scholarly journals Glucose and glutamine metabolism in rat thymocytes

1984 ◽  
Vol 221 (2) ◽  
pp. 471-475 ◽  
Author(s):  
K Brand ◽  
J F Williams ◽  
M J Weidemann
Keyword(s):  
Glucose Metabolism ◽  
Glutamate Dehydrogenase ◽  
Concanavalin A ◽  
Oxidative Degradation ◽  
Large Percentage ◽  
Glutamine Metabolism ◽  
Glucose Addition ◽  
End Products ◽  
Almost All

The metabolism of glucose and glutamine in freshly prepared resting and concanavalin A-stimulated rat thymocytes was studied. Concanavalin A addition enhanced uptake of both glucose and glutamine and led to an increase in oxidative degradation of both substrates to CO2. With variously labelled [14C]glucose, it was shown that the pathways of glucose dissimilation were equally stimulated by the mitogen. A disproportionately large percentage of the extra glucose taken up was converted into lactate, but concanavalin A also caused an increase in the oxidation of pyruvate as judged by the enhanced release of 14CO2 from [2-14C]-, [3,4-14C]- and [6-14C]-glucose. Addition of glutamine did not affect glucose metabolism. The major end products of glutamine metabolism by resting and mitogen-stimulated rat thymocytes were glutamate, aspartate, CO2 and NH3. Virtually no lactate was formed from glutamine. Concanavalin A enhanced the formation of all end products except glutamate, indicating that more glutamine was metabolized beyond the stage of glutamate in the mitogen-activated cells. Addition of glucose caused a significant decrease in the rates of glutamine utilization and conversion into aspartate and CO2 in the absence and in the presence of concanavalin A. In the presence of glucose, almost all nitrogen of the metabolized glutamine was accounted for as NH3 released via the glutaminase and/or glutamate dehydrogenase reactions. In the absence of glucose, part (18%) of the glutamine nitrogen was metabolized by the resting and to a larger extent (38%) by the mitogen-stimulated thymocytes via a transaminase or amidotransferase reaction.

scholarly journals Glutamine metabolism in lymphocytes of the rat

1983 ◽  
Vol 212 (3) ◽  
pp. 835-842 ◽  
Author(s):  
M S M Ardawi ◽  
E A Newsholme
Keyword(s):  
Amino Acids ◽  
Concanavalin A ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Thymidine Incorporation ◽  
Adenine Nucleotides ◽  
Glutamine Metabolism ◽  
Mesenteric Lymph Nodes ◽  
Mesenteric Lymph ◽  
End Products ◽  
Stimulation Of

The metabolism of glutamine in resting and concanavalin-A-stimulated lymphocytes was investigated. In incubated lymphocytes isolated from rat mesenteric lymph nodes, the rates of oxygen and glutamine utilization and that of aspartate production were approximately linear with respect to time for 60 min, and the concentrations of adenine nucleotides plus the ATP/ADP or ATP/AMP concentration ratios remained approximately constant for 90 min. The major end products of glutamine metabolism were glutamate, aspartate and ammonia: the carbon from glutamine may contribute about 30% to respiration. When both glucose and glutamine were presented to the cells, the rates of utilization of both substances increased. Evidence was obtained that the stimulation of glycolysis by glutamine could be due, in part, to an activation of 6-phosphofructokinase. Starvation of the donor animal increased the rate of glutamine utilization. The phosphoenolpyruvate carboxykinase inhibitor mercaptopicolinate decreased the rate of glutamine utilization by 28%; the rates of accumulation of glutamate and ammonia were decreased, whereas those of lactate, aspartate and malate were increased. The mitogen concanavalin A increased the rate of glutamine utilization (by about 51%). The rate of [3H]thymidine incorporation into DNA caused by concanavalin A in cultured lymphocytes was very low in the absence of glutamine; it was increased about 4-fold at 1 microM-glutamine and was maximal at 0.3 mM-glutamine; neither other amino acids nor ammonia could replace glutamine.

scholarly journals Glutamine and glucose metabolism during thymocyte proliferation. Pathways of glutamine and glutamate metabolism

1985 ◽  
Vol 228 (2) ◽  
pp. 353-361 ◽  
Author(s):  
K Brand
Keyword(s):  
Citric Acid ◽  
Glucose Metabolism ◽  
Glutamate Dehydrogenase ◽  
Aspartate Aminotransferase ◽  
Citric Acid Cycle ◽  
Glutamine Metabolism ◽  
Resting Cells ◽  
Glutamate Metabolism ◽  
Proliferating Cells ◽  
Acid Cycle

