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Biomedical subjects

G Lyon

Publications and source records attributed to G Lyon.

At least 19 recordsLinked to original sources
PubMed2001

MECP2 mutation in non-fatal, non-progressive encephalopathy in a male.

To study the clinical overlap between Rett (RTT) and Angelman syndromes (AS), we screened the MECP2 gene in a cohort of 78 patients diagnosed as possible AS but who showed a normal methylation pattern at the UBE3A locus. MECP2 missense (R106W, G428S), nonsense (R255X, R270X), and frameshift mutations (803 delG) were identified in 6/78 patients including 4/6 female cases consistent with RTT, one female case with progressive encephalopathy of neonatal onset, and one isolated male case with non-fatal, non-progressive encephalopathy of neonatal onset. This study shows that MECP2 mutations can account for a broad spectrum of clinical presentations and raises the difficult issue of the screening of the MECP2 gene in severe encephalopathy in both males and females.

Angelman Syndrome↗
PubMed2001

[Management of dyslipidemias diagnosed in general practice in France--The PRAGMA Study].

Several studies have reported the penetration and impact of national and international recommendations on the management of dyslipidaemia, a major cardiovascular risk factor. Most of them were carried out on patients participating in clinical trials or on in-hospital cases. The PRAGMA study was developed in order to evaluate management of this condition in general practice, at the heart of the health care system. From September to December 1998, 1,717 general practitioners were chosen randomly and included 6,623 patients considered to have a lipid disorder. In this sample, the prevalence of the main risk factors was as follows: hypertension: 39.6%, diabetes: 11.6%, obesity: 19.6%, past or present smokers: 33.8%. The main lines of management consisted in prescribing lipid lowering drugs (96.6%) with dietary recommendations (95.8%) and a fall lipid profile (59.9%). The main factors spontaneously cited by the general practitioners as being decisional were: the total cholesterol level (47.8%), diet (40.8%), body weight (29.4%) and drug therapy (19.2%). The cardiovascular risk factors were rarely taken into account in their totality. These results suggest that the management of dyslipidaemia patients by general practitioners is far from being optimal. Efforts should be made to change attitudes to take into consideration the global cardiovascular risk factors of patients with lipid disorders.

Adult↗
PubMed1999

Fatal infantile cardioencephalomyopathy with COX deficiency and mutations in SCO2, a COX assembly gene.

Mammalian cytochrome c oxidase (COX) catalyses the transfer of reducing equivalents from cytochrome c to molecular oxygen and pumps protons across the inner mitochondrial membrane. Mitochondrial DNA (mtDNA) encodes three COX subunits (I-III) and nuclear DNA (nDNA) encodes ten. In addition, ancillary proteins are required for the correct assembly and function of COX (refs 2, 3, 4, 5, 6). Although pathogenic mutations in mtDNA-encoded COX subunits have been described, no mutations in the nDNA-encoded subunits have been uncovered in any mendelian-inherited COX deficiency disorder. In yeast, two related COX assembly genes, SCO1 and SCO2 (for synthesis of cytochrome c oxidase), enable subunits I and II to be incorporated into the holoprotein. Here we have identified mutations in the human homologue, SCO2, in three unrelated infants with a newly recognized fatal cardioencephalomyopathy and COX deficiency. Immunohistochemical studies implied that the enzymatic deficiency, which was most severe in cardiac and skeletal muscle, was due to the loss of mtDNA-encoded COX subunits. The clinical phenotype caused by mutations in human SCO2 differs from that caused by mutations in SURF1, the only other known COX assembly gene associated with a human disease, Leigh syndrome.

Amino Acid Sequence↗
PubMed1999

Prognostic factors in congenital hemiplegia in full-term and preterm children.

OBJECTIVES: To determine whether the cerebral CT scan patterns, the type of E.E.G recording, the gestational age, the etiological factors and the side of hemiplegia would influence the functional prognosis in congenital hemiplegia. MATERIAL AND METHODS: 53 children (35 males, 18 females) suffering from congenital hemiplegia were included in the study. They were divided into prematures (16 cases) and full-term children (37 cases). All of them were evaluated for I.Q level, motor performance and language ability. CT scan was performed in all cases and E.E.G recording in the majority of them. RESULTS: Full-term gestational age, cortical and subcortical lesions in term children, irritative E.E.G recording and hemispheric atrophy in both gestational age groups were found to be bad prognostic indicators for functional status in congenital cerebral hemiplegia.

Adolescent↗
PubMed1996

Neuropathological study of a case of autistic syndrome with severe mental retardation.

Infantile autism is a syndrome of unknown aetiology and unknown neuro-anatomic substrate. The authors report a histological study of the brain of a well-documented 16-year-old female with autistic syndrome and severe mental retardation, using direct microscopic examination of the whole brain. The major findings are low brain weight, a thin corpus callosum and ventricular dilatation. No abnormalities were found in the hippocampus or cerebellum. Excessive axonal elimination during brain development is hypothesized. The relations of hypothetical developmental events with the clinical features of autistic syndrome are discussed.

