scholarly journals Computational evidence for protein-mediated fatty acid transport across the sarcolemma

2006 ◽  
Vol 393 (3) ◽  
pp. 669-678 ◽  
Author(s):  
Mark W. J. M. Musters ◽  
James B. Bassingthwaighte ◽  
Natal A. W. van Riel ◽  
Ger J. van der Vusse
Keyword(s):  
Uptake Rate ◽  
Cardiac Myocyte ◽  
Experimental Studies ◽  
Biological Properties ◽  
Fatty Acid Transport ◽  
Flip Flop ◽  
Model Calculations ◽  
Outer Leaflet ◽  
Pass Through ◽  
Sarcolemmal Transport

Long-chain fatty acids (FAs) are important substrates used by the heart to fulfil its energy requirements. Prior to mitochondrial oxidation, blood-borne FAs must pass through the cell membrane of the cardiac myocyte (sarcolemma). The mechanism underlying the sarcolemmal transport of FAs is incompletely understood. The aim of the present study was to estimate the trans-sarcolemmal FA uptake rate using a comprehensive computer model, in which the most relevant mechanisms proposed for cardiac FA uptake were incorporated. Our in silico findings show that diffusion of FA, present in its unbound form (uFA) in close proximity to the outer leaflet of the sarcolemma and serving as sole FA source, is insufficient to account for the physiological FA uptake rate. The inclusion of a hypothetical membrane-associated FA-TFPC (FA-transport-facilitating protein complex) in the model calculations substantially increased the FA uptake rate across the sarcolemma. The model requires that the biological properties of the FA-TFPC allow for increasing the rate of absorption of FA into the outer leaflet and the ‘flip-flop’ rate of FA from the outer to the inner leaflet of the sarcolemma. Experimental studies have identified various sarcolemma-associated proteins promoting cardiac FA uptake. It remains to be established whether these proteins possess the properties predicted by our model. Our findings also indicate that albumin receptors located on the outer leaflet of the sarcolemma facilitate the transfer of FA across the membrane to a significant extent. The outcomes of the computer simulations were verified with physiologically relevant FA uptake rates as assessed in the intact, beating heart in experimental studies.

scholarly journals Integrated assessment of the state of sewage mine waters based on gas-discharge radiation method

2020 ◽  
Vol 201 ◽  
pp. 01032
Author(s):  
Natalija Glukhova ◽  
Viktor Khilov ◽  
Yuliia Kharlamova ◽  
Mariia Isakova
Keyword(s):  
Fourier Transform ◽  
Integrated Assessment ◽  
Experimental Studies ◽  
Texture Features ◽  
Biological Properties ◽  
Gas Discharge ◽  
Mine Waters ◽  
Physical Chemical ◽  
Spatial Frequencies ◽  
The Fourier Transform

The existing environmental problems resulting from the use and subsequent discharge of water by mining and metallurgical enterprises are analyzed. The relevance of developing methods for an integrated assessment of water properties is presented, which will allow the study of not only physical-chemical, but also the biological parameters of water. Experimental studies of water samples are conducted based on the method of gas-discharge radiation. The existing methods for extracting informative features of gas-discharge radiation images of liquid-phase objects are analyzed. Histograms of gas-discharge radiation images of various types of water were constructed and studied. The expediency of dividing images into separate fragments, characterized by common texture features, is shown. The analysis of texture features is carried out based on the use of the Fourier transform. Using the Fourier transform for the corresponding luminance vectors, the spectra have been obtained of the spatial distribution of the frequencies of brightness changes, which are used as texture features to identify the specific characteristics of the gas-discharge tracks formation. It has been determined that the developed method of water analysis allows assessing its biological properties, which is based on the values of the spatial frequency range. The advantage of the proposed method over the existing ones is the possibility of quantitative assessment in the form of numerical values of the covered range of spatial frequencies. The proposed method of studying the biological properties of water can be used as part of modern environmental monitoring systems.

