A. Biraben - Academia.edu (original) (raw)

Papers by A. Biraben

Research paper thumbnail of Haplotype study of West European and North African Unverricht-Lundborg chromosomes: evidence for a few founder mutations

Human Genetics, 2002

Unverricht-Lundborg disease (ULD) is a progressive myoclonus epilepsy common in Finland and North... more Unverricht-Lundborg disease (ULD) is a progressive myoclonus epilepsy common in Finland and North Africa, and less common in Western Europe. ULD is mostly caused by expansion of a dodecamer repeat in the cystatin B gene ( CSTB) promoter. We performed a haplotype study of ULD chromosomes (ULDc) with the repeat expansion. We included 48 West European Caucasian (WEC) and 47 North African (NA) ULDc. We analysed eight markers flanking CSTB(GT10-D21S1890-D21S1885-D21S2040-D21S1259- CSTB-D21S1912-PFKL-D21S171) and one intragenic variant in the CSTB 3' UTR (A2575G). We observed a founder effect in most of the NA ULD patients, as 61.7% of the NA ULDc (29/47) shared the same haplotype, A1 (1-1-A-1-6-7), for markers D21S1885-D21S2040-A2575G-D21S1259-D21S1912-PFKL. Moreover, if we considered only the markers D21S1885, D21S2040, A2575G and D21S1259, 43 of the 47 NA ULDc shared the same alleles 1-1-A-1, haplotype A. As previously shown, the WEC ULDc were heterogeneous. However, the Baltic haplotype, A3 (5-1-1-A-1-1), was observed in ten WEC ULDc (20.8%) and the CSTB 3'UTR variant, which we called the Alps variant, was observed in 17 ULDc (35.4%). Finally, as almost all NA patients, like Scandinavian patients, were of the haplotype A, we assumed that there was an ancient common founder effect in NA and Baltic ULD patients. We estimated that the putative most recent common ancestral ULD carrier with this haplotype A must have existed about 2,500 years ago (100-150 generations). Finally, this work provides evidence for the existence of only a small number of founder mutations in ULD.

Research paper thumbnail of Basal ganglia involvement in temporal lobe epilepsy: A functional and morphologic study

Neurology, 2008

A decrease of [(18)F]fluoro-l-dopa uptake in basal ganglia was recently reported in medically ref... more A decrease of [(18)F]fluoro-l-dopa uptake in basal ganglia was recently reported in medically refractory epilepsy. The purpose of this study was to assess the involvement of dopaminergic neurotransmission in refractory temporal lobe epilepsy (TLE) and its relationship to glucose metabolism and morphologic changes. Twelve TLE patients were studied using [(18)F]fluorodeoxyglucose PET, [(18)F]fluoro-l-dopa PET, and MRI and compared with healthy control volunteers. Morphologic cerebral changes were assessed using voxel-based morphometry. Student t test statistical maps of functional and morphologic differences between patients and controls were obtained using a general linear model. In TLE patients, [(18)F]fluoro-l-dopa uptake was reduced to the same extent in caudate and putamen in both cerebral hemispheres as well as in the substantia nigra (SN). These dopaminergic functional alterations occurred without any glucose metabolism changes in these areas. The only mild morphologic abnormality was found in striatal regions without any changes in the SN. The present study provides support for dopaminergic neurotransmission involvement in temporal lobe epilepsy. The discrepancies between gray matter volume atrophy and the pattern of [(18)F]fluoro-l-dopa suggest that basal ganglia involvement is not related to structural subcortical abnormalities. A functional decrease can be ruled out because there was no change of the glycolytic pathway metabolism in these areas.

Research paper thumbnail of Effect of intrathecal baclofen on the monosynaptic reflex in humans: evidence for a postsynaptic action

Journal of Neurology, Neurosurgery & Psychiatry, 1993

Intrathecal baclofen is a very powerful antispastic agent. Its mechanism of action on the monosyn... more Intrathecal baclofen is a very powerful antispastic agent. Its mechanism of action on the monosynaptic H-reflex in spinal patients was investigated. It could inhibit rapidly and profoundly monosynaptic reflexes in lower limbs, but did not modify Ia vibratory inhibition of the soleus H-reflex. To assess more precisely its effect on Ia afferents, an experimental paradigm using Ia heteronymous facilitation of the soleus H-reflex was used. Intrathecal baclofen did not modify the amount of monosynaptic facilitation of the soleus H-reflex brought about by stimulation of the femoral nerve. This demonstrates that the main part of the inhibitory effect of baclofen on the H-reflex in spinal patients is not due to a presynaptic effect, suggesting a postsynaptic site of action.

Research paper thumbnail of Founder Effect in Patients with Unverricht-Lundborg Disease on Reunion Island

Epilepsia, 2003

Purpose: Unverricht-Lundborg disease (ULD) is the most frequent form of progressive myoclonus epi... more Purpose: Unverricht-Lundborg disease (ULD) is the most frequent form of progressive myoclonus epilepsy. ULD is caused mostly by a homozygous expansion of a dodecamer repeat in the cystatin B gene (CSTB) promoter. We present here a clinical and molecular study of 14 ULD patients originating from Reunion Island, a French island in the Indian Ocean.

