The role of metabolites in the interspecific interaction of bacteria (review)

2021 ◽  
pp. 26-33
Author(s):  
Irina O. Yunusova ◽  
Anatoly A. Yakovlev
Keyword(s):  
Antimicrobial Properties ◽  
Interspecific Interaction ◽  
Antimicrobial Substances ◽  
Current Period ◽  
Initial Stage ◽  
Low Concentrations ◽  
Metabolic Products ◽  
Number Of Publications ◽  
The Stability

In the current period, scientists both in our country and abroad are actively studying the processes of interaction between microorganisms since an understanding of the mechanisms of communication and competition between them will contribute to the development of new strategies in the fight against infectious diseases. Nevertheless, although in recent years there has been a significant increase in the number of publications on the indicated problem, studies covering far from all possible variants of interactions between various microorganisms, are still at their initial stage, and are still less focused on the understanding of direct mechanisms of interaction. Of particular interest is the study of antagonistic relationships in which the development of some forms of microbes is inhibited by others through the antimicrobial substances they produce. Metabolites that display antimicrobial properties at low concentrations are one such substance. In the present work, the authors present a literature analysis indicating that between-population relationships, realized through metabolic products, are among the main factors that are aimed at the stability of microbial communities and management of their productivity and species composition, including mixed biofilms.

scholarly journals Le rôle des entreprises et leurs comportements sur la stabilité du système financier

2021 ◽  
Vol 14 (2) ◽  
pp. 85-103
Author(s):  
Farelle Yandza Ikahaud ◽  
Mohamed El Haddad
Keyword(s):  
Bibliometric Analysis ◽  
Empirical Work ◽  
Financial System ◽  
The State ◽  
Scientific Interest ◽  
Number Of Publications ◽  
The Stability ◽  
The Impact

Investment determines the sustainability and prosperity of an economy. The paper seeks to (1) give an overview of the roles of companies on the stability of the financial system, based on existing theoretical and empirical work; and (2) to highlight the reasons which expose them to the non-application of their duties against the State. For this purpose, a bibliometric analysis using the Direct Science database was employed. The results of the analysis allowed us to study the search trend by analyzing the distribution of publications, authors, types of publications and fields of research and also showed that the themes of the study are of great scientific interest because of the surge in the number of publications on the role of companies over the last ten years averaging 76.3 per year while 1,690 were on the impact of company behaviour on the stability of the financial system.

scholarly journals Effect of the Width of Gaussian Wave Packets on the Stability of the Nuclei

2021 ◽  
Vol 9 (1) ◽  
pp. 7-14
Author(s):  
Supriya Goyal
Keyword(s):  
Equations Of State ◽  
Wave Packets ◽  
Mass Region ◽  
Quantum Molecular Dynamics ◽  
Long Period ◽  
Initial Stage ◽  
Low Mass ◽  
The Stability ◽  
Gaussian Wave Packets

The role of the range of interaction on the stability of the nuclei propagating with and without momentum dependent interactions is analyzed within the framework of Quantum Molecular Dynamics (QMD) model. A detailed study is carried out by taking different equations of state (i.e., static soft and hard and the momentum dependent soft and hard) for the selected nuclei from 12C to 197Au. Comparison is done by using the standard and the double width of the Gaussian wave packets. We find that the effect of the double width of the Gaussian wave packets on the stability of the initial stage nuclei cannot be neglected. The nuclei having double width do not emit free nucleons for a long period of time. Also, the ground state properties of all the nuclei are described well. In the low mass region, the obtained nuclei are less bound but stable. Heavy mass nuclei have proper binding energy and are stable.

The Role of Calcium in the Isolation of Brush Borders from Epithelial Cells of Rat Small Intestine

1966 ◽  
Vol 1 (4) ◽  
pp. 415-424
Author(s):  
P. F. MILLINGTON ◽  
D. R. CRITCHLEY ◽  
P.W. A. TOVELL
Keyword(s):  
Small Intestine ◽  
Calcium Ions ◽  
Chelating Agent ◽  
Tris Buffer ◽  
Good Separation ◽  
The Third ◽  
Low Concentrations ◽  
Brush Borders ◽  
The Stability

A chelating agent such as EDTA or EGTA used with a dilute TRIS buffer at pH 7.2-7.5 was used in order to effect a good separation of brush borders from the epithelium of the small intestine. A good separation was not obtained in low concentrations of TRIS buffer or saline alone. Brush borders were not obtained when the calcium-chelate complex of EDTA or EGTA was used, and only a partial fractionation was obtained when the magnesium complex of EDTA was tried. The involvement of calcium was further illustrated by adding calcium salts directly to the fractionation medium; separation was prevented when sufficient calcium had been added to saturate the chelating agent. It was found that there was no precise optimum concentration for EDTA but a separation could not be obtained below 2.4 mM/1. The effect of changing the pH of the buffer was also investigated and it was demonstrated that the onset of the ability to release brush borders coincided approximately with the ionization of the third acid radical of the chelating agent. This is in keeping with the suggested hypothesis that EDTA acts by chelating calcium ions. From these and electron-microscope studies it is suggested that the binding of calcium ions is an important factor in the maintenance of the stability of the epithelial cell membrane.

