Abductive reasoning on humans/AI interactions in medical contexts

The proposal of this talk is to explain alternatives to obtain ethical reasoning in the humans/AI interactions in medical (especially public health) contexts. One of the ethical problems in AI is the alignment mechanisms between human values and machines automatisms. This research is based on obtaining a system capable to infer from rational human activity in a certain behavior, so it can be captured how a human moves and the way that human beings learn and teach ethical values. One way is mimetic alignment, which are values imitation processes based trough big data preferences analysis, linguistic expressions, etc. However, this approximation commits two mistakes. First, preferences are confused with values, and then the second problem is that naturalistic fallacy is committed. From this point of view, naturalistic fallacy occurs if the research is focused on alignment meaning instead of value one, and the subsequent answer is preference analysis based. Therefore, prescriptions are derivate from descriptions. The chain of reasoning that leads us to commit this fallacy begins with the confusion that values and preferences are equivalent. An alternative proposal is anchored values alignment, which is based on anchoring normative values processes of a machine that has a behavior to interact. Through abductive reasoning, this way of thinking tries to capture the idea that a value is not in any set of things, instead it is some action guiding. The relevance of abduction is its temptative value to project beyond descriptive reasoning as statically one, which it is currently used in works on medical diagnosis precisely for the characteristics that clinical eye needs.

[Prognostic factors and profile in traumatic brain injury in the paediatric age]

INTRODUCTION

Traumatic brain injury (TBI) is a common cause of death and disability in the paediatric population, although the literature on the Spanish population is scarce. From the perspective of early vulnerability, recent research findings suggest that early brain injury has worse sequelae and a higher risk of impact.

AIMS

To analyse the intelligence profile, executive functions and behaviour, and examine the association between age at the time of the injury, severity of the TBI and environmental factors for cognitive and behavioural outcomes.

PATIENTS AND METHODS

Seventy-one participants with moderate to severe TBI, from 6 to 16 years of age, were assessed with measures of intelligence (intelligence quotient), executive functions and behaviour.

RESULTS

Children with TBI are at increased risk of disability in all aspects of intelligence, executive functions and behaviour. Children who suffered a traumatic brain injury in infancy and the preschool period had more overall effects on intelligence quotient and some aspects of the executive functions.

CONCLUSIONS

Socioeconomic and cultural factors are the best predictors for intelligence quotient and behaviour. These findings contribute to a better understanding of the sequelae of TBI in children, which will help in rehabilitation planning and re-adaptation to functional life.

Pharmacokinetics of multiple doses of co-crystal of tramadol-celecoxib: findings from a four-way randomized open-label phase I clinical trial

Aim

We compared the pharmacokinetic (PK) profiles of co‐crystal of tramadol–celecoxib (CTC) vs. each reference product (alone and in open combination) after single (first dose) and multiple dosing.

Methods

Healthy adults aged 18–50 years received, under fasted conditions, 15 twice‐daily doses of the following treatments (separated by ≥14‐day washout): 200 mg immediate‐release (IR) CTC (equivalent to 88 mg tramadol and 112 mg celecoxib; treatment 1); 100 mg IR tramadol (treatment 2), 100 mg celecoxib (treatment 3); and 100 mg IR tramadol and 100 mg celecoxib (treatment 4). The treatment sequence was assigned by computer‐generated randomization. PK parameters were calculated using non‐compartmental analysis. Parameters for CTC were adjusted according to reference product dose.

Results

A total of 30 subjects (20 males, mean age 35 years) were included. Multiple‐dose tramadol PK parameters for treatments 1, 2 and 4, respectively, were 551, 632 and 661 ng ml⁻¹ [mean maximum plasma concentration (C_max)]; 4796, 4990 and 5284 ng h ml⁻¹ (area under the plasma concentration–time curve over the dosing interval at steady state); and 3.0, 2.0 and 2.0 h (median time to C_max at steady state). For treatments 1, 3 and 4, multiple‐dose celecoxib PK parameters were 445, 536 and 396 ng ml⁻¹; 2803, 3366 and 2897 ng h ml⁻¹; and 2.0, 2.0 and 3.0 h. Single‐dose findings were consistent with multiple‐dose data. Types of adverse events were consistent with known reference product safety profiles.

Conclusion

After single (first dose) and multiple dosing, PK parameters for each active pharmaceutical ingredient in CTC were modified by co‐crystallization compared with reference products alone or in open combination.

Single-dose pharmacokinetics of co-crystal of tramadol-celecoxib: Results of a four-way randomized open-label phase I clinical trial in healthy subjects

Aims

Co‐crystal of tramadol–celecoxib (CTC) is a novel co‐crystal molecule containing two active pharmaceutical ingredients under development by Esteve (E‐58425) and Mundipharma Research (MR308). This Phase I study compared single‐dose pharmacokinetics (PK) of CTC with those of the individual reference products [immediate‐release (IR) tramadol and celecoxib] alone and in open combination.

Methods

Healthy adults aged 18–55 years were orally administered four treatments under fasted conditions (separated by 7‐day wash‐out period): 200 mg IR CTC (equivalent to 88 mg tramadol and 112 mg celecoxib; Treatment 1); 100 mg IR tramadol (Treatment 2); 100 mg celecoxib (Treatment 3); and 100 mg IR tramadol and 100 mg celecoxib (Treatment 4). Treatment sequence was assigned using computer‐generated randomization. PK parameters were calculated using noncompartmental analysis with parameters for CTC adjusted according to reference product dose (100 mg).

Results

Thirty‐six subjects (28 male, mean age 36 years) participated. Tramadol PK parameters for Treatments‐1, –2 and –4, respectively, were 263, 346 and 349 ng ml^–1 (mean maximum plasma concentration); 3039, 2979 and 3119 ng h ml^–1 (mean cumulative area under the plasma concentration–time curve); and 2.7, 1.8 and 1.8 h (median time to maximum plasma concentration). For Treatments 1, 3 and 4, the respective celecoxib PK parameters were 313, 449 and 284 ng ml^–1; 2183, 3093 and 2856 ng h ml^–1; and 1.5, 2.3 and 3.0 h. No unexpected adverse events were reported.

Conclusion

PK parameters of each API in CTC were modified by co‐crystallization compared with marketed formulations of tramadol, celecoxib, and their open combination.

[Current state of the attention deficit hyperactivity disorder approach in neuropediatrics]

AIM

To know the current state of the approach of attention deficit hyperactivity disorder (ADHD) in neuropediatricians.

SUBJECTS AND METHODS

A telematic survey was carried out to collect preliminary information on the interest, difficulties in the management and treatment of ADHD to the 437 fellowship of the Neuropediactric Spanish Society (SENEP).