A Solid-State NMR Approach to Structure Determination of Membrane-Associated Peptides and Proteins

1997 ◽  
Author(s):  
S.J. Opella ◽  
L.E. Chirlian
Keyword(s):  
Nmr Spectroscopy ◽  
Membrane Proteins ◽  
Structural Biology ◽  
Experimental Studies ◽  
Globular Proteins ◽  
Biological Properties ◽  
Cellular Functions ◽  
X Ray ◽  
X Ray Crystallography ◽  
Form And Function

Structural biology relies on detailed descriptions of the three-dimensional structures of peptides, proteins, and other biopolymers to explain the form and function of biological systems ranging in complexity from individual molecules to entire organisms. NMR spectroscopy and X-ray crystallography, in combination with several types of calculations, provide the required structural information. In recent years, the structures of several hundred proteins have been determined by one or both of these experimental methods. However, since the protein molecules must either reorient rapidly in samples for multidimensional solution NMR spectroscopy or form high quality single crystals in samples for X-ray crystallography, nearly all of the structures determined up to now have been of the soluble, globular proteins that are found in the cytoplasm and periplasmof cells and fortuitously have these favorable properties. Since only a minority of biological properties are expressed by globular proteins, and proteins, in general, have evolved in order to express specific functions rather than act as samples for experimental studies, there are other classes of proteins whose structures are currently unknown but are of keen interest in structural biology. More than half of all proteins appear to be associated with membranes, and many cellular functions are expressed by proteins in other types of supramolecular complexes with nucleic acids, carbohydrates, or other proteins. The interest in the structures of membrane proteins, structural proteins, and proteins in complexes provides many opportunities for the further development and application of NMR spectroscopy. Our understanding of polypeptides associated with lipids in membranes, in particular, is primitive, especially compared to that for globular proteins. This is largely a consequence of the experimental difficulties encountered in their study by conventional NMR and X-ray approaches. Fortunately, the principal features of two major classes of membrane proteins have been identified from studies of several tractable examples. Bacteriorhodopsin (Henderson et al., 1990), the subunits of the photosynthetic reaction center (Deisenhofer et al., 1985), and filamentous bacteriophage coat proteins (Shon et al., 1991; McDonnell et al., 1993) have all been shown to have long transmembrane hydrophobic helices, shorter amphipathic bridging helices in the plane of the bilayers, both structured and mobile loops connecting the helices, and mobile N- and C-terminal regions.

scholarly journals Crucian Carp (Carassius carassius) Strongly Affect C/N/P Stoichiometry of Suspended Particulate Matter in Shallow Warm Water Eutrophic Lakes

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 524 ◽  
Author(s):  
Hu He ◽  
Yanqing Han ◽  
Qisheng Li ◽  
Erik Jeppesen ◽  
Kuanyi Li ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Suspended Particulate Matter ◽  
Crucian Carp ◽  
Experimental Studies ◽  
Biological Properties ◽  
Light Limitation ◽  
Carassius Carassius ◽  
Eutrophic Lakes ◽  
Suspended Particulate ◽  
Crucian Carp Carassius Carassius

Crucian carp (Carassius carassius) is a key fish species in most Chinese subtropical and tropical shallow lakes. Through sediment feeding, crucian carp could greatly change water turbidity and nutrient levels, as well as the abundance of herbivorous consumers, which may have important influences on seston element stoichiometry. However, so far, experimental studies on this topic are lacking. We conducted a 36-day mesocosm experiment to explore the effects of crucian carp on water physicochemical and biological properties, and C/N/P ratios in suspended particulate matter (SPM) under eutrophic conditions. Our results provided three major findings: (1) Crucian carp resuspended sediments and along with them, reduced light penetration and lower light/total phosphorus (TP) ratios. (2) Crucian carp reduced biomasses of both zooplankton and macrozoobenthos, whereas their effect on phytoplankton was weak, potentially because of resuspension-induced light limitation. (3) Both C/P and N/P ratios in SPM were significant lower in mesocosms with crucian carp than in fish-free controls, which may be attributed to the high contribution of P-rich sediments and low light to nutrient supply caused by fish-induced resuspension. Our results suggest that besides planktivorous fish, benthivore (e.g., crucian carp) in warm shallow waters could also affect pelagic C/N/P stoichiometry via sediment feeding, which may further influence energy transfer efficiency in lake food chain.