The role of magnesium ion in the adenine phosphoribosyltransferase reaction

1970 ◽  
Vol 48 (3) ◽  
pp. 302-307 ◽  
Author(s):  
R. E. A. Gadd ◽  
J. Frank Henderson
Keyword(s):  
Stability Constant ◽  
Initial Velocity ◽  
Adenosine Monophosphate ◽  
Magnesium Ion ◽  
Adenine Phosphoribosyltransferase ◽  
Good Correspondence ◽  
Low Concentrations ◽  
High Concentrations ◽  
The Stability

Low concentrations of magnesium ion stimulate, and high concentrations inhibit, the adenine phosphoribosyltransferase reaction. The stability constant of the Mg–pyrophosphoryl moiety of phosphoribosylpyrophosphate was assumed to be the same as that of Mg–adenosine triphosphate; the stability constant of the Mg–phosphoryl moiety of phosphoribosylpyrophosphate was assumed to be the same as that of Mg–adenosine monophosphate, and the concentration of the monomagnesium complex of phosphoribosylpyrophosphate was calculated as a function of magnesium ion and phosphoribosylpyrophosphate concentrations. The good correspondence between these curves and those of initial velocity under the same conditions suggest that the monomagnesium complex of phosphoribosylpyrophosphate is the true substrate of this reaction.

Kinetics of Various 99mTc-Sn-Pyrophosphate Compounds in the Rat

1977 ◽  
Vol 16 (04) ◽  
pp. 157-162 ◽  
Author(s):  
C. Schümichen ◽  
B. Mackenbrock ◽  
G. Hoffmann
Keyword(s):  
Normal Saline ◽  
Half Life ◽  
Compound A ◽  
Short Half Life ◽  
Low Concentrations ◽  
The Stability ◽  
Kinetics Of ◽  
In Vitro Stability

SummaryThe bone-seeking 99mTc-Sn-pyrophosphate compound (compound A) was diluted both in vitro and in vivo and proved to be unstable both in vitro and in vivo. However, stability was much better in vivo than in vitro and thus the in vitro stability of compound A after dilution in various mediums could be followed up by a consecutive evaluation of the in vivo distribution in the rat. After dilution in neutral normal saline compound A is metastable and after a short half-life it is transformed into the other 99mTc-Sn-pyrophosphate compound A is metastable and after a short half-life in bone but in the kidneys. After dilution in normal saline of low pH and in buffering solutions the stability of compound A is increased. In human plasma compound A is relatively stable but not in plasma water. When compound B is formed in a buffering solution, uptake in the kidneys and excretion in urine is lowered and blood concentration increased.It is assumed that the association of protons to compound A will increase its stability at low concentrations while that to compound B will lead to a strong protein bond in plasma. It is concluded that compound A will not be stable in vivo because of a lack of stability in the extravascular space, and that the protein bond in plasma will be a measure of its in vivo stability.

Testosterone Potentiation of Ionophore and ADP Induced Platelet Aggregation : Relationship to Arachidonic Acid Metabolism

1981 ◽  
Vol 46 (02) ◽  
pp. 538-542 ◽  
Author(s):  
R Pilo ◽  
D Aharony ◽  
A Raz
Keyword(s):  
Arachidonic Acid ◽  
Platelet Aggregation ◽  
Unsaturated Fatty Acids ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Arachidonic Acid Metabolism ◽  
Ionophore A23187 ◽  
Low Concentrations ◽  
Induced Aggregation

SummaryThe role of arachidonic acid oxygenated products in human platelet aggregation induced by the ionophore A23187 was investigated. The ionophore produced an increased release of both saturated and unsaturated fatty acids and a concomitant increased formation of TxA2 and other arachidonate products. TxA2 (and possibly other cyclo oxygenase products) appears to have a significant role in ionophore-induced aggregation only when low concentrations (<1 μM) of the ionophore are employed.Testosterone added to rat or human platelet-rich plasma (PRP) was shown previously to potentiate platelet aggregation induced by ADP, adrenaline, collagen and arachidonic acid (1, 2). We show that testosterone also potentiates ionophore induced aggregation in washed platelets and in PRP. This potentiation was dose and time dependent and resulted from increased lipolysis and concomitant generation of TxA2 and other prostaglandin products. The testosterone potentiating effect was abolished by preincubation of the platelets with indomethacin.

