Micropipette analysis of the hemolytic stress of hypotonic erythrocytes: the influence of lipid-soluble compounds

1978 ◽  
Vol 56 (3) ◽  
pp. 435-442 ◽  
Author(s):  
Y. F. Missirlis ◽  
F. Fong ◽  
M. C. Brain
Keyword(s):  
Protein Interactions ◽  
Chemical Compounds ◽  
Micropipette Aspiration ◽  
Membrane Action ◽  
A Value ◽  
Critical Tension ◽  
Biphasic Effect ◽  
Lipid Protein Interactions ◽  
Individual Erythrocytes

The technique of micropipette aspiration of individual erythrocytes has been used to determine the critical tension (Ter) for lysis of hypotonically slightly swollen normal erythrocytes and erythrocytes exposed to the influence of lipid-soluble chemical compounds. The value of Ter of preswollen normal erythrocytes was 12.23 ± 1.84 dyn/cm (1 dyn = 10 μN), a value which agrees well with that found by other workers. The Ter was increased in normal erythrocytes following exposure to four aliphatic alcohols, chloroform, and phenol. The optimal concentration resulting in 24–33% increase in Ter for the six compounds studied was very similar to the concentration previously found to be optimal in conferring increased resistance to osmotic hemolysis.The determination of Ter by micropipette aspiration of individual erythrocytes enables a range of concentrations of lipid-soluble compounds to be studied and led to the demonstration of a biphasic effect of the alcohols on the surface area elastic modulus.The studies now reported confirm the findings of Seeman (SEEMAN, P. 1972. The membrane action of anesthetics and tranquilizers. Pharmacol. Rev. 24(4), 583.) and suggest that incorporation of relatively short chain alcohols is concentration dependent and is associated with alterations in the mechanical-rheological properties of the membrane in a manner which appears analogous to the previously published reports on effects of alcohols on membrane transport and enzymatic activity. These findings suggest that lipid-soluble compounds at optimal concentrations influence both material properties and membrane-related functions, presumptively due to alterations in lipid–lipid, and (or) lipid–protein interactions.

Spin-label studies of lipid-protein interactions with reconstituted band 3, the human erythrocyte chloride-bicarbonate exchanger

1998 ◽  
Vol 76 (5) ◽  
pp. 815-822 ◽  
Author(s):  
Andrew M Taylor ◽  
Anthony Watts
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Protein Interactions ◽  
Spin Label ◽  
Acyl Chain ◽  
Lateral Diffusion ◽  
Band 3 ◽  
Paramagnetic Resonance ◽  
A Value ◽  
Lipid Protein Interactions ◽  
Electron Paramagnetic

Lipid-protein interactions in reconstituted band 3 preparations were investigated by using spin-labeled lipids in conjunction with electron paramagnetic resonance (EPR) spectroscopy. Purified erythrocyte band 3 was reconstituted into egg phosphatidylcholine liposomes at high protein density with preservation predominantly of the dimeric state. Lipid-protein associations were revealed by the presence of a component in the EPR spectra that, when compared to spectra obtained from protein-free bilayers, indicated that lipid chain motions are restricted by interactions with the protein. From the fraction of the motionally restricted component obtained from the phosphatidylcholine spin-label, a value of 64 ± 14 annular lipids per band 3 dimer was obtained. This agrees with a value of 62 for the number of lipids that may be accommodated around the electron density map of a band 3 dimer. Selectivity of various spin-labeled lipids for the protein revealed that androstanol had a lower affinity for the band 3 interface, whereas a distinct preference was observed for the negatively charged lipids phosphatidylglycerol and stearic acid over phosphatidylcholine. This preference for negatively charged lipids could not be screened by 1-M salt, indicating that electrostatic lipid-protein interactions are not dominant. Estimates of annular lipid exchange rates from measured acyl chain segmental motions suggested that the rate of exchange between bilayer and boundary lipids was ~106 s-1, at least an order of magnitude slower than the rate of lipid lateral diffusion in protein-free bilayers.Key words: band 3, reconstitution, electron paramagnetic resonance, lipid-protein interactions.