RESULTS

Only 32.49% of the sent questionnaires were answered, with important geographic variability. 97.89% stated that 50% of their consultations were children with learning disabilities and ADHD. Regarding who started treatment for ADHD in their area, the majority answered that the neuropediatrician (57.97%), followed by the child psychiatrist (34.78%) and the primary care pediatrician (5.31%). The lack of a psycho-pedagogical study by the school (49.79%), followed by the lack of time in the consultation (29.11%), was cited as the greatest difficulty in the initial assessment of children with suspected ADHD. Concerning the difficulties in the follow-up, the biggest complaint was the lack of coordination between professionals, the school and parents. And, lastly, regarding the type of treatment use, most patients were on prolonged-release methylphenidate, a stable percentage using immediate release methylphenidate as a single or combined treatment, and in a lower range was the use of clonidine and atomoxetine, and an incipient use of lisdexamphetamine were observed. 80% of the patient showed adherence to pharmacological treatment after one year.

CONCLUSIONS

It is necessary to advance in the training and continuous education of our neuropediatric specialists in ADHD and to homogenize the clinical practice and coordination with education system in the Spanish territory.

Phonon-Modulated Magnetic Interactions and Spin Tomonaga-Luttinger Liquid in the p-Orbital Antiferromagnet CsO2

The magnetic response of antiferromagnetic CsO2, coming from the p-orbital S=1/2 spins of anionic O2(-) molecules, is followed by 133Cs nuclear magnetic resonance across the structural phase transition occurring at T(s1)=61  K on cooling. Above T(s1), where spins form a square magnetic lattice, we observe a huge, nonmonotonic temperature dependence of the exchange coupling originating from thermal librations of O2(-) molecules. Below T(s1), where antiferromagnetic spin chains are formed as a result of p-orbital ordering, we observe a spin Tomonaga-Luttinger-liquid behavior of spin dynamics. These two interesting phenomena, which provide rare simple manifestations of the coupling between spin, lattice, and orbital degrees of freedom, establish CsO2 as a model system for molecular solids.

Food effects on the pharmacokinetics of doxylamine hydrogen succinate 25 mg film-coated tablets: a single-dose, randomized, two-period crossover study in healthy volunteers

BACKGROUND

Doxylamine succinate, an ethanolamine-based antihistamine, is used in the short-term management of insomnia because of its sedative effects. The data available on the pharmacokinetic profile of doxylamine in humans are limited, notwithstanding that this drug has been marketed in European countries for more than 50 years. In fact, no data on the effect of food on the pharmacokinetic parameters of doxylamine are available.

OBJECTIVE

The objective of this study was to evaluate the pharmacokinetic parameters of doxylamine following a single oral dose of doxylamine hydrogen succinate 25 mg in healthy human subjects under fed and fasting conditions.

STUDY DESIGN

This was a single-center, randomized, single-dose, laboratory-blinded, two-period, two-sequence, crossover study.

SETTING

The study was conducted in a phase I clinical unit.

SUBJECTS AND METHODS

A single oral dose of doxylamine hydrogen succinate 25 mg (equivalent to 17.4 mg of doxylamine base) was administered to healthy volunteers under either fed conditions (high-fat, high-calorie food intake) or fasting conditions in each study period. The drug administrations were separated by a wash-out period of seven calendar days. Plasma samples were collected for up to 60 hours postdose, and plasma doxylamine concentrations were determined by a high-performance liquid chromatography method with tandem mass spectrometry detection. Pharmacokinetic parameters were calculated using noncompartmental analysis. Safety was evaluated through assessment of adverse events, standard laboratory evaluations, vital signs, and 12-lead electrocardiography.

RESULTS

In total, 24 healthy subjects (12 male and 12 female) were included in the study. Doxylamine succinate 25 mg tablets exhibited similar oral bioavailability of doxylamine in the fasting state (mean maximum plasma drug concentration [C(max)] 118.21 ng/mL, coefficient of variation [CV] 19.2%; mean area under the plasma concentration time curve from time zero to time t [AUC(t)] 1746.97 ng · h/mL, CV 31.6%) and in the fed state (mean C(max) 120.99 ng/mL, CV 15.0%; mean AUC(t) 1712.20 ng · h/mL, CV 26.7%). No statistically significant between-treatment differences were observed for any of the pharmacokinetic parameters under study. The fed : fasting ratios of the geometric least squares means with corresponding 90% confidence intervals for C(max) and AUC(t) were within the range of 80-125%.

CONCLUSION

High-fat, high-calorie food intake does not affect the kinetics of doxylamine in healthy subjects. The drug was safe and well tolerated by the subjects in this study.

[Genetic bases of attention deficit hyperactivity disorder]

AIMS

The purpose of this study is to update the information available on the main group of genes that have been related with a susceptibility to attention deficit hyperactivity disorder (ADHD) or with the pharmacological response to different drugs used in the treatment of ADHD, in a number of different association and meta-analysis studies.

DEVELOPMENT

Different studies have provided evidence of the importance of the genetic load in the susceptibility to ADHD. The work carried out to date point to genes in the dopaminergic system, such as the gene that codes for the dopamine transporter (DAT1 or SLC6A3) and for the dopamine receptor D4 (DRD4); in the noradrenergic system, like the gene coding for the adrenergic alpha-2A receptor (ADRA2A), the COMT gene, which codes for the enzyme catechol-O-methyltransferase and the gene that codes for latrophilin 3 (LPHN3), as genes that are candidates for playing a part in the susceptibility to ADHD, and being involved in the pharmacological response as well as in the risk of presenting associated behavioural disorders. On the other hand, the genes involved in regulating the metabolism of the drugs used in the treatment of ADHD, such as the gene CYP2D6 and gene CES1, play a role in the efficiency and tolerance of these psycho-pharmaceuticals.

CONCLUSIONS

Although in recent years there has been an increase in the number of pharmacogenetic studies conducted on ADHD, findings differ significantly from one study to another. Integrating and meta-analytical studies are needed to be able to develop a more personalised treatment for ADHD.

[Gastroschisis. Preterm elective cesarean and immediate primary closure: our experience]

PURPOSE

Our experience en treatment of gastroschisis using a protocol with elective preterm delivery by caesarean section at 34-35 weeks and immediate primary abdominal wall closure.

METHODS

During a period of 18 month we treated 5 patients with gastroschisis using the following management pathway: Starting at 30th week of gestation, weekly ultrasound evaluation of fetal gut and pulmonary maturation with corticosteroids. Delivery by elective caesarean section between 34-35 weeks or earlier if evidence of bowel compromise was reported en ultrasound study. Immediate surgical correction after birth with primary closure was preformed under control of abdominal pressure.

RESULTS

Mean gestational age of our patient was 33,94 weeks, and mean birth weight was 2154 gr. None of the cases present inflammatory peel and we found no difficulties for reduction of the gut at time of surgery. Two patients presented an intestinal malrotation. Extubation was preformed 36-48 hours after surgery. We started a trofic diet at 3,6 days and parental nutrition was retired after a mean period of 15,8 days. The mean time of hospital stay was 33,4 days. One patient with intestinal obstruction had a consideriously increased length of hospital stay of 74 days.