A Statistical Study of Process Variables to Optimize a High Speed Curtain Coater: Part I

TAPPI Journal ◽  
2009 ◽  
Vol 8 (1) ◽  
pp. 20-26 ◽  
Author(s):  
PEEYUSH TRIPATHI ◽  
MARGARET JOYCE ◽  
PAUL D. FLEMING ◽  
MASAHIRO SUGIHARA
Keyword(s):  
Boundary Layer ◽  
Experimental Design ◽  
High Speed ◽  
Statistical Study ◽  
Process Variables ◽  
High Speeds ◽  
The Stability ◽  
Air Removal ◽  
Removal System

Using an experimental design approach, researchers altered process parameters and material prop-erties to stabilize the curtain of a pilot curtain coater at high speeds. Part I of this paper identifies the four significant variables that influence curtain stability. The boundary layer air removal system was critical to the stability of the curtain and base sheet roughness was found to be very important. A shear thinning coating rheology and higher curtain heights improved the curtain stability at high speeds. The sizing of the base sheet affected coverage and cur-tain stability because of its effect on base sheet wettability. The role of surfactant was inconclusive. Part II of this paper will report on further optimization of curtain stability with these four variables using a D-optimal partial-facto-rial design.

DEVELOPMENT OF STREAMFLOW DROUGHT INDICES IN THE MORAVA RIVER BASIN

2020 ◽  
Author(s):  
Ondrej Ledvinka ◽  
◽  
Pavel Coufal ◽  
Keyword(s):  
Time Series ◽  
Kendall Test ◽  
Drought Indices ◽  
Drought Period ◽  
Left Hand ◽  
Low Flows ◽  
Current Period ◽  
Catchment Size ◽  
Morava River ◽  
The Stability

The territory of Czechia currently suffers from a long-lasting drought period which has been a subject of many studies, including the hydrological ones. Previous works indicated that the basin of the Morava River, a left-hand tributary of the Danube, is very prone to the occurrence of dry spells. It also applies to the development of various hydrological time series that often show decreases in the amount of available water. The purpose of this contribution is to extend the results of studies performed earlier and, using the most updated daily time series of discharge, to look at the situation of the so-called streamflow drought within the basin. 46 water-gauging stations representing the rivers of diverse catchment size were selected where no or a very weak anthropogenic influences are expected and the stability and sensitivity of profiles allow for the proper measurement of low flows. The selected series had to cover the most current period 1981-2018 but they could be much longer, which was considered beneficial for the next determination of the development direction. Various series of drought indices were derived from the original discharge series. Specifically, 7-, 15- and 30-day low flows together with deficit volumes and their durations were tested for trends using the modifications of the Mann– Kendall test that account for short-term and long-term persistence. In order to better reflect the drivers of streamflow drought, the indices were considered for summer and winter seasons separately as well. The places with the situation critical to the future water resources management were highlighted where substantial changes in river regime occur probably due to climate factors. Finally, the current drought episode that started in 2014 was put into a wider context, making use of the information obtained by the analyses.

The Role of Hydrophobicity in the Stability and pH-Switchability of (RXDX)4 and Coumarin-RXDX Conjugate β-Sheets

2020 ◽  
Author(s):  
Ryan Weber ◽  
Martin McCullagh
Keyword(s):  
Biological Imaging ◽  
Ph Sensing ◽  
Hydrophobic Residue ◽  
Ideal Candidate ◽  
Self Assembling ◽  
Sensing Applications ◽  
Β Sheets ◽  
The Stability ◽  
Dynamics Simulations

<p>pH-switchable, self-assembling materials are of interest in biological imaging and sensing applications. Here we propose that combining the pH-switchability of RXDX (X=Ala, Val, Leu, Ile, Phe) peptides and the optical properties of coumarin creates an ideal candidate for these materials. This suggestion is tested with a thorough set of all-atom molecular dynamics simulations. We first investigate the dependence of pH-switchabiliy on the identity of the hydrophobic residue, X, in the bare (RXDX)<sub>4</sub> systems. Increasing the hydrophobicity stabilizes the fiber which, in turn, reduces the pH-switchabilty of the system. This behavior is found to be somewhat transferable to systems in which a single hydrophobic residue is replaced with a coumarin containing amino acid. In this case, conjugates with X=Ala are found to be unstable and both pHs while conjugates with X=Val, Leu, Ile and Phe are found to form stable β-sheets at least at neutral pH. The (RFDF)<sub>4</sub>-coumarin conjugate is found to have the largest relative entropy value of 0.884 +/- 0.001 between neutral and acidic coumarin ordering distributions. Thus, we posit that coumarin-(RFDF)<sub>4</sub> containing peptide sequences are ideal candidates for pH-sensing bioelectronic materials.</p>

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