Developmental and physiological responses of Brachypodium distachyon to fluctuating nitrogen availability

The Nitrogen Use Efficiency (NUE) of grain cereals depends on nitrate (NO3-) uptake from the soil, translocation to the aerial parts, nitrogen (N) assimilation and remobilization to the grains. Brachypodium distachyon has been proposed as a model species to identify the molecular players and mechanisms that affects these processes, for the improvement of temperate C3 cereals. We report on the developmental, physiological and grain-characteristic responses of the Bd21-3 accession of Brachypodium to variations in NO3- availability. As previously described in wheat and barley, we show that vegetative growth, shoot/root ratio, tiller formation, spike development, tissue NO3- and N contents, grain number per plant, grain yield and grain N content are sensitive to pre- and/or post-anthesis NO3- supply. We subsequently described constitutive and NO3--inducible components of both High and Low Affinity Transport Systems (HATS and LATS) for root NO3- uptake, and BdNRT2/3 candidate genes potentially involved in the HATS. Taken together, our data validate Brachypodium Bd21-3 as a model to decipher cereal N nutrition. Apparent specificities such as high grain N content, strong post-anthesis NO3- uptake and efficient constitutive HATS, further identify Brachypodium as a direct source of knowledge for crop improvement.

Autoimmune disorders and quadrivalent human papillomavirus vaccination of young female subjects

OBJECTIVES

The aim of this study was to investigate whether the quadrivalent human papillomavirus (HPV) vaccine Gardasil is associated with a change in the risk of autoimmune disorders (ADs) in young female subjects.

DESIGN

Systematic case-control study of incident ADs associated with quadrivalent HPV vaccination in young women across France.

PARTICIPANTS AND SETTING

A total of 113 specialised centres recruited (from December 2007 to April 2011) females aged 14-26 years with incident cases of six types of ADs: idiopathic thrombocytopenic purpura (ITP), central demyelination/multiple sclerosis (MS), Guillain-Barré syndrome, connective tissue disorders (systemic lupus erythematosus, rheumatoid arthritis/juvenile arthritis), type 1 diabetes mellitus and autoimmune thyroiditis. Control subjects matched to cases were recruited from general practice.

ANALYSIS

Multivariate conditional logistic regression analysis; factors included age, geographical origin, smoking, alcohol consumption, use of oral contraceptive(s) or vaccine(s) other than Gardasil received within 24 months before the index date and personal/family history of ADs.

RESULTS

Overall, 211 definite cases of ADs were matched to 875 controls. The adjusted odds ratio (OR) for any quadrivalent HPV vaccine use was 0.9 [95% confidence interval (CI) 0.5-1.5]. The individual ORs were 1.0 (95% CI 0.4-2.6) for ITP, 0.3 (95% CI 0.1-0.9) for MS, 0.8 (95% CI 0.3-2.4) for connective disorders and 1.2 (95% CI 0.4-3.6) for type 1 diabetes. No exposure to HPV vaccine was observed in cases with either Guillain-Barré syndrome or thyroiditis.

CONCLUSIONS

No evidence of an increase in the risk of the studied ADs was observable following vaccination with Gardasil within the time periods studied. There was insufficient statistical power to allow conclusions to be drawn regarding individual ADs.

[Infratentorial ischemic stroke in children: Three case reports]

Ischemic stroke is rare in children, most of which occur in the supratentorial brain, and infratentorial infarcts are very rare. Some clinical manifestations may be similar but others such as ataxia and cranial nerve palsy are more specific. Vertebral artery dissection is the most frequent cause of stroke in the vertebrobasilar territory, but the cause most often remains unknown in children. We report three cases of infratentorial stroke in children. The first observation concerns a 4-year-old boy brought to medical attention because left hemicorporal motor deficit associated with ataxia following a minor cranial traumatism. While computed tomography (CT) of the brain was normal, magnetic resonance imaging (MRI) revealed an area of signal alteration on the diffusion-weighted image within the right protuberance. The second observation is a 15-year-old girl who developed sudden-onset ataxia. The CT scan and MRI of the brain revealed an acute bilateral cerebellar stroke. MRI angiography showed an anatomical variant of the left vertebral artery that did not participate in the Willis polygon. In these two observations, no other abnormalities were detected except they were homozygotous for MTHFR mutation in the first observation and minor alpha-thalassemia for the second one. The outcome in these two children was good without sequelae after a 6-month follow-up. The third observation is a 6-year-old girl who suddenly exhibited cephalalgia, ataxia, and left visual impairment. The brain MRI revealed left occipital and cerebellar strokes due to vertebral artery dissection. The authors recommend the systematic search for vertebral artery dissection in cases of infratentorial stroke.