CONCLUSIONS

A management pathway for gastroschisis with selective preterm delivery by caesarean section and immediate surgical treatment probably reduces the experience of inflammatory peel. This pathway permits a early initiation of oral feeding, reduces times of parenteral nutrition and need of central catheters, and shortens length of hospital stay.

Analysis of relapses in anti-NMDAR encephalitis

OBJECTIVE

The clinical characteristics of patients with relapsing anti-NMDA receptor (NMDAR) encephalitis are not well-defined. In this study, we report the clinical profile and outcome of relapses in a series of anti-NMDAR encephalitis.

METHODS

We did a retrospective review of relapses that occurred in 25 patients with anti-NMDAR encephalitis. Relapses were defined as any new psychiatric or neurologic syndrome, not explained by other causes, which improved after immunotherapy or, less frequently, spontaneously.

RESULTS

A total of 13 relapses were identified in 6 patients. Four of them had several, 2 to 4, relapses. There was a median delay of 2 years (range 0.5 to 13 years) for the first relapse. Median relapse rate was 0.52 relapses/patient-year. Relapse risk was higher in patients who did not receive immunotherapy in the first episode (p = 0.009). Most cases (53%) presented partial syndromes of the typical anti-NMDAR encephalitis. Main symptoms of relapses were speech dysfunction (61%), psychiatric (54%), consciousness-attention disturbance (38%), and seizures (31%). Three relapses (23%) presented with isolated atypical symptoms suggestive of brainstem-cerebellar involvement. An ovarian teratoma was detected at relapse in only 1 patient (17%). Relapses did not add residual deficit to that caused by the first episode.

CONCLUSIONS

Relapses in anti-NMDAR encephalitis are common (24%). They may occur many years after the initial episode. Relapses may present with partial aspects or with isolated symptoms of the full-blown syndrome. Immunotherapy at first episode reduces the risk of relapses.

[Predictive variables for mental retardation in a Pediatric Epilepsy Monitoring Unit. Neuropsychological assessment]

AIM

We sought to describe the epidemiological and clinical data from our patients in the Pediatric Epilepsy Monitoring Unit (PEMU) of the Sant Joan de Deu Hospital of Barcelona, and determine the variables of risk for mental retardation.

PATIENTS AND METHODS

A retrospective review of PEMU reports and hospital discharge summaries from March 2005 to December 2008 was conducted. The data from patients with intelligence quotient (IQ) estimated, older than 3 years of age and with epileptic electroencephalography (EEG) activity was analyzed in 158 patients (8.8 +/- 5.2 years; 55.1% boys). Of those pediatric patients, 63 had IQ less than 70 and 47 an IQ greater than or equal to 70. Intractable epilepsy was present in all of them.

RESULTS

The percentage of the patients with mental retardation is significantly higher in patients with onset of epilepsy before 24 months (68.3%) than patients with later onset (27.7%). Onset of seizures, EEG findings and epilepsy etiology are significant risk factors for mental retardation.

CONCLUSIONS

Early age at seizure, multifocal epilepsy and cryptogenic etiology are factors of worse prognosis to normal development of cognitive functions in pediatric intractable epilepsy.

[Non-verbal learning disorder: cognitive-behavioural characteristics and neuropsychological aspects]

INTRODUCTION AND DEVELOPMENT

Non verbal learning disorder is a neurological condition which is considered to be a developmental disability. It is characterised by a specific dysfunction in motor, visuospatial and social skills in patients with a normal intellect and development of language. Warning signs in school are poor psychomotor coordination, arithmetic skills and drawing activities. Social judgment and social problem solving are also typically impaired. Furthermore, these patients seem to have increasing risk of emotional disorders.

CONCLUSIONS

Current evidence and theories suggest that dysfunction of white matter in the right hemisphere could be the cause. The clinical characteristics and the diagnostic criteria have not fully agreed on. A comprehensive neuropsychological evaluation reveals specific and heterogeneous patterns of difficulties for each child that would make possible to address and accommodate an educational program.

[Neuropsychological aspects of acquired diffuse brain injury in paediatric childhood]

INTRODUCTION AND DEVELOPMENT

Acquired brain injury is one of the most common causes of long-term disability in childhood and traumatisms are the most prevalent cause. Diffuse axonal injury is associated with poor neuropsychological outcome. In contrast to early focal lesions, young age confers no advantage in the outcome of severe diffuse brain injury. Plasticity is incomplete for structural and functional deficits in children. The traditional view of enhanced reorganization of function after localized brain injury it can't be applied in early severe diffuse brain injury. In the paediatric population where the central nervous system is in a rapid state of growth, developmental factors may mask the difficulties and deficits in certain skills may not be evident until that skill is expected to emerge at a certain age.

CONCLUSION

Like in adults the neuropsychological domains more affected in childhood are psychomotor speed, memory, attention and executive functioning. In childhood neuropsychological deficits will affect learning and adaptive behaviour. Sometimes deficits will be cumulative over time.

[Retrospective diagnosis of congenital infection by cytomegalovirus in the case of one infant]

INTRODUCTION

10-15% of asymptomatic congenital infections by cytomegalovirus (CMV) in the neonatal period develop persistent problems with varying degrees of severity, fundamentally involving neurological disorders, neurosensory hypoacusis and hypovision, which appear from the age of 6-9 months onwards, when a diagnosis is no longer possible. The PCR (polymerase chain reaction) technique can detect DNA of CMV in blood samples on filter paper used for screening hypothyroidism and metabolic pathologies that were kept from the neonatal period.

CASE REPORT

A child aged 3 years and 8 months with delayed intrauterine growth, autism, mental retardation, microcephalus and neurosensory hypoacusis; periventricular calcifications, leukoencephalopathy and bilateral malformation of the temporal lobe; and a diagnosis of congenital CMV confirmed by detection of DNA by PCR in the blood sample on filter paper saved from the neonatal period.

CONCLUSIONS

The retrospective study of congenital infection by CMV should be considered when faced with severity and varying association of delayed intrauterine growth, microcephalus, neurosensory hypoacusis, chorioretinitis, mental retardation, autism or other behavioural disorders, intracranial calcifications, encephaloclastic alterations, leukoencephalopathy, cortical dysplasia and malformations of the temporal lobe and the hippocampus. Since the filter papers from neonatal screening are not kept for ever, perhaps the idea of doing so ought to be considered, given the possibilities they offer for retrospective studies.

