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Rashidi A, Fritz J. Sports Imaging of COVID-19: A Multi-Organ System Review of Indications and Imaging Findings. Sports Health 2022; 14:618-631. [PMID: 35746891 DOI: 10.1177/19417381221106448] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first identified in December 2019 in Wuhan, China. Although coronavirus disease-19 (COVID-19) affects every population group, the sports community and athletes require special consideration of the effects on cardiovascular, musculoskeletal, neurologic, and respiratory systems. A comprehensive understanding of imaging indications, findings, and features of COVID-19 supports appropriate imaging utilization and effective patient management and treatment. PURPOSE To review the spectrum of sports imaging in COVID-19 infection, organ system manifestations, vaccine effects, and complications in recreational and competitive athletes. STUDY DESIGN Narrative review. LEVEL OF EVIDENCE Levels 4 and 5. METHODS Based on a PubMed database search, studies describing the imaging findings of COVID-19 infection, organ system manifestations, vaccine effects, and complications in recreational and competitive athletes were included. RESULTS On March 11, 2020, World Health Organization officially declared COVID-19 a global pandemic. As of May 9, 2022, more than 515 million confirmed cases of COVID-19 were reported globally. While the multisystem effects of COVID-19 are incompletely understood, the role of imaging in diagnosing, monitoring, and prognosticating active disease, long-term effects, and complications is evolving. In the respiratory system, imaging plays an important role in diagnosing, characterizing, and monitoring pulmonary COVID-19 infections, barotrauma, and COVID-19-associated chronic pulmonary opacities and fibrotic-like lung changes. Ultrasonography, computed tomography, and magnetic resonance imaging aid in the timely diagnosis of ischemic, embolic, and thrombotic peripheral and central cardiovascular events, including deep venous thrombosis, pulmonary embolism, myocarditis, and stroke. COVID-19-associated musculoskeletal and peripheral nervous system manifestations include rhabdomyolysis and myonecrosis, plexus and peripheral neuropathies, Guillain-Barré syndrome, and shoulder injury related to vaccine administration. CONCLUSIONS In athletes, COVID-19 infections and associated effects on cardiovascular, musculoskeletal, neurologic, and respiratory systems require special consideration. With the increasing understanding of the multisystem effects of COVID-19, the role of imaging in diagnosing, monitoring, and prognosticating active disease, long-term effects, and complications is evolving. A comprehensive understanding of imaging indications, COVID-19 imaging features, and organ system effects aids in appropriate imaging utilization and effective patient management and treatments.
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Affiliation(s)
- Ali Rashidi
- Department of Radiology, Molecular Imaging Program at Stanford, Stanford University School of Medicine, Stanford, CA
| | - Jan Fritz
- Department of Radiology, NYU Grossman School of Medicine, New York, New York
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Lopes SC, Ivanova G, de Castro B, Gameiro P. Revealing cardiolipins influence in the construction of a significant mitochondrial membrane model. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:2465-2477. [PMID: 30040925 DOI: 10.1016/j.bbamem.2018.07.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 07/13/2018] [Accepted: 07/17/2018] [Indexed: 12/24/2022]
Abstract
Cardiolipins are essential for the integrity and the dynamics of the mitochondria membrane, where they exclusively exist in eukaryotes. Changes in cardiolipins membrane levels have been related to several cardiac health disorders. To evaluate cardiolipins impact on membrane properties a physico-chemical study was conducted using steady-state fluorescence anisotropy, dynamic light scattering and Nuclear Magnetic Resonance (1H and 31P NMR). Different binary and ternary mixtures of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine and a natural extract of bovine heart cardiolipin were used as models of mitochondrial membrane. The main transition temperatures, obtained by the first two techniques, revealed to be cardiolipins dependent. Cardiolipins also showed to act as a bidirectional regulator of membrane fluidity. 1H and 31P NMR results revealed that cardiolipins affects the conformation, mobility and structural order of the phospholipid molecules. According to 1H NMR results, cardiolipins disturbs the overall structure and packing order of membrane demonstrated with the decrease of the line broadening and shift of all resonances. The 31P NMR line shape analysis confirmed that, at distinct temperatures, different lipid phases coexist in the systems, and their type and quantitative distribution are cardiolipins dependent. In summary, cardiolipins presence/absence dramatically changes the membrane properties and has a major impact in the construction of a mitochondrial membrane model.
