-3-gallate, reduce the incorporation of cholesterol into mixed micelles. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2008; 56:12031-12036. [PMID: 19049290 DOI: 10.1021/jf8022035] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Tea is one of the most widely consumed beverages in the world and may be associated with reduced heart disease rates. Theaflavins, which are formed in the production of black tea, have been suggested being responsible for the blood-cholesterol-lowering (BCL) effects of tea. We hypothesized that the effect of theaflavins on BCL could be through interference in the formation of dietary mixed micelles, which could result in reduced intestinal cholesterol absorption. Micelles were produced by mixing oleic acid, bile acids, lyso-phosphatidylcholine, and cholesterol. Theaflavin-treated micelles/particles were analyzed using electron microscopy (cryo-TEM), high-performance liquid chromatography (HPLC) analysis, and light-scattering particle size measurements. A dose-dependent inhibitory effect of theaflavins on the incorporation of (14)C-labeled cholesterol into micelles and a theaflavin-dependent increase in particle size was found. These particles consisted of insoluble large multilamellar vesicles with onion-like structures. Ultracentrifugation and HPLC analysis revealed that the pellets contained mainly theaflavin-3-gallate, while the remaining theaflavins were found to be present in the supernatant. Using purified theaflavin subtypes confirmed that mainly theaflavin-3-gallate is responsible for multilamellar vesicle formation. These results show that theaflavins can play a role in decreased intestinal cholesterol absorption via inhibition of micelle formation.
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Affiliation(s)
- Mario A Vermeer
- Unilever Food and Health Research Institute, Olivier van Noortlaan 120, P. O. Box 114, 3130 AC, 3133 AT Vlaardingen, The Netherlands.
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Duteyrat JL, Gelfi J, Bertagnoli S. Ultrastructural study of myxoma virus morphogenesis. Arch Virol 2006; 151:2161-80. [PMID: 16763732 DOI: 10.1007/s00705-006-0791-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2005] [Accepted: 04/26/2006] [Indexed: 10/24/2022]
Abstract
Poxviruses are among the largest and most complex viruses known. Vaccinia virus, the prototype of the family Poxviridae, has been studied much more than myxoma virus. The aim of this work was to have a better knowledge about myxoma virus morphogenesis. The characterization of the main stages of MV morphogenesis was achieved by ultrastructural and immunological analysis. Specific antibodies were raised against M022L and M071L, two envelope proteins of extracellular enveloped virus and intracellular mature virus, respectively. The main stages of assembly were similar to those seen with other poxviruses, and the duration of the whole replication cycle was estimated to be around 16 h, longer than what was described for vaccinia virus. Morphological changes of infected cells were associated with the development of long cellular projections and enlarged microvilli. Intracellular enveloped viruses are associated with the cytoskeleton to move through the cell. Unlike earlier studies, as many cell-associated enveloped viruses as intracellular enveloped viruses were observed in relation with specialized microvilli, although these structures were rarely noticed. Finally, an unusual spreading process was observed, which uses cytoplasmic corridors.
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Affiliation(s)
- J-L Duteyrat
- UMR 1225 Interactions Hôtes-Agents pathogènes, INRA/ENVT, Ecole Nationale Vétérinaire de Toulouse, Toulouse, France
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Hills BA. Surface-active phospholipid: a Pandora's box of clinical applications. Part I. The lung and air spaces. Intern Med J 2002; 32:170-8. [PMID: 11951930 DOI: 10.1046/j.1444-0903.2001.00200.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Almost everywhere in the body there are phospholipids, not only comprising the lipid bilayer of membranes, but also in the free state. What is seldom appreciated, except in respirology, is that these 'free' phospholipids are unusual in that many are highly surface active. Surface activity is a property of certain substances (surfactants), conferred by their molecular constitution and configuration, which predisposes them to locate at interfaces because, in doing so, they reduce interfacial energy. When adsorbed (reversibly bound) to solid surfaces, surfactants can impart many highly desirable properties that have been widely studied and long accepted in the physical sciences, while their commercial applications have withstood the test of time. These desirable properties include lubricity (boundary lubrication), release (antistick) and dewatering, while providing a barrier to corrosion, abrasion, solute transmission and to biological microorganisms. Many of these offer obvious roles for surface-active phospholipid (SAPL), ranging from a corrosion inhibitor in the stomach to a load-bearing lubricant in the joints. This opens a veritable 'Pandora's box' of potential clinical applications. Part I of this review challenges traditional beliefs in respirology that 'surfactant' is unique to the lung and, moreover, that its actions are confined to the liquid-air interface. Evidence is discussed that, by binding to alveolar epithelium, SAPL imparts semi-permeability needed before channels pumping ions can also pump water vital for maintaining fluid balance. Evidence is also reviewed for a lining to upper airways, sinuses and Eustachian tube where it can act like a standard release agent.
