EFFECT OF STEROIDS AND COFACTORS ON THE ACTIVITY AND STABILITY OF HUMAN PLACENTAL GLUTAMATE DEHYDROGENASE

1966 ◽  
Vol 51 (4) ◽  
pp. 599-608
Author(s):  
Dale M. Peterson ◽  
James C. Warren
Keyword(s):  
Glutamate Dehydrogenase ◽  
Sex Hormones ◽  
Human Placenta ◽  
Initial Velocity ◽  
Significant Inhibition ◽  
The Other ◽  
Other Hand ◽  
High Concentrations ◽  
The Stability ◽  
Uncompetitive Inhibitor

ABSTRACT Glutamate dehydrogenase (EC 1. 4. 1. 3.) has been purified approximately 3700 fold from human placenta. The effects of sex hormones and co-factors on the activity and stability of this preparation have been studied. NAD+ was noted to activate this enzyme at high concentrations while NADP+ did not. Mg2+ was shown to be a competitive activator of glutamate with NADP+ as cofactor and an uncompetitive inhibitor of glutamate with NAD+ as cofactor. With NAD+ as cofactor, steroids at concentrations physiological for placenta had no effect on activity while significant inhibition of initial velocity by 1.0 μm oestrone and 17β-oestradiol and 2.0 μm progesterone was seen with NADP+ as co-factor. The stability of the enzyme was uneffected by several steroids alone at 20 μm concentrations. The stability of the enzyme was markedly decreased by NADPH but natural steroids at physiological concentrations failed to potentiate this cofactor induced instability. Mg2+ ion, ATP and ADP at physiological concentrations, on the other hand, clearly protect the enzyme against NADPH. These observations militate against steroid effects on stability but do not exclude steroid inhibition of activity with NADP+ as cofactor as a possible mechanism of steroid action, at least in placenta.

Catabolite-controlled regulation of glutamate dehydrogenases of Neurospora crassa

1970 ◽  
Vol 16 (1) ◽  
pp. 33-40 ◽  
Author(s):  
M. Kapoor ◽  
A. K. Grover
Keyword(s):  
Neurospora Crassa ◽  
Glutamate Dehydrogenase ◽  
Growth Medium ◽  
Nicotinamide Adenine Dinucleotide ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Reciprocal Relationship ◽  
The Other ◽  
Nicotinamide Adenine ◽  
Specific Enzyme ◽  
Other Hand

The effect of the presence of catabolites in the growth medium on the synthesis of the two glutamate dehydrogenases of Neurospora crassa is reported. It has been demonstrated that the nicotinamide adenine dinucleotide (NAD) specific glutamate dehydrogenase is subject to repression by sucrose and glucose. Nicotinamide adenine dinucleotide phosphate (NADP) specific glutamate dehydrogenase, on the other hand, is induced by increasing concentrations of the catabolite. These data suggest that a reciprocal relationship exists between these two enzymes during synthesis in the presence of catabolites. Growth in higher concentrations of sucrose led to the formation of two isoenzymes of the NADP-specific enzyme; the second or the minor isozyme is not produced at very low catabolite concentrations. The catabolite effects produced by sucrose are overcome by glutamate, if the latter is incorporated into the growth medium. Glutamate represses both the isozymes of NADP-specific enzyme.

Linear Stability of a Plasma Diode

1969 ◽  
Vol 24 (8) ◽  
pp. 1235-1243 ◽  
Author(s):  
M Dobrowolny ◽  
F Engelmann ◽  
A Sestero
Keyword(s):  
Boundary Conditions ◽  
Linear Stability ◽  
Plane Waves ◽  
The Other ◽  
Other Hand ◽  
Free Particles ◽  
Plasma Diode ◽  
The Stability

AbstractThe stability of a plasma diode with respect to longitudinal oscillations is investigated. If there are free particles emitted by the electrodes, the perturbations do not have the same dynamics as they would in an infinite plasma, contrary to the case where only particles trapped in the diode are present. This can be interpreted as due to a coupling of plane waves of different wave lengths, introduced by the boundary conditions at the electrodes. The occurrence of resonant-particle effects, on the other hand, is subjected to precisely the same conditions as in an infinite plasma.