Energy metabolism in proliferating cultured rat thymocytes was compared with that of freshly prepared non-proliferating resting cells. Cultured rat thymocytes enter a proliferative cycle after stimulation by concanavalin A and Lymphocult T (interleukin-2), with maximal rates of DNA synthesis at 60 h. Compared with incubated resting thymocytes, glucose metabolism by incubated proliferating thymocytes was 53-fold increased; 90% of the amount of glucose utilized was converted into lactate, whereas resting cells metabolized only 56% to lactate. However, the latter oxidized 27% of glucose to CO2, as opposed to 1.1% by the proliferating cells. Activities of hexokinase, 6-phosphofructokinase, pyruvate kinase and aldolase in proliferating thymocytes were increased 12-, 17-, 30- and 24-fold respectively, whereas the rate of pyruvate oxidation was enhanced only 3-fold. The relatively low capacity of pyruvate degradation in proliferating thymocytes might be the reason for almost complete conversion of glucose into lactate by these cells. Glutamine utilization by rat thymocytes was 8-fold increased during proliferation. The major end products of glutamine metabolism are glutamate, aspartate, CO2 and ammonia. A complete recovery of glutamine carbon and nitrogen in the products was obtained. The amount of glutamate formed by phosphate-dependent glutaminase which entered the citric acid cycle was enhanced 5-fold in the proliferating cells: 76% was converted into 2-oxoglutarate by aspartate aminotransferase, present in high activity, and the remaining 24% by glutamate dehydrogenase. With resting cells the same percentages were obtained (75 and 25). Maximal activities of glutaminase, glutamate dehydrogenase and aspartate aminotransferase were increased 3-, 12- and 6-fold respectively in proliferating cells; 32% of the glutamate metabolized in the citric acid cycle was recovered in CO2 and 61% in aspartate. In resting cells this proportion was 41% and 59% and in mitogen-stimulated cells 39% and 65% respectively. Addition of glucose (4 mM) or malate (2 mM) strongly decreased the rates of glutamine utilization and glutamate conversion into 2-oxoglutarate by proliferating thymocytes and also affected the pathways of further glutamate metabolism. Addition of 2 mM-pyruvate did not alter the rate of glutamine utilization by proliferating thymocytes, but decreased the rate of metabolism beyond the stage of glutamate significantly. Formation of acetyl-CoA in the presence of pyruvate might explain the relatively enhanced oxidation of glutamate to CO2 (56%) by proliferating thymocytes.

Economic expertise as a tool to counter the shadow economy

2021 ◽  
pp. 131-136
Author(s):  
С.В. Банк ◽  
В.Ф. Вакуленко
Keyword(s):  
Shadow Economy ◽  
Negative Impact ◽  
Economic Security ◽  
The State ◽  
Large Percentage ◽  
Economic Situation ◽  
Public Finances ◽  
Economic Relations ◽  
Current State ◽  
Almost All

Теневая экономика проникает практически во все экономические сферы жизнедеятельности общества. Она включает в себя различные экономические отношения, которые находятся за рамками закона в областях производства, потребления, обмена и распределения. Воспрепятствование теневой экономике, предстающей одной из базовых угроз экономической безопасности страны, есть необычайно актуальное явление в настоящее время. Современное состояние сектора теневой экономики в России весьма динамично развивается, что влечет за собой негативное воздействие на социально-экономическое положение государства. В основном, это относится к представителям малого и среднего бизнеса, который занимается предоставлением услуг и производством разнообразных товаров. Актуальность избранной тематики заключается в том, что сейчас в России большой процент теневых доходов, тогда, как эти деньги могли быть направлены на становление и развитие МСП, особенно во времена обостренной пандемии, что позволило бы минимизировать экономическую напряженность и нарастить результативность государственных финансов. The shadow economy penetrates almost all economic spheres of society. It includes various economic relations that are outside the scope of the law in the areas of production, consumption, exchange and distribution. The obstruction of the shadow economy, which appears to be one of the basic threats to the economic security of the country, is an extremely relevant phenomenon at the present time. The current state of the shadow economy sector in Russia is developing very dynamically, which entails a negative impact on the socio-economic situation of the state. This mainly applies to representatives of small and medium-sized businesses that provide services and produce a variety of goods. The relevance of the chosen topic lies in the fact that now there is a large percentage of shadow income in Russia, while this money could be used for the formation and development of SMEs, especially during times of an acute pandemic, which would minimize economic tension and increase the effectiveness of public finances.

scholarly journals Effects of cytochalasin B, colchicine and vincristine on the metabolism of isolated fat-cells

1974 ◽  
Vol 140 (2) ◽  
pp. 185-192 ◽  
Author(s):  
Ernest G. Loten ◽  
Bernard Jeanrenaud
Keyword(s):  
Glucose Metabolism ◽  
Transport System ◽  
Cytochalasin B ◽  
Fat Cells ◽  
Isolated Fat Cells ◽  
Prolonged Incubation ◽  
Glucose Transport System ◽  
End Products ◽  
Release Of Glycerol ◽  
Cytochalasin A

1. Colchicine and vincristine only slightly inhibit the metabolism of glucose to CO2 and lipids by isolated fat-cells. 2. Prolonged incubation with these agents causes no further inhibition. 3. Cytochalasin B, however, inhibits glucose metabolism to both CO2 and lipids in fat-cells. 4. However, at a concentration that causes a strong inhibition of glucose metabolism cytochalasin B is without effect on the metabolism of pyruvate, lactate or arginine to these end products. The uptake of labelled α-aminoisobutyrate is likewise not modified. Similarly it does not affect release of glycerol or free fatty acid, or the actions of adrenaline, insulin or caffeine on these parameters. At 10μg/ml it slightly lowers ATP concentrations, an effect that does not occur at 2μg/ml. 5. The transport of fructose into adipocytes by a specific fructose-transport system is also not affected by the agent, but the uptake of 2-deoxyglucose is strongly inhibited. It is concluded that cytochalasin B may specifically inhibit the glucose-transport system of isolated fat-cells. 6. Cytochalasin A has a much weaker action than cytochalasin B on glucose metabolism.