Vitamin A Value of Plant Food Provitamin A - Evaluated by the Stable Isotope Technologies

2014 ◽  
Vol 84 (Supplement 1) ◽  
pp. 25-29 ◽  
Author(s):  
Guangwen Tang
Keyword(s):  
Stable Isotope ◽  
Vitamin A ◽  
Provitamin A ◽  
Animal Origin ◽  
Plant Food ◽  
Plant Foods ◽  
A Value ◽  
Provitamin A Carotenoids ◽  
Β Carotene

Humans need vitamin A and obtain essential vitamin A by conversion of plant foods rich in provitamin A and/or absorption of preformed vitamin A from foods of animal origin. The determination of the vitamin A value of plant foods rich in provitamin A is important but has challenges. The aim of this paper is to review the progress over last 80 years following the discovery on the conversion of β-carotene to vitamin A and the various techniques including stable isotope technologies that have been developed to determine vitamin A values of plant provitamin A (mainly β-carotene). These include applications from using radioactive β-carotene and vitamin A, depletion-repletion with vitamin A and β-carotene, and measuring postprandial chylomicron fractions after feeding a β-carotene rich diet, to using stable isotopes as tracers to follow the absorption and conversion of plant food provitamin A carotenoids (mainly β-carotene) in humans. These approaches have greatly promoted our understanding of the absorption and conversion of β-carotene to vitamin A. Stable isotope labeled plant foods are useful for determining the overall bioavailability of provitamin A carotenoids from specific foods. Locally obtained plant foods can provide vitamin A and prevent deficiency of vitamin A, a remaining worldwide concern.

Changes of some sewage sludge parameters prepared with an ultrasonic field

1997 ◽  
Vol 36 (11) ◽  
pp. 101-106 ◽  
Author(s):  
January Bien ◽  
Lidia Wolny
Keyword(s):  
Sewage Sludge ◽  
Microscopic Analysis ◽  
Chemical Compounds ◽  
Ultrasonic Field ◽  
Water Removal ◽  
Vacuum Filter ◽  
Additional Criterion ◽  
New Methods ◽  
Sludge Conditioning

Studies of sewage sludge conditioning by ultrasonic field concentrate on determination of the increase of water removal effect, which depends on kind of sludge and chemical compounds used in the dewatering process. An attempt was made to find new methods of sludge preparation before dewatering. Tests presented here focused on digested and difficult dewatered sludge. The sludge was dewatered on a vacuum filter after conditioning with polyelectrolytes and the ultrasonic field. The microscopic analysis was an additional criterion to evaluate changes in the sludge structure after preparation. The polyelectrolyte dose of 3 mg/g d.m. sonicated within 15 sec. resulted in the 50% decrease of sludge volume. Results presented confirmed our previous experiences, concerning the relation between conglomerates of sludge and the effect of dewatering.

Determination of Agarwood oil’s significant chemical compounds using principal component analysis

2020 ◽  
Author(s):  
Mohamad Hushnie Haron ◽  
Mohd Nasir Taib ◽  
Nurlaila Ismail ◽  
Nor Azah Mohd Ali ◽  
Saiful Nizam Tajuddin
Keyword(s):  
Principal Component Analysis ◽  
Principal Component ◽  
Chemical Compounds ◽  
Component Analysis ◽  
Significant Chemical

scholarly journals Temperature Dependence of G and D’ Phonons in Monolayer to Few-Layer Graphene with Vacancies

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Mingming Yang ◽  
Longlong Wang ◽  
Xiaofen Qiao ◽  
Yi Liu ◽  
Yufan Liu ◽  
...  
Keyword(s):  
Negative Temperature Coefficient ◽  
Negative Temperature ◽  
Intrinsic Properties ◽  
Temperature Dependent ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Layer Graphene ◽  
A Value ◽  
Few Layer Graphene

Abstract The defects into the hexagonal network of a sp2-hybridized carbon atom have been demonstrated to have a significant influence on intrinsic properties of graphene systems. In this paper, we presented a study of temperature-dependent Raman spectra of G peak and D’ band at low temperatures from 78 to 318 K in defective monolayer to few-layer graphene induced by ion C+ bombardment under the determination of vacancy uniformity. Defects lead to the increase of the negative temperature coefficient of G peak, with a value almost identical to that of D’ band. However, the variation of frequency and linewidth of G peak with layer number is contrary to D’ band. It derives from the related electron-phonon interaction in G and D’ phonon in the disorder-induced Raman scattering process. Our results are helpful to understand the mechanism of temperature-dependent phonons in graphene-based materials and provide valuable information on thermal properties of defects for the application of graphene-based devices.

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