scholarly journals Rapid Elimination of Blood Alcohol Using Erythrocytes: Mathematical Modeling and In Vitro Study

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Yuliya G. Alexandrovich ◽  
Elena A. Kosenko ◽  
Elena I. Sinauridze ◽  
Sergey I. Obydennyi ◽  
Igor I. Kireev ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Ethanol Oxidation ◽  
Alcohol Intoxication ◽  
Limiting Factors ◽  
Blood Alcohol ◽  
Cell Recovery ◽  
Optimal Method ◽  
Metabolic System ◽  
Rate Limiting

Erythrocytes (RBCs) loaded with alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALD) can metabolize plasma ethanol and acetaldehyde but with low efficiency. We investigated the rate-limiting factors in ethanol oxidation by these enzymes loaded into RBCs. Mathematical modeling and in vitro experiments on human RBCs loaded simultaneously with ADH and ALD (by hypoosmotic dialysis) were performed. The simulation showed that the rate of nicotinamide-adenine dinucleotide (NAD+) generation in RBC glycolysis, but not the activities of the loaded enzymes, is the rate-limiting step in external ethanol oxidation. The rate of oxidation could be increased if RBCs are supplemented by NAD+ and pyruvate. Our experimental data verified this theoretical conclusion. RBCs loaded with the complete system of ADH, ALD, NAD+, and pyruvate metabolized ethanol 20–40 times faster than reported in previous studies. The one-step procedure of hypoosmotic dialysis is the optimal method to encapsulate ADH and ALD in RBCs after cell recovery, encapsulation yield, osmotic resistance, and RBC-indexes. Consequently, transfusion of the RBCs loaded with the complete metabolic system, including ADH, ALD, pyruvate, and NAD+ in the patients with alcohol intoxication, may be a promising method for rapid detoxification of blood alcohol based on metabolism.

Metabolic Photofragmentation Kinetics for a Minimal Protocell: Rate-Limiting Factors, Efficiency, and Implications for Evolution

2008 ◽  
Vol 14 (2) ◽  
pp. 189-201 ◽  
Author(s):  
Chad Knutson ◽  
Gil Benkö ◽  
Tristan Rocheleau ◽  
Fouzi Mouffouk ◽  
Jerzy Maselko ◽  
...  
Keyword(s):  
Kinetic Equations ◽  
Building Blocks ◽  
Reaction Rates ◽  
Limiting Factors ◽  
Metabolic System ◽  
Evolutionary Selection ◽  
Gene Replication ◽  
Analytical Approximations ◽  
Rate Limiting ◽  
Analytical Expressions

A key requirement of an autonomous self-replicating molecular machine, a protocell, is the ability to digest resources and turn them into building blocks. Thus a protocell needs a set of metabolic processes fueled by external free energy in the form of available chemical redox potential or light. We introduce and investigate a minimal photodriven metabolic system, which is based on photofragmentation of resource molecules catalyzed by genetic molecules. We represent and analyze the full metabolic set of reaction-kinetic equations and, through a set of approximations, simplify the reaction kinetics so that analytical expressions can be obtained for the building block production. The analytical approximations are compared with the full equation set and with corresponding experimental results to the extent they are available. It should be noted, however, that the proposed metabolic system has not been experimentally implemented, so this investigation is conducted to obtain a deeper understanding of its dynamics and perhaps to anticipate its limitations. We demonstrate that this type of minimal photodriven metabolic scheme is typically rate-limited by the front-end photoexcitation process, while its yield is determined by the genetic catalysis. We further predict that gene-catalyzed metabolic reactions can undergo evolutionary selection only for certain combinations of the involved reaction rates due to their intricate interactions. We finally discuss how the expected range of metabolic rates likely affects other key protocellular processes such as container growth and division as well as gene replication.

Effect of acute alcohol intoxication on steroid output of rat adrenals in vitro

1963 ◽  
Vol 204 (5) ◽  
pp. 849-855 ◽  
Author(s):  
Harold Kalant ◽  
Rosemary D. Hawkins ◽  
Caroline Czaja
Keyword(s):  
Alcohol Intoxication ◽  
Rate Of Change ◽  
Blood Alcohol ◽  
Acute Alcohol Intoxication ◽  
Significant Elevation ◽  
Stomach Tube ◽  
Adrenal Steroid ◽  
Rat Adrenals ◽  
Blood Alcohol Levels

Ethyl alcohol, 2 g/kg in 20% solution, was given to rats by gavage and the adrenals were removed 1 1/2 hr later and incubated in vitro. Their corticosteroid production was not significantly different from that of glands from water-treated or untreated controls. However, when this dose of alcohol was administered by intraperitoneal injection, a significant elevation in adrenal steroid output was observed. Increasing the dose of alcohol to 4 g/kg by stomach tube also evoked an increased adrenocortical response, but when this total dose was divided into two spaced doses, each one of 2 g/kg by stomach tube, 1 1/2 hr apart, no significant alteration in adrenocortical production was observed, despite higher blood alcohol levels and equally deep intoxication. Thus, although the blood alcohol level attained may influence the activity of the adrenal cortex, the rate of change in blood and tissue alcohol levels also seems to be a significant factor in determining whether adrenal cortical stimulation will occur. None of the treatments appeared to modify the relative proportions of the various steroids released.

scholarly journals Plk4 and Aurora A cooperate in the initiation of acentriolar spindle assembly in mammalian oocytes

2017 ◽  
Vol 216 (11) ◽  
pp. 3571-3590 ◽  
Author(s):  
Leah Bury ◽  
Paula A. Coelho ◽  
Angela Simeone ◽  
Samantha Ferries ◽  
Claire E. Eyers ◽  
...  
Keyword(s):  
Subsequent Development ◽  
Meiotic Spindle ◽  
Limiting Factors ◽  
Drug Resistant ◽  
Aurora A ◽  
Microtubule Nucleation ◽  
Microtubule Growth ◽  
Chemical Inhibition ◽  
Rate Limiting