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Affiliation(s)
- B A Hills
- Mater Children's Hospital and Department of Medicine, University of Queensland, Australia.
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Hills BA, Chen Y. Suppression of neural activity of bronchial irritant receptors by surface-active phospholipid in comparison with topical drugs commonly prescribed for asthma. Clin Exp Allergy 2000; 30:1266-74. [PMID: 10971473 DOI: 10.1046/j.1365-2222.2000.00850.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Much indirect evidence has been put forward previously in support of the concept that surface-active phospholipid (SAPL) normally masks irritant receptors in the lungs and upper respiratory tract; but this physical barrier is deficient in asthmatics, imparting hyperresponsiveness of the bronchoconstrictor reflex. OBJECTIVE To determine whether exogenous SAPL applied to bronchial mucosa reduces the sensitivity of irritant receptors to a standard challenge used clinically to diagnose asthma and to compare the effects with those of corticosteroids and beta-stimulation. METHODS Nerve fibres in the vagi were monitored to record action potentials from irritant receptors identified in the upper airways of rat lungs in response to a methacholine challenge. SAPL in the form of dipalmitoyl phosphatidylcholine (PC) and phosphatidylglycerol (PG) - 7 : 3 PC:PG - was applied as a fine dry powder to enhance surface activity and, hence, chemisorption to epithelium. Comparison was also made with clinical doses of i.v. hydrocortisone and instilled salbutamol together with liquid or solid controls, as appropriate. RESULTS Neural activity of irritant receptors was found to be significantly (P = 0.0018) decreased by topical SAPL by 35.8% in response to a methacholine challenge in contrast to an increase of 11.2% in response to a solid (lactose) control. Instilled salbutamol and i.v. hydrocortisone also decreased responses to the same challenge by 43.4% and 14.7%, respectively, in contrast to a liquid (saline) control which increased by 24.5%. CONCLUSIONS Surface-active phospholipid has an appreciable effect upon irritant receptors in rat airways, reducing neural response to a methacholine challenge by an amount comparable to that of Salbutamol. These results support the concept of SAPL masking bronchial irritant receptors and warrant placebo-controlled clinical trials of this dry powder as a means of controlling asthma without the side-effects of current medication. Other possible roles discussed for the SAPL epithelial barrier include the exclusion of viruses and allergens.
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Affiliation(s)
- B A Hills
- Paediatric Respiratory Research Centre, Mater Children's Hospital, Brisbane, Australia
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McIntosh TJ, Pollastri MP, Porter NA, Simon SA. Polyphenols increase adhesion between lipid bilayers by forming interbilayer bridges. BASIC LIFE SCIENCES 2000; 66:451-70. [PMID: 10800456 DOI: 10.1007/978-1-4615-4139-4_24] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Affiliation(s)
- T J McIntosh
- Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
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Chen Y, Hills BA. Surgical adhesions: evidence for adsorption of surfactant to peritoneal mesothelium. THE AUSTRALIAN AND NEW ZEALAND JOURNAL OF SURGERY 2000; 70:443-7. [PMID: 10843402 DOI: 10.1046/j.1440-1622.2000.01841.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND It has been speculated that the formation of surgical adhesions must be preceded by physical adhesion of the two surfaces, a process normally prevented by a lining of adsorbed surface-active phospholipid (surfactant) acting as both a superb boundary (solid-to-solid) lubricant and a release (antistick) agent. Animal trials administering exogenous surfactant as a dry powder (ALEC) have previously demonstrated a reduction of 80% in abdominal adhesions. METHODS Incubation of rat peritoneum (both live and excised) with radiolabelled dipalmitoyl phosphatidylcholine (DPPC) has been used to demonstrate adsorption; while the normal lining of surfactant in the human abdominal cavity has been confirmed by epifluorescence microscopy using Phosphin E as the hydrophobic probe. AIMS The overall aim is to confirm that peritoneal mesothelium has a lining of surfactant known for its lubricating and release properties, and that this lining can be enhanced by the adsorption of exogenous material. RESULTS Adsorption of DPPC to peritoneal mesothelium was 470 ng/cm2 (n = 8) ex vivo and 598 ng/cm2 (n = 18) in vivo, these rates being enhanced by EggPG by 62% ex vivo and 47% in vivo to reach the equivalent of almost three close-packed monolayers. CONCLUSIONS These results can explain the reduction in surgical adhesions previously reported in animals by administering ALEC (7:3 DPPC:EggPG) as a highly surface-active dry powder, although it is now used in saline suspension to treat respiratory distress syndrome in newborns, in whom it has no side-effects. These findings would appear to justify clinical trials for dry ALEC in suppressing surgical adhesions with minimal risk of an adverse reaction. The results of these trials are also discussed and found to be compatible with the known ability of surfactant to resist physical adhesion by fibronectin, the tacky 'glue' by which fibroblasts attach to surfaces as the first step in formation of fibrinous adhesions.