Research paper thumbnail of Haplotype study of West European and North African Unverricht-Lundborg chromosomes: evidence for a few founder mutations

Human Genetics, 2002

Unverricht-Lundborg disease (ULD) is a progressive myoclonus epilepsy common in Finland and North... more Unverricht-Lundborg disease (ULD) is a progressive myoclonus epilepsy common in Finland and North Africa, and less common in Western Europe. ULD is mostly caused by expansion of a dodecamer repeat in the cystatin B gene ( CSTB) promoter. We performed a haplotype study of ULD chromosomes (ULDc) with the repeat expansion. We included 48 West European Caucasian (WEC) and 47 North African (NA) ULDc. We analysed eight markers flanking CSTB(GT10-D21S1890-D21S1885-D21S2040-D21S1259- CSTB-D21S1912-PFKL-D21S171) and one intragenic variant in the CSTB 3' UTR (A2575G). We observed a founder effect in most of the NA ULD patients, as 61.7% of the NA ULDc (29/47) shared the same haplotype, A1 (1-1-A-1-6-7), for markers D21S1885-D21S2040-A2575G-D21S1259-D21S1912-PFKL. Moreover, if we considered only the markers D21S1885, D21S2040, A2575G and D21S1259, 43 of the 47 NA ULDc shared the same alleles 1-1-A-1, haplotype A. As previously shown, the WEC ULDc were heterogeneous. However, the Baltic haplotype, A3 (5-1-1-A-1-1), was observed in ten WEC ULDc (20.8%) and the CSTB 3'UTR variant, which we called the Alps variant, was observed in 17 ULDc (35.4%). Finally, as almost all NA patients, like Scandinavian patients, were of the haplotype A, we assumed that there was an ancient common founder effect in NA and Baltic ULD patients. We estimated that the putative most recent common ancestral ULD carrier with this haplotype A must have existed about 2,500 years ago (100-150 generations). Finally, this work provides evidence for the existence of only a small number of founder mutations in ULD.

Research paper thumbnail of Basal ganglia involvement in temporal lobe epilepsy: A functional and morphologic study

Neurology, 2008

A decrease of [(18)F]fluoro-l-dopa uptake in basal ganglia was recently reported in medically ref... more A decrease of [(18)F]fluoro-l-dopa uptake in basal ganglia was recently reported in medically refractory epilepsy. The purpose of this study was to assess the involvement of dopaminergic neurotransmission in refractory temporal lobe epilepsy (TLE) and its relationship to glucose metabolism and morphologic changes. Twelve TLE patients were studied using [(18)F]fluorodeoxyglucose PET, [(18)F]fluoro-l-dopa PET, and MRI and compared with healthy control volunteers. Morphologic cerebral changes were assessed using voxel-based morphometry. Student t test statistical maps of functional and morphologic differences between patients and controls were obtained using a general linear model. In TLE patients, [(18)F]fluoro-l-dopa uptake was reduced to the same extent in caudate and putamen in both cerebral hemispheres as well as in the substantia nigra (SN). These dopaminergic functional alterations occurred without any glucose metabolism changes in these areas. The only mild morphologic abnormality was found in striatal regions without any changes in the SN. The present study provides support for dopaminergic neurotransmission involvement in temporal lobe epilepsy. The discrepancies between gray matter volume atrophy and the pattern of [(18)F]fluoro-l-dopa suggest that basal ganglia involvement is not related to structural subcortical abnormalities. A functional decrease can be ruled out because there was no change of the glycolytic pathway metabolism in these areas.

Research paper thumbnail of Effect of intrathecal baclofen on the monosynaptic reflex in humans: evidence for a postsynaptic action

Journal of Neurology, Neurosurgery & Psychiatry, 1993

Intrathecal baclofen is a very powerful antispastic agent. Its mechanism of action on the monosyn... more Intrathecal baclofen is a very powerful antispastic agent. Its mechanism of action on the monosynaptic H-reflex in spinal patients was investigated. It could inhibit rapidly and profoundly monosynaptic reflexes in lower limbs, but did not modify Ia vibratory inhibition of the soleus H-reflex. To assess more precisely its effect on Ia afferents, an experimental paradigm using Ia heteronymous facilitation of the soleus H-reflex was used. Intrathecal baclofen did not modify the amount of monosynaptic facilitation of the soleus H-reflex brought about by stimulation of the femoral nerve. This demonstrates that the main part of the inhibitory effect of baclofen on the H-reflex in spinal patients is not due to a presynaptic effect, suggesting a postsynaptic site of action.

Research paper thumbnail of Founder Effect in Patients with Unverricht-Lundborg Disease on Reunion Island

Epilepsia, 2003

Purpose: Unverricht-Lundborg disease (ULD) is the most frequent form of progressive myoclonus epi... more Purpose: Unverricht-Lundborg disease (ULD) is the most frequent form of progressive myoclonus epilepsy. ULD is caused mostly by a homozygous expansion of a dodecamer repeat in the cystatin B gene (CSTB) promoter. We present here a clinical and molecular study of 14 ULD patients originating from Reunion Island, a French island in the Indian Ocean.