1978
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Hume, D. A.; Weidemann, M. J.
On the stimulation of rat thymocyte 3‐0‐methyl‐glucose transport by mitogenic stimuli (Journal Article)
In: Journal of Cellular Physiology, vol. 96, no. 3, pp. 303–308, 1978, ISSN: 00219541.
@article{hume_stimulation_1978,
title = {On the stimulation of rat thymocyte 3‐0‐methyl‐glucose transport by mitogenic stimuli},
author = {D. A. Hume and M. J. Weidemann},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0018254930&doi=10.1002%2fjcp.1040960305&partnerID=40&md5=0fbfc815ab2326a6d15eb5876cd48f49},
doi = {10.1002/jcp.1040960305},
issn = {00219541},
year = {1978},
date = {1978-01-01},
journal = {Journal of Cellular Physiology},
volume = {96},
number = {3},
pages = {303--308},
abstract = {Pretreatment of rat thymus lymphocytes with N‐ethyl‐maleimide prevents the stimulation of 3‐0‐methyl‐glucose transport by concanavalin A or ionophore A23187 but does not affect the ability of concanavalin A to induce a rapid increase in cellular Ca2+ uptake. N‐ethyl‐maleimide added after concanavalin A amplifies rather than prevents the subsequent stimulation of 3‐0‐methyl‐glucose transport. Incubation of thymocytes with concanavalin A produces a decrease of 43% in the apparent Ki for phloretin, a competitive inhibitor of 3‐0‐methyl‐glucose transport, without affecting the apparent Km for the substrate. Similarly, very low concentrations of cytochalasin B inhibit concanavalin A‐stimulated glucose transport preferentially, without markedly affecting the unstimulated transport rates. The similarity between concanavalin A‐stimulated 3‐0‐methyl‐glucose transport in thymocytes and insulin‐stimulated glucose transport in adipose tissue, with particular emphasis on the effects of the modifying agents described in this paper, is discussed. Copyright © 1978 Wiley‐Liss, Inc.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Pretreatment of rat thymus lymphocytes with N‐ethyl‐maleimide prevents the stimulation of 3‐0‐methyl‐glucose transport by concanavalin A or ionophore A23187 but does not affect the ability of concanavalin A to induce a rapid increase in cellular Ca2+ uptake. N‐ethyl‐maleimide added after concanavalin A amplifies rather than prevents the subsequent stimulation of 3‐0‐methyl‐glucose transport. Incubation of thymocytes with concanavalin A produces a decrease of 43% in the apparent Ki for phloretin, a competitive inhibitor of 3‐0‐methyl‐glucose transport, without affecting the apparent Km for the substrate. Similarly, very low concentrations of cytochalasin B inhibit concanavalin A‐stimulated glucose transport preferentially, without markedly affecting the unstimulated transport rates. The similarity between concanavalin A‐stimulated 3‐0‐methyl‐glucose transport in thymocytes and insulin‐stimulated glucose transport in adipose tissue, with particular emphasis on the effects of the modifying agents described in this paper, is discussed. Copyright © 1978 Wiley‐Liss, Inc.
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Hume, D. A.; Weidemann, M. J.
Effect of NH4 and Ca2+ on gluconeogenesis from lactate by isolated rat hepatocytes (Journal Article)
In: Hormone and Metabolic Research, vol. 10, no. 5, pp. 449–450, 1978, ISSN: 00185043.
@article{hume_effect_1978,
title = {Effect of NH4 and Ca2+ on gluconeogenesis from lactate by isolated rat hepatocytes},
author = {D. A. Hume and M. J. Weidemann},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0018195925&doi=10.1055%2fs-0028-1095840&partnerID=40&md5=4e440c2d85ffcfa3bad0d6b289ea5574},
doi = {10.1055/s-0028-1095840},
issn = {00185043},
year = {1978},
date = {1978-01-01},
journal = {Hormone and Metabolic Research},
volume = {10},
number = {5},
pages = {449--450},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
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Hume, D. A.; Vijayakumar, E. K.; Schweinberger, F.; Russell, L. M.; Weidemann, M. J.