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Affiliation(s)
- Y Chen
- Paediatric Respiratory Research Centre, Mater Children's Hospital, and Department of Medicine, The University of Queensland, Brisbane, Australia
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Abstract
Evidence is reviewed for the concept that the body employs essentially the same lubrication system in many sites in the body where tissues slide over each other with such ease. This system consists of fluid adjacent to surfaces coated with an oligolamellar lining of surface-active phospholipid (SAPL) acting as a back-up boundary lubricant wherever the fluid film fails to support the load--a likely event at physiological velocities. Particular attention is paid to the load-bearing joints, where the issue of identifying the vital active ingredient in synovial fluid is reviewed, coming down--perhaps predictably--in favour of SAPL. It is also explained how Lubricin and hyaluronic acid (HA) could have 'carrier' functions for the highly insoluble SAPL, while HA has good wetting properties needed to promote hydrodynamic lubrication of a very hydrophobic articular surface by an aqueous fluid wherever the load permits. In addition to friction and wear, release is included as another major role of boundary lubricants, especially relevant in environments where proteins are found, many having adhesive properties. The discussion is extended to a mention of the lubrication of prosthetic implants and to disease states where a deficiency of boundary lubricant is implicated, particular attention being paid to osteoarthritis.
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Affiliation(s)
- B A Hills
- Department of Medicine, University of Queensland and Mater Children's Hospital, Brisbane, Australia
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Mizuhira V, Hasegawa H, Notoya M. Fixation and Imaging of Biological Elements: Heavy Metals, Diffusible Substances, Ions, Peptides, and Lipids. ACTA ACUST UNITED AC 2000. [DOI: 10.1016/s0079-6336(00)80001-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Abstract
Currently, the study of surfactant proteins is much in vogue, but, in the early days, the physics underlying surfactant function was treated somewhat superficially, leaving assumptions that have become culturally embedded, such as the "bubble" model of the alveolus. This review selectively reexamines these assumptions, comparing each combination of alveolar model and role of surfactant for compatibility with the major features of pulmonary mechanics and alveolar stability, morphology, and fluid balance.