Madreporic coral: a new bone graft substitute for cranial surgery

1988 ◽  
Vol 69 (4) ◽  
pp. 510-513 ◽  
Author(s):  
François X. Roux ◽  
Daniel Brasnu ◽  
Bernard Loty ◽  
Bernard George ◽  
Geneviève Guillemin
Keyword(s):  
Bone Graft ◽  
Reconstructive Surgery ◽  
Experimental Studies ◽  
Bone Graft Substitute ◽  
Biological Properties ◽  
Content Type ◽  
Skull Defects ◽  
Cranial Fossa ◽  
Burr Holes ◽  
Fine Print

✓ Since 1985, the authors have been using madreporic coral fragments (genera Porites) as a bone graft substitute. Of the 167 coral grafts implanted, 150 were coral “corks” used to obliterate burr holes (diameter 10 mm), five were large implants (length 20 to 40 mm) to repair skull defects, and 12 were coral blocks to reconstruct the floor of the anterior cranial fossa. Previous experimental studies suggested that coral grafts would be well tolerated and become partially reossified as the calcific skeleton was resorbed. The authors describe their experience and detail the main biological properties of these materials, which appear to be very promising for use in cranial reconstructive surgery.

First Principles Computer Simulation of the Defect Chemistry of Rutile TiO2

1996 ◽  
Vol 453 ◽  
Author(s):  
I. Dawson ◽  
P. D. Bristowe ◽  
J. A. White ◽  
M. C. Payne
Keyword(s):  
First Principles ◽  
Formation Energy ◽  
Experimental Studies ◽  
Parallel Computer ◽  
Model Calculations ◽  
Interesting Insight ◽  
First Results ◽  
Dominant Point ◽  
Defect Mechanism

AbstractThere exists a long-standing controversy concerning the nature of the dominant point defect mechanism in rutile TiO2. Previous classical shell model calculations by Catlow el al [1] find a strong preference for Schottky as opposed to Frenkel-type defects, lending support for oxygen vacancy rather than titanium interstitial compensation in reduced rutile. However, reviews of experimental studies [2], show that many conflicting conclusions have been reached. Ab initio total-energy calculations have been performed on a parallel computer to help resolve this controversy. First results indicate a Schottky formation energy (of the bound Schottky trio) consistent with the Mott-Littleton values of Catlow et al [1]. A first attempt is made at calculating the heat of reduction through determination of the formation energy of a neutral oxygen atom vacancy. As a. result some interesting insight is gained into the redox chemistry of reduced rutile.

Proteinase 3, the Wegener autoantigen, is externalized during neutrophil apoptosis: evidence for a functional association with phospholipid scramblase 1 and interference with macrophage phagocytosis

Blood ◽  
2007 ◽  
Vol 110 (12) ◽  
pp. 4086-4095 ◽  
Author(s):  
Chahrazade Kantari ◽  
Magali Pederzoli-Ribeil ◽  
Omid Amir-Moazami ◽  
Valérie Gausson-Dorey ◽  
Ivan Cruz Moura ◽  
...  
Keyword(s):  
Serine Proteinase ◽  
Human Macrophage ◽  
Proteinase 3 ◽  
Neutrophil Apoptosis ◽  
Wegener Granulomatosis ◽  
Flip Flop ◽  
Phospholipid Scramblase ◽  
Outer Leaflet ◽  
Macrophage Phagocytosis ◽  
Phospholipid Scramblase 1

Abstract Proteinase 3 (PR3), a serine proteinase contained in neutrophil azurophilic granules, is considered a risk factor for vasculitides and rheumatoid arthritis when expressed on the outer leaflet of neutrophil plasma membrane and is the preferred target of antineutrophil cytoplasm autoantibodies (ANCA) in Wegener granulomatosis. ANCA binding to PR3 expressed at the surface of neutrophils activates them. Evidence is provided that neutrophil apoptosis induced significantly more membrane PR3 expression without degranulation (but no enhanced membrane CD35, CD66b, CD63, myeloperoxidase, or elastase expression). This observation was confirmed on cytoplasts, a model of granule-free neutrophils. We hypothesized that PR3 could interact with proteins involved in membrane flip-flop (eg, phospholipid scramblase 1 [PLSCR1]). PR3-PLSCR1 interaction in neutrophils was demonstrated by confocal microscopy and coimmunoprecipitation. In the RBL-2H3 rat mast-cell line stably transfected with PR3 or its inactive mutant (PR3S203A), PR3 externalization depended on PLSCR1, as shown by less PR3 externalization in the presence of rPLSCR1 siRNA, but independently of its serine-proteinase activity. Finally, apoptosis-externalized PR3 decreased the human macrophage-phagocytosis rate of apoptotic PR3 transfectants. Therefore, in addition to ANCA binding in vasculitis, the proinflammatory role of membrane PR3 expression may involve interference with macrophage clearance of apoptotic neutrophils.

