Biomedical subjects

T Roig

Publications and source records attributed to T Roig.

15 recordsLinked to original sources

PubMed2000

Cells overexpressing fructose-2,6-bisphosphatase showed enhanced pentose phosphate pathway flux and resistance to oxidative stress.

Changes in the content of fructose-2,6-bisphosphate, a modulator of glycolytic flux, also affect other metabolic fluxes such as the non-oxidative pentose phosphate pathway. Since this is the main source of precursors for biosynthesis in proliferating cells, PFK-2/FBPase-2 has been proposed as a potential target for neoplastic treatments. Here we provide evidence that cells with a low content of fructose-2,6-bisphosphate have a lower energy status than controls, but they are also less sensitive to oxidative stress. This feature is related to the activation of the oxidative branch of the pentose phosphate pathway and the increased production of NADPH.

Animals↗

PubMed2000

MPP(+)-induced mitochondrial dysfunction is potentiated by dopamine.

MPP(+), the major metabolite of the Parkinsonism-inducing compound MPTP, responsible for the destruction of the nigrostriatal pathway in primates and rodents, has been assayed in isolated rat liver mitochondria in the presence of physiological concentrations of dopamine or analogous concentrations of melanin-dopamine. 5 microM MPP(+) in the presence of 70 microM dopamine or melanin-dopamine, but not alone, decreased the heat production and oxygen consumption of a mitochondrial suspension activated with succinate and ADP. Both dopamine and oxidized dopamine plus MPP(+) also decreased the mitochondrial reductive power measured with MTT. Mitochondrial swelling was observed, associated with an increase in membrane mitochondrial potential, as a synergistic effect between low concentrations of MPP(+) and dopamine. It is suggested that cytosolic dopamine, by itself or via its autooxidation products, may play a relevant role in the mitochondrial toxicity of MPP(+). A failure in the regulation of the storage/release of dopamine could aggravate a mitochondrial damage and trigger the neurodegenerative process underlying MPTP toxicity and Parkinson's disease.

1-Methyl-4-phenylpyridinium↗

PubMed2000

Overexpression of fructose 2,6-bisphosphatase decreases glycolysis and delays cell cycle progression.

The ability to overexpress 6-phosphofructo-2-kinase/fructose 2, 6-bisphosphatase (PFK-2)/(FBPase-2) or a truncated form of the enzyme with only the bisphosphatase domain allowed us to analyze the relative role of the kinase and the bisphosphatase activities in regulating fructose 2,6-bisphosphate (Fru-2,6-P(2)) concentration and to elucidate their differential metabolic impact in epithelial Mv1Lu cells. The effect of overexpressing PFK-2/FBPase-2 resulted in a small increase in the kinase activity and in the activity ratio of the bifunctional enzyme, increasing Fru-2,6-P(2) levels, but these changes had no major effects on cell metabolism. In contrast, expression of the bisphosphatase domain increased the bisphosphatase activity, producing a significant decrease in Fru-2,6-P(2) concentration. The fall in the bisphosphorylated metabolite correlated with a decrease in lactate production and ATP concentration, as well as a delay in cell cycle. These results provide support for Fru-2,6-P(2) as a regulator of glycolytic flux and point out the role of glycolysis in cell cycle progression.

Adenosine Triphosphate↗

PubMed1999

Na(+)-K(+) pump and metabolic activities of trout erythrocytes during anoxia.

Metabolic activity in the red blood cells of brown trout was monitored under conditions of oxygen depletion and chemically induced anoxia. Although metabolic activity was reduced during anoxia to one-third of the normoxic value, these cells maintained their ATP contents stable and were viable for hours in the absence of oxygen. In addition, Na(+)-K(+) pump activity was not down-regulated when metabolic activity was reduced during anoxia. The compatibility of this finding with energy equilibrium and ion homeostasis was investigated.

Adenosine Triphosphate↗

PubMed1997

Serum-liposome interaction is an oxygen-dependent process.

Measurements of heat dissipation, oxygen concentration and average vesicle size were correlated to study the effect of serum components on different types of liposome. The results indicate that the interaction between serum components and liposomes is exothermic and oxygen dependent, and leads to disruption of vesicles. The dependence of this effect on serum concentration, vesicle surface charge and type of liposome was also evaluated. Serum components did not produce any effect on conventional liposomes in the absence of oxygen. Moreover, in hypoxic conditions the serum-liposome interaction was delayed. Both results suggest that this interaction is an oxygen-dependent event. Finally, we confirmed that sterically stabilised liposomes remain unalterated in the presence of serum.

Animals↗

PubMed1997

Exogenous fructose 1,6-bisphosphate reduces K+ permeability in isolated rat hepatocytes.

