Skip header and navigation

Refine By

9 records – page 1 of 1.

Changes in a phospholipid bilayer induced by the hydrolysis of a phospholipase A2 enzyme: a molecular dynamics simulation study.

https://arctichealth.org/en/permalink/ahliterature10304
Source
Biophys J. 2001 Feb;80(2):565-78
Publication Type
Article
Date
Feb-2001
Author
M T Hyvönen
K. Oörni
P T Kovanen
M. Ala-Korpela
Author Affiliation
NMR Research Group, Department of Physical Sciences, University of Oulu, FIN-90014 Oulu, Finland.
Source
Biophys J. 2001 Feb;80(2):565-78
Date
Feb-2001
Language
English
Publication Type
Article
Keywords
Biophysics
Electrostatics
Glycerol - chemistry
Hydrolysis
In Vitro
Lipid Bilayers - chemistry - metabolism
Models, Molecular
Phosphatidylcholines - chemistry - metabolism
Phospholipases A - metabolism
Research Support, Non-U.S. Gov't
Sodium - chemistry
Water - chemistry
Abstract
Phospholipase A2 (PLA2) enzymes are important in numerous physiological processes. Their function at lipid-water interfaces is also used as a biophysical model for protein-membrane interactions. These enzymes catalyze the hydrolysis of the sn-2 bonds of various phospholipids and the hydrolysis products are known to increase the activity of the enzymes. Here, we have applied molecular dynamics (MD) simulations to study the membrane properties in three compositionally different systems that relate to PLA2 enzyme action. One-nanosecond simulations were performed for a 1-palmitoyl-2-linoleoyl-sn-glycero-3-phosphatidylcholine (PLPC) bilayer and for two of its PLA2-hydrolyzed versions, i.e., bilayers consisting of lysophospholipids and of either free charged linoleate or free uncharged linoleic acid molecules. The results revealed loosening of the structure in the hydrolyzed bilayer due to increased mobility of the molecules in the direction normal to the bilayer. This loss of integrity due to the hydrolysis products is in accord with observations that not only the presence of hydrolysis products, but also a variety of other perturbations of the membrane may activate PLA2. Additionally, changes were observed in other structural parameters and in the electrostatic potential across the membrane-water interface. These changes are discussed in relation to the simulation methodology and the experimental observations of PLA2-hydrolyzed membranes.
PubMed ID
11159426 View in PubMed
Less detail

The Cryoprotectant Effect of Polysaccharides from Plants and Microalgae on Human White Blood Cells.

https://arctichealth.org/en/permalink/ahliterature273583
Source
Biopreserv Biobank. 2015 Aug;13(4):240-6
Publication Type
Article
Date
Aug-2015
Author
Andrey Nikolayevich Khudyakov
Tatyana Vitalyevna Polezhaeva
Oksana Olegovna Zaitseva
Elena Aleksandrovna Gunter
Olga Nurzadinovna Solomina
Oksana Viktorovna Popeyko
Anatolyi Aleksandrovich Shubakov
Konstantin Aleksandrovich Vetoshkin
Source
Biopreserv Biobank. 2015 Aug;13(4):240-6
Date
Aug-2015
Language
English
Publication Type
Article
Keywords
Adult
Carbohydrates - chemistry
Cryopreservation - methods
Cryoprotective Agents - chemistry
Glycerol - chemistry
Humans
Leukocytes - cytology - metabolism
Microalgae - chemistry
Osmolar Concentration
Pectins - chemistry
Phagocytosis
Plants - chemistry
Polysaccharides - chemistry
Russia
Temperature
Abstract
The use of carbohydrates as cryoprotectants is increasing. In this study the effects of incorporating polysaccharides extracted from plants and microalgae originating in northern Russia, into cryoprotectant solutions used to preserve human white blood cells were investigated. Cells in the presence of the polysaccharides were cooled to either -40°C or -80°C, using a two-step cooling process. The morphological and functional indicators of the cryopreserved leukocytes were assessed by light microscopy. When combined with glycerol, the pectin-polysaccharides Lemnan from common duckweed (Lemna minor L.) and Comaruman from marsh cinquefoil (Comarum palustre L), were capable of lowering the freezing point of the cryoprotectant solution and helped to preserve the integrity of the human white blood cell membranes at temperatures below zero. In addition, the increase in phagocytic activity of neutrophils was confirmed. In the context of the contemporary search for effective cell cryoprotectants, the results of this research demonstrate that the cryopreservation of biospecimens in a polysaccharide environment is a promising trend in applied medicine, which can be considered an alternative to traditional cryogenic nitrogen techniques.
PubMed ID
26186407 View in PubMed
Less detail
Source
Appl Biochem Biotechnol. 2004;113-116:433-45
Publication Type
Article
Date
2004
Author
Carla C B Pereira
Mônica A P da Silva
Marta A P Langone
Author Affiliation
Escola de Química, Universidade Federal do Rio de Janeiro, Centro de Tecnologia, Bloco E, Lab I 221, Cidade Universitária, Brazil.
Source
Appl Biochem Biotechnol. 2004;113-116:433-45
Date
2004
Language
English
Publication Type
Article
Keywords
Biotechnology - methods
Chromatography, Gas
Enzymes - chemistry
Enzymes, Immobilized
Esters
Glycerides - biosynthesis - chemistry
Glycerol - chemistry
Laurates - chemistry
Lauric Acids - chemistry
Lipase - chemistry
Models, Theoretical
Monoglycerides
Research Support, Non-U.S. Gov't
Temperature
Time Factors
Abstract
The aim of this study was to produce monolaurin utilizing a commercial immobilized lipase (Lipozyme IM-20; Novo Nordisk, Bagsvaerd, Denmark) through the direct esterification of lauric acid and glycerol in a solvent-free system. The influence of fatty acid/glycerol molar ratio, temperature, and Lipozyme (IM-20) concentration on the molar fraction of monolaurin were determined using an experimental design. The best conditions employed were 55 degrees C, lauric acid/glycerol molar ratio of 1.0, and 3.0% (w/w) enzyme concentration. The final product, obtained after 6 h of reaction, was 45.5% monolaurin, 26.8% dilaurin, 3.1% trilaurin, and 24.6% lauric acid. The reusability of the enzyme was also studied.
PubMed ID
15054269 View in PubMed
Less detail

