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Biomedical subjects

C Billard

Publications and source records attributed to C Billard.

At least 19 recordsLinked to original sources
PubMed2001

Biological activity of soluble CD100. II. Soluble CD100, similarly to H-SemaIII, inhibits immune cell migration.

CD100 is a human 150-kDa homodimer expressed at the surface of most hemopoietic cells, and its gene belongs to the Ig and semaphorin gene families. Semaphorin genes encode soluble and membrane-bound proteins, most of which have been shown to act as chemorepellents on growth cone guidance. CD100 is discrete, as it is a transmembrane leukocyte surface molecule that can also exist in a soluble form. While our previous studies using mAbs suggested that the transmembrane form of CD100 plays a role in lymphocyte activation, no function was shown for its soluble form. Here, we investigated the effect of soluble CD100 in a cell migration assay; both CD100 spontaneously shed from a stable transfectant and soluble recombinant CD100 inhibited spontaneous and chemokine-induced migration of human monocytes. Interestingly, only the dimeric form of CD100 exerted an effect. Moreover, soluble CD100 inhibited migration of cells from monocytic and B cell lineages. A similar inhibitory effect on migration was observed with H-SemaIII, but not H-SemaIV, semaphorins. In addition, both CD100 and H-SemaIII were recognized by two CD100 mAbs in an ELISA, and one of these mAb abolished the inhibitory effect of each of these semaphorins. We also provide evidence that CD100 and H-SemaIII act through the same receptor on immune cells, which is not neuropilin-1. Furthermore, we describe a function on immune cells for H-SemaIII, a semaphorin to date only studied in the nervous system.

3T3 Cells↗
PubMed2001

Domoic acid accumulation in French shellfish in relation to toxic species of Pseudo-nitzschia multiseries and P. pseudodelicatissima.

Within the French phytoplankton monitoring network (REPHY), domoic acid (DA), the toxin responsible for amnesic shellfish poisoning, was first detected in samples collected in 1998. Toxin analysis by the official method [liquid chromatography with diode array detection (LC/DAD)] was performed when Pseudo-nitzschia cell concentration was greater than 1.0 x 10(5) cells/l. LC/DAD results obtained in 1999 and 2000 showed increased DA accumulation in bivalves sampled at different sites along French coasts. The toxin maximum in 1999 was 3.2 microg DA/g of whole tissue, whereas the levels in 2000 (53 microg) were above the sanitary threshold (20 microg DA/g tissue). Phytoplankton samples collected during blooms were observed by both light and scanning electron microscopy (SEM). Identification of phytoplankton species by SEM analyses confirmed the presence of two known DA-producing species, P. pseudodelicatissima and P. multiseries. LC/DAD results for a mass culture of P. multiseries indicated that this species was involved in DA accumulation in French shellfish.

Animals↗
PubMed2001

Vagal nerve stimulation in tuberous sclerosis complex patients.

This is an open-label, retrospective, multicenter study to determine the outcome of intermittent stimulation of the left vagal nerve in children with tuberous sclerosis complex and medically refractory epilepsy. The records of all children treated with vagal nerve stimulation were reviewed in five pediatric epilepsy centers to locate those with tuberous sclerosis complex who had been treated with vagal nerve stimulation for at least 6 months. These patients were compared with (1) a series of patients obtained from the literature, (2) 10 similar control patients with epilepsy obtained from a registry of patients receiving vagal nerve stimulation, and (3) four published series of tuberous sclerosis complex patients whose epilepsy was surgically managed. Ten tuberous sclerosis complex patients with medically refractory epilepsy treated with vagal nerve stimulation were found. Nine experienced at least a 50% reduction in seizure frequency, and half had a 90% or greater reduction in seizure frequency. No adverse events were encountered. Comparison with published and registry patients revealed improved seizure control in the tuberous sclerosis complex patients. Comparison with the group undergoing seizure surgery demonstrated improved outcomes after surgery. Vagal nerve stimulation appears to be an effective and well-tolerated adjunctive therapy in patients with tuberous sclerosis complex and seizures refractory to medical therapy. Resective surgery has a better prospect for improved seizure control.

Adolescent↗
PubMed2001

[Identification of language disorders in children. A contribution to the prevention of illiteracy].

