Jose Medina - Academia.edu (original) (raw)

Papers by Jose Medina

Research paper thumbnail of Comparison of Mexican-American and Anglo-American Attitudes Toward Money

Journal of Consumer Affairs, 2005

This study compared attitudes toward money of Mexican- and Anglo-American consumers. Based on the... more This study compared attitudes toward money of Mexican- and Anglo-American consumers. Based on the Hispanic/Mexican-American literature, hypotheses were generated for four dimensions of a money attitude scale (MAS) developed by Yamauchi and Templer (1982). Mexican-Americans were found to have lower scores on a Retention/Time dimension that reflects willingness to delay spending money to achieve gratification. Contrary to previous studies, Mexican-Americans were found to have lower scores on a Quality dimension, calling into question an assumption found in much of the literature that Hispanic consumers prefer high prestige goods/services. Hypotheses pertaining to Power/Prestige and Distrust/Anxiety dimensions were also not confirmed suggesting further reservations about Hispanic consumer characterizations found in the consumer behavior literature.

Research paper thumbnail of Experiences with mixed integer linear programming based approaches on short-term hydro scheduling

IEEE Transactions on Power Systems, 2001

Research paper thumbnail of Percutaneous needle aponeurotomy: complications and results

Journal of Hand Surgery-british and European Volume, 2003

Research paper thumbnail of Metabolic trafficking through astrocytic gap junctions

Research paper thumbnail of Endothelin1 regulates glucose utilization in cultured astrocytes by controlling intercellular communication through gap junctions

Glia, 1996

The role played by endothelin-1 and intercellular communication mediated by gap junctions in the ... more The role played by endothelin-1 and intercellular communication mediated by gap junctions in the regulation of glucose disposal by astrocytes has been studied in primary culture. Endothelin-1 increased glucose uptake by astrocytes as did one of its putative messenger arachidonic acid and the non-physiological gap junction uncoupler alpha-glycyrrhetinic acid (AGA). None of these agents increased glucose uptake by C6 glioma cells, a cell line in which gap junction proteins are poorly expressed. In confluent astrocytes, the inhibition of gap junction permeability caused by AGA doubled the activity of the pentose phosphate shunt with minimal changes in the activity of the pyruvate dehydrogenase-catalyzed reaction and that of the tricarboxylic acid cycle. By contrast, these effects were not observed in dissociated astrocytes in which intercellular communication is lacking. The scraped loading dye transfer technique was modified to follow the passage of glucose and its metabolites through astrocyte gap junctions. The diffusion of glucose, the phosphorylated derivative glucose-6-phosphate, the phosphorylisable but not metabolisable derivative ortho-methyl-glucose, and the anaerobic glycolytic product L-lactate was much higher in astrocytes than in C6 glioma cells and was inhibited by the inhibition of gap junction permeability caused by endothelin-1, arachidonic acid, octanol, or AGA. It is concluded that gap junction permeability may regulate brain metabolism by controlling the uptake, utilization, and intercellular distribution of glucose and its metabolites in astrocytes.

Research paper thumbnail of Lactate Utilization by Isolated Cells from Early Neonatal Rat Brain

Journal of Neurochemistry, 1991

: The utilization of lactate, glucose, 3-hydroxybutyrate, and glutamine has been studied in isola... more : The utilization of lactate, glucose, 3-hydroxybutyrate, and glutamine has been studied in isolated brain cells from early newborn rats. Isolated brain cells actively utilized these substrates, showing saturation at concentrations near physiological levels during the perinatal period. The rate of lactate utilization was 2.5-fold greater than that observed for glucose, 3-hydroxybutyrate, or glutamine, suggesting that lactate is the main metabolic substrate for the brain immediately after birth. The apparent Km for glucose utilization suggested that this process is limited by the activity of hexokinase. However, lactate, 3-hydroxybutyrate, and glutamine utilization seems to be limited by their transport through the plasma membrane. The presence of fatty acid-free bovine serum albumin (BSA) in the incubation medium significantly increased the rate of lipogenesis from lactate or 3-hydroxybutyrate, although this was balanced by the decrease in their rates of oxidation in the same circumstances. BSA did not affect the rate of glucose utilization. The effect of BSA was due not to the removal of free fatty acid, but possibly to the binding of long-chain acyl-CoA, resulting in the disinhibition of acetyl-CoA carboxylase and citrate carrier.

