References of "Bettendorff, Lucien"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailBrain Levels of Thiamine and Its Phosphate Esters in Friedreich's Ataxia and Spinocerebellar Ataxia Type 1
Bettendorff, Lucien ULg; Mastrogiacomo, Frank; LaMarche, J. et al

in Movement Disorders : Official Journal of the Movement Disorder Society (1996), 11(4), 437-439

Decreased blood and cerebrospinal fluid levels of thiamine have been reported in patients with spinocerebellar ataxia disorders. To determine whether a thiamine deficiency is present in the brain, we ... [more ▼]

Decreased blood and cerebrospinal fluid levels of thiamine have been reported in patients with spinocerebellar ataxia disorders. To determine whether a thiamine deficiency is present in the brain, we measured levels of thiamine and its phosphate esters thiamine monophosphate (TMP) and thiamine diphosphate (TDP), in postmortem cerebellar and cerebral cortices of patients with Friedreich's ataxia (FA) and spinocerebellar ataxia type 1 (SCA1). Brain levels of free (nonphosphorylated) thiamine, TMP, TDP, and total thiamine in FA and SCA1 were, on average, not significantly different from control values. However, a nonsignificant trend was observed for slightly reduced levels of TDP and total thiamine in cerebellar cortex of the SCA1 patients, a finding that might be related to the severe neuronal damage in this brain area. We conclude that in FA, brain thiamine concentrations are normal, whereas in SCA1 the levels are, at most, only slightly reduced. [less ▲]

Detailed reference viewed: 23 (5 ULg)
Full Text
Peer Reviewed
See detailImmunoreactive levels of α-ketoglutarate dehydrogenase subunits in Friedreich's ataxia and spinocerebellar ataxia type 1
Mastrogiacomo, Frank; LaMarche, Jacques; Dozic, Slobodan et al

in Neurodegeneration : A Journal for Neurodegenerative Disorders, Neuroprotection, and Neuroregeneration (1996), 5

Detailed reference viewed: 12 (2 ULg)
Full Text
Peer Reviewed
See detailA Non-Cofactor Role of Thiamine Derivatives in Excitable Cells?
Bettendorff, Lucien ULg

in Archives of Physiology & Biochemistry (1996), 104(6), 745-751

Thiamine diphosphate (TDP) is an important cofactor of pyruvate (PDH) and alpha-ketoglutarate (KGDH) dehydrogenases and transketolase. Thiamine deficiency leads to reversible and irreversible brain ... [more ▼]

Thiamine diphosphate (TDP) is an important cofactor of pyruvate (PDH) and alpha-ketoglutarate (KGDH) dehydrogenases and transketolase. Thiamine deficiency leads to reversible and irreversible brain lesions due to impaired oxidative metabolism. A specific non-cofactor role for thiamine has also been proposed in excitable cells and thiamine triphosphate (TTP) might be involved in the regulation of ion channels. Thiamine is taken up by neuroblastoma cells through a high affinity transporter. Inside the cells, it is rapidly phosphorylated to TDP. This high turnover TDP pool is the precursor for TTP. Most of the TDP however has a low turnover and is associated with PDH and KGDH in mitochondria. In excised inside-out patches from neuroblastoma cells, TTP, at a concentration of 1 microM, activates chloride channels of large unitary conductance, the so-called maxi-Cl- channels. These channels are inhibited by oxythiamine from the outide. In addition to the role of TTP in the regulation of chloride channels, thiamine itself, or a presently unknown analog, may have trophic effects on neuronal cells. [less ▲]

Detailed reference viewed: 24 (9 ULg)
Full Text
Peer Reviewed
See detailThiamine, Thiamine Phosphates, and Their Metabolizing Enzymes in Human Brain
Bettendorff, Lucien ULg; Mastrogiacomo, Frank; Kish, Stephen J et al

in Journal of Neurochemistry (1996), 66(1), 250-8

Total thiamine (the sum of thiamine and its phosphate esters) concentrations are two- to fourfold lower in human brain than in the brain of other mammals. There were no differences in the total thiamine ... [more ▼]