Early identification of disorders of oral and written language development is essential for effective action before the vicious circle of educational failure and established psychosocial consequences. There has been growing awareness among health and education professionals that the means of recognizing, treating and teaching children with specific oral and written language disorders are inadequate. There is still a limited number of diagnostic tools that have not been fully evaluated. Nevertheless, considerable effort has been made in recent years to develop instruments for early detection and precise diagnostic evaluation. Developments in cognitive neuropsychology provide new approaches for the management of these disorders.

Child, Preschool↗
PubMed2001

[BREV: a new clinical scale for the evaluation of cognitive function in school-age and preschool-age children].

BREV (Batterie Rapide d'Evaluation des fonctions cognitives) is a new evaluation test for the screening of cognitive disorders in 4-9-year-old children, based on a neuropsychological process. It is made up of 17 subtests which have been carefully standardized. It is not an intelligence test but a tool for children' health professionals to use as a rapid neuropsychological screening test. It is particularly recommended for any child with a school learning disorder or neurological history with a high risk of cognitive disturbances such as epilepsy. It may also be used as a systematic screening test.

Child↗
PubMed2000

Switch in the protein tyrosine phosphatase associated with human CD100 semaphorin at terminal B-cell differentiation stage.

Human CD100, the first semaphorin identified in the immune system, is a transmembrane protein involved in T-cell activation. In the present study, we showed that activation of peripheral blood or tonsillar B lymphocytes induced the expression of CD100 in CD38(+)CD138(-) cell populations, including in CD148(+) subpopulations, thus expressing a memory B-cell-like phenotype. Using an in vitro enzymatic assay, we found that protein tyrosine phosphatase (PTP) activities were immunoprecipitated with CD100 in these cell populations, which were isolated by cell sorting, as well as in most B-cell lines representing various stages of B-cell differentiation. Immunodepletion and Western blotting experiments demonstrated that CD45 was the PTP associated with CD100 in cell lines displaying pre-B, activated B, and pre-plasma cell phenotypes. CD45 also accounted for PTP activity immunoprecipitated with CD100 in CD38(+)CD138(-) cells sorted after activation of peripheral blood or tonsillar B lymphocytes. In contrast, no CD100-CD45 association was observed in plasma cell lines corresponding to the terminal B-cell differentiation stage. CD148, the other transmembrane PTP known to be implicated in lymphocyte signaling pathways, was either only partly involved in the CD100-associated PTP activity or not expressed in plasma cell lines, indicating the association of CD100 with another main PTP. Our data show that CD100 is differentially expressed and can functionally associate with distinct PTPs in B cells depending on their activation and maturation state. They also provide evidence for a switch in the CD100-associated PTP at terminal stage of B-cell differentiation.

ADP-ribosyl Cyclase↗
PubMed2000

Severe cognitive impairment in DMD: obvious clinical indication for Dp71 isoform point mutation screening.

Duchenne muscular dystrophy is associated with variable degrees of selective cognitive defect with lower scores for verbal intelligence and reading abilities. A number of findings have shown that rearrangements located in the second part of the gene seem to be preferentially associated with cognitive impairment. Several dystrophin transcripts are expressed in the brain. The more distal of them, Dp71, is predominant. We have carried out a mutational analysis of Dp71 transcript in 12 DMD patients severely, mildly or not retarded, all without detectable deletion or duplication. We have detected five point mutations causing Dp71 premature translation termination. All were found among the more severely mentally retarded patients of this group (VIQ < 50 and/or no reading acquisition).

Adolescent↗
PubMed2000

Continuous spikes and waves during slow sleep (CSWS): outcome in adulthood.

We report a longitudinal, electroencephalographic and neuropsychological analysis of epilepsy with continuous spikes and waves during slow sleep (CSWS) in a 19 year-old boy. The clinical course fluctuated, with temporary worsening or improvement of the paroxysmal abnormalities, epilepsy and cognitive functions. At the end of the follow-up period, seizures persisted. Evaluation of the boy's behaviour, language and cognitive function suggested a dysexecutive syndrome. We discuss the relationship between paroxysmal abnormalities and neuropsychological disorders.

Adult↗
PubMed1999

A placebo-controlled trial of lamotrigine add-on therapy for partial seizures in children. Lamictal Pediatric Partial Seizure Study Group.