Research paper thumbnail of Regulation of Lactate Metabolism by Albumin in Rat Neurons and Astrocytes from Primary Culture

Research paper thumbnail of Comparison of Mexican-American and Anglo-American Attitudes Toward Money

Journal of Consumer Affairs, 2005

This study compared attitudes toward money of Mexican- and Anglo-American consumers. Based on the... more This study compared attitudes toward money of Mexican- and Anglo-American consumers. Based on the Hispanic/Mexican-American literature, hypotheses were generated for four dimensions of a money attitude scale (MAS) developed by Yamauchi and Templer (1982). Mexican-Americans were found to have lower scores on a Retention/Time dimension that reflects willingness to delay spending money to achieve gratification. Contrary to previous studies, Mexican-Americans were found to have lower scores on a Quality dimension, calling into question an assumption found in much of the literature that Hispanic consumers prefer high prestige goods/services. Hypotheses pertaining to Power/Prestige and Distrust/Anxiety dimensions were also not confirmed suggesting further reservations about Hispanic consumer characterizations found in the consumer behavior literature.

Research paper thumbnail of Experiences with mixed integer linear programming based approaches on short-term hydro scheduling

IEEE Transactions on Power Systems, 2001

Research paper thumbnail of Percutaneous needle aponeurotomy: complications and results

Journal of Hand Surgery-british and European Volume, 2003

Research paper thumbnail of Metabolic trafficking through astrocytic gap junctions

Research paper thumbnail of Endothelin1 regulates glucose utilization in cultured astrocytes by controlling intercellular communication through gap junctions

Glia, 1996

The role played by endothelin-1 and intercellular communication mediated by gap junctions in the ... more The role played by endothelin-1 and intercellular communication mediated by gap junctions in the regulation of glucose disposal by astrocytes has been studied in primary culture. Endothelin-1 increased glucose uptake by astrocytes as did one of its putative messenger arachidonic acid and the non-physiological gap junction uncoupler alpha-glycyrrhetinic acid (AGA). None of these agents increased glucose uptake by C6 glioma cells, a cell line in which gap junction proteins are poorly expressed. In confluent astrocytes, the inhibition of gap junction permeability caused by AGA doubled the activity of the pentose phosphate shunt with minimal changes in the activity of the pyruvate dehydrogenase-catalyzed reaction and that of the tricarboxylic acid cycle. By contrast, these effects were not observed in dissociated astrocytes in which intercellular communication is lacking. The scraped loading dye transfer technique was modified to follow the passage of glucose and its metabolites through astrocyte gap junctions. The diffusion of glucose, the phosphorylated derivative glucose-6-phosphate, the phosphorylisable but not metabolisable derivative ortho-methyl-glucose, and the anaerobic glycolytic product L-lactate was much higher in astrocytes than in C6 glioma cells and was inhibited by the inhibition of gap junction permeability caused by endothelin-1, arachidonic acid, octanol, or AGA. It is concluded that gap junction permeability may regulate brain metabolism by controlling the uptake, utilization, and intercellular distribution of glucose and its metabolites in astrocytes.

Research paper thumbnail of Lactate Utilization by Isolated Cells from Early Neonatal Rat Brain

Journal of Neurochemistry, 1991

: The utilization of lactate, glucose, 3-hydroxybutyrate, and glutamine has been studied in isola... more : The utilization of lactate, glucose, 3-hydroxybutyrate, and glutamine has been studied in isolated brain cells from early newborn rats. Isolated brain cells actively utilized these substrates, showing saturation at concentrations near physiological levels during the perinatal period. The rate of lactate utilization was 2.5-fold greater than that observed for glucose, 3-hydroxybutyrate, or glutamine, suggesting that lactate is the main metabolic substrate for the brain immediately after birth. The apparent Km for glucose utilization suggested that this process is limited by the activity of hexokinase. However, lactate, 3-hydroxybutyrate, and glutamine utilization seems to be limited by their transport through the plasma membrane. The presence of fatty acid-free bovine serum albumin (BSA) in the incubation medium significantly increased the rate of lipogenesis from lactate or 3-hydroxybutyrate, although this was balanced by the decrease in their rates of oxidation in the same circumstances. BSA did not affect the rate of glucose utilization. The effect of BSA was due not to the removal of free fatty acid, but possibly to the binding of long-chain acyl-CoA, resulting in the disinhibition of acetyl-CoA carboxylase and citrate carrier.

Research paper thumbnail of Regulation of Lactate Metabolism by Albumin in Rat Neurons and Astrocytes from Primary Culture