Maturation of response time and attentional control in ADHD: evidence from an attentional capture paradigm

Inattention and hyperactivity/impulsivity are the core symptoms of Attention Deficit/Hyperactivity Disorder (ADHD). Slowness, although less known, has been also recently reported in children with ADHD and may contribute to their learning difficulties. Slow response time and greater response time variability have been highlighted by several computerized tasks. The goal of the present work was to evaluate the age-related response time in ADHD children and in a group of matched control children during an attentional capture paradigm. The study population included 75 children with ADHD (aged between 6 and 13) and 75 age- and gender-matched typical developing children (Control group). The children with ADHD made more errors than children on the control group. The response times and the response time variability decreased with age in both groups and were significantly greater in ADHD than in controls. The distractor effect was similar in both groups. The maturation of response times and response time variability with age is quite similar in children with ADHD and typical developing children but whatever the age-class, children with ADHD were slower and exhibited greater response time variability than control children that could explain the variation during day-time of attention capacities in ADHD.

Visual sensory processing deficit in the occipital region in children with attention-deficit / hyperactivity disorder as revealed by event-related potentials during cued continuous performance test

AIMS OF THE STUDY

Recent studies described several changes of attention-related components of late frontal event-related potentials (ERPs) during Go/NoGo paradigm in children with attention-deficit/hyperactivity disorder (ADHD). We aimed to determine whether ERP components corresponding to earlier encoding of visual incoming information are also modulated by attentional disorders.

METHODS

We recorded high-resolution EEG in 15 children meeting DSM-IV criteria for ADHD, comprising 15 age-matched control groups during an equiprobable Go/NoGo task in a cued continuous performance test (CPT-AX) paradigm. Both P100 and N200 ERP components were measured in response to both Go and NoGo stimuli. We analyzed both components with SwLORETA in order to localize their brain sources.

RESULTS

A low rate of Go correct response and high rate of omission errors were observed in ADHD children. When compared to controls, these displayed delayed P100 and N200 latency, and lower P100-NoGo amplitude. In addition, the P100 latency was delayed for NoGo compared to Go condition. The source of P100 was located in occipital area. A sizable decrease in early electrical activity was found in ADHD, especially in the NoGo condition.

CONCLUSION

Our results suggest an early deficit in visual sensory integration within the occipital cortex in children with ADHD.

Differences in effective connectivity between dyslexic children and normal readers during a pseudoword reading task: an fMRI study

PURPOSE

This fMRI study investigated phonological and lexicosemantic processing in dyslexic and in chronological age- and reading level-matched children in a pseudoword reading task.

MATERIALS AND METHODS

The effective connectivity network was compared between the three groups using a structural model including the supramarginal cortex (BA 40; BA: Brodmann area), fusiform cortex (BA 37) and inferior frontal cortex (BA 44/45) areas of the left hemisphere.

RESULTS

The results revealed differences in connectivity patterns. In dyslexic patients, in contrast with chronological age- and reading level-matched groups, no causal relationship was demonstrated between BA 40 and BA 44/45. However, a significant causal relationship was demonstrated between BA 37 and BA 44/45 both in dyslexic children and in the reading level-matched group.

CONCLUSIONS

These findings were interpreted as evidence for a phonological deficit in developmental dyslexia.

Postnatal changes in Fos-like immunoreactivity evoked by hypoxia in the rat brainstem and hypothalamus

We have recently used Fos expression in adult rats to map neuronal populations activated in the brainstem and hypothalamus during the acute ventilatory response to moderate hypoxia (O(2) 11%). Although present at birth, this response evolves postnatally. The present investigation aimed at a better understanding of these maturational processes by delineating structures that might functionally develop after birth. The developmental pattern Fos expression evoked by hypoxia was analysed in rats aged from 0 to 26 postnatal days. The numbers of Fos positive neurons markedly increased with the age in the medullary areas related to respiratory control during the 2 first postnatal weeks. Thereafter, the response plateaued in the nucleus tractus solitarius and attenuated in the ventral medulla. In the upper brainstem (parabrachial area, central grey) and the hypothalamus (posterior and dorsomedial nuclei, ventral zone), Fos response to hypoxia was absent or weak at birth and increased until late development. The significance of the development of evoked Fos expression in these rostral sites is discussed together with their possible contribution to the maturation of O(2)-sensitive chemoreflex pathways.