The relationship between the protective effect of fructose 1,6-bisphosphate (F-1,6-P2) against cell injury and the modifications produced in the metabolic fluxes and in the membrane permeability to K+ was studied in isolated rat hepatocytes. Incubation of these cells in the presence of F-1,6-P2 reduced metabolic activity without affecting the ATP content, which suggests a downregulation of the ATP turnover. Using 86Rb+ as a tracer, we analyzed the relationship between these metabolic changes and alterations in K+ fluxes. In the presence of F-1,6-P2 the passive and the active K+ fluxes in hepatocytes decreased. However, the Na(+)-K+ pump from semipurified membranes was not directly affected by F-1,6-P2, which suggests a secondarily induced reduction of Na(+)-K+ pump activity. Moreover, galactosamine-treated cells showed a marked increase in permeability to K+ that was abolished by the presence of F-1,6-P2. This protective effect may be related to the prevention of K+ efflux. The results reported here strongly suggest the induction of channel arrest, and the associated metabolic downregulation, as the primary protective effect of F-1,6-P2, as has been shown in the prevention of galactosamine-induced hepatotoxicity.

Animals↗

PubMed1997

Adrenergic stimulation of sea bream (Sparus aurata) red blood cells in normoxia and anoxia: effects on metabolism and on the oxygen affinity of haemoglobin

The metabolic response of sea bream (Sparus aurata) red blood cells to adrenergic stimulation was determined in normoxia and anoxia. In the presence of oxygen, red blood cells swelled and then recovered their resting volume. Continuous monitoring of oxygen uptake displayed the kinetics of the increase in the oxygen affinity of haemoglobin. Cell volume recovery correlated with an activation of ATP consumption, and the energy equilibrium was restored by increasing the rates of respiration and glycolysis. When the respiratory chain was blocked, adrenergic stimulation increased the rates of ATP consumption and glycolysis of red blood cells. Moreover, adrenergic stimulation of deoxygenated erythrocytes also increased cell volume but did not enhance glycolysis or ATP consumption, and the cells remained swollen. Our results suggest that there is an oxygen-linked signal transducer that activates ATP-consuming processes, provided that the adrenergic stimulation occurs in the presence of oxygen.

Journal Article↗

PubMed1996

Early effects of basic fibroblast growth factor on foetal rat mesencephalic cell suspensions.

Mesencephalic cell suspensions are used, experimentally but also clinically, to compensate for neurological deficiencies, by implantation into the striatum. Here, we have studied the metabolism of mesencephalic cell suspensions obtained from rat embryos by measuring heat dissipation, oxygen consumption, ATP and lactate production. The effect of basic fibroblast growth factor (bFGF) at a 50 ng/ml concentration on these parameters was studied in order to assess the effect of in vitro exposure of cell suspensions to this trophic factor. Heat production and oxygen consumption were low, as could be expected from an immature nervous tissue, and they further decreased after addition of bFGF. This trophic factor decreased the total ATP concentration and increased the lactate production. The viability of the cell suspensions was reduced by nearly a half, 2 h after the addition of bFGF, and numerous fragmented nuclei were observed. It seems that, in contrast to the neuroprotective effect of bFGF on mesencephalic cultures and nigrostriatal neurons, this factor could have an initial sorting effect in the development of mesencephalic structures.

Acridine Orange↗

PubMed1996

Effects of taxol on isolated rat hepatocyte metabolism.

Taxol is a natural product, isolated from Taxus brevifolia, with increasing clinical applications because of its potent antitumor activity. Although it is mainly metabolized in the liver, its effect on hepatocyte metabolism has been scarcely investigated. In this study, the response of isolated rat hepatocytes to taxol was evaluated by correlating the changes observed in global indexes such as viability and heat dissipation with those produced in oxygen consumption and intracellular metabolites (ATP, fructose 2,6-bisphosphate, and lactate). The results indicate that taxol reduces aerobic metabolism, which induces an insufficient increase of the ATP via anaerobic glycolysis. Moreover, incubations of isolated mitochondria with taxol indicate that the respiratory chain is directly affected by this drug.

Animals↗

PubMed1995

Microcalorimetric evaluation of the effect of combined chemotherapeutic drugs.

A study of the effect of combined antineoplastic drugs in vitro was carried out by microcalorimetric monitoring of the metabolic activity of treated cells. Power-time curves of growing T-lymphoma cell suspensions, treated with single or combined drugs, were recorded. The extent of the effect was evaluated by changes in the slopes of the microcalorimetric curves and the kinetics of the drug action were interpreted from the time at which these changes reached their maximum value. The method was validated using two well-established drug combinations, the potentiatory effect of dipyridamole on methotrexate cytotoxicity, and the synergism between methotrexate and 6-thioguanine. In the first case, where one drug is not toxic, the modulation may be evaluated by comparing the inhibition produced by the toxic drug alone and in combination with its modulator. Otherwise, when both drugs are toxic, the combined effect must be evaluated by means of their combination index. The measurement procedure is simple, the electric signal is well suited to automation of data acquisition and the response may be evaluated within 5 to 6 h of drug administration. Moreover, we demonstrate that microcalorimetry is a reliable method for the detection of modulatory effects in combination chemotherapy.

Antineoplastic Agents↗

PubMed1994

Fructose 1,6-bisphosphate protects against D-galactosamine toxicity in isolated rat hepatocytes.