The role of calcium ions in the regulation of rat thymocyte pyruvate oxidation by mitogens (Journal Article)
In: Biochemical Journal, vol. 174, no. 3, pp. 711–716, 1978, ISSN: 02646021.
@article{hume_role_1978,
title = {The role of calcium ions in the regulation of rat thymocyte pyruvate oxidation by mitogens},
author = {D. A. Hume and E. K. Vijayakumar and F. Schweinberger and L. M. Russell and M. J. Weidemann},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0018133775&doi=10.1042%2fbj1740711&partnerID=40&md5=7a97ef1778b609c14be884122bcce013},
doi = {10.1042/bj1740711},
issn = {02646021},
year = {1978},
date = {1978-01-01},
journal = {Biochemical Journal},
volume = {174},
number = {3},
pages = {711--716},
abstract = {Calcium concentrations in the nanomolar range cause a specific stimulation of the oxidation of pyruvate by isolated mitochondria from rat thymus that is sufficient to account precisely for the stimulation of pyruvate oxidation observed when rat thymocytes are incubated with the mitogens concanavalin A or ionophore A23187. Higher concentrations of Ca2+ (more than 50 nM) inhibit the oxidation of NAD+ linked substrates by rat thymus mitochondria without affecting the oxidation of succinate or ascorbate + NNN'N'-tetramethyl-p-phenylenediamine. The addition of Ni2+ or Co2+ (2 mM) to rat thymocytes prevents the response to concanavalin A at the level of pyruvate oxidation without affecting the stimulation of glycolysis induced by this mitogen. In contrast, the complete metabolic response to the ionophore A23187 is abolished by these lesions. Ni2+ and Co2+ interfere with the ability of the ionophore to transport Ca2+ across the plasma membrane. Concanavalin A, but not ionophore A23187, increases the respiratory inhibition induced by Ni2+ and Co2+. These results support the view that mitogens stimulate lymphocyte pyruvate oxidation through an increase in cellular Ca2+ uptake.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Calcium concentrations in the nanomolar range cause a specific stimulation of the oxidation of pyruvate by isolated mitochondria from rat thymus that is sufficient to account precisely for the stimulation of pyruvate oxidation observed when rat thymocytes are incubated with the mitogens concanavalin A or ionophore A23187. Higher concentrations of Ca2+ (more than 50 nM) inhibit the oxidation of NAD+ linked substrates by rat thymus mitochondria without affecting the oxidation of succinate or ascorbate + NNN’N’-tetramethyl-p-phenylenediamine. The addition of Ni2+ or Co2+ (2 mM) to rat thymocytes prevents the response to concanavalin A at the level of pyruvate oxidation without affecting the stimulation of glycolysis induced by this mitogen. In contrast, the complete metabolic response to the ionophore A23187 is abolished by these lesions. Ni2+ and Co2+ interfere with the ability of the ionophore to transport Ca2+ across the plasma membrane. Concanavalin A, but not ionophore A23187, increases the respiratory inhibition induced by Ni2+ and Co2+. These results support the view that mitogens stimulate lymphocyte pyruvate oxidation through an increase in cellular Ca2+ uptake.
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Hume, D. A.; Radik, J. L.; Ferber, E.; Weidemann, M. J.
Aerobic glycolysis and lymphocyte transformation (Journal Article)
In: Biochemical Journal, vol. 174, no. 3, pp. 703–709, 1978, ISSN: 02646021.