Influence of glycerol on production and structural-physical properties of cellulose from Acetobacter sp. V6 cultured in shake flasks.

https://arctichealth.org/en/permalink/ahliterature98349
Source
Bioresour Technol. 2010 May;101(10):3602-8
Publication Type
Article
Date
May-2010
Author
Ho-Il Jung
Jin-Ha Jeong
O-Mi Lee
Geun-Tae Park
Keun-Ki Kim
Hyean-Cheal Park
Sang-Mong Lee
Young-Gyun Kim
Hong-Joo Son
Author Affiliation
Department of Life Science and Environmental Biochemistry, Pusan National University, Miryang 627-706, Republic of Korea.
Source
Bioresour Technol. 2010 May;101(10):3602-8
Date
May-2010
Language
English
Publication Type
Article
Keywords
Acetobacter - chemistry - cytology
Cellulose - chemistry
Culture Media
Glycerol - chemistry
Microscopy, Electron, Scanning
Spectroscopy, Fourier Transform Infrared
X-Ray Diffraction
Abstract
Cost-effective production of bacterial cellulose (BC) by Acetobacter sp. V6 was investigated in shake culture using glycerol as carbon source and its structural and physical properties were determined. In medium containing 3% (w/v) glycerol, BC production was 4.98+/-0.03g/l after 7 days. This value was 3.8-fold higher than the yield in the glucose medium. FT-IR spectra revealed that all the BC samples were highly crystalline and were cellulose type capital I, Ukrainian. The crystallinity index value of the BC produced was 9% higher in the glycerol medium than in the glucose medium. Scanning electron micrographs showed that BC from the glycerol medium was more compact than that from the glucose medium. Water-holding capacity and viscosity of BC from the glycerol medium had 61.3% and 22.4% lower values than those from the glucose medium. These results suggest that glycerol could be a potential low-cost substrate for BC production by Acetobacter sp. V6, leading to the reduction in the production cost.
PubMed ID
20080401 View in PubMed
Less detail

The influence of viscosity on the shear strain remotely induced by focused ultrasound in viscoelastic media.