Total thiamine (the sum of thiamine and its phosphate esters) concentrations are two- to fourfold lower in human brain than in the brain of other mammals. There were no differences in the total thiamine content between biopsied and autopsied human brain, except that in the latter, thiamine triphosphate was undetectable. The main thiamine phosphate-metabolizing enzymes could be detected in autopsied brain, and the kinetic parameters were comparable to those reported in other species. Thiamine diphosphate levels were lowest in hippocampus (15 +/- 4 pmol/mg of protein) and highest in mammillary bodies (24 +/- 4 pmol/mg of protein). Maximal levels of thiamine and its phosphate ester were found to be present at birth. In parietal cortex and globus pallidus, mean levels of total thiamine in the oldest age group (77-103 years) were, respectively, 21 and 26% lower than those in the middle age group (40-55 years). Unlike cerebral cortex, the globus pallidus showed a sharp drop in thiamine diphosphate levels during infancy, with concentrations in the oldest group being only approximately 50% of the levels present during the first 4 months of life. These data, consistent with previous observations conducted in blood, suggest a tendency toward decreased thiamine status in older people. [less ▲]

Detailed reference viewed: 20 (1 ULg)
Full Text
Peer Reviewed
See detailBrain protein and alpha-ketoglutarate dehydrogenase complex activity in Alzheimer's disease
Mastrogiacomo, Frank; Lindsay, J. Gordon; Bettendorff, Lucien ULg et al

in Annals of Neurology (1996), 39

Detailed reference viewed: 40 (2 ULg)
Full Text
Peer Reviewed
See detailBrain thiamine, its phosphate esters, and its metabolizing enzymes in Alzheimer's disease.
Mastrogiacomo, Frank; Bettendorff, Lucien ULg; Grisar, Thierry ULg et al

in Annals of Neurology (1996), 39

Detailed reference viewed: 25 (1 ULg)
Full Text
Peer Reviewed
See detailThiamine Deficiency--Induced Partial Necrosis and Mitochondrial Uncoupling in Neuroblastoma Cells Are Rapidly Reversed by Addition of Thiamine
Bettendorff, Lucien ULg; Sluse, Francis ULg; Goessens, Guy ULg et al

in Journal of Neurochemistry (1995), 65(5), 2178-2184

Culture of neuroblastoma cells in a medium of low-thiamine concentration (6 nM) and in the presence of the transport inhibitor amprolium leads to the appearance of overt signs of necrosis; i.e., the ... [more ▼]

Culture of neuroblastoma cells in a medium of low-thiamine concentration (6 nM) and in the presence of the transport inhibitor amprolium leads to the appearance of overt signs of necrosis; i.e., the chromatin condenses in dark patches, the oxygen consumption decreases, mitochondria are uncoupled, and their cristae are disorganized. Glutamate formed from glutamine is no longer oxidized and accumulates, suggesting that the thiamine diphosphate-dependent alpha-ketoglutarate dehydrogenase activity is impaired. When thiamine (10 microM) is added to the cells, the O2 consumption increases, respiratory control is restored, and normal cell and mitochondrial morphology is recovered within 1 h. Succinate, which is oxidized via the thiamine diphosphate-independent succinate dehydrogenase, is also able to restore a normal O2 consumption (with respiratory control) in digitonin-permeabilized thiamine-deficient cells. Our results therefore suggest that the slowing of the citric acid cycle is the main cause of the biochemical lesion induced by thiamine deficiency as observed in Wernicke's encephalopathy. [less ▲]

Detailed reference viewed: 52 (24 ULg)
Full Text
Peer Reviewed
See detailThiamine Deficiency in Cultured Neuroblastoma Cells: Effect on Mitochondrial Function and Peripheral Benzodiazepine Receptors
Bettendorff, Lucien ULg; Goessens, Guy ULg; Sluse, Francis ULg et al

in Journal of Neurochemistry (1995), 64(5), 2013-2021

When neuroblastoma cells were transferred to a medium of low (6 nM) thiamine concentration, a 16-fold decrease in total intracellular thiamine content occurred within 8 days. Respiration and ATP levels ... [more ▼]