Radical yields in DNA exposed to ionizing radiation: Role of energy and charge transfer

1990 ◽  
Vol 68 (9) ◽  
pp. 962-966 ◽  
Author(s):  
John H. Miller ◽  
Charles E. Swenberg
Keyword(s):  
Charge Transfer ◽  
Ionizing Radiation ◽  
Mechanistic Model ◽  
Experimental Studies ◽  
High Mobility ◽  
Orientation Dependence ◽  
Model Calculations ◽  
Insight Into ◽  
High Linear Energy Transfer

Theoretical and experimental studies of free-radical yields in oriented DNA samples exposed to ionizing radiation with high linear energy transfer at 77 K are discussed. The dependence of radical yields on the orientation of DNA chains relative to the particle flux is being investigated to gain insight into the role of intramolecular energy and charge transfer processes in radical production and decay. Model calculations based on a thermal-spike approximation are presented and their limitations for predicting the orientation dependence of radical yields observed after neutron irradiation (see C. M. Arroyo et al. Int. J. Radiat. Biol. 50, 789 (1986)) are discussed. A more mechanistic model based on the high mobility of excess electrons in hydrated DNA (D. van Lith et al. J. Chem. Soc. Faraday Trans. 1, 82, 2933 (1986)) is outlined.

scholarly journals Effect of Leakage Delay on Hopf Bifurcation in a Fractional BAM Neural Network

2019 ◽  
Vol 29 (06) ◽  
pp. 1950077 ◽  
Author(s):  
Jiazhe Lin ◽  
Rui Xu ◽  
Liangchen Li
Keyword(s):  
Neural Network ◽  
Hopf Bifurcation ◽  
Experimental Studies ◽  
Rank Correlation ◽  
Correlation Coefficients ◽  
Leakage Delay ◽  
Scatter Plots ◽  
Bam Neural Network ◽  
Pass Through ◽  
The Impact

Recently, experimental studies show that fractional calculus can depict the memory and hereditary attributes of neural networks more accurately. In this paper, we introduce temporal fractional derivatives into a six-neuron bidirectional associative memory (BAM) neural network with leakage delay. By selecting two different bifurcation parameters and analyzing corresponding characteristic equations, it is verified that the delayed fractional neural network generates Hopf bifurcation when the bifurcation parameters pass through some critical values. In order to measure how much is the impact of leakage delay on Hopf bifurcation, sensitivity analysis methods, such as scatter plots and partial rank correlation coefficients (PRCCs), are introduced to assess the sensitivity of bifurcation amplitudes to leakage delay. Numerical examples are carried out to illustrate the theoretical results and help us gain an insight into the effect of leakage delay.

Determination of the Composition of Substances Migrating from Plugs Based on Bromo-Butyl Rubber into Infusion and Injection Preparations

2020 ◽  
Vol 869 ◽  
pp. 135-139
Author(s):  
Yuri N. Khakimullin ◽  
Larisa Yuryevna Zakirova ◽  
Alfred D. Khusainov
Keyword(s):  
Inorganic Compounds ◽  
Experimental Studies ◽  
Atomic Emission ◽  
Spectral Studies ◽  
Mass Spectral ◽  
Standard Glass ◽  
Volatile Organic ◽  
Pass Through ◽  
Direct Acting

The results of experimental studies of the composition of individual substances migrating from medical rubber plugs produced both in and abroad based on technical bromobutyl rubber are presented. The quantitative content of volatile organic compounds related to species impurities of gasoline was determined by gas chromatography from a standard glass bottle sealed with a sterile stopper based on bromobutyl rubber. The method of atomic emission spectroscopy was used to determine (indirect) the presence of organometallic, organosulfur and metal-inorganic compounds that did not pass through chromatographic columns, and the presence of organometallic, organosulfur and metal-inorganic compounds was determined by the content of metal and non-metal cations. The results of mass spectral studies of extracts of aqueous extracts from plugs based on bromobutyl rubber showed that they contain impurities of bromo-alkanes and bromo-arenes, which are direct-acting carcinogens.

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