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Affiliation(s)
- B A Hills
- Paediatric Respiratory Research Centre, Mater Children's Hospital, and Department of Medicine, The University of Queensland, Brisbane, Queensland 4101, Australia
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13
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Affiliation(s)
- B A Hills
- Department of Respiratory, Medicine, Mater Children's Hospital, South Brisbane, Australia
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Huh NW, Porter NA, McIntosh TJ, Simon SA. The interaction of polyphenols with bilayers: conditions for increasing bilayer adhesion. Biophys J 1996; 71:3261-77. [PMID: 8968596 PMCID: PMC1233814 DOI: 10.1016/s0006-3495(96)79519-x] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Because proteins and other molecules with a high polyphenol content are commonly involved in adhesion processes, we are investigating the interactions between polyphenols and biological materials. A naturally occurring polyphenol that binds a variety of proteins and lipids is tannic acid (TA), which contains five digallic acid residues covalently linked to a central D-glucose. A previous study has shown that TA increases the adhesion between apposing phosphatidylcholine (PC) bilayers and over a very narrow concentration range collapses the interbilayer fluid space from about 15 A to 5 A. To determine the chemical requirements a polyphenolic molecule must possess to increase bilayer adhesion, we have synthesized several simpler TA analogs that vary in their size, shape, and number of gallic acid and hydroxyl groups. X-ray diffraction, absorbance, binding, and differential scanning calorimetry measurements were used to investigate the interaction of these polyphenolic molecules with egg PC (EPC) and dipalmitoyl PC (DPPC) bilayers. Of these synthetic polyphenols, only penta-O-galloyl-alpha-D-glucose (PGG) was able to completely mimic the effects of TA by collapsing the interbilayer fluid space from 15 A to 5 A, decreasing the dipole potential by about 300 mV, increasing the transition enthalpy of DPPC liposomes, and inducing an interdigitated phase in DPPC. Binding studies indicated that the fluid space was reduced to 5 A at an EPC:PGG mole ratio of 5:1. We conclude that these polyphenols collapse the fluid space of PC bilayers because they 1) are amphipathic and partition into the bilayers interfacial region, 2) are long enough to span the interbilayer space, 3) contain several gallic acids distributed so that they can partition simultaneously into apposing bilayers, and 4) have sufficient gallic acid residues to interact with all lipid headgroups and cover the bilayer surface. Under these conditions we conclude that the polyphenols from interbilayer bridges. We argue that these bridges are stabilized by increased adhesion arising from an increased van der Waals interaction between apposing bilayers, electrostatic interactions between the pi electrons in the phenol ring and the -(N+CH3)3 groups on the PC headgroups, decreased hydration repulsion between bilayers, and hydrogen bonds between the H-bond-donating moieties on the polyphenols and H-bond-accepting groups in the bilayer.
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Affiliation(s)
- N W Huh
- Department of Neurobiology, Duke University Medical Center, Durham, North Carolina 27710, USA
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Simon SA, Disalvo EA, Gawrisch K, Borovyagin V, Toone E, Schiffman SS, Needham D, McIntosh TJ. Increased adhesion between neutral lipid bilayers: interbilayer bridges formed by tannic acid. Biophys J 1994; 66:1943-58. [PMID: 8075329 PMCID: PMC1275920 DOI: 10.1016/s0006-3495(94)80988-9] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Tannic acid (TA) is a naturally occurring polyphenolic compound that aggregates membranes and neutral phosolipid vesicles and precipitates many proteins. This study analyzes TA binding to lipid membranes and the ensuing aggregation. The optical density of dispersions of phosphatidylcholine (PC) vesicles increased upon the addition of TA and electron micrographs showed that TA caused the vesicles to aggregate and form stacks of tightly packed disks. Solution calorimetry showed that TA bound to PC bilayers with a molar binding enthalpy of -8.3 kcal/mol and zeta potential measurements revealed that TA imparted a small negative charge to PC vesicles. Monolayer studies showed that TA bound to PC with a dissociation constant of 1.5 microM and reduced the dipole potential by up to 250 mV. Both the increase in optical density and decrease in dipole potential produced by TA could be reversed by the addition of polyvinylpyrrolidone, a compound that chelates TA by providing H-bond acceptor groups. NMR, micropipette aspiration, and x-ray diffraction experiments showed that TA incorporated into liquid crystalline PC membranes, increasing the area per lipid molecule and decreasing the bilayer thickness by 2 to 4%. 2H-NMR quadrupole splitting measurements also showed that TA associated with a PC molecule for times much less than 10(-4) s. In gel phase bilayers, TA caused the hydrocarbon chains from apposing monolayers to fully interdigitate. X-ray diffraction measurements of both gel and liquid crystalline dispersions showed that TA, at a critical concentration of about 1 mM, reduced the fluid spacing between adjacent bilayers by 8-10 A. These data place severe constraints on how TA can pack between adjacent bilayers and cause vesicles to adhere. We conclude that TA promotes vesicle aggregation by reducing the fluid spacing between bilayers by the formation of transient interbilayer bridges by inserting its digallic acid residues into the interfacial regions of adjacent bilayers and spanning the interbilayer space.