When neuroblastoma cells were transferred to a medium of low (6 nM) thiamine concentration, a 16-fold decrease in total intracellular thiamine content occurred within 8 days. Respiration and ATP levels were only slightly affected, but addition of a thiamine transport inhibitor (amprolium) decreased ATP content and increased lactate production. Oxygen consumption became low and insensitive to oligomycin and uncouplers. At least 25% of mitochondria were swollen and electron translucent. Cell mortality increased to 75% within 5 days. [3H]PK 11195, a specific ligand of peripheral benzodiazepine receptors (located in the outer mitochondrial membrane) binds to the cells with high affinity (KD = 1.4 +/- 0.2 nM). Thiamine deficiency leads to an increase in both Bmax and KD. Changes in binding parameters for peripheral benzodiazepine receptors may be related to structural or permeability changes in mitochondrial outer membranes. In addition to the high-affinity (nanomolar range) binding site for peripheral benzodiazepine ligands, there is a low-affinity (micromolar range) saturable binding for PK 11195. At micromolar concentrations, peripheral benzodiazepines inhibit thiamine uptake by the cells. Altogether, our results suggest that impairment of oxidative metabolism, followed by mitochondrial swelling and disorganization of cristae, is the main cause of cell mortality in severely thiamine-deficient neuroblastoma cells. [less ▲]

Detailed reference viewed: 33 (13 ULg)
Full Text
Peer Reviewed
See detailThiamine Homeostasis in Neuroblastoma Cells
Bettendorff, Lucien ULg

in Neurochemistry International (1995), 26(3), 295-302

We recently showed that thiamine uptake by neuroblastoma cells is mediated by two saturable transport system: the first with high affinity for thiamine (Km = 35 nM) is blocked by veratridine; the other ... [more ▼]

We recently showed that thiamine uptake by neuroblastoma cells is mediated by two saturable transport system: the first with high affinity for thiamine (Km = 35 nM) is blocked by veratridine; the other, with low affinity is blocked by Ca2+. The driving force for thiamine uptake is its phosphorylation to thiamine diphosphate (TDP) by thiamine pyrophosphokinase and subsequent binding of this cofactor to apoenzymes. Our results suggest that cells of neuronal origin possess mechanisms regulating the intracellular concentration of thiamine. At low external thiamine, the vitamin is taken up by a high-affinity transporter and pyrophosphorylated in thiamine diphosphate (TDP): this is the TDP pool of slow turnover. An intraover extracellular concentration gradient of free thiamine is observed at low external concentration of the vitamin. At higher external thiamine concentration, TDP accumulation is limited by the binding capacity to the apoenzymes and unbound TDP (i.e. a small pool of fast turnover) is quickly hydrolyzed. Thiamine is slowly released by the cells by at least two different mechanisms. The first, accounting for a maximum of 50% of total thiamine release, is stimulated by external thiamine and is blocked by veratridine, suggesting that it is a self-exchange mechanism catalyzed by the high affinity thiamine transporter. The remaining thiamine efflux is neither sensitive to veratridine nor to Ca2+ and its mechanism is unknown. About 25% of intracellular thiamine is not released, even after treatment of the cells with digitonin, thus maintaining an apparent gradient. This suggests a binding or sequestration in intracellular compartments.(ABSTRACT TRUNCATED AT 250 WORDS) [less ▲]

Detailed reference viewed: 22 (1 ULg)
Peer Reviewed
See detailAn Atypical Anion Transporter Functioning at Acid pH in Neuroblastoma Cells
Bettendorff, Lucien ULg; Margineanu, Ilca; Wins, Pierre et al

in Biochemical and Biophysical Research Communications (1995), 207(1), 375-381

At pH 7.4, 36Cl- uptake by neuroblastoma cells was Na(+)-independent, saturable and blocked by submicromolar concentrations of DIDS. This suggests that at this pH, Cl- transport is mediated by an ... [more ▼]