https://arctichealth.org/en/permalink/ahliterature9477
Source
J Acoust Soc Am. 2004 May;115(5 Pt 1):2358-64
Publication Type
Article
Date
May-2004
Author
E A Barannik
S A Girnyk
V V Tovstiak
A I Marusenko
V A Volokhov
A P Sarvazyan
S Y Emelianov
Author Affiliation
Kharkiv National University, 4 Svobody Sq., Kharkiv, Ukraine 61077.
Source
J Acoust Soc Am. 2004 May;115(5 Pt 1):2358-64
Date
May-2004
Language
English
Publication Type
Article
Keywords
Animals
Cattle
Elasticity
Gelatin - chemistry
Glycerol - chemistry
Humans
Models, Theoretical
Muscles - physiology
Phantoms, Imaging
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.
Ultrasonics
Viscosity
Abstract
Shear wave elasticity imaging (SWEI), an emerging acoustic technology for medical diagnostics, is based on remote generation of shear waves in tissue by radiation force in the focal region of an ultrasonic beam. In this study, the feasibility of Doppler ultrasonic technique to visualize the remotely induced shear waves was demonstrated. The generation of shear displacement in the focal region of a pulsed 1-MHz ultrasound beam with pulse duration of approximately about 2 ms and intensity levels on the order of 145 W/cm2, and consequent propagation of shear wave in tissue-mimicking and muscle tissue in vitro, were measured. The analysis of temporal behavior of shear displacement within the focal plane allowed estimation of shear wave velocities. The velocities were 4 and 7 m/s in hard phantom and tissue containing phantom, respectively. The measured shear displacements on the order of micrometers in gel-based phantoms are in reasonable agreement with theoretical estimates derived from an earlier developed model of shear wave generation by radiation force of focused ultrasound. The study revealed significant dependence of shear strain on the medium viscosity. The complex oscillatory character of shear strain relaxation in viscoelastic phantom and muscle tissue in vitro was observed.
PubMed ID
15139649 View in PubMed
Less detail

[Role of Cu, Zn- and Mn-containing superoxide dismutases during the yeast Saccharomyces cerevisiae growing on ethanol and glycerol]

https://arctichealth.org/en/permalink/ahliterature77745
Source
Mikrobiol Z. 2007 Mar-Apr;69(2):35-42
Publication Type
Article
Author
Mandryk S Ia
Lushchak O V
Semchyshyn H M
Lushchak V I
Source
Mikrobiol Z. 2007 Mar-Apr;69(2):35-42
Language
Ukrainian
Publication Type
Article
Keywords
Culture Media - chemistry
Cytosol - enzymology
Ditiocarb - pharmacology
Enzyme Inhibitors - pharmacology
Ethanol - chemistry
Glycerol - chemistry
Isoenzymes
Saccharomyces cerevisiae - enzymology - growth & development
Saccharomyces cerevisiae Proteins - antagonists & inhibitors - physiology
Superoxide Dismutase - antagonists & inhibitors - physiology
Abstract
Growth of the yeast Saccharomyces cerevisiae deficient as to superoxidedismutase (SOD) genes in the media containing ethanol or glycerol has been investigated. It was shown that the role of the two isoforms of SOD was different under conditions used in this study. The strain which has only mitochondrial Mn-SOD demonstrated higher velocity of culture growth on ethanol compared with the other strains investigated. In contrast to that, cytosolic Cu, Zn-SOD played more important role under growth on glycerol than Mn-SOD. The levels of carbonyl proteins in SOD-deficient strains grown on glycerol and in the cells of strain producing only Cu, Zn-SOD exposed to inhibitor diethyldithiocarbamate were investigated. The strains lacking Mn-SOD and Cu, Zn-SOD demonstrated virtually the same levels of carbonyl proteins. It is supposed that Cu, Zn-SOD can compensate Mn-SOD and vice versa. Nonlinear correlation between SOD activity and the level of carbonyl proteins was found that indicates to the uncertain role of SOD in protein oxidation.
PubMed ID
17494333 View in PubMed
Less detail

Russian isolates enlarge the known geographic diversity of Francisella tularensis subsp. mediasiatica.