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Affiliation(s)
- S C Lopes
- Requimte, LAQV, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal.
| | - G Ivanova
- Requimte, LAQV, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal.
| | - B de Castro
- Requimte, LAQV, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal.
| | - P Gameiro
- Requimte, LAQV, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal.
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Lopes SC, Neves CS, Eaton P, Gameiro P. Improved model systems for bacterial membranes from differing species: Theimportance of varying composition in PE/PG/cardiolipin ternary mixtures. Mol Membr Biol 2012; 29:207-17. [DOI: 10.3109/09687688.2012.700491] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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4
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Lopes S, Neves CS, Eaton P, Gameiro P. Cardiolipin, a key component to mimic the E. coli bacterial membrane in model systems revealed by dynamic light scattering and steady-state fluorescence anisotropy. Anal Bioanal Chem 2010; 398:1357-66. [PMID: 20680614 DOI: 10.1007/s00216-010-4028-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2010] [Revised: 07/11/2010] [Accepted: 07/12/2010] [Indexed: 12/01/2022]
Abstract
The phase transition temperatures of several lipidic systems were determined using two different techniques: dynamic light scattering (DLS) and steady-state fluorescence anisotropy, using two fluorescent probes that report different membrane regions (TMA-DPH and DPH). Atomic force microscopy (AFM) was used as a complementary technique to characterize different lipid model systems under study. The systems were chosen due to the increased interest in bacterial membrane studies due to the problem of antibiotic drug resistance. The simpler models studied comprised of mixtures of POPE and POPG lipids, which form a commonly used model system for Escherichia coli membranes. Given the important role of cardiolipin (CL) in natural membranes, a ternary model system, POPE/POPG/CL, was then considered. The results obtained in these mimetic systems were compared with those obtained for the natural systems E. coli polar and total lipid extract. DLS and fluorescence anisotropy are not commonly used to study lipid phase transitions, but it was shown that they can give useful information about the thermotropic behaviors of model systems for bacterial membranes. These two techniques provided very similar results, validating their use as methods to measure phase transitions in lipid model systems. The temperature transitions obtained from these two very different techniques and the AFM results clearly show that cardiolipin is a fundamental component to mimic bacteria membranes. The results suggest that the less commonly used ternary system is a considerably better mimic for natural E. coli membranes than binary lipid mixture.
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Affiliation(s)
- S Lopes
- Requimte, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007, Porto, Portugal
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5
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Runge AF, Saavedra SS, Mendes SB. Combination of Polarized TIRF and ATR Spectroscopies for Determination of the Second and Fourth Order Parameters of Molecular Orientation in Thin Films and Construction of an Orientation Distribution Based on the Maximum Entropy Method. J Phys Chem B 2006; 110:6721-31. [PMID: 16570978 DOI: 10.1021/jp056048m] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This article describes two mathematical formalisms for the determination of the second and fourth order parameters of molecular films using optical spectroscopy. Method A uses polarized total internal reflection fluorescence (TIRF) to calculate the second and fourth order parameters, {P2(cos theta)} and {P4(cos theta)}, using an independently determined value for the angle between the absorption and emission dipoles, gamma. Method B uses {P2(cos theta)} obtained from attenuated total reflectance (ATR) data, along with polarized TIRF measurements to calculate {P4(cos theta)} and {cos2 gamma}. The choice of a specific method should rely on experimental considerations. We also present a method to separate the contributions of substrate surface roughness and dipole orientation with respect to the molecular axis from the spectroscopically determined second and fourth order parameters. Finally, a maximum entropy approach for construction of an orientation distribution from order parameters is compared with the commonly used delta and Gaussian distributions.
