scholarly journals Accelerations in the Lactonization of Trimethyl Lock Systems Are due to Proximity Orientation and not to Strain Effects

2009 ◽  
Vol 2009 ◽  
pp. 1-5 ◽  
Author(s):  
Rafik Karaman
Keyword(s):  
Kinetic Parameters ◽  
Semiempirical Calculations ◽  
Strain Effect ◽  
Strain Effects ◽  
Enzyme Model ◽  
Trimethyl Lock ◽  
Important Enzyme

DFT at B3LYP/6-31G(d,p) and HF at 6-31G and AM1 semiempirical calculations of thermodynamc and kinetic parameters for the trimethyl lock system (an important enzyme model) indicate that the remarkable enhancement in the lactonizations is largely the result of a proximity orientation as opposed to the currently advanced strain effect.

The Possibility of Manufacturing Long-Length Metal Products with Ultra-Fine Grain Structure by Combination of Strain Effects

2016 ◽  
Vol 685 ◽  
pp. 487-491 ◽  
Author(s):  
Mikhail Chukin ◽  
Marina Polyakova ◽  
Alexandr Gulin ◽  
Olga Nikitenko
Keyword(s):  
Steel Wire ◽  
Continuous Method ◽  
Grain Structure ◽  
Strain Effect ◽  
Strain Effects ◽  
Fine Grain ◽  
Wide Range ◽  
Processing Modes ◽  
Efficiency Estimation ◽  
Metal Products

It is shown that combination of strain effects leads to possessing the ultra-fine grain structure in carbon wire. The continuous method of wire deformation nanostructuring was developed on the basis of simultaneous applying of tension deformation by drawing, bending deformation when going through the system of rolls and torsional deformation on a continuously moving wire. One of the main advantages of the developed method is that various hardware devices and tools already applied for steel wire production can be used to implement this method thus simplifying its introduction to the current industrial equipment. The efficiency estimation of the developed continuous method of deformation nanostructuring was carried out using carbon wire with different carbon content. It is shown that the mechanical properties of the wire after combination of different kinds of strain can vary over a wide range. This method makes it possible to choose such modes of strain effect, which can provide the necessary combination of strength and ductile properties of carbon wire depending on its further processing modes and application.

scholarly journals Lactate dehydrogenase C4 (LDH-C4) is essential for the sperm count and motility: A case-control study

2021 ◽  
Vol 2 (03) ◽  
pp. 152-165
Author(s):  
Baraa Saeed ◽  
Rayah Baban ◽  
Usama Al-Nasiri
Keyword(s):  
Lactate Dehydrogenase ◽  
Kinetic Parameters ◽  
Seminal Fluid ◽  
Sperm Count ◽  
Maximum Velocity ◽  
Fluid Analysis ◽  
Infertile Men ◽  
Km Value ◽  
Motility Of Sperm ◽  
Important Enzyme

Background: The lactate dehydrogenase C4 (LDH-C4) isoenzyme is an important enzyme involved in metabolic processes that are needed for spermatogenesis and sperm motility. Objectives: This study aims to assess the activity and kinetic parameters (maximum velocity, Vmax and Michaelis constant, Km) of LDH-C4 in fertile and infertile (azoospermia and oligospermia) men in Baghdad City, Iraq. Methods: A total of 120 participants (80 infertile and 40 healthy fertile men) were included in the current study. The patients were sub-grouped into: 40 infertile men with oligospermia, and 40 infertile men with azoospermia. The oligospermia patients were further subdivided into subgroups based on sperm count and motility. Semen samples were obtained by masturbation after 3-5 days abstain for seminal fluid analysis. The microscopic test included the assessment of the count, motility and morphology of the sperms. In addition, the coulometric assay was used for measuring the activity and kinetic parameters of LDH-C4 enzyme. Results: The activity of LDH-C4 is significantly higher in fertile men when compared with infertile subjects (fertile: 403.13±189.90, oligospermia: 110.01±58.13, azoospermia: 39.06±28.15; p≤0.01). Statistically significant differences in LDH-C4 activity were also noted among patients with oligospermia based on sperms count and motility. Based on sperms’ count in patients with oligospermia, a significantly higher LDH-C4 activity (p≤0.01) was noted in those with higher sperm count (10-15 million/ml) when compared to others who have lesser count. Significant elevation in enzyme activity (p≤0.01) was also observed in oligospermia patients with higher percentages of motile sperms when compared with others who have fewer percentages of motile sperms. Moreover, the highest Vmax value (0.483 mmol/L.min) and the lowest Km value (0.39 mmol/L.min) were recorded in fertile men. While, the lowest Vmax value (0.174 mmol/L.min) and the lowest Km value (0.75 mmol/L.min) were detected in azoospermia patients. Conclusions: Our results suggest that LDH-C4 is essential for the count and motility of sperm and may be considered as a therapeutic approach for infertility.