https://arctichealth.org/en/permalink/ahliterature286665
Source
PLoS One. 2017;12(9):e0183714
Publication Type
Article
Date
2017
Author
Vitalii Timofeev
Irina Bakhteeva
Galina Titareva
Pavel Kopylov
David Christiany
Alexander Mokrievich
Ivan Dyatlov
Gilles Vergnaud
Source
PLoS One. 2017;12(9):e0183714
Date
2017
Language
English
Publication Type
Article
Keywords
Alleles
Animals
Biodiversity
Citrulline - chemistry
Cluster analysis
Female
Francisella tularensis - genetics - pathogenicity
Genotype
Geography
Glycerol - chemistry
Humans
Male
Mice
Mice, Inbred BALB C
Minisatellite Repeats
Phylogeography
Polymorphism, Single Nucleotide
Russia
Stem Cells
Tularemia - microbiology
Vaccination
Virulence
Abstract
Francisella tularensis, a small Gram-negative bacterium, is capable of infecting a wide range of animals, including humans, and causes a plague-like disease called tularemia-a highly contagious disease with a high mortality rate. Because of these characteristics, F. tularensis is considered a potential agent of biological terrorism. Currently, F. tularensis is divided into four subspecies, which differ in their virulence and geographic distribution. Two of them, subsp. tularensis (primarily found in North America) and subsp. holarctica (widespread across the Northern Hemisphere), are responsible for tularemia in humans. Subsp. novicida is almost avirulent in humans. The fourth subspecies, subsp. mediasiatica, is the least studied because of its limited distribution and impact in human health. It is found only in sparsely populated regions of Central Asia. In this report, we describe the first focus of naturally circulating F. tularensis subsp. mediasiatica in Russia. We isolated and characterized 18 strains of this subspecies in the Altai region. All strains were highly virulent in mice. The virulence of subsp. mediasiatica in a vaccinated mouse model is intermediate between that of subsp. tularensis and subsp. holarctica. Based on a multiple-locus variable number tandem repeat analysis (MLVA), we show that the Altaic population of F. tularensis subsp. mediasiatica is genetically distinct from the classical Central Asian population, and probably is endemic to Southern Siberia. We propose to subdivide the mediasiatica subspecies into three phylogeographic groups, M.I, M.II and M.III.
Notes
Cites: BMC Bioinformatics. 2013 May 01;14:14823635100
Cites: Eur Respir J. 2003 Feb;21(2):361-7312608453
Cites: BMC Genomics. 2012 Jun 22;13:26822727144
Cites: J Clin Microbiol. 1992 Jan;30(1):172-51370846
Cites: Emerg Infect Dis. 2014 Jul;20(7):1191-424963721
Cites: Emerg Infect Dis. 2015 Dec;21(12):2213-626583383
Cites: Appl Environ Microbiol. 2017 Jan 17;83(3):27881415
Cites: BMC Microbiol. 2009 Oct 07;9:21319811647
Cites: PLoS Pathog. 2009 May;5(5):e100045919478886
Cites: Proc Natl Acad Sci U S A. 2013 Jan 8;110(2):577-8223271803
Cites: Biochem J. 1967 Aug;104(2):627-336048802
Cites: Front Cell Infect Microbiol. 2014 Mar 13;4:3524660164
Cites: J Med Microbiol. 2003 Sep;52(Pt 9):839-4212909664
Cites: Int J Syst Evol Microbiol. 2010 Aug;60(Pt 8):1717-8; author reply 1718-2020688748
Cites: Nucleic Acids Res. 1990 Nov 25;18(22):6531-51979162
Cites: Nat Genet. 2005 Feb;37(2):153-915640799
Cites: J Bacteriol. 2004 Sep;186(17):5808-1815317786
Cites: Jpn J Infect Dis. 2008 May;61(3):223-518503176
Cites: Front Microbiol. 2011 Jan 28;1:15021687803
Cites: PLoS One. 2009 Jun 22;4(6):e600019543392
Cites: Int J Syst Evol Microbiol. 2010 Aug;60(Pt 8):1887-9619783615
Cites: Infect Ecol Epidemiol. 2016 Oct 26;6:3283827790972
Cites: Lab Delo. 1970;1:42-34192178
Cites: Clin Infect Dis. 2009 Apr 1;48(7):863-7019245342
Cites: Emerg Infect Dis. 2008 Dec;14(12):1935-719046526
Cites: Balkan Med J. 2014 Mar;31(1):3-1025207161
Cites: Emerg Infect Dis. 2012 Feb;18(2):290-322305204
Cites: BMC Res Notes. 2009 Nov 06;2:22319895698
Cites: Annu Rev Microbiol. 2006;60:167-8516704343
Cites: Environ Microbiol. 2013 Feb;15(2):634-4523253075
Cites: J Clin Microbiol. 1996 Aug;34(8):1995-20008818897
Cites: J Bacteriol. 2014 Oct;196(20):3571-8125092026
Cites: Ann N Y Acad Sci. 2007 Jun;1105:30-6617435120
Cites: PLoS One. 2012;7(2):e3062422363455
Cites: J Bacteriol. 2009 Apr;191(8):2474-8419251856
Cites: J Clin Microbiol. 1989 Jul;27(7):1601-82671019
Cites: JAMA. 2001 Jun 6;285(21):2763-7311386933
Cites: J Clin Microbiol. 2003 Jul;41(7):2924-3112843022
PubMed ID
28873421 View in PubMed
Less detail