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Affiliation(s)
- Anne F Runge
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721, USA
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6
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Zhai X, Kleijn JM. Order in phospholipid Langmuir-Blodgett monolayers determined by total internal reflection fluorescence. Biophys J 1997; 72:2651-9. [PMID: 9168040 PMCID: PMC1184462 DOI: 10.1016/s0006-3495(97)78908-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Orientational order parameters of two diphenylhexatriene (DPH)-based fluorescent probes, 2-(3-(diphenylhexatrienyl)propanoyl)-1-hexadecanoyl-sn-glycero-3-p hosphocholine (DPHpPC) and 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH), in dipalmitoylphosphatidylcholine (DPPC) Langmuir-Blodgett monolayers on quartz have been determined by total internal reflection fluorescence (TIRF). From these order parameters orientation distributions were reconstructed by the maximum-entropy method. For monolayers transferred from the liquid-condensed phase, preferential tilt angles with respect to the substrate normal around 14 degrees in the tail region and 5 degrees near the glycerol-acyl chain linkage were found, as reflected by the DPHpPC and TMA-DPH probes, respectively. The degree of ordering near the headgroup region seems to be larger than that further away from the surface. A substantial fraction of the TMA-DPH probes have a flat orientation and are probably located between the phospholipid headgroups and the substrate surface. Monolayers transferred from the liquid-expanded phase show a more random ordering, and most of the probe molecules (DPHpPC) are more or less flat on the surface. The results are consistent with earlier atomic force microscopy measurements on identical monolayers and are in reasonable agreement with previously published data on other organized phospholipid systems.
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Affiliation(s)
- X Zhai
- Department of Physical and Colloid Chemistry, Wageningen Agricultural University, The Netherlands
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7
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van Zandvoort MAMJ, Gerritsen HC, van Ginkel G, Levine YK, Tarroni R, Zannoni C. Distribution of Hydrophobic Probe Molecules in Lipid Bilayers. 2. Time-Resolved Fluorescence Anisotropy Study of Perylene in Vesicles. J Phys Chem B 1997. [DOI: 10.1021/jp9634159] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- M. A. M. J. van Zandvoort
- Department of Molecular Biophysics, Debye Institute, Buys Ballot Laboratory, Utrecht University, P.O Box 80000, 3508 TA Utrecht, The Netherlands, and Dipartimento di Chimica Fisica ed Inorganica, Universitá degli studi di Bologna, Viale Risorgimento 4, 40136 Bologna, Italy
| | - H. C. Gerritsen
- Department of Molecular Biophysics, Debye Institute, Buys Ballot Laboratory, Utrecht University, P.O Box 80000, 3508 TA Utrecht, The Netherlands, and Dipartimento di Chimica Fisica ed Inorganica, Universitá degli studi di Bologna, Viale Risorgimento 4, 40136 Bologna, Italy
| | - G. van Ginkel
- Department of Molecular Biophysics, Debye Institute, Buys Ballot Laboratory, Utrecht University, P.O Box 80000, 3508 TA Utrecht, The Netherlands, and Dipartimento di Chimica Fisica ed Inorganica, Universitá degli studi di Bologna, Viale Risorgimento 4, 40136 Bologna, Italy
| | - Y. K. Levine
- Department of Molecular Biophysics, Debye Institute, Buys Ballot Laboratory, Utrecht University, P.O Box 80000, 3508 TA Utrecht, The Netherlands, and Dipartimento di Chimica Fisica ed Inorganica, Universitá degli studi di Bologna, Viale Risorgimento 4, 40136 Bologna, Italy
| | - R. Tarroni
- Department of Molecular Biophysics, Debye Institute, Buys Ballot Laboratory, Utrecht University, P.O Box 80000, 3508 TA Utrecht, The Netherlands, and Dipartimento di Chimica Fisica ed Inorganica, Universitá degli studi di Bologna, Viale Risorgimento 4, 40136 Bologna, Italy