Adolescent↗
PubMed1995

Prolonged dysphagia caused by congenital pharyngeal dysfunction.

We describe two patients with severe, isolated, congenital dysphagia caused by paralysis of the pharyngeal muscles, who recovered at the ages of 40 months and 20 months, respectively. No other evidence of neurologic or muscular dysfunction was present except for a transient paralysis of the adductors of the vocal cords in one child. Radiocinematographic studies showed paralysis of the pharyngeal stage of swallowing, with minimal involvement of the oral stage. One child refused oral feeding for several months after apparent radiologic recovery. Two other patients with a similar disorder died of tracheal aspiration at the ages of 8 months and 4 months, respectively. Autopsies showed no abnormality of the central nervous system, and the cranial nerves involved in swallowing were normal. Only five other well-studied cases of this syndrome have been reported. These observations demonstrate the existence of a type of severe, idiopathic, congenital dysphagia related to paralysis of the constrictor muscles of the pharynx, with a propensity to recover after several months or years if properly managed. The cause of the disorder is obscure, but it is probably related to a dysfunction of the central nervous system.

Child, Preschool↗
PubMed1993

[Congenital paralysis due to compression. Apropos of 4 cases].

Four cases of congenital dysfunction of major peripheral nerves are reported and discussed. The first patient was a girl born by spontaneous delivery with an area of skin and muscle necrosis on the dorsal aspect of the forearm and a palsy of the three major nerves of the upper limb. The second patient was a boy born by caesarean section with the same necrotic lesions and a palsy of the ulnar and median nerve. The third patient was a boy born uneventfully with a truncal lesion of the sciatic nerve at the thigh. The fourth who was delivered by caesarean section for alteration of the monitoring presented a severe strangulation of the arm by the umbilical cord with palsy of the radial and ulnar nerve. The palsies recovered spontaneously and the sequelae are mostly due to the muscle necrosis. Congenital dysfunction of major peripheral nerves have been described as a complication of congenital constriction band syndrome, in association with subcutaneous fat necrosis, neonatal gangrene or aplasia cutis congenita. Intrauterine compression of a limb may be favoured by decreased foetal activity, by spontaneous rupture of the amniotic sac, particularly if there is a delay in delivery and by abnormal uterine activity during labour. Our three first cases confirm that the compression may arise before the labour. The fourth demonstrates that umbilical cord strangulation may lead to anoxia of the foetus together with compression of the limb.

Arm↗
PubMed1993

Disorder of cerebellar foliation in Walker's lissencephaly and neu-laxova syndrome.

A diffuse disorder of cerebellar foliation was found in eight infants and one fetus with Walker's lissencephaly. The cerebellar cortex consisted of fused and irregularly distorted folia. In the white matter, trilaminated rings of cortex were concentrically arranged around blood vessels and mesenchymal tissue. The normal relative position of the different classes of cortical nerve cells was preserved. Cells of the external granular layer invaded the meninges and migrated along penetrating blood vessels. We believe that this foliation disorder is caused by a defect in the external basal lamina that allows adjacent folia to be fused and sulci obliterated by intrameningeal ectopias of external granule layer cells. Physical forces applied during development probably contribute to the distortion of the gyral pattern. There was a volumetric reduction of the neocerebellum, which might also be a consequence of the basal lamina defect. The cerebellum of a fetus with the Neu-Laxova syndrome showed the same abnormalities as in Walker's lissencephaly. It is postulated that these two conditions belong to a class of prenatal developmental disorders that involves a defect of the extracellular matrix.

Abnormalities, Multiple↗
PubMed1993

[Epilepsy disclosing neuroborreliosis].

After two seizures, a 13 year-old boy experienced headache, fatigue and loss of appetite over a period of 3 weeks. There was a bilateral papilledema with normal visual acuity. CT and MRI disclosed two ischemic foci, that were interpreted as evidence of vasculitis. High serum levels of IgG and IgM antibodies specific to Borrelia burgdorferi, were present. The patient had attended an outdoor scout camp in a area, in south-east Belgium, known to be endemic for tick-born borreliosis. The clinical symptoms, the levels of the specific antibodies and the radiologic abnormalities responded dramatically to treatment. We believe that seizures in this case were related to cerebral vasculitis. This case confirms the extreme diversity of the neurological manifestations of Borreliosis.

Adolescent↗
PubMed1992

The human transient subpial granular layer: an optical, immunohistochemical, and ultrastructural analysis.