Three-dimensional culture of newborn rat utricle using an extracellular matrix promotes formation of a cyst

The vestibule is the end organ devoted to sensing of head movements in space. To function properly, its mechano-receptors require the presence of a unique apical extracellular medium, the endolymph. Numerous studies have elucidated the mechanisms involved in the production and homeostasis of this unique medium and the responses of sensory cells to stimulation. However, anatomical constraints have prevented direct and simultaneous studies of their relationships. The aim of this study was the development of an in vitro model that would allow concomitant investigations on maturation and physiological properties of both the hair cells and their endolymphatic compartment. A three-dimensional (3D) culture of newborn rat utricles using an extracellular matrix sustaining 3D cellular growth was developed during 3, 6, or 10 days in vitro (DIV). Using morphological and electrophysiological techniques, we describe the de novo formation of a cyst. It was composed of the sensory epithelium and non-sensory cells-canalar, dark and intermediate cells-that polarized so that their apical surface faced its lumen. During the time of culture, the utricular potential (UP) was steady (-1.1+/-5.0 mV) in oxygenated condition, while in anoxia, the UP significantly decreased to -8.4+/-1.0 mV at 8 DIV. Over the same period, the K+ concentration in the cyst increased up to 86.1+/-33.9 mM (versus 5.6+/-1.5 mM in the bath). These observations indicated that the mechanisms generating the UP and the K-secretory activity were functional at this stage. Concomitantly, the hair cells acquired mature and functional properties: the type 1 and type 2 phenotypes, a mean resting membrane potential of -68.1+/-4.6 mV and typical electrophysiological responses. This preparation provides a powerful means to simultaneous access the hair cells and their endolymphatic compartment, with the possibility to use multi-technical approaches to investigate their interdependent relationships.

Molecular diversity of voltage-gated sodium channel alpha subunits expressed in neuronal and non-neuronal excitable cells

In order to investigate the role of molecular diversity of voltage-activated sodium channel alpha-subunits in excitability of neuronal and non-neuronal cells, we carried out patch-clamp recordings and single-cell RT-PCR on two different types of mammalian excitable cells i.e. hippocampal neurons and non-neuronal utricular epithelial hair cells. In each cell type, multiple different combinations of sodium channel alpha-subunits exist from cell to cell despite similar sodium current properties. The mRNA isoforms, Nav1.2 and Nav1.6, are the most frequently detected by single cell analysis in the two cell types while Nav1.3 and Nav1.7 are also moderately expressed in embryonic hippocampal neurons and in neonatal utricular hair cells respectively. By investigating the particular alternate splice isoforms of Nav1.6 occurring at the exon 18 of the mouse orthologue SCN8A, we revealed that this subunit co-exist in the two cell types under different alternative spliced isoforms. The expression of non-functional isoforms of Nav1.6 in utricular epithelial hair cells excludes the involvement of this subunit in supporting their excitability. Thus, from a functional point of view, the present results suggest that, at the single cell level, both neuronal and non-neuronal excitable cells expressed different and complex patterns of sodium channel gene transcripts but this diversity alone cannot explain the sodium current properties of these cell types.

[Growth charts for the Spanish population with neurofibromatosis type 1]

OBJECTIVE

To make the charts of stature and head circumference of Spanish pediatric patients affected with neurofibromatosis type 1 (NF1), to compare them with the ones from a healthy population and to review the possible causes of its alterations.

PATIENTS AND METHODS

We obtained the data from 251 Spanish patients (122 women and 129 men) with NF1 seen in seven hospitals between the years 2000 and 2002, with ages between 1 month and 18 years old. The calculation of the 50th centile or median was done using the method of mobile variables, and the 3rd and 97th centiles where calculated from this median.

RESULTS

Girls with NF1 have a shorter stature than the healthy ones, which becomes evident after 10 years of age. We have not found differences in the stature between boys with the disease and those without it. In regards to head circumference, in boys and girls we have observed that it is bigger throughout life in patients affected with NF1, and that the 50th centile of healthy people correlates with the 3rd centile of those affected, the 97th centile of the healthy ones with the 50th centile of those affected, being the 3rd centile of the healthy people well below the 3rd centile of the affected ones, and the 97th centile of the affected ones well above the 97th of the healthy people.

CONCLUSIONS

The short stature in postpuberal girls and the macrocephaly in both sexes at all ages, are primary characteristics in the NF1 and they are not usually related with other alterations, although they are not specific for this illness.

[Value of intrathecal baclofen in the treatment of spastic cerebral palsy]

Spasticity is the most common movement disorder in cerebral palsy. Cerebral spasticity has traditionally been treated with physical therapy and orthopedic surgery. Oral medications have been used with limited success. Intrathecal administration of baclofen may be a valuable alternative in selected patients. We comment the patient management and clinical practice guidelines on the use of intrathecal baclofen for the treatment of spasticity.

[Angelman syndrome: physical characteristics and behavioural phenotype in 37 patients with confirmed genetic diagnosis]

INTRODUCTION

Angelman syndrome (AS) is characterised by mental retardation, ataxic gait, epilepsy, absence of language and a special series of physical traits behavioural phenotype. Its incidence is estimated as one in every 20,000 individuals. On the basis of discoveries made in molecular biology, patients can be classified as belonging to five types: deletion, paternal uniparental disomy (UPD), imprinting defects, mutation of the UBE3A ubiquitin protein ligase gene and unidentified mechanism (15% 20% of patients). Some studies report significant correlations between the phenotype and the genetic cause.

PATIENTS AND METHODS

We reviewed, retrospectively, 37 patients suffering from AS with a positive genetic study and who had been controlled for at least two years in the Neurological Service at the Hospital Sant Joan de D u. Data was collected on physical characteristics, behavioural phenotype, type of communication, sleep disorders and the medication they needed, as well as epilepsy, start age, types of seizures, medication, schooling and social integration.

RESULTS

87% of cases were due to de novo deletion, 8% were caused by UPD, and 5% had their origins in imprinting defects. The average age of diagnosis was 6.5 years. The sleep disorders present in 48% of the patients required medication in 67% of cases, and 95% presented epilepsy. The most frequent seizures were myoclonic, tonic clonic and atonic. The electroencephalogram (EEG) was the characteristic found in the AS in 68%. The most effective treatment was afforded by valproate and clonazepam.

CONCLUSIONS

As regards the phenotype, no differences were found according to the genetic alteration. The most effective treatment for the sleep disorders was melatonin. Epilepsy was an almost constant finding in our series, as was cognitive affectation. Lastly, it must be pointed out that educational and socio occupational integration is difficult for patients suffering from AS.

[The contribution of the cerebellum to cognitive function in childhood]

INTRODUCTION

Cerebellum traditionally has been considered as a neural structure dedicated to motor control. Published studies in the last decades suggest that the cerebellum has an important role in behaviour and cognition specially in paediatric age.

OBJECTIVE

We review the cerebellum role in cognitive function in developmental and acquired cerebellar pathology.

Comparative studies of female sex pheromone components and male response of the corn stalk borer Sesamia nonagrioides in three different populations

Studies to determine possible differences in the pheromone communication system of three different populations of the corn stalk borer Sesamia nonagrioides (Lef.) in France. Spain. and Greece were carried out. The two main pheromone components (Z)-11-hexadecenyl acetate (Z11-16:Ac) and (Z)-11-hexadecenol (Z11-16:OH), were detected in all analyses with very small differences in the three populations. Among the minor components, analyzed by GC-MS on concentrated gland extracts from French and Greek origin females, (Z)-l1-hexadecenal (Z11-16:Ald) was detected in minor amounts. Wind-tunnel and field studies revealed similar a male response in the three populations to pheromone glands extracts and synthetic pheromone regardless of the female/male origin. The results do not support the assumption of the existence of different pheromone types of the corn stalk borer S. nonagrioides due to geographic isolation.