@article{hume_aerobic_1978,
title = {Aerobic glycolysis and lymphocyte transformation},
author = {D. A. Hume and J. L. Radik and E. Ferber and M. J. Weidemann},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0018077453&doi=10.1042%2fbj1740703&partnerID=40&md5=dbb75c64b1e56a9cf88643d55f57a92c},
doi = {10.1042/bj1740703},
issn = {02646021},
year = {1978},
date = {1978-01-01},
journal = {Biochemical Journal},
volume = {174},
number = {3},
pages = {703--709},
abstract = {The role of enhanced aerobic glycolysis in the transformation of rat thymocytes by concanavalin A has been investigated. Concanavalin A addition doubled [U-14C]glucose uptake by rat thymocytes over 3h and caused an equivalent increased incorporation into protein, lipids and RNA. A disproportionately large percentage of the extra glucose taken up was converted into lactate, but concanavalin A also caused a specific increase in pyruvate oxidation, leading to an increase in the percentage contribution of glucose to the respiratory fuel. Acetoacetate metabolism, which was not affected by concanavalin A, strongly suppressed pyruvate oxidation in the presence of [U-14C]glucose, but did not prevent the concanavalin A-induced stimulation of this process. Glucose uptake was not affected by acetoacetate in the presence or absence of concanavalin A, but in each case acetoacetate increased the percentage of glucose uptake accounted for by lactate production. [3H]Thymidine incorporation into DNA in concanavalin A-treated thymocyte cultures was sensitive to the glucose concentration in the medium in a biphasic manner. Very low concentrations of glucose (25 μM) stimulated DNA synthesis half-maximally, but maximum [3H]thymidine incorporation was observed only when the glucose concentration was raised to 1mM. Lactate addition did not alter the sensitivity of [3H]-thymidine uptake to glucose, but inosine blocked the effect of added glucose and strongly inhibited DNA synthesis. It is suggested that the major function of enhanced aerobic glycolysis in transforming lymphocytes is to maintain higher steady-state amounts of glycolytic intermediates to act as precursors for macromolecule synthesis.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The role of enhanced aerobic glycolysis in the transformation of rat thymocytes by concanavalin A has been investigated. Concanavalin A addition doubled [U-14C]glucose uptake by rat thymocytes over 3h and caused an equivalent increased incorporation into protein, lipids and RNA. A disproportionately large percentage of the extra glucose taken up was converted into lactate, but concanavalin A also caused a specific increase in pyruvate oxidation, leading to an increase in the percentage contribution of glucose to the respiratory fuel. Acetoacetate metabolism, which was not affected by concanavalin A, strongly suppressed pyruvate oxidation in the presence of [U-14C]glucose, but did not prevent the concanavalin A-induced stimulation of this process. Glucose uptake was not affected by acetoacetate in the presence or absence of concanavalin A, but in each case acetoacetate increased the percentage of glucose uptake accounted for by lactate production. [3H]Thymidine incorporation into DNA in concanavalin A-treated thymocyte cultures was sensitive to the glucose concentration in the medium in a biphasic manner. Very low concentrations of glucose (25 μM) stimulated DNA synthesis half-maximally, but maximum [3H]thymidine incorporation was observed only when the glucose concentration was raised to 1mM. Lactate addition did not alter the sensitivity of [3H]-thymidine uptake to glucose, but inosine blocked the effect of added glucose and strongly inhibited DNA synthesis. It is suggested that the major function of enhanced aerobic glycolysis in transforming lymphocytes is to maintain higher steady-state amounts of glycolytic intermediates to act as precursors for macromolecule synthesis.
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1977
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Yasmeen, D.; Laird, A. J.; Hume, D. A.; Weidemann, M. J.
Activation of 3-O-methyl-glucose transport in rat thymus lymphocytes by concanavalin A temperature and calcium ion dependence and sensitivity to puromycin but not to cycloheximide (Journal Article)
In: BBA – General Subjects, vol. 500, no. 1, pp. 89–102, 1977, ISSN: 03044165.