MEASUREMENT OF STEROID BINDING PROTEINS

1970 ◽  
Vol 65 (1_Suppl) ◽  
pp. S104-S121 ◽  
Author(s):  
E. E. Baulieu ◽  
J. P. Raynaud ◽  
E. Milgrom
Keyword(s):  
Kinetic Parameters ◽  
Binding Proteins ◽  
Binding Specificity ◽  
Binding Parameters ◽  
Target Organs ◽  
Biological Mixtures ◽  
Steroid Binding Proteins ◽  
Steroid Binding ◽  
Steroid Binding Protein

ABSTRACT A brief review of the characteristics of steroid binding proteins found in the plasma and in some target organs is presented, followed by some general remarks on binding »specificity« and binding parameters. Useful techniques for measuring binding parameters at equilibrium are reported, both those which keep the equilibrium intact and those which implicate its disruption. A concept is developed according to which the determination of a specific steroid binding protein is based on the »differential dissociation« of the several steroid binding complexes present in most biological mixtures. Methods which allow determination of the kinetic parameters of the binding systems are also presented. Various representations of the binding and therefore different modes of graphic representation and calculation are discussed, including the recent »proportion graph« method.

THE INFLUENCE OF ETHANOL ON THE CONVERSION OF PREGNENOLONE TO PROGESTERONE BY HUMAN PLACENTAL MICROSOMES

1974 ◽  
Vol 76 (1) ◽  
pp. 178-188 ◽  
Author(s):  
H. Lübbert ◽  
K. Pollow ◽  
R. Wagner ◽  
J. Hammerstein
Keyword(s):  
Kinetic Parameters ◽  
Enzyme Preparation ◽  
Ethanol Concentration ◽  
Hydroxysteroid Dehydrogenase ◽  
Product Formation ◽  
Linear Increase ◽  
Maximal Velocity ◽  
Microsomal Enzyme ◽  
Temperature Optima ◽  
Substrate Concentrations

ABSTRACT The effects of ethanol on kinetic parameters of placental Δ5-3β-hydroxysteroid dehydrogenase were studied. In the presence of high pregnenolone concentrations (50 μm, [S] > Km) the microsomal enzyme preparation exhibited an almost linear increase in activity as the ethanol concentration in the medium was raised from 2.5 to 15 % (v/v). At lower substrate concentrations ([S] << Km) ethanol caused inhibition. Other effects of ethanol were: linearity of product formation with time was prolonged; the maximal velocity was markedly increased; the Km for pregnenolone slightly decreased with increasing ethanol concentrations (2.5 to 10 %, v/v) whereas the Km for NAD remained the same. The pH and temperature optima of the reaction were unaffected by ethanol. Other organic solvents caused similar effects.