| | - C. Zannoni
- Department of Molecular Biophysics, Debye Institute, Buys Ballot Laboratory, Utrecht University, P.O Box 80000, 3508 TA Utrecht, The Netherlands, and Dipartimento di Chimica Fisica ed Inorganica, Universitá degli studi di Bologna, Viale Risorgimento 4, 40136 Bologna, Italy
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8
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Separovic F, Gawrisch K. Effect of unsaturation on the chain order of phosphatidylcholines in a dioleoylphosphatidylethanolamine matrix. Biophys J 1996; 71:274-82. [PMID: 8804610 PMCID: PMC1233478 DOI: 10.1016/s0006-3495(96)79223-8] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The properties of phosphatidylcholines (PCs) having a perdeuterated stearic acid, 18:0d35, in the sn-1 position and the fatty acid 18:0, 18:1 omega 9, 18:2 omega 6, 18:3 omega 3, 20:4 omega 6, 20:5 omega 3, or 22:6 omega 3 at the sn-2 position were investigated in a matrix of dioleoylphosphatidylethanolamine (DOPE) by 2H and 31P NMR spectroscopy. At a mole ratio of DOPE/PC = 5:1, the lipids form liquid crystalline lamellar phases below 40 degrees C and coexisting lamellar, inverse hexagonal (Hll), and cubic phases at higher temperatures. The sn-1 chain of the PCs in a DOPE matrix is appreciably more ordered than in pure PCs, corresponding to an increase in the hydrophobic bilayer thickness of approximately 1 A. Distearoylphosphatidylcholine in the DOPE matrix has a higher sn-1 chain order than the unsaturated PCs. We observed distinct differences in the lipid order of upper and lower sections of the hydrocarbon chains caused by changes of temperature, unsaturation, headgroups, and ethanol. Unsaturation lowers chain order, mostly in the lower third of the hydrocarbon chains. By contrast, the increase in chain order caused by the DOPE matrix and the decrease in order with increasing temperature have a constant magnitude for the upper two-thirds of the chain and are smaller for the lower third. Addition of 2 M ethanol reduced order parameters, in effect reversing the increase in chain order caused by the DOPE matrix.
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Affiliation(s)
- F Separovic
- Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, Maryland 20852, USA
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9
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Basanez G, Nieva JL, Rivas E, Alonso A, Goni FM. Diacylglycerol and the promotion of lamellar-hexagonal and lamellar-isotropic phase transitions in lipids: implications for membrane fusion. Biophys J 1996; 70:2299-306. [PMID: 9172753 PMCID: PMC1225204 DOI: 10.1016/s0006-3495(96)79795-3] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Changes in steady-state fluorescence anisotropy of 1 -(4-trimethylaminophenyl)-6-phenyl-1,3,5-hexatriene TMA-DPH) are applied to the detection of lamellar-hexagonal transitions in egg phosphatidylethanolamine. Even low (2 mole%) proportions of diacylglycerol decrease the hexagonal transition temperature considerably, as confirmed by differential scanning calorimetry. Diacylglycerol is also found to promote a lamellar to "isotropic" (Q(224) cubic) transition in mixtures of phosphatidylcholine: phosphatidylethanolamine:cholesterol. This nonreversible transition is also observed by (31)P nuclear magnetic resonance and detected as a large increase in TMA-DPH steady-state anisotropy. The same technique reveals as well that lysophosphatidylcholine counteracts the effect of diacylglycerol and stabilizes the lamellar phase in both transitions. Diacylglycerol and lysophosphatidylcholine are known to respectively promote and inhibit membrane fusion in a variety of systems. These data are interpreted in support of the hypothesis of a highly bent structural fusion intermediate ("stalk"). They also show the interest of lipid-phase studies in predicting and rationalizing membrane fusion mechanisms.