[Visuo-constructive disorders in periventricular leukomalacia]

INTRODUCTION

Cerebral palsy involves not only motor impairment but also the impairment of cognitive functions. Visuo spatial impairment has often been reported in preterm children with spastic diplegia due to periventricular leukomalacia.

PATIENTS AND METHODS

Eight children with periventricular leukomalacia diagnosis. When examined their ages were between 3 and 13 years.

RESULTS

We found visuo spatial anomalies in all subjects. These anomalies don't result in reading and writing learning difficulties.

CONCLUSION

Constructional dyspraxia is frequently found in children with periventricular leukomalacia and correlates with reduction of peritrigonal white matter in parietal lobe.

[A ketogenic diet: is this a valid alternative in refractory epilepsy]

INTRODUCTION

The ketogenic diet was first used in refractory epilepsy of childhood in the early 1920s. It was forgotten when new antiepileptic drugs were introduced, but recently has been used again. Although its efficacy in the treatment of epilepsy, in some patients, is beyond doubt, its mechanism of action is still not clear. There are three types of diet: the classical diet with a proportion of 4:1 of long chain fatty acids, with MCT oil and with modified MCT oil.

OBJECTIVE

To present a protocol recently designed in our hospital. We include the type of diet, form of onset, subsequent follow up of complications, clinical and electroencephalographic response and side effects seen in the patients.

PATIENTS AND METHODS

Introduction of the ketogenic diet with MCT oil in six patients aged between 2 and 11 years, with various types of epilepsy, all resistant to treatment, who had been unsuccessfully treated for 28 months in one case and between 4 and 6 months in the others. We evaluated the response on the criteria of Huttenlocher and Panic electroencephalograms.

RESULTS

Two of the patients improved with good control of their disorder and the EEG became normal. No serious side effects were seen apart from gastrointestinal symptoms which improved when the quantity of MCT oil was reduced.

CONCLUSIONS

In patients with drug resistant epilepsy it is convenient to have a guideline for treatment using a ketogenic diet. It is also useful to have a multi disciplinary team for management, follow up to detect late side effects and obtain the cooperation of the patient s family in following the protocol.

Pheromone response inhibitors of the corn stalk borer Sesamia nonagrioides. Biological evaluation and toxicology

The behavioral activity of some trifluoromethyl ketones (TFMKs) as inhibitors of the pheromone activity of the corn stalk borer Sesamia nonagrioides (Lef.) (Lepidoptera: Noctuidae) is reported. The most closely-related analogue to the pheromone tested, (Z)-11-hexadecenyl trifluoromethyl ketone (Z11-16:TFMK), elicited a significant decrease in the number of male catches in traps baited with mixtures with the pheromone in 1:1 and 10:1 ratios in comparison to the pheromone alone. The E isomer of the analogue as well as two highly hydrated ketones, 3-octylthio-1,1,1-trifluoropropan-2-one (OTFP) and 1,1-difluoropentadecyl trifluoromethyl ketone, were inactive. Conversely, the saturated TFMKs n-dodecyl trifluoromethyl ketone and, particularly, n-hexadecyl trifluoromethyl ketone induced a synergistic effect when mixed with the synthetic pheromone in 10:1 ratio. However, in a wind tunnel these chemicals did not elicit any differential effect on flying moths attracted to a source containing a 10:1 blend of the analogue and the pheromone. In a dual choice bioassay with two dispensers, containing the pheromone alone, and mixtures of Z11-16:TFMK and the pheromone and separated 5 cm apart, males showed no particular preference for either dispenser. The ketone mixture, however, induced moths to execute erratic flights with frequent crosswind counter-turns and intersections with plume boundaries. The total number of contacts with the source were reduced when a control dispenser was paired with a dispenser containing Z11-16:TFMK and pheromone. Z11-16:TFMK and OTFP showed little toxicity on mice with a LD50 of 1 g/kg after the 6th day of treatment. For comparitive purposes, the major component of the pheromone, Z11-16:Ac, displayed a LD50 of 5 g/kg 6 days after application. Our results provide additional information about the activity of the TFMKs, which might be useful for the utilization of these chemicals in future pest control studies.

Hyperpolarization-activated (Ih) current in mouse vestibular primary neurons

The presence of a hyperpolarization-activated inward current (Ih) was investigated in mouse vestibular primary neurons using the whole-cell patch-clamp technique. In current-clamp configuration, injection of hyperpolarizing currents induced variations of membrane voltage with prominent time-dependent rectification increasing with current amplitudes. This effect was abolished by 2 mM Cs+ or 100 microM ZD7288. In voltage-clamp configuration, hyperpolarization pulses from -60 mV to -140 mV triggered a slow activating and non inactivating inward current that was sensitive to the two blockers, but insensitive to 5 mM Ba2+. Changing Na+ and K+ concentrations demonstrated that Ih current is carried by both these monovalent cations. This is the first demonstration of a Ih current in vestibular primary neurons.

Contribution of the plasmalemma to Ca2+ homeostasis in hair cells

Calcium influx through transduction channels and efflux via plasmalemmal Ca(2+)-ATPases (PMCAs) are known to contribute to calcium homeostasis and modulate sensory transduction in vertebrate hair cells. To examine the relative contributions of apical and basolateral pathways, we analyzed the calcium dynamics in solitary ciliated and deciliated guinea pig type I and type II vestibular hair cells. Whole-cell patch-clamp recordings demonstrated that these cells had resting potentials near -70 mV and could be depolarized by 10-20 mV by superfusion with high potassium. Fura-2 measurements indicated that ciliated type II cells and deciliated cells of either type had low basal [Ca(2+)](i), near approximately 90 nm, and superfusion with high potassium led to transient calcium increases that were diminished in the presence of Ca(2+) channel blockers. In contrast, measurements of type I ciliated cells, hair cells with large calyceal afferents, were associated with a higher basal [Ca(2+)](i) of approximately 170 nm. High-potassium superfusion of these cells induced a paradoxical decrease in [Ca(2+)](i) that was augmented in the presence of Ca(2+) channel blockers. Optical localization of dihydropyridine binding to the kinocilium suggests that they contain L-type calcium channels, and as a result apical calcium influx includes a contribution from voltage-dependent ion channels in addition to entry via transduction channels localized to the stereocilia. Eosin block of PMCA significantly altered both [Ca(2+)](i) baseline and transient responses only in ciliated cells suggesting that, in agreement with immunohistochemical studies, PMCA is primarily localized to the bundles.