COMPARISON OF THE ANTI-FERTILITY AND SEX HORMONAL ACTIVITIES OF SEX HORMONES AND THEIR DERIVATIVES

1964 ◽  
Vol 47 (3) ◽  
pp. 444-456 ◽  
Author(s):  
P. A. Desaulles ◽  
C. Krähenbühl
Keyword(s):  
Sex Hormones ◽  
Relative Intensity ◽  
Sex Steroids ◽  
Inhibitory Action ◽  
Inhibitory Effect ◽  
The Other ◽  
Potent Effect ◽  
Other Hand ◽  
Activity Ratios ◽  
Blastocyst Implantation

ABSTRACT The following effects exerted by sex steroids were measured: androgenic, oestrogenic, and progestational effects; the inhibition action on gonadotrophic function in castrated animals; and the inhibitory action on ovulation and blastocyst implantation in intact animals. The steroids investigated consisted of oestradiol and its ethinyl and methoxyethinyl derivatives, oestrone, oestriol, testosterone, progesterone, and certain synthetic gestagens derived from nortestosterone, i. e. norethisterone, norethynodrel, and ethinyl-oestrenol. Oestradiol and its derivatives show potent anti-gonadotrophic activity, a relatively less potent anti-ovulatory effect, and a marked inhibitory action on implantation. Progesterone, on the other hand, which has only a very weak inhibitory effect on gonadotrophic function, shows an anti-ovulatory activity which, though inferior in absolute terms to that of oestradiol, is still appreciable, whereas it exerts almost no effect at all on implantation. With regard to its activity ratios, testosterone occupies a position mid-way between the two female hormones. Norethisterone, norethynodrel, and ethinyl-oestrenol have a more potent effect on gonadotrophic function than progesterone. The activity ratios for the effects of these three compounds on ovulation and implantation are comparable to those of oestradiol or progesterone, depending on the relative intensity of their oestrogenic and progestational action. The nature of the endocrine changes produced by these compounds are discussed with reference to the inhibition of ovulation and implantation.

On Wake-Induced Flutter of a Circular Conductor in the Wake of Another

1980 ◽  
Vol 102 (2) ◽  
pp. 125-137 ◽  
Author(s):  
Y. T. Tsui ◽  
C. C. Tsui
Keyword(s):  
Transmission Line ◽  
Coupling Coefficient ◽  
Frequency Ratio ◽  
Horizontal Axis ◽  
The Other ◽  
Two Dimensional ◽  
Coupling Ratio ◽  
Aeroelastic Stability ◽  
Other Hand ◽  
The Stability

This paper, which is an extension of [1], treats two-dimensional aeroelastic stability of two coupled conductors. It is found that the wake-induced flutter is symmetric with respect to the horizontal axis of the wake for all cases provided that the sign of the static coupling coefficient, ε = kxy/kxx, is changed. It appears that the spacer coupling ratio, K/kxx = Ω/ωx, is the most important factor in determining stability. For practical purposes, the system is almost always stable for K/kxx = Ω/ωx = 0.8, because the frequency ratio, κ = ωy/ωx, deviates less than ten percent from unity for a typical transmission line. On the other hand, within our range of interest, damping has little or no effect on the stability of coupled conductors. When the windward conductor is fixed, i.e., K = 0, then damping does influence the stability of the leeward conductor.

Nutritional Requirement for 4-Aminobenzoate Caused by Mutation of Dihydropteroate Synthetase

1976 ◽  
Vol 31 (5-6) ◽  
pp. 285-287 ◽  
Author(s):  
Helmut Rappold ◽  
Adelbert Bacher
Keyword(s):  
Parent Strain ◽  
The Other ◽  
Synthetase Activity ◽  
Nutritional Requirement ◽  
Wild Type ◽  
Aerobacter Aerogenes ◽  
Low Level ◽  
Other Hand ◽  
High Concentrations

Abstract Aerobacter aerogenes mutant 62-1 AC requires high concentrations of 4-aminobenzoate for growth. The mutant accumulates N-glucosyl-4-aminobenzoate and has an intact 4-aminobenzoate synthetase (Bacher, Gilch, Rappold, and Lingens, Z. Naturforsch. 28c, 614 - 617 [1973]). On the other hand the ability of the mutant to synthesize dihydropteroate is markedly reduced. The dihydropteroate synthetase level of mutant 62-1 AC is 1% as compared to the parent strain. Spontaneous revertants of mutant 62-1 AC show wild type levels of dihydropteroate synthetase. We conclude that the requirement for 4-aminobenzoate in mutant 62-1 AC is due to poor utilization of 4-aminobenzoate as a consequence of the low level of dihydropteroate synthetase activity.