Saliva stimulation with glycerine and citric acid does not affect salivary cortisol levels.

https://arctichealth.org/en/permalink/ahliterature261424
Source
Clin Endocrinol (Oxf). 2014 Aug;81(2):244-8
Publication Type
Article
Date
Aug-2014
Author
Camilla Brorsson
Per Dahlqvist
Leif Nilsson
Silvana Naredi
Source
Clin Endocrinol (Oxf). 2014 Aug;81(2):244-8
Date
Aug-2014
Language
English
Publication Type
Article
Keywords
Adult
Citric Acid - chemistry
Female
Finland
Glycerol - chemistry
Humans
Hydrocortisone - chemistry
In Vitro Techniques
Male
Middle Aged
Prospective Studies
Saliva - chemistry
Abstract
In critically ill patients with hypotension, who respond poorly to fluids and vasoactive drugs, cortisol insufficiency may be suspected. In serum over 90% of cortisol is protein-bound, thus routine measures of total serum cortisol may yield 'false lows' due to hypoproteinaemia. Thus, the occurrence of cortisol insufficiency could be overestimated in critically ill patients. Salivary cortisol can be used as a surrogate for free serum cortisol, but in critically ill patients saliva production is decreased, and insufficient volume of saliva for analysis is a common problem. The aim of this study was to investigate if a cotton-tipped applicator with glycerine and citric acid could be used for saliva stimulation without affecting salivary cortisol levels.
Prospective, observational study.
Thirty-six volunteers (six males, 30 females), age 49 ± 9 years, without known oral mucus membrane rupture in the mouth.
Forty-two pairs of saliva samples (22 paired morning samples, 20 paired evening samples) were obtained before and after saliva stimulation with glycerine and citric acid. Salivary cortisol was analysed using Spectria Cortisol RIA (Orion Diagnostica, Finland).
The paired samples correlated significantly (P
PubMed ID
24521305 View in PubMed
Less detail

Structure and dynamic properties of diunsaturated 1-palmitoyl-2-linoleoyl-sn-glycero-3-phosphatidylcholine lipid bilayer from molecular dynamics simulation.

https://arctichealth.org/en/permalink/ahliterature10959
Source
Biophys J. 1997 Dec;73(6):2907-23
Publication Type
Article
Date
Dec-1997
Author
M T Hyvönen
T T Rantala
M. Ala-Korpela
Author Affiliation
NMR Research Group, Department of Physical Sciences, University of Oulu, Finland.
Source
Biophys J. 1997 Dec;73(6):2907-23
Date
Dec-1997
Language
English
Publication Type
Article
Keywords
Biophysics
Computer simulation
Glycerol - chemistry
Lipid Bilayers - chemistry
Models, Molecular
Molecular Conformation
Molecular Structure
Phosphatidylcholines - chemistry
Research Support, Non-U.S. Gov't
Stereoisomerism
Thermodynamics
Water - chemistry
Abstract
Unsaturated fatty acid chains are known to be an essential structural part of biomembranes, but only monounsaturated chains have been included in the molecular dynamics (MD) simulations of membrane systems. Here we present a 1-ns MD simulation for a diunsaturated 1-palmitoyl-2-linoleoyl-sn-glycero-3-phosphatidylcholine (PLPC; 16:0/18:2[delta9,12]) bilayer. The structural behavior of the phosphatidylcholine headgroup, the glycerol backbone, and the hydrating water were assessed and found to be consistent with the existing information about similar systems from both experimental and computational studies. Further analysis was focused on the structure of the double bond region and the effects of the diunsaturation on the bilayer interior. The behavior of the diunsaturated sn-2 chains is affected by the tilted beginning of the chain and the four main conformations of the double bond region. The double bonds of the sn-2 chains also influenced the characteristics of the saturated chains in the sn-1 position. Furthermore, extreme conformations of the sn-2 chains existed that are likely to be related to the functional role of the double bonds. The results here point out the importance of polyunsaturation for the biological interpretations deduced from the membrane MD simulations.
PubMed ID
9414205 View in PubMed
Less detail

9 records – page 1 of 1.