Three types of depolarization-activated potassium currents in acutely isolated mouse vestibular neurons

The nature and electrophysiological properties of Ca(2+)-independent depolarization-activated potassium currents were investigated in vestibular primary neurons acutely isolated from postnatal mice using the whole cell configuration of the patch-clamp technique. Three types of currents were identified. The first current, sensitive to TEA (I(TEA)) and insensitive to 4-aminopyridine (4-AP), activated at -40 mV and exhibited slow activation (tau(ac), 38.4 +/- 7.8 ms at -30 mV, mean +/- SD). I(TEA) had a half activation potential [V(ac(1/2))] of -14.5 +/- 2.6 mV and was inactivated by up to 84.5 +/- 5.7% by 10-s conditioning prepulses with a half inactivation potential [V(inac(1/2))] of -62.4 +/- 0.2 mV. The second current, sensitive to 4-AP (maximum block around 0.5 mM) and to alpha-dendrotoxin (I(DTX)) appeared at -60 mV. Complete block of I(DTX) was achieved using either 20 nM alpha-DTX or 50 nM margatoxin. This current activated 10 times faster than I(TEA) (tau(ac), 3.5 +/- 0.8 ms at -50 mV) with V(ac(1/2)) of -51.2 +/- 0.6 mV, and inactivated only slightly compared with I(TEA) (maximum inactivation, 19.7 +/- 3.2%). The third current, also sensitive to 4-AP (maximum block at 2 mM), was selectively blocked by application of blood depressing substance (BDS-I; maximum block at 250 nM). The BDS-I-sensitive current (I(BDS-I)) activated around -60 mV. It displayed fast activation (tau(ac), 2.3 +/- 0.4 ms at -50 mV) and fast and complete voltage-dependent inactivation. I(BDS-I) had a V(ac(1/2)) of -31.3 +/- 0.4 mV and V(inac(1/2)) of -65.8 +/- 0.3 mV. It displayed faster time-dependent inactivation and recovery from inactivation than I(TEA). The three types of current were found in all the neurons investigated. Although I(TEA) was the major current, the proportion of I(DTX) and I(BDS-I) varied considerably between neurons. The ratio of the density of I(BDS-I) to that of I(DTX) ranged from 0.02 to 2.90 without correlation with the cell capacitances. In conclusion, vestibular primary neurons differ by the proportion rather than the type of the depolarization-activated potassium currents they express.

[Mitochondrial encephalomyelitis, lactic acidosis and cerebrovascular accidents (MELAS) in pediatric age with the A3243G mutation in the tRNALeu(UUR) gene of mitochondrial DNA]

OBJECTIVES

To evaluate three patients with the mitochondrial encephalopathy, lactic acidosis and cerebrovascular accident syndrome (MELAS) diagnosed in childhood, with particular reference to the initial symptoms and clinical evolution during the first stage at a pediatric age, and to compare them with other studies on the subject.

PATIENTS AND METHODS

Two boys and a girl of 10, 11 and 13 years had tests on lactate, pyruvate and aminoacids in biological fluids under basal conditions and also functional tests and enzyme activity assay of the mitochondrial respiratory chain of a muscle biopsy. We also analysed the particular DNA mutations related to MELAS in different tissues from these patients and in lymphocytes from members of the mothers' families who could be tested.

RESULTS

The patients fulfilled the clinical criteria for the MELAS syndrome. Neuroimaging showed cerebrovascular accidents. Neurophysiological studies showed myopathy in one patient and neuroaxonal neuropathy in another. In two cases ophthalmological study showed retinitis pigmentaria and during cerebrovascular accidents transient phenomena of homonymous hemianopsia and cortical blindness were seen. In all patients muscle biopsy showed ragged red fibres and the biochemical study showed an enzyme deficit in the respiratory mitochondrial chain. On molecular genetic study of the mitochondrial DNA (mtDNA) there was a particular mutation A3243G on the tRNA(Leu) in all patients and some members of the mothers' families.

CONCLUSIONS

In children with frequent episodes of migraine headaches, vomiting, refractory epilepsy and fatigue the presence of a mitochondrial disease should be suspected. On detection of mtDNA mutations MELAS may be diagnosed even without all the clinical criteria which characterise this syndrome.

Glutaryl-CoA dehydrogenase deficiency in Spain: evidence of two groups of patients, genetically, and biochemically distinct

Glutaryl-CoA dehydrogenase (GCDH) deficiency causes glutaric aciduria type I (GA I), an inborn error of metabolism that is characterized clinically by dystonia and dyskinesia and pathologically by neural degeneration of the caudate and putamen. Studies of metabolite excretion allowed us to categorize 43 GA I Spanish patients into two groups: group 1 (26 patients), those presenting with high excretion of both glutarate and 3-hydroxyglutarate, and group 2 (17 patients), those who might not be detected by routine urine organic acid analysis because glutarate might be normal and 3-hydroxyglutarate only slightly higher than controls. Single-strand conformation polymorphism (SSCP) screening and sequence analysis of the 11 exons and the corresponding intron boundaries of the GCDH gene allowed us to identify 13 novel and 10 previously described mutations. The most frequent mutations in group 1 were A293T and R402W with an allele frequency of 30% and 28%, respectively. These two mutations were also found in group 2, but always in heterozygosity, in particular in combination with mutations V400M or R227P. Interestingly, mutations V400M and R227P were only found in group 2, and at least one of these mutations was found in 11 of 15 unrelated alleles, accounting together for 53% of the mutant alleles in group 2. Therefore, it seems clear that two genetically and biochemically distinct groups of patients exist. The severity of the clinical phenotype seems to be closely linked to the development of encephalopathic crises rather than to residual enzyme activity or genotype. Comparison of GCDH protein with other acyl-CoA dehydrogenases (whose x-ray crystal structure has been determined) reveals that most of the mutations identified in GCDH protein seem to affect folding and tetramerization, as has been described for a number of mutations affecting mitochondrial beta-oxidation acyl-CoA dehydrogenases.

Detection and localization of BDNF in vestibular nuclei during the postnatal development of the rat

The changes in expression and the subcellular localization of brain-derived neurotrophic factor (BDNF) protein in the rat vestibular nuclear complex (VNC), have been investigated at different postnatal stages. Immunoblotting and ELISA analyses showed a down-regulation of BDNF protein expression in VNC with age. In addition, observations by confocal microscopy revealed that BDNF is mainly located in neuronal somata at postnatal day 8 (P8) and restricted to processes by P15. These results support the idea that BDNF could have different roles in the VNC according to the stage of development The protein could act as a neurotrophic factor in embryonic and early postnatal stages whereas in later developmental stages of the VNC it could be involved in neuronal maturation and regulation of neuronal circuitry.

[Acute childhood gastroenteritis study at Central University Hospital of Pointe-à-Pitre/Abymes, Guadeloupe, from November 1997 to March 1998]

To determine the role of enteric pathogens in acute childhood diarrhoea in Guadeloupe, 161 children (108 cases and 53 controls) from 0 to 2 years of age, admitted to Pointe-à-Pitre/Abymes University Hospital, were evaluated over a five-month period. A known enteric pathogen was identified in 40.8% of children. The most commonly identified aetiologic agents were Salmonella (16.7% of cases), especially Haddar serotype and Rotavirus (20.5%). This virus was isolated more often in the dry season. Adenovirus were detected in 3.6% of diarrhoeal stools and were not significatively associated with diarrhoeal disease. No Shigella, Campylobacter or parasites were found.