Effects of Fetus Weight, Dam Strain, Dam Weight, and Litter Size on the Craniofacial Morphogenesis of CL/Fr Mouse Fetuses Affected with Cleft Lip and Palate

1997 ◽  
Vol 34 (4) ◽  
pp. 325-330 ◽  
Author(s):  
Kazuaki Nonaka ◽  
Yasunori Sasaki ◽  
Yoshihisa Watanabe ◽  
Ken-ichi Yanagita ◽  
Minoru Nakata
Keyword(s):  
Litter Size ◽  
Cleft Lip ◽  
Cleft Lip And Palate ◽  
Craniofacial Morphology ◽  
Strain Effect ◽  
Craniofacial Growth ◽  
Lateral Cephalogram ◽  
Mouse Fetus ◽  
Mouse Fetuses ◽  
Craniofacial Morphogenesis

Objective: This study examined the factors related to the morphogenesis of the craniofacial complex of the CL/Fr mouse fetus affected with CLP based on the findings of a lateral cephalogram. Design: Embryo transfer experiments were performed to determine the effect of the fetus weight, dam strain, dam weight, and litter size on the intra-uterine craniofacial morphogenesis of CL/Fr mouse fetuses. On the 18th gestational day, each pregnant dam that had received CL/Fr mouse embryos was laparotomized to remove the transferred fetuses that had developed in the uteri of the cleft lip and palate (CLP)-susceptible CL/Fr strain dam and the CLP-resistant C57BL strain dam. A cephalometric observation of the craniofacial morphology of each fetus was subsequently performed. Results: Based on a multiple regression analysis, the standardized partial regression coefficients of the affected fetus weight, the dam weight, and the litter size on the maxillary size of the affected CL/Fr fetus were 0.71 (p < .01), 0.03, and −0.07. According to a least-squares analysis of variance, the dam strain effect in addition to the effect of the affected fetus weight on the maxillary size and the cranial size of the affected fetuses was significant (p < .01 for cranial size, p < .05 for maxillary size) and close to a significant level (p = .09) for the mandibular size of the affected fetuses. The adjusted maxillary size and cranial size after statistically eliminating the effects of the affected fetus weight, dam weight, and lifter size on each original craniofacial size of the affected fetuses that had developed in the CL/Er dam strain were also significantly smaller than those of the affected fetuses that had developed in the C57BL dam strain. Conclusions: The present results indicate that the craniofacial growth of the CL/Fr mouse fetus affected with CLP increased in proportion to the fetus weight. The dam strain effect, in addition to the effect of the affected fetus weight, could thus not be ignored when the etiology of the spontaneous CLP was examined, while the uterine environment, provided by the CL/Fr strain dam, retarded the intra-uterine craniofacial growth of the affected fetuses. It was therefore concluded that the dam strain effect, as well as the effect of the affected fetus weight, both play an important role on the craniofacial morphogenesis of the CL/Fr strain of the affected fetuses that developed in both strain dams.

Evaluation of Kinetic Parameters at the Transport of Indole-3-acetic Acid Through Bulk Liquid Membranes

2017 ◽  
Vol 68 (5) ◽  
pp. 903-907
Author(s):  
Ecaterina Anca Serban ◽  
Ioana Diaconu ◽  
Elena Ruse ◽  
Georgiana Ileana Badea ◽  
Adriana Cuciureanu ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Kinetic Parameters ◽  
Trioctylphosphine Oxide ◽  
Bulk Liquid ◽  
Transport Parameters ◽  
Kinetics Parameters ◽  
First Order ◽  
Phase Concentration ◽  
Feed Phase ◽  
Indole 3 Acetic Acid

Indole-3-acetic acid is a growth phytohormone considered the most important representative of auxin class. This paper presents the assessment of some kinetic parameters in the process of transport of indole-3-acetic acid taking into consideration the kinetic model of consecutive irreversible first order reactions. It was pursued the influence upon the process of parameters such as: feed phase concentration, stripping phase concentration in the presence of two type carriers: tributyl phosphate (TBP) and trioctylphosphine oxide (TOPO). Depending on these transport parameters were calculated kinetics parameters such as: pseudo-first-order apparent membrane entrance and exit rate constants, the maximum flux at the entrance and exit out of the membrane. The highest values of the transport flux is obtained in the presence of carrier trioctylphosphine oxide (TOPO) at the concentration in the feed phase of 10-4 mol/L indole-3-acetic acid and a concentration of 10--2mol/L NaOH in the stripping phase.

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