At pH 7.4, 36Cl- uptake by neuroblastoma cells was Na(+)-independent, saturable and blocked by submicromolar concentrations of DIDS. This suggests that at this pH, Cl- transport is mediated by an exchanger analogous to erythroid band 3. At pH 6. [less ▲]

Detailed reference viewed: 14 (8 ULg)
See detailTransport and metabolism of thiamine
Bettendorff, Lucien ULg

Scientific conference (1994)

Detailed reference viewed: 6 (0 ULg)
Full Text
Peer Reviewed
See detailThiamine in Excitable Tissues: Reflections on a Non-Cofactor Role
Bettendorff, Lucien ULg

in Metabolic Brain Disease (1994), 9(3), 183-209

Detailed reference viewed: 15 (1 ULg)
Full Text
Peer Reviewed
See detailThe Compartmentation of Phosphorylated Thiamine Derivatives in Cultured Neuroblastoma Cells
Bettendorff, Lucien ULg

in Biochimica et Biophysica Acta (1994), 1222(1), 7-14

Thiamine transport in cultured neuroblastoma cells is mediated by a high-affinity carrier (KM = 40 nM). In contrast, the uptake of the more hydrophobic sulbutiamine (isobutyrylthiamine disulfide) is ... [more ▼]

Thiamine transport in cultured neuroblastoma cells is mediated by a high-affinity carrier (KM = 40 nM). In contrast, the uptake of the more hydrophobic sulbutiamine (isobutyrylthiamine disulfide) is unsaturable and its initial transport rate is 20-times faster than for thiamine. In the cytoplasm, sulbutiamine is rapidly hydrolyzed and reduced to free thiamine, the overall process resulting in a rapid and concentrative thiamine accumulation. Incorporation of radioactivity from [14C]thiamine or [14C]sulbutiamine into intracellular thiamine diphosphate is slow in both cases. Despite the fact that the diphosphate is probably the direct precursor for both thiamine monophosphate and triphosphate, the specific radioactivity increased much faster for the latter two compounds than for thiamine diphosphate. This suggests the existence of two pools of thiamine diphosphate, the larger one having a very slow turnover (about 17 h); a much smaller, rapidly turning over pool would be the precursor of thiamine mono- and triphosphate. The turnover time for thiamine triphosphate could be estimated to be 1-2 h. When preloading the cells with [14C]sulbutiamine was followed by a chase with the same concentration of the unlabeled compound, the specific radioactivities of thiamine and thiamine monophosphate decreased exponentially as expected, but labeling of the diphosphate continued to increase slowly. Specific radioactivity of thiamine triphosphate increased first, but after 30 min it began to slowly decrease. These results show for the first time the existence of distinct thiamine diphosphate pools in the same homogeneous cell population. They also suggest a complex compartmentation of thiamine metabolism. [less ▲]

Detailed reference viewed: 25 (2 ULg)
Full Text
Peer Reviewed
See detailMechanism of Thiamine Transport in Neuroblastoma Cells. Inhibition of a High Affinity Carrier by Sodium Channel Activators and Dependence of Thiamine Uptake on Membrane Potential and Intracellular Atp
Bettendorff, Lucien ULg; Wins, Pierre

in Journal of Biological Chemistry (1994), 269(20), 14379-14385

Nerve cells are particularly sensitive to thiamine deficiency. We studied thiamine transport in mouse neuroblastoma (Neuro 2a) cells. At low external concentration, [14C]thiamine was taken up through a ... [more ▼]