Developmental changes in low and high voltage-activated calcium currents in acutely isolated mouse vestibular neurons

1. The development of low voltage-activated (LVA) and high voltage-activated (HVA) calcium currents was studied in neurons acutely dissociated from mouse vestibular ganglia at embryonic stages (E)14, 15, 17 and birth using the whole-cell patch-clamp technique. 2. LVA current was present in almost all neurons tested at stages E14 to E17, although at birth this current was restricted to a few neurons. Two populations of neurons were characterized based on the amplitude of the LVA current. In the first population, LVA current densities decreased between E17 and birth by which time this current tended to disappear in most neurons. A second population of neurons with high density LVA current appeared at E17, and in this group the mean density increased during development. 3. Among HVA currents, the dihydropyridine-sensitive L-type current remained constant between E15 and birth. Over the same period, the density of N- and Q-type currents continuously increased as shown using omega-conotoxin-GVIA (N-type), and high concentrations of omega-agatoxin-IVA (Q-type). The P-type current, sensitive to low concentrations of omega-agatoxin-IVA, transiently increased between E15 and E17, and then both current density and its proportion of the global current decreased. 4. Our results reveal large modifications in the expression of voltage-dependent calcium channels during embryonic development of primary vestibular neurons. The changes in the expression of LVA current and the transient augmentation of P-type HVA current occur during a period characterized by massive neuronal growth and by the beginning of synaptogenesis. These results suggest a specific role of these currents in the ontogenesis of vestibular primary afferents.

K+-dependence of Na+-Ca2+ exchange in type I vestibular sensory cells of guinea-pig

The properties of the vestibular Na+-Ca2+ exchanger in mammalian type I vestibular sensory cells were studied using fura-2 fluorescence and immunocytochemical techniques. In the absence of external Na+, the activation of Na+-Ca2+ exchange in reverse mode required the presence of external K+ (K+o) and depended on K+o concentration. Alkali cations Rb+ and NH4+ but not Li+ or Cs+ substituted for K+o to activate the exchange. For pressure applications of 10 mm K+, the contribution of voltage-sensitive calcium channels to the increase in [Ca2+]i was < 15%. The dependence of the exchange on [K+]o was also recorded when the membrane potential was clamped using carbonyl cyanide p-trifluoromethoxy-phenylhydrazone (FCCP) and monensin ionophores. In these conditions, where there was no intracellular Na+, the increase in [Ca2+]i was completely blocked. These physiological results suggest that in reverse mode, Ca2+ entry is driven by both an outward transport of Na+ and an inward transport of K+. The dependence of the vestibular Na+-Ca2+ exchanger on K+ is more reminiscent of the properties of the retinal type Na+-Ca2+ exchanger than those of the more widely distributed cardiac type exchanger. Moreover, the immunocytochemical localization of both types of exchange proteins in the vestibular sensory epithelium confirmed the presence in the vestibular sensory cells of a Na+-Ca2+ exchanger which is recognized by an antibody raised against retinal type and not by an antibody raised against the cardiac type.

Ionic currents and current-clamp depolarisations of type I and type II hair cells from the developing rat utricle

Ionic currents and the voltage response to injected currents were studied in an acutely dissected preparation of the rat utricle between birth and postnatal day 12 (PN12). Based upon morphological criteria, the sensory cells examined were divided into two classes, "type I" and "type 2 category," the latter of which may include some immature type I cells. The former group comprises a clearly defined electrophysiological population, with one large outwardly rectifying potassium conductance that is sensitive to 4-aminopyridine (4-AP), insensitive to tetraethylammonium (TEA) and displays voltage-dependent activation kinetics. In the absence of enzymatic dissociation procedures, and with the epithelium left largely intact, the mean half activation of this conductance was -30.3 mV at PN3, and -37.5 mV at PN12. At both stages it was almost entirely turned off at -74 mV. Omission of ATP from the intracellular solution appeared to prevent rundown of this conductance. Type II category hair cells formed a more heterogeneous population, exhibiting a distinct TEA-sensitive delayed rectifier potassium conductance; the rapidly activating and inactivating IA; an inward rectifier; and inward sodium currents at around PN3. Both cell types depolarised strongly in response to injected currents, with time courses reflecting the activation kinetics of their major outward conductances.

Vestibular semicircular canal epithelium of the rat in culture on filter support: polarity and barrier properties

The inner ear of mammals contains the vestibular apparatus which is involved in the maintenance of posture and balance. The tubular structure of the apparatus is bathed by the potassium-rich endolymph and sodium-rich perilymph in the luminal and abluminal compartments, respectively. The luminal compartment is lined by a continuous epithelium with islets of receptor organs, which separates the luminal from the abluminal compartment. The present work focuses on the epithelium, without the receptor organs, and shows that it can be reconstituted in culture. The epithelium from 4-day-old Wistar rats was grown on microporous membranes. High transepithelial electrical resistances (4000-6000 Omega.cm2) were achieved after 4-8 days in culture. The epithelium was characterized by the presence of cytokeratin, ZO-1 protein, occludin, and the presence of tight junctions and kinocilia. The transepithelial resistance of the cell monolayer withstood endolymph/perilymph dual bathing when the apical pole of the cells was in contact with endolymph, but collapsed in the reverse configuration. Weak but statistically highly significant basal to apical rubidium (86Rb) transport was observed. These findings show that this epithelium maintains its in vivo polarity and could enhance the potassium composition of endolymph up to maturity. This new culture model, in which dual bathing is possible, should enable further in vitro studies of the sensory vestibular epithelia.

Potassium depolarization of mammalian vestibular sensory cells increases [Ca2+]i through voltage-sensitive calcium channels

The existence of voltage-sensitive Ca2+ channels in type I vestibular hair cells of mammals has not been conclusively proven. Furthermore, Ca2+ channels present in type II vestibular hair cells of mammals have not been pharmacologically identified. Fura-2 fluorescence was used to estimate, in both cell types, intracellular Ca2+ concentration ([Ca2+]i) variations induced by K+ depolarization and modified by specific Ca2+ channel agonists and antagonists. At rest, [Ca2+]i was 90 +/- 20 nM in both cell types. Microperifusion of high-K+ solution (50 mM) for 1 s increased [Ca2+]i to 290 +/- 50 nM in type I (n = 20) and to 440 +/- 50 nM in type II cells (n = 10). In Ca2+-free medium, K+ did not alter [Ca2+]i. The specific L-type Ca2+ channel agonist, Bay K, and antagonist, nitrendipine, modified in a dose-dependent manner the K+-induced [Ca2+]i increase in both cell types with maximum effect at 2 microM and 400 nM, respectively. Ni2+, a T-type Ca2+ channel blocker, reduced K+-evoked Ca2+ responses in a dose-dependent manner. For elevated Ni2+ concentrations, the response was differently affected by Ni2+ alone, or combined to nitrendipine (500 nM). In optimal conditions, nitrendipine and Ni2+ strongly depressed by 95% the [Ca2+]i increases. By contrast, neither omega-agatoxin IVA (1 microM), a specific P- and Q-type blocker, nor omega-conotoxin GVIA (1 microM), a specific N-type blocker, affected K+-evoked Ca2+i responses. These results provide the first direct evidence that L- and probably T-type channels control the K+-induced Ca2+ influx in both types of sensory cells.