Regulation of glutamine metabolism in dog kidney cortex: effect of pH and chronic acidosis

1992 ◽  
Vol 262 (6) ◽  
pp. F1007-F1014
Author(s):  
A. C. Schoolwerth ◽  
B. C. Smith ◽  
K. Drewnowska
Keyword(s):  
Glutamate Dehydrogenase ◽  
Mitochondrial Membrane ◽  
Glutamine Metabolism ◽  
Kidney Cortex ◽  
Cytosolic Ph ◽  
Isolated Mitochondria ◽  
Significant Difference ◽  
Dog Kidney ◽  
Ammonium Production ◽  
Krebs Henseleit Buffer

To examine the interrelationships of proton compartmentation and ammoniagenesis, experiments were performed in tubules and mitochondria isolated from dog kidney cortex. Tubules were incubated in Krebs-Henseleit buffer at different pH (pHe), and cytosolic pH (pHi) was estimated with the fluorescent probe 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein. Mitochondrial pH (pHm) was determined simultaneously in intact tubules by use of dimethyloxazolidine-2,4-dione. Over the pHe range 6.9-7.7, pHi was similar in control and acidotic dogs and linearly related to pHe. At pHe 7.4 in control tubules. pHm was 7.78 +/- 0.07, and varied little over the pHe range of 7.0-7.7. The pH gradient across the mitochondrial membrane rose at acid pHe. pHm was more alkaline when estimated in tubules from acidotic dogs compared with controls. Ammonium and glucose productions from glutamine were inversely related to pHe and pHi in tubules from both control and acidotic animals and were higher in acidosis. In contrast, ammonium production by isolated mitochondria did not vary as pHe was altered. Enzyme fluxes, calculated from metabolite changes, demonstrated that glutamate dehydrogenase (GDH) flux was altered. Enzyme fluxes, calculated from metabolite changes, demonstrated that glutamate dehydrogenase (GDH) flux was inversely and glutaminase (PDG) flux was linearly related to pHe. Ammonium production was significantly greater in mitochondria from acidotic dogs because of accelerated flux through PDG but not GDH. The present study demonstrates significant difference between proton compartmentation and regulation of ammoniagenesis in kidneys from acidotic dog compared with rat.

The assimilation of bicarbonate by Neocosmospora vasinfecta

1969 ◽  
Vol 15 (5) ◽  
pp. 389-398 ◽  
Author(s):  
K. Budd
Keyword(s):  
Protein Synthesis ◽  
Carbon Source ◽  
Tricarboxylic Acid Cycle ◽  
Carbon Sources ◽  
Dry Weight ◽  
Insoluble Fraction ◽  
Tricarboxylic Acid ◽  
End Products ◽  
Almost All ◽  
Exogenous Nitrogen

The assimilation of 14C-bicarbonate under controlled conditions was examined in midlog-phase mycelium grown on dextrose as sole carbon source. Sustained assimilation depended on the presence of exogenous nitrogen and carbon sources. When these were provided, assimilation rates of 20–30 μmoles/hour per 100 mg dry weight were maintained for at least 4 hours. After the second hour, almost all of the assimilated bicarbonate-C entered the 80% ethanol-insoluble fraction. Amino acids, especially aspartic and glutamic, were the main destination of assimilated bicarbonate-C; nucleic acids and acids of the tricarboxylic acid cycle accounted for smaller amounts of this carbon. The apparent Km for overall assimilation was 1.4 – 2.2 × 10−4 M with respect to bicarbonate.Assimilation was inhibited by inhibitors of protein synthesis, especially actidione and p-fluorophenylalanine. Evidence was obtained for regulation of assimilation by its end products, and also by the carbon source on which the mycelium was grown. It is concluded that assimilation of bicarbonate or CO2 has an anaplerotic function during protein synthesis in this organism.

scholarly journals Glioblastoma Cells Require Glutamate Dehydrogenase to Survive Impairments of Glucose Metabolism or Akt Signaling

2009 ◽  
Vol 69 (20) ◽  
pp. 7986-7993 ◽  
Author(s):  
Chendong Yang ◽  
Jessica Sudderth ◽  
Tuyen Dang ◽  
Robert G. Bachoo ◽  
Jeffrey G. McDonald ◽  
...  
Keyword(s):  
Glucose Metabolism ◽  
Glutamate Dehydrogenase ◽  
Akt Signaling ◽  
Glioblastoma Cells
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