Nerve cells are particularly sensitive to thiamine deficiency. We studied thiamine transport in mouse neuroblastoma (Neuro 2a) cells. At low external concentration, [14C]thiamine was taken up through a saturable high affinity mechanism (Km = 35 nM). This was blocked by low concentrations of the Na+ channel activators veratridine (IC50 = 7 +/- 4 microM) and batrachotoxin (IC50 = 0.9 microM). These effects were not antagonized by tetrodotoxin and were also observed in cell lines devoid of Na+ channels, suggesting that these channels are not involved in the mechanism of inhibition. At high extracellular concentrations, thiamine uptake proceeds essentially via a low affinity carrier (Km = 0.8 mM), insensitive to veratridine but blocked by divalent cations. In both cases, the uptake was independent on external sodium, partially inhibited (10-35%) by depolarization and sensitive to metabolic inhibitors. A linear relationship between the rate of thiamine transport and intracellular ATP concentration was found. When cells grown in a medium of low thiamine concentration (6 nM) were exposed to 100 nM extracellular thiamine, a 3-fold increase in intracellular thiamine diphosphate was observed after 2 h while the concomitant increase in intracellular free thiamine was barely significant. These data suggest a secondary active transport of thiamine, the main driving force being thiamine phosphorylation rather than the sodium gradient. [less ▲]

Detailed reference viewed: 25 (1 ULg)
Peer Reviewed
See detailChloride Permeability of Rat Brain Membrane Vesicles Correlates with Thiamine Triphosphate Content
Bettendorff, Lucien ULg; Hennuy, Benoît ULg; De Clerck, Anne et al

in Brain Research (1994), 652(1), 157-160

Incubation of rat brain homogenates with thiamine or thiamine diphosphate (TDP) leads to a synthesis of thiamine triphosphate (TTP). In membrane vesicles subsequently prepared from the homogenates ... [more ▼]

Incubation of rat brain homogenates with thiamine or thiamine diphosphate (TDP) leads to a synthesis of thiamine triphosphate (TTP). In membrane vesicles subsequently prepared from the homogenates, increased TTP content correlates with increased 36Cl- uptake. A hyperbolic relationship was obtained with a K0.5 of 0.27 nmol TTP/mg protein. In crude mitochondrial fractions from the brains of animals previously treated with thiamine or sulbutiamine, a positive correlation between 36Cl- uptake and TTP content was found. These results, together with other results previously obtained with the patch-clamp technique, suggest that TTP is an activator of chloride channels having a large unit conductance. [less ▲]

Detailed reference viewed: 38 (3 ULg)
Full Text
Peer Reviewed
See detailSubcellular Localization and Compartmentation of Thiamine Derivatives in Rat Brain
Bettendorff, Lucien ULg; Wins, Pierre; Lesourd, Monique

in Biochimica et Biophysica Acta (1994), 1222(1), 1-6

The subcellular distribution of thiamine derivatives in rat brain was studied. Thiamine diphosphate content was highest in the mitochondrial and synaptosomal fractions, and lowest in microsomal, myelin ... [more ▼]

The subcellular distribution of thiamine derivatives in rat brain was studied. Thiamine diphosphate content was highest in the mitochondrial and synaptosomal fractions, and lowest in microsomal, myelin and cytosolic fractions. Only 3-5% of total thiamine diphosphate was bound to transketolase, a cytosolic enzyme. Thiamine triphosphate was barely detectable in the microsomal and cytosolic fraction, but synaptosomes were slightly enriched in this compound compared to the crude homogenate. Both myelin and mitochondrial fractions contained significant amounts of thiamine triphosphate. In order to estimate the relative turnover rates of these compounds, the animals received an intraperitoneal injection of either [14C]thiamine or [14C]sulbutiamine (isobutyrylthiamine disulfide) 1 h before decapitation. The specific radioactivities of thiamine compounds found in the brain decreased in the order: thiamine > thiamine triphosphate > thiamine monophosphate > thiamine diphosphate. Incorporation of radioactivity into thiamine triphosphate was more marked with [14C]sulbutiamine than with [14C]thiamine. The highest specific radioactivity of thiamine diphosphate was found in the cytosolic fraction of the brain, though this pool represents less than 10% of total thiamine diphosphate. Cytosolic thiamine diphosphate had a twice higher specific radioactivity when [14C]sulbutiamine was used as precursor compared with thiamine though no significant differences were found in the other cellular compartments. Our results suggest the existence of two thiamine diphosphate pools: the bound cofactor pool is essentially mitochondrial and has a low turnover; a much smaller cytosolic pool (6-7% of total TDP) of high turnover is the likely precursor of thiamine triphosphate. [less ▲]