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Affiliation(s)
- G Basanez
- Unidad Asociada al C.S.I.C., Departamento de Bioquimica, Universidad del Pais Vasco, Bilbao, Spain
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10
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Bos MA, Kleijn JM. Determination of the orientation distribution of adsorbed fluorophores using TIRF. I. Theory. Biophys J 1995; 68:2566-72. [PMID: 7647259 PMCID: PMC1282166 DOI: 10.1016/s0006-3495(95)80439-x] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The spectroscopic technique total internal reflection fluorescence can be used for determination of the orientation of adsorbed fluorescent molecules. The underlying theory is presented in general terms and elaborated in detail for the case that the fluorescent group is a porphyrin ring. It is shown that order parameters of the orientation distribution can be obtained if both the fluorescence intensity and its polarization are measured as functions of the polarization of the incident laser beam. From these order parameters an approximation of the orientation distribution can be derived by the maximum-entropy method.
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Affiliation(s)
- M A Bos
- Department of Physical and Colloid Chemistry, Agricultural University, Wageningen, The Netherlands
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11
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Van der Meer BW, Cheng KH, Chen SY. Effects of lateral diffusion on the fluorescence anisotropy in hexagonal lipid phases. I. Theory. Biophys J 1990; 58:1517-26. [PMID: 2275966 PMCID: PMC1281103 DOI: 10.1016/s0006-3495(90)82496-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
It is shown that fluorescence anisotropy from lipidlike probes in the hexagonal HII phase gives information of (a) orientational order parameters, (b) the wobbling diffusion constant, and (c) the hopping diffusion constant of the probe, DH, equals DL/R2, the lateral diffusion constant over the square of the radius of the hexagonal tubes. Here we consider only lipidlike probes having the absorption transition movement and/or the emission transition moment along the long axis of the molecule. Three models are introduced for analysis of time-resolved data: the "WOBHOP," the "reduced WOBHOP," and the "P2P4HOP" model. The fluorescence anisotropy in response to a very short excitation pulse in each of the three models is a constant plus a number of exponentials. The WOBHOP and reduced WOBHOP models have 3 and 2 exponentials, respectively, and both contain four fitting parameters: r0 (the fundamental anisotropy), (P2) (the second rank orientational order parameter), DW (the wobbling diffusion constant), and DH (the hopping diffusion constant). The P2P4HOP model has eight exponentials and five fitting parameters: the four parameters listed above and (P4) (the fourth rank orientational order parameter). Analysis of fluorescence anisotropy data in the hexagonal HII phase using one of these models allows for obtaining the hopping diffusion constant, and, if the lateral diffusion constant is known, the radius of the hexagonal tubes. Substitution of DH = 0 in each of the three models yields an expression for the fluorescence anisotropy that is used in the literature for lamellar (L alpha or L beta) phases. The fluorescence anisotropy in coexisting L alpha/HII phases is discussed.