OBJECTIVE: To compare the safety and efficacy of add-on lamotrigine and placebo in the treatment of children and adolescents with partial seizures. BACKGROUND: Add-on and monotherapy lamotrigine is safe and effective in adults with partial seizures, and reports of preliminary uncontrolled trials suggest similar benefits in children. METHODS: We studied 201 children with diagnoses of partial seizures of any subtype currently receiving stable conventional regimens of antiepileptic therapy at 40 study sites in the United States and France. After a baseline observation period (to confirm that more than four seizures occurred in each of two consecutive 4-week periods), patients were randomized to add-on lamotrigine or placebo therapy. A 6-week dose-escalation period was followed by a 12-week maintenance period. RESULTS: Compared with placebo, lamotrigine significantly reduced the frequency of all partial seizures and the frequency of secondarily generalized partial seizures in these treatment-resistant patients. The most commonly reported adverse events in the lamotrigine-treated patients were vomiting, somnolence, and infection; the frequency of these and other adverse events was similar to that in the placebo-treated group, with the exception of ataxia, dizziness, tremor, and nausea, which were more frequent in the lamotrigine-treated group. The frequency of withdrawals for adverse events was similar between groups. Two patients were hospitalized for skin rash, which resolved after discontinuation of lamotrigine therapy. CONCLUSIONS: Lamotrigine was effective for the adjunctive treatment of partial seizures in children and demonstrated an acceptable safety profile.

Adolescent↗
PubMed1999

[Symptoms of epilepsy in the child].

Convulsions and epilepsy in the child include widely diverse disorders, ranging from simple and benign to complex and severe. Initially, the general practitioner must consider the various diagnoses in order to prescribe appropriate investigations and treatment (now complex and numerous), or to orient the diagnosis. In the case of paroxysm, the initial step is to affirm the diagnosis of epileptic seizure, especially on the basis of the descriptions made by the child and by witnesses, possibly with the aid of an EEG. The second step is to determine the etiology, differentiating isolated seizures occurring in a particular context (for example febrile convulsions) from epileptic seizures with no special context. The description of the seizure and the inter-critical EEG lead to classifying the seizure as partial or generalised and, if it is repeated, to consider it as composing one of the childhood epileptic syndromes.

Child↗
PubMed1999

[Benign infantile convulsions. French collaborative study].

BACKGROUND: Benign infantile non febrile seizures are not well known, leading us to study their clinical and EEG characteristics. METHODS: Between 1981 and 1994, we assembled 34 patients with the following inclusion criteria: non febrile seizures between 1 month and 2 years of age, normal personal history, no abnormality on clinical, biological and radiological investigations, normal developmental outcome with at least 1 year follow-up. RESULTS: These 34 patients were recognized as 14 familial cases (identical seizures affecting parents) and 11 non familial cases. The other nine cases had different or undefined epilepsy in the family. The clinical and EEG characteristics were the same: at the mean age of 6 months, brief partial seizures (often secondarily or apparently generalized) occurring in a cluster of two to 12 episodes a day for a mean duration of 2.5 days, with ictal EEG showing focal discharge, often slow waves or focal spikes on post-ictal tracing and normal interictal EEG. CONCLUSION: The clinical and EEG characteristics are important in order to recognize this type of infantile convulsions (familial or not familial), which have a good prognosis and need no aggressive treatment.

Age of Onset↗
PubMed1999

[Epilepsy due to mesiotemporal sclerosis in children: 10 cases].

BACKGROUND: Mesio-temporal sclerosis is a frequent and probably underestimated cause of resistant temporal epilepsy in childhood. PATIENTS AND METHODS: Ten patients originating from West and North-East France are reported in this retrospective study. They were referred for partial temporal epilepsy which had begun between the ages of 3.5 and 15 years. Mesio-temporal sclerosis was diagnosed on MRI (ten cases) and on neuropathological examination (three cases). RESULTS: Complex partial seizures were noted in all patients, with most frequently fear, abnormal epigastric perception and oro-alimentary automatisms. Social and educational issues were altered due to frequent seizures and amnesic disturbances. An initial event, always a complex febrile seizure, was found in six patients. MRI study showed in all patients unilateral hippocampal atrophy and/or an increase in hippocampal T2 signal intensity on coronal sections. Ictal EEG showed homolateral temporal seizures six times. Hippocampo-amygdalectomy was performed in three patients with a good outcome. CONCLUSION: Epilepsy associated with mesio-temporal sclerosis belongs to intractable epilepsy in childhood. Early recognition of its symptoms would allow early pre-operative assessment in order to minimize developmental defects due to continuing epilepsy, and adverse cognitive effects of anti-epileptics.