Detailed reference viewed: 24 (2 ULg)
Full Text
Peer Reviewed
See detailMetabolism of Thiamine Triphosphate in Rat Brain: Correlation with Chloride Permeability
Bettendorff, Lucien ULg; Peeters, Maryline; Wins, Pierre et al

in Journal of Neurochemistry (1993), 60(2), 423-434

Our results show that a net synthesis of thiamine triphosphate (TTP) can be demonstrated in vitro using rat brain extracts. The total homogenate was preincubated with thiamine or its diphosphate ... [more ▼]

Our results show that a net synthesis of thiamine triphosphate (TTP) can be demonstrated in vitro using rat brain extracts. The total homogenate was preincubated with thiamine or its diphosphate derivative (TDP), centrifuged, and washed twice. With TDP (1 mM) as substrate, a 10-fold increase in TTP content was observed in this fraction (nuclear fraction, membrane vesicles). A smaller, but significant, increase was observed in the P2 fraction (mitochondrial/synaptosomal fraction). In view of the low TTP content of our fractions, it was carefully assessed that authentic TTP was being formed. Incorporation of radioactivity from [beta-32P]TDP and [gamma-32P]ATP in TTP suggests that these two compounds are its precursors. Furthermore, TTP synthesis was inhibited by ADP and relatively low concentrations of Zn2+. These results suggest that TTP synthesis is catalyzed by an ATP:TDP transphosphorylase rather than by the cytoplasmic adenylate kinase that may be present in the vesicles. After osmotic lysis of the vesicles at alkaline pH, TTP was recovered in protein-bound form. Concomitantly, a soluble thiamine triphosphatase, with alkaline pH optimum, was also released from the vesicles. No net synthesis could be obtained in the cytosolic fraction or in detergent-solubilized systems. Like TTP synthesis, chloride permeability of the vesicles was increased when the homogenate had been incubated with thiamine and particularly with TDP. Our results suggest a regulatory role of TTP on chloride permeability, but the target remains to be characterized. [less ▲]

Detailed reference viewed: 23 (1 ULg)
Peer Reviewed
See detailThiamine Triphosphate Activates an Anion Channel of Large Unit Conductance in Neuroblastoma Cells
Bettendorff, Lucien ULg; Kolb, Hans-Albert; Schoffeniels, E.

in Journal of Membrane Biology (1993), 136(3), 281-8

In neuroblastoma cells, the intracellular thiamine triphosphate (TTP) concentration was found to be about 0.5 microM, which is several times above the amount of cultured neurons or glial cells. In inside ... [more ▼]

In neuroblastoma cells, the intracellular thiamine triphosphate (TTP) concentration was found to be about 0.5 microM, which is several times above the amount of cultured neurons or glial cells. In inside-out patches, addition of TTP (1 or 10 microM) to the bath activated an anion channel of large unit conductance (350-400 pS) in symmetrical 150 mM NaCl solution. The activation occurred after a delay of about 4 min and was not reversed when TTP was washed out. A possible explanation is that the channel has been irreversibly phosphorylated by TTP. The channel open probability (Po) shows a bell-shaped behavior as a function of pipette potential (Vp). Po is maximal for -25 mV < Vp < 10 mV and steeply decreases outside this potential range. From reversal potentials, permeability ratios of PCl/PNa = 20 and PCl/Pgluconate = 3 were estimated. ATP (5 mM) at the cytoplasmic side of the channel decreased the mean single channel conductance by about 50%, but thiamine derivatives did not affect unit conductance; 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (0.1 mM) increased the flickering of the channel between the open and closed state, finally leading to its closure. Addition of oxythiamine (1 mM), a thiamine antimetabolite, to the pipette filling solution potentiates the time-dependent inactivation of the channel at Vp = -20 mV but had the opposite effect at +30 mV. This finding corresponds to a shift of Po towards more negative resting membrane potentials. These observations agree with our previous results showing a modulation of chloride permeability by thiamine derivatives in membrane vesicles from rat brain. [less ▲]

Detailed reference viewed: 20 (3 ULg)