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Affiliation(s)
- B W Van der Meer
- Department of Physics and Astronomy, Western Kentucky University, Bowling Green, Kentucky 42101
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12
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Chen SY, Cheng KH, Van der Meer BW, Beechem JM. Effects of lateral diffusion on the fluorescence anisotropy in hexagonal lipid phases. II. An experimental study. Biophys J 1990; 58:1527-37. [PMID: 2275967 PMCID: PMC1281104 DOI: 10.1016/s0006-3495(90)82497-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The polymorphic phase behavior of unsaturated phosphatidylethanolamine (PE)/diacylglycerol (DG) binary lipid mixtures was investigated by the use of time-resolved fluorescence anisotropy. Using a fluorescent lipid, 1-palmitoyl-2-[[2-[4-(6-phenyl-trans-1,3,5-hexatrienyl)phenylethyl] carbonyl]3-sn-phosphatidyl-choline (DPH-PC), the orientational order and rotational dynamics of the above lipid mixtures in the liquid crystalline lamellar (L alpha) and inverted hexagonal (HII) phases were studied. By employing a one-exponential model (Cheng, K.H. 1989: Biophys. J. 55:1025-1031) to fit the anisotropy decay data, abrupt decreases in the normalized initial anisotropy decay slope and the residual anisotropy of DPH-PC were observed at approximately 6-8% DG, signifying a L alpha/HII phase transition. Using our new theoretical WOBHOP and P2P4HOP models as described in a preceding paper (Van Der Meer, B.W., K.H. Cheng, and S.Y. Chen. 1990. Biophys. J. 58:000-000), two or more rotational correlation times were required to describe the anisotropy decay behavior of DPH-PC in the HII phase. These rotation correlation times were further related to the second and fourth rank order parameters, and the wobbling and hopping diffusion constants of the fluorescent probe in the highly curved lipid cylindrical tubes of the HII phase. The hopping diffusion constant (DH) equals the lateral diffusion constant (DL) divided by R2 (R = radius of the lipid cylindrical tubes). The value of DL was estimated by measuring the excimer formation rate of 1-palmitoyl-2-[10-(1-pyrenl)decanoyl] phosphatidyl choline (py-PC) in the same PE/DG mixtures. Upon comparing the values of DH and DL, the value of R was determined to be approximately 10-15 A, and agreed with that derived from x-ray diffraction (Tate, M.W., and S.M. Gruner, 1989, Biochemistry. 28:4245-4253; Rand, R.P., N.L. Fuller, S.M. Gruner, and V.A. Parsegian. 1990. Biochemistry. 29:76-87).
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Affiliation(s)
- S Y Chen
- Department of Physics, Texas Tech University, Lubbock 79409
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Cheng KH. Headgroup hydration and motional order of lipids in lamellar liquid crystalline and inverted hexagonal phases of unsaturated phosphatidylethanolamine--a time-resolved fluorescence study. Chem Phys Lipids 1990; 53:191-202. [PMID: 2337976 DOI: 10.1016/0009-3084(90)90045-s] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
By the use of frequency domain cross-correlation fluorometry, the fluorescence lifetime of the water soluble probe 8,1-anilinonapthalene sulfonic acid (ANS) in aqueous dispersions of dioleoylphosphatidylethanolamine (DOPE) and phosphatidylethanolamine transphosphatidylated from egg phosphatidylcholine (TPE) was measured. The orientational order parameter and rotational diffusion constant of the lipophilic probe 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) were also determined in TPE dispersions. In agreement with a previous study on DOPE (Cheng (1989) Biophys. J. 55, 1025-1031), abrupt changes in both the order packing and rotational diffusion constant were found at the lamellar liquid crystalline (L alpha) to inverted hexagonal (HII) phase transition of TPE. Owing to the subnanosecond resolution capability of this frequency domain fluorometric technique, the heterogeneous fluorescence decay of ANS was resolved into three distinct components with different decay lifetimes (tau's). They were 0 less than tau less than 0.5 ns, 2 less than tau less than 9 ns and tau greater than 15 ns. These lifetime regions were attributed to the partitioning of ANS into the bulk aqueous medium, the lipid/water interface and the lipid hydrocarbon region, respectively. These classifications of lifetime regions were further supported by the sensitivity of those lifetime components with the solvent isotopic shift of D2O. Similar to the changes of orientational order and rotational diffusion of lipophilic probe, the lifetime and intensity fraction of ANS associated with the lipid/water interfacial region declined abruptly at the L alpha-HII transition of both DOPE and TPE. This observation suggested that a dehydration of the lipid headgroup surface occurs at the L alpha-HII transition. This study provided evidence that both the lipid headgroup surface hydration and the lipid dynamics change drastically as a result of the macroscopic rearrangement of lipids at the L alpha-HII transition.
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Affiliation(s)
- K H Cheng
- Physics Department, Texas Tech. University, Lubbock 79409
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