Isoprene and Rubber. XVIII. Viscosity Studies on Balata

1930 ◽  
Vol 3 (3) ◽  
pp. 516-518 ◽  
Author(s):  
H. Staudinger ◽  
E. O. Leupold
Keyword(s):  
Colloidal Particles ◽  
Colloidal Particle ◽  
Colloidal Solution ◽  
Elementary Particles ◽  
The Other ◽  
Colloidal Solutions ◽  
Specific Viscosity ◽  
Micellar Structure ◽  
Other Hand ◽  
The Stability

Abstract Varied views prevail as to the structure of the colloidal particles present in a rubber solution. According to Harries, Pummerer, and many others, these colloidal particles are formed through the association or aggregation of smaller molecules. According to Meyer and Mark they have a micellar structure, the micelles forming through the apposition of main valence chains. On the other hand, it was assumed by one of the present authors that the elementary particles in a colloidal solution of rubber are identical with the rubber molecules, these large, especially labile molecules being called macromolecules. Thus the existence of much larger molecules than any hitherto known was postulated. This view was confirmed by the conversion of rubber to hydro-rubber capable of forming colloidal solutions, and also by the pyrogenic decomposition of rubber. In order to decide definitely between the two conceptions, the stability of the colloidal particle in a rubber solution was studied by means of viscosity measurements at various temperatures as was done in the case of the polystyrols. If these colloidal particles form aggregates or if they have a micellar structure, they should decrease in size with increase in temperature, and this change should be evidenced by a diminution of the specific viscosity of the colloidal solution. On the other hand, if such a solution is composed of molecules, the specific viscosity at various temperatures is the same, provided that the molecules are not decomposed at higher temperatures. This line of research led to an explanation of the constitution of the colloidal particles in a polystyrol solution and was now applied to balata, since the latter is especially easily purified.

scholarly journals STUDIES ON OXIDATION AND REDUCTION BY PNEUMOCOCCUS

1924 ◽  
Vol 39 (5) ◽  
pp. 745-755 ◽  
Author(s):  
Oswald T. Avery ◽  
James M. Neill
Keyword(s):  
Hydrogen Peroxide ◽  
Molecular Oxygen ◽  
Hemolytic Activity ◽  
Active Agent ◽  
Organic Peroxide ◽  
Cell Extract ◽  
The Other ◽  
Cell Extracts ◽  
Other Hand ◽  
The Stability

In the present work on oxidation and reduction by sterile extracts of pneumococcus, the preparations employed contain among other constituents, a hemolytic substance the properties of which have been described by Cole (1, 2) in his studies on pneumococcus hemotoxin. Pneumococcus extracts prepared by the methods described are actively hemolytic, 0.005 cc. of extract causing complete lysis of 2.5 cc. of a 1 per cent suspension of red cells from rabbit blood. This hemolytic property of pneumococcus extracts is destroyed by 10 minutes exposure to 55°C. When pneumotoxin-containing extracts are protected from the action of molecular oxygen, their hemolytic activity remains unimpaired for considerable periods of time. In the presence of air, on the other hand, the stability of the hemolytic substance depends upon whether the particular type of extract contains a "complete" or "incomplete" oxidation-reduction system. Sterile broth extracts of unwashed pneumococci are reactive with molecular oxygen, and as a result of this union peroxide is formed whenever these extracts are exposed to air. The hemolytic activity of "complete" extracts of this type is rapidly decreased and finally destroyed in the presence of molecular oxygen. On the other hand, the "incomplete" type of extract prepared by saline extraction of washed pneumococci may be exposed to air with little or no loss of hemolytic power. This "incomplete" washed cell extract, unless reactivated, does not undergo autoxidation in the presence of air; under these circumstances peroxide is not formed and the hemolytic activity of this type of extract is not impaired by exposure to air. The stability of the hemolytic agent in the "incomplete" type of extract is evidence that this substance is itself not reactive with or affected by molecular oxygen, even in the presence of the cell enzymes. The destruction of the same hemolytic substance in extracts capable of undergoing autoxidation may be ascribed to the action of some peroxide formed by the union of molecular oxygen with easily oxidized or autoxidizable substances of the extract. It is now known that a peroxide, having the reactions of hydrogen peroxide, accumulates in sterile pneumococcus extracts during oxidation. It has been shown in the present study that the addition of preformed hydrogen peroxide destroys the hemolytic activity of pneumococcus extracts, although higher concentrations were required than were detected in oxidized extracts themselves. These facts and the known action of superoxides in analogous types of reaction make it seem not unlikely that the active agent in the destruction of pneumotoxin in oxidized cell extracts may be a peroxide; either hydrogen peroxide or some higher organic peroxide formed during autoxidation of the extract.