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Affiliation(s)
- S A Simon
- Department of Neurobiology, Duke University Medical Center, Durham, North Carolina 27710
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Fehrenbach H, Richter J, Schnabel PA. Electron spectroscopic study (ESI, EELS) of Nanoplast-embedded mammalian lung. J Microsc 1992; 166:401-16. [PMID: 1495094 DOI: 10.1111/j.1365-2818.1992.tb01538.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The potential of Nanoplast melamine resin embedding for the study of mammalian lung parenchyma was examined by means of electron spectroscopic imaging (ESI) and electron energy-loss spectroscopy (EELS). Samples were either fixed with glutaraldehyde-paraformaldehyde or glutaraldehyde-tannic acid, or were directly transferred to the embedding medium without prior fixation. Organic dehydrants, as well as fixatives containing heavy metals and stains, were omitted. A very high level of ultrastructural detail of chromatin, ribosomes, mitochondria and plasma membranes was achieved by ESI from the Nanoplast-embedded samples. The most prominent gain in ultrastructural detail was achieved when moving from an energy loss just below the L2,3 edge of phosphorus at 132 eV to an energy loss just beyond this edge. This reflects the prominent P L2,3 edge observed by EELS of Nanoplast-embedded samples in comparison with conventionally processed samples. Thus, taking into account possible sectioning artefacts, excellent heterochromatin images which rely on the phosphorus distribution can be obtained from Nanoplast-embedded samples by computer-assisted analysis of electron spectroscopic images. In this respect glutaraldehyde-paraformaldehyde fixation is preferable to glutaraldehyde-tannic acid fixation because the presence of silicon, revealed by EELS, in tannic-acid-fixed samples may introduce artefacts in phosphorus distribution images obtained by the three-window method because of the close proximity of the L2,3 edges of silicon and phosphorus.
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Affiliation(s)
- H Fehrenbach
- Abt. Elektronenmikroskopie, Zentrum Anatomie, Göttingen, Germany
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Williams MC, Hawgood S, Hamilton RL. Changes in lipid structure produced by surfactant proteins SP-A, SP-B, and SP-C. Am J Respir Cell Mol Biol 1991; 5:41-50. [PMID: 1878252 DOI: 10.1165/ajrcmb/5.1.41] [Citation(s) in RCA: 172] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Pulmonary surfactant phospholipids may assume several different structures including tubular myelin, unilamellar and multilamellar vesicles, and others. These populations of materials appear to have similar phospholipid compositions but may differ in their association with surfactant proteins SP-A, SP-B, or SP-C. We have used electron microscopy to determine the changes in structure of simple lipid mixtures (phosphatidylglycerol, dipalmitoylphosphatidylcholine) produced by adding one or combinations of the three proteins. Adding SP-A to lipids generated multilamellar structures composed of membranes with fuzzy or particulate surfaces. In contrast, SP-B or SP-C generated discoidal particles and structures that appeared to be sheets of membrane formed by associated particles. Used together, SP-A and SP-B reorganized some of the lipid into tubular myelin, a structure that was not observed in SP-A, SP-C recombinants. These observations confirm the in vitro formation of tubular myelin reported by others and support the possibility that surfactant materials with defined structure can be produced in vitro for analyses of their molecular organizations.
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Affiliation(s)
- M C Williams
- Department of Anatomy, Cardiovascular Research Institute, University of California, San Francisco
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Fehrenbach H, Richter J, Schnabel PA. Improved preservation of phospholipid-rich multilamellar bodies in conventionally embedded mammalian lung tissue--an electron spectroscopic study. J Microsc 1991; 162:91-104. [PMID: 1908012 DOI: 10.1111/j.1365-2818.1991.tb03119.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Different conventional methods of tissue processing were studied to determine the extent to which phospholipid-rich multilamellar bodies of pulmonary alveolar epithelial type II cells of the pig were preserved. Prolonged treatment with half-saturated aqueous uranyl acetate yielded excellent results on the stabilization of the multilamellar substructure, irrespective of whether glutaraldehyde-paraformaldehyde or glutaraldehyde-tannic acid was used as a primary fixative. The lamellar periodicities were observed to be 5.5-6.1 nm. Differences in the phosphorus distribution among several types of lipid bodies of alveolar epithelial type II cells were studied by means of electron spectroscopic imaging and electron energy-loss spectroscopy. Multilamellar bodies gave phosphorus signals which were significantly higher than those obtained from granular regions of composite bodies, whereas homogeneous bodies gave phosphorus signals which were even lower than those obtained from mitochondria, endoplasmic reticulum membranes or ribosomes.
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Affiliation(s)
- H Fehrenbach
- Abt. Elektronenmikroskopie, Zentrum Anatomie, Göttingen, Germany
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