@article{yasmeen_activation_1977,
title = {Activation of 3-O-methyl-glucose transport in rat thymus lymphocytes by concanavalin A temperature and calcium ion dependence and sensitivity to puromycin but not to cycloheximide},
author = {D. Yasmeen and A. J. Laird and D. A. Hume and M. J. Weidemann},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0017704917&doi=10.1016%2f0304-4165%2877%2990049-6&partnerID=40&md5=22a011c68aa041b5b778ba01cfdf6001},
doi = {10.1016/0304-4165(77)90049-6},
issn = {03044165},
year = {1977},
date = {1977-01-01},
journal = {BBA - General Subjects},
volume = {500},
number = {1},
pages = {89--102},
abstract = {1. 1. A method is described for the determination of the rate of 3-O-methyl-D-[U-14C]glucose transport into rat thymuse lymphocytes. Some kinetic properties of this facilitated diffusion transport process have been determined, both before and after stimulation with concanavalin A, and the effects of Ca2+, puromycin and cycloheximide have been investigated. 2. 2. The initial rate of 3-O-methyl-D-glucose transport into rat thymus lymphocytes is significantly stimulated within 5 min of concanavalin A addition and is approximately doubled after 30 min. 3. 3. Maximun stimulation of sugar transport by concanavalin A requires at least 30 μM free Ca2+ in the extracellular medium, and is sigmoidally dependent on free Ca2+ up to this concentration; in contrast, the unstimulated transport process appears to be Ca2+-independent. 4. 4. In both the presence and absence of concanavalin A, 3-O-methyl-D-glucose transport is a saturable process with a Km of approx. 4.5 mM; the stimulation by concanavalin A can be attributed solely to a two-fold increase in the value of V, as the Km value remains essentially unaltered. 5. 5. Concanavalin A alters the temperature-dependence of 3-O-methyl-D-glucose transport so that the activation energy at 37°C is substantially increased. 6. 6. The enhancement of sugar transport by concanavalin A is independent of de novo protein synthesis, as it is not prevented by cycloheximide, which blocks the incorporation of [14C]leucine into trichloroacetic acid-precipitation protein. 7. 7. On the other hand, the stimulation of 3-0-methyl-D-glucose transport by concanavalin A, as well as the enhanced utilization of D-glucose, is suppressed by puromycin, which also blocks [14C]leucine incorporation into protein. This suppression appears to be due to a hitherto unreported inhibitory effect of puromycin on glucose transport. © 1977.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
1. 1. A method is described for the determination of the rate of 3-O-methyl-D-[U-14C]glucose transport into rat thymuse lymphocytes. Some kinetic properties of this facilitated diffusion transport process have been determined, both before and after stimulation with concanavalin A, and the effects of Ca2+, puromycin and cycloheximide have been investigated. 2. 2. The initial rate of 3-O-methyl-D-glucose transport into rat thymus lymphocytes is significantly stimulated within 5 min of concanavalin A addition and is approximately doubled after 30 min. 3. 3. Maximun stimulation of sugar transport by concanavalin A requires at least 30 μM free Ca2+ in the extracellular medium, and is sigmoidally dependent on free Ca2+ up to this concentration; in contrast, the unstimulated transport process appears to be Ca2+-independent. 4. 4. In both the presence and absence of concanavalin A, 3-O-methyl-D-glucose transport is a saturable process with a Km of approx. 4.5 mM; the stimulation by concanavalin A can be attributed solely to a two-fold increase in the value of V, as the Km value remains essentially unaltered. 5. 5. Concanavalin A alters the temperature-dependence of 3-O-methyl-D-glucose transport so that the activation energy at 37°C is substantially increased. 6. 6. The enhancement of sugar transport by concanavalin A is independent of de novo protein synthesis, as it is not prevented by cycloheximide, which blocks the incorporation of [14C]leucine into trichloroacetic acid-precipitation protein. 7. 7. On the other hand, the stimulation of 3-0-methyl-D-glucose transport by concanavalin A, as well as the enhanced utilization of D-glucose, is suppressed by puromycin, which also blocks [14C]leucine incorporation into protein. This suppression appears to be due to a hitherto unreported inhibitory effect of puromycin on glucose transport. © 1977.
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1976
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hume, D. A.; weidemann, M. J.
Hormonal regulation of gluconeogenesis in isolated rat hepatocytes: An undergraduate experiment (Journal Article)
In: Biochemical Education, vol. 4, no. 1, pp. 13–14, 1976, ISSN: 03074412.
@article{hume_hormonal_1976,
title = {Hormonal regulation of gluconeogenesis in isolated rat hepatocytes: An undergraduate experiment},
author = {D. A. hume and M. J. weidemann},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-49349131450&doi=10.1016%2f0307-4412%2876%2990013-3&partnerID=40&md5=df39fc2584e6cac609881b31209a4d6d},
doi = {10.1016/0307-4412(76)90013-3},
issn = {03074412},
year = {1976},
date = {1976-01-01},
journal = {Biochemical Education},
volume = {4},
number = {1},
pages = {13--14},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
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