A role for BDNF in early postnatal rat vestibular epithelia maturation: implication of supporting cells

The early development of the inner ear is largely determined by two members of the neurotrophic family: brain-derived neurotrophic factor (BDNF) and neurotrophin 3 (NT-3). Little information is available on the role of these neurotrophins during the late stages of vestibular development in the rat which take place during the first postnatal weeks. At this period where terminal synaptogenesis and maturation occur, we have investigated the expression and the activity of BDNF, the most important neurotrophin in the vestibular system. Using different experimental approaches, we show that BDNF is released by vestibular epithelia on postnatal day 3 (P3) and continues to have a trophic effect on vestibular neurones in vitro. Immunocytochemistry coupled to confocal microscopy revealed a remarkable evolution in BDNF localization during later stages of development. Whereas BDNF is present in both supporting cells and hair cells at P3, its distribution gradually changed and is highly compartmentalized within the upper part of supporting cells at P8 and P15. In parallel, we observed the presence of a truncated form of the BDNF receptor in sensory hair cells. These results suggest an original role for supporting cells, which could be involved in the release of BDNF during the late stages of synaptogenesis in mammalian vestibular epithelia. In particular, BDNF could participate to the set up of the calyx, a specific nerve structure surrounding type I vestibular hair cells.

Short-term response of postnatal rat vestibular neurons following brain-derived neurotrophic factor or neurotrophin-3 application

The effects of the application of brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) neurotrophins on the intracellular calcium level ([Ca2+]i) were studied in vestibular ganglion neurons (VGNs) from postnatal day 3 (P3) rats cultured for 50 hr. We first assessed the expression of trkB and trkC mRNA receptors in cultured VGNs. Immunobloting and immunocytochemistry confirmed the presence of the neurotrophin receptors on neurons. Both neurotrophins induced transient [Ca2+]i elevations in VGNs: BDNF-treated neurons responded in 65% and NT-3-treated neurons in 56%. The responses could be inhibited by anti-BDNF or anti-NT-3 antibodies. The [Ca2+]i elevation was dependent on extracellular calcium since it was abolished in calcium-free medium but also implicates the release of calcium from intracellular stores as tested by prior depletion with thapsigargin. Our results suggest the implication of a short-term calcium regulation in VGNs, which could reflect specific fast effects of neurotrophins in the early postnatal rat vestibular system.

Regulation of NMDA receptor subunit mRNA expression in the guinea pig vestibular nuclei following unilateral labyrinthectomy

The localization of neurons expressing mRNAs for the NR1 and NR2A-D subunits of the glutamatergic NMDA receptor was examined by non-radioactive in situ hybridization throughout the guinea pig vestibular nuclei. After deafferentation of the vestibular nuclei by unilateral labyrinthectomy, modifications of the mRNA distributions were followed for 30 days. A quantitative analysis was performed in the medial vestibular nucleus by comparison of the labelled neurons in the ipsi- and contra-lateral nuclei. In vestibular nuclei, the NR1 subunit mRNA was found in various populations of neurons. The NR2A and NR2C subunit mRNAs were less widely distributed, whereas little NR2D mRNA was detected and only rare cells contained NR2B mRNA. NR1 and NR2A-D mRNAs were colocalized in some but not other neuronal types. Twenty hours after the lesion, there was a transient ipsilateral increase of NR1 mRNA level in the medial vestibular nucleus, followed by a decrease 48 h after the lesion and, at 3 days, by recovery to the control level. An ipsilateral increase in the mRNA level of NR2C subunit was detected 20 h after lesion and maintained at 48 h. No significant changes were apparent in NR2A, NR2B and NR2D mRNA levels. The distributions and the differential signal intensities of NR2A-D mRNAs suggest various subunit organizations of the NMDA receptors in different neurons of the vestibular nuclei. Neuronal plasticity reorganizations in the vestibular nuclei following unilateral labyrinthectomy appear to include only changes in NR1 and NR2C mRNA levels modifying the functional diversity of the NMDA receptor in the ipsilateral medial vestibular nucleus neurons. The transient changes in NR1 and the NR2C subunit mRNA expressions in response to sensory deprivation are consistent with an active role for NMDA receptors in the appearance and development of the vestibular compensatory process.

[Late onset of pseudobulbar paralysis and dystonia in a case of hemispheric cortical dysplasia]

The atypical clinical course of a young male with encephalopathy due to right hemispheric cortical dysplasia (pachygiria) is described. From the first months of life the course of the disease was a static encephalopathy with left hemiparesis, epilepsy and mild mental retardation. When he was 14 years old a subacute pseudobulbar palsy, dystonia and spread of the paresis to the right side occurred. Epileptic seizures, paroxysmal EEG abnormalities and drug ingestion were excluded. Neuropsychological studies showed a low level of cognitive functions, probably related to the malformative encephalopathy and expressive language deficit due to the pseudobulbar paresis. We speculate that this case could be an atypical case of delayed onset dyskiesia.

Multiple voltage-dependent calcium currents in acutely isolated mouse vestibular neurons

We investigated the presence of voltage-gated calcium currents in vestibular neurons acutely isolated from postnatal mice vestibular ganglions using the whole-cell patch-clamp technique. The neuronal origin of the recorded cells was confirmed by immunohistochemical detection of neurofilaments and calretinin. High and low voltage-activated calcium currents were recorded. High voltage-activated currents were present in all investigated neurons. Low voltage-activated currents were recorded in only a few large vestibular neurons. High and low voltage-activated currents were distinguished by their thresholds of activation and their ability to run-up during early recordings. Among high voltage-activated currents. L-, N- and P-type currents were identified by their sensitivity to, respectively, the dihydropyridines agonist Bay K 8644 (3 microM) and antagonist nitrendipine (3 microM), the co-conotoxin GVIA (3 microM) and the omega-agatoxin IVA at low concentration (50 nM). An inactivating current sensitive to 1 microM omega-agatoxin IVA with characteristics similar to those of the Q-type current was also recorded in vestibular neurons. When L-, N-, P-, Q-type barium currents were blocked, a residual high voltage-activated current defined by its resistance to saturating concentrations of all above blockers was detected. This residual current was completely blocked by 0.5 mM nickel and cadmium. Our results reveal that primary vestibular neurons express a variety of voltage-activated calcium currents with distinct physiological and pharmacological properties. This diversity could be related both with their functional synaptic characteristic, and with the intrinsic physiological properties of each class of vestibular afferents.