Incubation of hepatocytes with D-galactosamine (GalN) produced a dose-dependent alteration in cell viability and a fall in ATP and fructose 2,6-bisphosphate (Fru-2,6-P2) levels. The reduction in Fru-2,6-P2 can be explained by changes in the substrates or modulators of 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase, because neither the adenosine 3',5'-cyclic monophosphate level nor the activity ratio of the enzyme was modified. Microcalorimetric measurements showed that GalN produced an exothermic peak followed by a progressive decrease in heat dissipation. Simultaneous administration of GalN and fructose 1,6-bisphosphate (Fru-1,6-P2) significantly increased cell viability, and concentrations of ATP and Fru-2,6-P2 and led to stable heat production. In the presence of Fru-1,6-P2 alone, hepatocytes kept ATP and Fru-2,6-P2 levels constant, whereas they increased the oxygen uptake-to-heat output ratio. Our results suggest that GalN initiates the hepatotoxic effect by means of an energy-dissipating interaction, produced before its metabolism and presumably at the membrane level, whereas Fru-1,6-P2 protects the cells against this injury in a way that prevents the initial interaction and increases the metabolic efficiency of the cell.

Adenosine Triphosphate↗

PubMed1994

ENERGY METABOLISM BY TROUT RED BLOOD CELLS: SUBSTRATE UTILISATION

The present study investigates energy metabolism by trout red blood cells. It is shown that they are able to use pyruvate at physiological concentrations as an aerobic source of energy. Moreover, microcalorimetric data suggest that trout erythrocytes are also able to use internal substrates, at least when maintained in vitro. Although the actual nature of these substrates has not been elucidated, glycogen appears to be the most probable. The relationship between heat dissipation and oxygen consumption suggests that most of the oxygen is used to oxidize substrates, and the inhibition of respiratory activity by antimycin A indicates that there is no substantial utilisation of non-respiratory oxygen. However, the oxygen uptake by these cells does not appear to be related to substrate utilisation, measured from transformation of labelled molecules (either pyruvate or glucose); this may be due to mixing of labelled compounds with non-labelled molecules in the intracellular pools, because of the low metabolic rate of these cells.

Journal Article↗

PubMed1993

Double luminal and vascular perfusion of chicken jejunum: studies on 3-O-methyl-D-glucose absorption.

The aims of the present study were: (1) to set up a procedure for simultaneous vascular and luminal perfusion of the chicken jejunum; (2) to assess the transport capacity of the tissue under such conditions, and (3) to study the effects of phloretin and theophylline, given through the vascular perfusate, on 3-O-methyl-D-glucose intestinal transport. The perfusion procedure described allowed the control of intestinal and vascular inflow rates and perfusion pressures so that these parameters could be adjusted to physiological values. A perfluorochemical emulsion was used as oxygen carrier for the vascular perfusate. The absorptive function of the perfused tissue was assessed by means of its ability to transport 3-O-methyl-D-glucose. Furthermore, ultrastructure preservation was evaluated by scanning and transmission electron microscopy. Results indicate that the perfused tissue kept its transport capacity and morphology intact throughout the 120-min experimental period. Moreover, no hypersecretion was observed as indicated by the constancy of perfusate volumes and perfusion pressures. Phloretin (1 mM) or theophylline (10 mM) added to the vascular perfusate markedly reduced the transfer of 3-O-methyl-D-glucose from the enterocyte to the vascular fluid without affecting the uptake from the lumen. Our results suggest that this preparation may be used as an alternative tool for the study of intestinal absorption processes in avian species, particularly when complete examination is required of the efflux of substrates from the intestinal lumen to the vascular fluid.

3-O-Methylglucose↗

PubMed1991

Intestinal perfusion in vivo for the study of absorptive processes.

1. Intestinal absorption can be studied by in vitro and in vivo techniques. Among the in vivo ones, intestinal perfusion is the one more employed. 2. Intestinal perfusion could be performed by a simple perfusion of an intestinal segment or by a double perfusion of the intestine and the vascular bed simultaneously. 3. The double perfusion has the advantage of measuring the substrate appearance in the vascular circuit. 4. In this review we compare the different techniques described in the literature, paying attention to their advantages. 5. The best method is the one that maintains the animal alive throughout the experiment, because it provides information about intestinal absorption under conditions similar to the natural ones.

Animals↗

PubMedDate not supplied

Intracavernous pharmacotherapy for management of erectile dysfunction in multiple sclerosis patients.

Intracavernous self-injection of vasoactive drugs is a well accepted therapy for the management of erectile dysfunction in neurogenic disorders. We present the results of a self-injection program in seven MS patients who were admitted in Institut Guttmann of Barcelona and who presented with an insufficient erection. All patients showed an excellent erectile response and had penile rigidity sufficient for sexual intercourse during acceptable time, with minimal complications. A patient reported improvement of erectile capacity so as not to need another cavernously injection for 2-3 months.

Adult↗