Adolescent↗
PubMed1999

Hemispheric specialization using SPECT and stimulation tasks in children with dysphasia and dystrophia.

Developmental dysphasia, a severe childhood learning disorder, is thought to result from problems in hemispheric specialization involving both left and right cerebral hemispheres. Regional cerebral blood flow (rCBF) was measured at rest and during stimulation of both hemispheres independently: dichotic listening for the left, dichaptic palpation for the right. Eight right-handed boys with expressive dysphasia, aged 8 to 12 years, were investigated using SPECT and compared with eight right-handed age-matched boys with Duchenne muscular dystrophy with reading disorders but normal speech. rCBF values at rest were also compared with those of five right-handed age-matched normal boys. In the dichotic task, children with dysphasia differed from children with dystrophia by failure to increase rCBF in the left hemisphere, in Broca's area, but rCBF increased in the right hemisphere, in the region homologous to Broca's area. In the dichaptic task, rCBF increased bilaterally for children with dysphasia whereas in children with dystrophia rCBF increased only in the right hemisphere. At rest the physiological asymmetry was reversed in favor of the right hemisphere in all areas except Broca's area. Surprisingly, the same applied at rest and for all areas in children with dystrophia. These results confirm that functional specialization of both hemispheres is impaired in developmental dysphasia. Moreover, they suggest that learning disabilities associated with Duchenne muscular dystrophy could also be related to abnormal hemispheric specialization.

Adolescent↗
PubMed1999

Recurrence of the T666M calcium channel CACNA1A gene mutation in familial hemiplegic migraine with progressive cerebellar ataxia.

Familial hemiplegic migraine (HM) is an autosomal dominant migraine with aura. In 20% of HM families, HM is associated with a mild permanent cerebellar ataxia (PCA). The CACNA1A gene encoding the alpha1A subunit of P/Q-type voltage-gated calcium channels is involved in 50% of unselected HM families and in all families with HM/PCA. Four CACNA1A missense mutations have been identified in HM: two in pure HM and two in HM/PCA. Different CACNA1A mutations have been identified in other autosomal dominant conditions: mutations leading to a truncated protein in episodic ataxia type 2 (EA2), small expansions of a CAG trinucleotide in spinocerebellar ataxia type 6 and also in three families with EA2 features, and, finally, a missense mutation in a single family suffering from episodic ataxia and severe progressive PCA. We screened 16 families and 3 nonfamilial case patients affected by HM/PCA for specific CACNA1A mutations and found nine families and one nonfamilial case with the same T666M mutation, one new mutation (D715E) in one family, and no CAG repeat expansion. Both T666M and D715E substitutions were absent in 12 probands belonging to pure HM families whose disease appears to be linked to CACNA1A. Finally, haplotyping with neighboring markers suggested that T666M arose through recurrent mutational events. These data could indicate that the PCA observed in 20% of HM families results from specific pathophysiologic mechanisms.

Calcium Channels↗
PubMed1999

Neuropsychologic and adaptive functioning in adolescents and young adults shunted for congenital hydrocephalus.

The major aim of this study was to assess whether the syndrome of nonverbal learning disabilities described in hydrocephalic children is observed in adulthood. Eleven adults shunted for congenital hydrocephalus related to spina bifida and eight adults shunted for hydrocephalus related to aqueductal stenosis were administered an extensive neuropsychologic battery to investigate discrepancies between verbal and visuospatial cognition, verbal and visuospatial long-term memory, and psycho-social adaptive abilities. The results showed no discrepancies between Wechsler Performance IQ or Verbal IQ in either hydrocephalic group. Nevertheless, the subjects with spina bifida appeared more cognitively impaired than the subjects with aqueductal stenosis, who performed normally on the Wechsler Adult Intelligence Scale-Revised. Memory assessment using Signoret's Memory Battery revealed no discrepancy between verbal and visuospatial memory in the hydrocephalic group. Nevertheless, the subjects with spina bifida had poorer verbal and visuospatial memory performance than the subjects with aqueductal stenosis. There were no differences on the Vineland Adaptive Behavioral Scale between subjects with spina bifida and those with aqueductal stenosis in autonomy, socialization, and daily living skills. These results suggest that shunted congenital hydrocephalus is not characterized by nonverbal learning disabilities syndrome in adolescence or in adulthood.

Adaptation, Psychological↗