Brainstem and hypothalamic areas involved in respiratory chemoreflexes: a Fos study in adult rats

The adaptation to hypoxia and hypercapnia requires the activation of several anatomical structures along the neuraxis. In this study, using Fos immunoreactivity, we sought to map neuronal populations involved in chemoreflex networks activated during the responses to moderate hypoxia (O(2) 11%), and hypercapnia (CO(2) 5%) in the brainstem and the hypothalamus of the rat. In the medulla, hypoxia elicited marked and significant staining in the nucleus of the solitary tract (NTS), and in parapyramidal neurons located near the ventral surface, whereas hypercapnia evoked significantly c-fos only near the ventral surface in paraolivar neurons. In contrast, within pontine and suprapontine structures, both hypoxia and hypercapnia evoked similarly Fos immunoreactivity in the lateral parabrachialis area, the central grey, the caudal hypothalamus (dorsomedial and posterior hypothalamic nuclei), and in a ventro-lateral hypothalamic area, extending from the rostral limit of the mammillary nuclei to the retrochiasmatic area. More rostrally, labelling was observed in the paraventricular nucleus of the hypothalamus in response to hypercapnia, and in the supraoptic nucleus in response to hypoxia. These results support the hypothesis that chemoreflexes pathways are not only restricted to medulla and pons but also involved mesencephalic and hypothalamic regions. The parabrachialis area and the central grey may be key relays between caudal and ventral hypothalamic neurons, and medullary neurons involved in the response to hypoxia and hypercapnia.

Cerebral white matter disease in children may be caused by mitochondrial respiratory chain deficiency

Several mitochondrial diseases are known to occasionally involve the cerebral white matter, namely Leigh syndrome, Kearns-Sayre syndrome, and MELAS syndrome, but in these cases the major finding is alteration in the basal ganglia and brainstem. Here we report on severe diffuse white matter involvement and respiratory chain enzyme deficiency or mitochondrial DNA rearrangement in 5 unrelated families. It is interesting that white matter lesions were the only abnormal neuroradiologic feature in 3 of the 5 families, and multiple small cyst-like white matter lesions were found in 2 of 5 probands. Respiratory chain deficiency should be considered in the diagnosis of severe white matter involvement in childhood.

[Use of the admission service and pediatric emergency service of a university hospital center by adolescents (12-19 years): utilization and messages]

A retrospective survey concerning all patients ages 12-19 who had registered themselves at the admitting service of the paediatric emergency unit in the university hospital centre of Amiens was carried out in 1995. 2812 adolescents were received (18% of total admissions). The male/female sex-ratio was 1 to 3. The average age was 13.2 years old. Hospitalisations were more frequent in the spring and were predominantly on Mondays (17%). More than 2/3 of the adolescents were accompanied by their parents and 20% were referred by their doctors or by the SAMU (mobile emergency medical service). Two percent arrive alone. Traumatic pathology is the main reason for admission (1960 patients). Organic pathologies represent 24% of admissions and are essentially digestive pathologies (40%). "Suffering" adolescents (defined as those requiring an intervention with a psychotherapist as a matter of priority) only represent 6% of visits to the emergency unit, of which 2/3 correspond to suicide attempts. 24% of adolescents are hospitalised at the university hospital centre of Amiens within the paediatric services or specialised services (ENT, stomatology, etc.).

[Symptomatic and cryptogenic epilepsies in the child]

Symptomatic and cryptogenic epilepsies are related to detected or suspected cerebral lesions. Early identification of defined epileptic syndromes and etiology is helpful to adapt treatment. Generalized epilepsies are severe, often refractory and generally associated with cognitive dysfunction or regression. Partial symptomatic or cryptogenic epilepsies represent about 40% of all epilepsies in childhood and diagnosis as well as therapeutic strategy can be difficult. Semiology of partial seizures is related to epileptogenic focus and discharge propagation. Causes are numerous and are to be always extensively searched.

[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.

Familial infantile convulsions and paroxysmal choreoathetosis: a new neurological syndrome linked to the pericentromeric region of human chromosome 16

Benign infantile familial convulsions is an autosomal dominant disorder characterized by nonfebrile seizures, with the first attack occurring at age 3-12 mo. It is one of the rare forms of epilepsy that are inherited as monogenic Mendelian traits, thus providing a powerful tool for mapping genes involved in epileptic syndromes. Paroxysmal choreoathetosis is an involuntary-movement disorder characterized by attacks that occur spontaneously or are induced by a variety of stimuli. Classification is still elusive, and the epileptic nature of this movement disorder has long been discussed and remains controversial. We have studied four families from northwestern France in which benign infantile convulsions was inherited as an autosomal dominant trait together with variably expressed paroxysmal choreoathetosis. The human genome was screened with microsatellite markers regularly spaced, and strong evidence of linkage for the disease gene was obtained in the pericentromeric region of chromosome 16, with a maximum two-point LOD score, for D16S3133, of 6.76 at a recombination fraction of 0. Critical recombinants narrowed the region of interest to a 10-cM interval around the centromere. Our study provides the first genetic evidence for a common basis of convulsive and choreoathetotic disorders and will help in the understanding and classification of paroxysmal neurological syndromes.