Source of N-nitrosodimethylamine in river waters of the upper Tone River basin in Japan

2010 ◽  
Vol 62 (11) ◽  
pp. 2550-2557 ◽  
Author(s):  
K. Kosaka ◽  
K. Fukui ◽  
M. Asami ◽  
M. Akiba
Keyword(s):  
River Basin ◽  
The Other ◽  
Processing Plant ◽  
Sewage Effluent ◽  
River Waters ◽  
Industrial Discharge ◽  
Other Hand ◽  
High Concentrations ◽  
Kanto Region

The presence of N-nitrosodimethylamine (NDMA) in the Hirose River and its tributaries, located in the upper Tone River basin, in the Kanto region of Japan, was investigated. NDMA was detected at high levels in the Arato River, one of the tributaries of the Hirose River, at high concentrations (up to 2,100 ng/L). Due to the confluence of the Arato River, NDMA concentration in the Hirose River increased (up to 61 ng/L). The NDMA in the Arato River was due to industrial discharge from a livestock processing plant located near the river. There were three discharges at the plant, with NDMA concentrations of 78, 11, and 33,000 ng/L. The industrial discharges from the livestock processing plant did not contain significant amounts of NDMA precursors on chloramination. On the other hand, sewage effluent was shown to contain NDMA precursors. The amounts of NDMA precursors in the sewage effluent that were rapidly transformed into NDMA were considered to be lower than those slowly transformed into NDMA.

scholarly journals Stability and Volumetric Properties of Colored Asphalt Mixtures Containing Iron Oxide

2021 ◽  
Vol 24 (2) ◽  
pp. 130-136
Author(s):  
Samer Ali Naji ◽  
Alaa H. Abed
Keyword(s):  
Iron Oxide ◽  
The Other ◽  
Volumetric Properties ◽  
Oxide Content ◽  
Test Results ◽  
Other Hand ◽  
Marshall Test ◽  
The Stability ◽  
Limestone Dust ◽  
Marshall Stability

The objective of this paper is find the effect of using iron oxide as a filler on the Marshall stability, flow and the volumetric properties of HMA and compared the results with conventional HMA using limestone dust. Three blends were used: coarse, mid and fine with neat bitumen (AC 40-50). One aggregate type (crushed) with two types of fillers: limestone and iron oxide III (α- ) with three different filler content 6%, 8% and 10%. The Marshall mix design was conducted on the three blends and the optimum binder content is computed for each blend. The Marshall stability test results and the volumetric properties analysis showed that increasing the iron oxide content from 6% to 10%  increases the stability about 28%, 17% , 16% for the coarse , mid and fine mixtures respectively. This increment in stability of mixtures using iron oxide related to the increment in specific gravity of the mix (Gmb) by (1.3% to 1.5% about 30 to 50 kg/m3). On the other hand, the flow of mixtures is decreased about (5%) for mixes using iron oxide than the ones that used limestone as filler. The fine blend with 10% iron oxide exhibit the highest stability of 13.3 kN. While the coarse blend stability was 10 kN for the same filler type and content. Generally, the Marshall Test results of HMA using iron oxide as filler showed better resistance to plastic deformation, also produce denser HMA with higher stiffness. On the other hand, the volumetric properties analysis showed lesser values as compared with conventional mixture where the void in mineral aggregates and void filled with asphalt has decreased but within the acceptable limits.

scholarly journals Beggars, scammers, discriminated against by the whole of Europe: Romania’s Roma in Finnish tabloids, 2008-2011

2012 ◽  
Vol 4 (2) ◽  
pp. 87-109 ◽  
Author(s):  
Kari Alenius
Keyword(s):  
The Other ◽  
Significant Part ◽  
Radical Right ◽  
Recent Case ◽  
Short Term ◽  
Host Countries ◽  
Other Hand ◽  
The Stability ◽  
Critical Perspectives

The unrestricted movement of EU citizens from one country to another has been one of the fundamental principles of the Union. On the other hand, this issue has also attracted criticism, particularly from the radical right and so-called populist parties, or the supporters of these movements. Part of the population of Europe regards immigration and the unrestricted movement of people as a threat to the stability and prosperity of their own society. Through these critical perspectives, permanent immigration is viewed as a larger problem, as its effects on the host countries are more permanent than in the case of temporary residence. Through the same perspectives, the short-term but uncontrolled stay of foreigners is often linked to crime. This study concentrates on what kind of image a significant part of the Finnish media has given of a recent case of the foreigners that have attracted large attention in the country.

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