Establishing the bipolar spindle in mammalian oocytes after their prolonged arrest is crucial for meiotic fidelity and subsequent development. In contrast to somatic cells, the first meiotic spindle assembles in the absence of centriole-containing centrosomes. Ran-GTP can promote microtubule nucleation near chromatin, but additional unidentified factors are postulated for the activity of multiple acentriolar microtubule organizing centers in the oocyte. We now demonstrate that partially overlapping, nonredundant functions of Aurora A and Plk4 kinases contribute to initiate acentriolar meiosis I spindle formation. Loss of microtubule nucleation after simultaneous chemical inhibition of both kinases can be significantly rescued by drug-resistant Aurora A alone. Drug-resistant Plk4 can enhance Aurora A–mediated rescue, and, accordingly, Plk4 can phosphorylate and potentiate the activity of Aurora A in vitro. Both kinases function distinctly from Ran, which amplifies microtubule growth. We conclude that Aurora A and Plk4 are rate-limiting factors contributing to microtubule growth as the acentriolar oocyte resumes meiosis.

scholarly journals The reversibility of cytosolic dehydrogenase reactions in hepatocytes from starved and fed rats. Effect of fructose

1984 ◽  
Vol 222 (2) ◽  
pp. 437-446 ◽  
Author(s):  
C Vind ◽  
N Grunnet
Keyword(s):  
Lactate Dehydrogenase ◽  
Alcohol Dehydrogenase ◽  
Ethanol Oxidation ◽  
Maximal Activity ◽  
Isolated Hepatocytes ◽  
Single Compartment ◽  
Dehydrogenase Reaction ◽  
Order Of Magnitude ◽  
Rate Limiting

The metabolism of [2-3H]lactate was studied in isolated hepatocytes from fed and starved rats metabolizing ethanol and lactate in the absence and presence of fructose. The yields of 3H in ethanol, water, glucose and glycerol were determined. The rate of ethanol oxidation (3 mumol/min per g wet wt.) was the same for fed and starved rats with and without fructose. From the detritiation of labelled lactate and the labelling pattern of ethanol and glucose, we calculated the rate of reoxidation of NADH catalysed by lactate dehydrogenase, alcohol dehydrogenase and triosephosphate dehydrogenase. The calculated flux of reducing equivalents from NADH to pyruvate was of the same order of magnitude as previously found with [3H]ethanol or [3H]xylitol as the labelled substrate [Vind & Grunnet (1982) Biochim. Biophys. Acta 720, 295-302]. The results suggest that the cytoplasm can be regarded as a single compartment with respect to NAD(H). The rate of reduction of acetaldehyde and pyruvate was correlated with the concentration of these metabolites and NADH, and was highest in fed rats and during fructose metabolism. The rate of reoxidation of NADH catalysed by lactate dehydrogenase was only a few per cent of the maximal activity of the enzymes, but the rate of reoxidation of NADH catalysed by alcohol dehydrogenase was equal to or higher than the maximal activity as measured in vitro, suggesting that the dissociation of enzyme-bound NAD+ as well as NADH may be rate-limiting steps in the alcohol dehydrogenase reaction.

scholarly journals Assembly of the B subunit pentamer of Escherichia coli heat-labile enterotoxin. Kinetics and molecular basis of rate-limiting steps in vitro.

1996 ◽  
Vol 271 (43) ◽  
pp. 27188
Author(s):  
Lloyd W. Ruddock ◽  
Jeremy J.F. Coen ◽  
Caroline Cheesman ◽  
Robert B. Freedman ◽  
Timothy R. Hirst
Keyword(s):  
Escherichia Coli ◽  
Molecular Basis ◽  
B Subunit ◽  
Heat Labile ◽  
Rate Limiting

scholarly journals Reversal of senescence-associated beta-galactosidase expression during in vitro three-dimensional tissue-engineering of human chondrocytes in a polymer scaffold

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shojiro Katoh ◽  
Atsuki Fujimaru ◽  
Masaru Iwasaki ◽  
Hiroshi Yoshioka ◽  
Rajappa Senthilkumar ◽  
...  
Keyword(s):  
Regenerative Medicine ◽  
Replicative Senescence ◽  
Cultured Cells ◽  
Three Dimensional ◽  
Human Chondrocytes ◽  
Cartilage Tissue ◽  
Optimal Method ◽  
Beta Galactosidase

AbstractRegenerative medicine applications require cells that are not inflicted with senescence after in vitro culture for an optimal in vivo outcome. Methods to overcome replicative senescence include genomic modifications which have their own disadvantages. We have evaluated a three-dimensional (3D) thermo-reversible gelation polymer (TGP) matrix environment for its capabilities to reverse cellular senescence. The expression of senescence-associated beta-galactosidase (SA-βgal) by human chondrocytes from osteoarthritis-affected cartilage tissue, grown in a conventional two-dimensional (2D) monolayer culture versus in 3D-TGP were compared. In 2D, the cells de-differentiated into fibroblasts, expressed higher SA-βgal and started degenerating at 25 days. SA-βgal levels decreased when the chondrocytes were transferred from the 2D to the 3D-TGP culture, with cells exhibiting a tissue-like growth until 42–45 days. Other senescence associated markers such as p16INK4a and p21 were also expressed only in 2D cultured cells but not in 3D-TGP tissue engineered cartilage. This is a first-of-its-kind report of a chemically synthesized and reproducible in vitro environment yielding an advantageous reversal of aging of human chondrocytes without any genomic modifications. The method is worth consideration as an optimal method for growing cells for regenerative medicine applications.

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