Possible person-to-person transmission of Escherichia coli O111--associated hemolytic uremic syndrome

Over a 3-month period, ten children (aged 1-13 years) from a 15-km radius in southern Picardy developed typical D+ hemolytic uremic syndrome (HUS). Polymerase chain reaction, using two pairs of verocytotoxin 1-(VT1) and VT2-specific oligonucleotide primers and an internal control was used to detect VT genes directly from stools samples. VT2 gene was detected in seven of nine patients' stools and in 5 of 14 contacts' stool samples. A VT2-producing Escherichia coli (VTEC) O111 was isolated from five of nine children's stools and in 3 adults' stools of the 14 tested. A retrospective case-control study was performed which showed a higher rate of absence in school A, where the first four cases were detected, compared with a control school. The odds ratio for the whole school was 2.77 (confidence interval 1.46-5.26), and 15 (confidence interval 2.54-115.6) if only the nursery classes were considered. A culture of all food samples from households was always negative for VTEC. A retrospective cohort study performed in 89% of children attending school A showed no linkage between food or drink and gastroenteritis. These findings emphasize the potential for person-to-person transmission of VT2-producing E. coli O111, since the only salient risk factor was close contact.

Fragile X mutation and FG syndrome-like phenotype

We present data on 4 mentally retarded brothers, 2 of whom were dizygotic twins with congenital hypotonia, constipation, head size disproportionately large for length or height, and a combination of minor anomalies suggestive of FG syndrome. These brothers have a mentally retarded full sister with similar minor anomalies and an older half-brother with the Martin-Bell syndrome. The mother is mentally retarded; 4 of 7 individuals are positive for fragile X, but all have a CGG expansion ranging from 0.2-2 to 4 kb. Although the phenotype is not completely typical of the FG syndrome and the coincidence of the FMR1 mutation and segregation of the MCA/MR phenotype are highly unlikely, the FMR1 mutation may affect morphogenesis more extensively and differently than the Martin-Bell syndrome does to effect an FG syndromelike phenotype in certain families. This phenotype does not appear to be a contiguous gene syndrome, but an effect of the FMR1 mutation on an adjacent gene must be considered.

c-fos-like immunoreactivity in the cat's neuraxis following moderate hypoxia or hypercapnia

The overall pattern of c-fos immunoreactivity was studied in the brainstem and spinal cord of cats subjected to moderate hypoxia or hypercapnia. In control cats (normoxic, normocapnic), c-fos was expressed mainly in pontine and periaqueductal grey but not in brainstem structures engaged in respiratory control nor in the spinal cord. Both hypoxia and hypercapnia induced c-fos expression in the parabrachial area (pneumotaxic center). In the retrotrapezoid nucleus, a structure involved in respiratory rhythmogenesis and chemoreception, immunoreactivity was detected in hypoxic but not in hypercapnic cats. Neurons in the nucleus raphe pallidus preferentially expressed c-fos in response to hypercapnia. Labelled neurons were concentrated in the dorsal and gelatinosus subnuclei of the solitary tract following hypoxia and hypercapnia, respectively. Our data suggest that some neurons that express c-fos in hypoxic or hypercapnic cats may be involved in coordination of cardiovascular and respiratory function.

[Dubowitz syndrome. A diagnosis not to be missed]

Dubowitz syndrome is a rare hereditary disorder whose main features are intra-uterine and post-natal growth retardation, characteristic facies, microcephaly, mental retardation and poor feeding. Because of the eczema which was present in half of the cases after 4 years of age, it cannot be mistaken for the more frequent fetal alcohol syndrome. We report 5 cases, among whom two sibs, confirming the recessive autosomal mode of inheritance and the necessity for genetic counseling.

[Diverticulum of the stomach in children. Apropos of a case of congenital diverticulum]

We describe a patient with a large diverticulum of the gastric fundus disclosed by an episode of epigastric pain. Hematemesis occurred, requiring surgical removal of the diverticulum. Gastric diverticula are uncommon embryologic anomalies that are usually asymptomatic. Surgical treatment is necessary if a complication develops.

[Tumor epilepsy. Apropos of a case of temporal astrocytoma]

We report the case of a 15-year-old who sustained neonatal distress and subsequently presented temporal seizures. These were ascribed only several years later to a temporal astrocytoma. Tumor-related epilepsy is infrequent in children. Tumors may be responsible for a pattern of isolated partial epilepsy of several years duration. Advances in medical imaging techniques ensure earlier diagnosis, but some CT scan images may be difficult to read. CT scan is not indicated in functional epilepsy but should be performed in partial epilepsy with no known etiology.