The cytological features, origin, migration, and fate of the subpial granular layer cells of the human embryonic cerebral cortex are studied with light and electron microscopy, Golgi impregnations, and immunocytochemical staining with the microtubule associated protein 2 and glial fibrillary acidic protein antibodies. Subpial granular layer (SGL) cells form a distinct neuronal population in the molecular layer, characterized by a small dark nucleus with abundant chromatin clumps and prominent nucleoli, and a lightly stained cytoplasm containing few organelles. Somata and processes of SGL cells are intensively stained with microtubule-associated protein 2 antibody but do not express glial fibrillary acidic protein antibody. These cells apparently originate from the olfactory germinative zone. They follow two major strands from the olfactory subventricular zone to the subpial region. Subsequently, they migrate tangentially at the subpial level to all cortical regions, as is observed on Golgi and ultrastructural preparations. They constitute a transient population that penetrates the deep molecular layer and subsequently disappear from it. Several cytological features of these cells suggest an inward migration with growth of a radial process toward the cortical plate and subsequent nuclear translocation. The fate and the role of this new phylogenetic neuronal population has yet to be determined although the abundance of degenerating SGL cells in the deep molecular layer suggests at least partial degeneration.

Cerebral Cortex↗
PubMed1992

Prenatal diagnosis of fetal cytomegalovirus infection.

A prospective study (1988 to 1990) to evaluate the risk of fetal cytomegalovirus transmission was conducted with 1771 pregnant women; the test results of 861 were seronegative (48.6%). At each prenatal visit they were tested for serologic data and cytomegalovirus excretion in urine, saliva, and cervical secretions. If seroconversion occurred (with or without cytomegalovirus excretion), ultrasonography, amniocentesis, and cordocentesis were performed at 22 weeks' gestation; 7 cases of primary cytomegalovirus infection were investigated. In 5 cases the amniotic fluid cultures were positive; in 3 cases the fetal blood test results were positive for specific immunoglobulin M; and in 2 cases brain ultrasonography results were positive. Infection was confirmed with biopsies of fetal tissue. In two other cases, the cord blood and amniotic fluid test results were negative, and the neonates were free of infection.

Adult↗
PubMed1991

Symptomatology of late onset Krabbe's leukodystrophy: the European experience.

The authors present a study of 50 patients with late onset Krabbe's leukodystrophy (LOKL), including 27 from a pooled European Series collected in 1987, and 23 published between 1906 and 1987. In Europe, the disease appears to be relatively frequent in Sicily and exceedingly rare in Sweden. Most cases started before the age of 5 years. The initial signs consisted mainly of progressive motor impairment, although, characteristically, visual failure was the initial manifestation in 25% of patients. Low nerve conduction velocities and a high protein content in the CSF were only present in 50%. There was no age-linked symptomatic predominance. The pace and length of the disease was very variable, but in one-third of the children before the age of 3 the course was remarkably rapid. There was no difference in the residual activity of galactosylceramide galactosidase in LOKL compared to the early infantile form.

Ataxia↗
PubMed1990

A disorder of axonal development, necrotizing myopathy, cardiomyopathy, and cataracts: a new familial disease.

We report severe congenital encephalopathy and profound hypotonia associated with necrotizing myopathy, cardiomyopathy, and cataracts in 3 infants, including 2 sisters. Brain scans suggested agenesis of the corpus callosum. Neuropathological findings consisted of severe atrophy of the corpus callosum (not the usual agenesis with longitudinal callosal bundles), atrophy of the white matter, and absence of pyramidal tracts in the medulla. Multiple axonal swellings were present in the white matter and in Purkinje cells. Except for the corpus subthalamicum, gray matter structures were preserved. These findings are considered to be the expression of a primary disorder of axonal development leading to a reduction in interneuronal synaptic contacts. It is suggested that the anomaly may be due to an extension of the normal phenomenon of axonal elimination, related to a primary defect of the axonal cytoskeleton. The concept of a primary axonal disorder may also apply to other, mostly familial, conditions with progressive atrophy of the cerebral white matter and corpus callosum.

Atrophy↗
PubMed1990

Periventricular leukomalacia: ultrasonic and neuropathological correlations.

Ultrasound scans of a preterm neonate (27 weeks gestation) at seven weeks of age showed periventricular echo-free cavities, but these were no longer visible at 15 weeks, three weeks before the infant died. At autopsy, a linear glial scar, extending from the periventricular white-matter into the white axis of the parasagittal gyrus, was found in the area occupied by the periventricular cysts. The larger cavity was reduced to a slit-like excavation in the midst of glial tissue. Unsuspected focal infarcts in the cerebral cortex were also found. This observation demonstrates that transient echo-free cavities represent foci of cystic necrosis, which are subject to secondary collapse. In the authors' experience, the linear extension of periventricular leukomalacia (PVL) into the core of parasagittal gyri is a frequent feature of PVL, and one which cannot easily be accounted for by the usual explanations of border-zone ischaemic softening.

Brain↗
PubMed1989

Distal infantile spinal muscular atrophy associated with paralysis of the diaphragm: a variant of infantile spinal muscular atrophy.

We report the clinical, electrophysiological, and morphological observations of five infants with an unusual form of spinal muscular atrophy (SMA). In these infants muscular weakness and atrophy were initially restricted to the distal limbs and this pattern was associated with paralysis of the diaphragm. The difference between the clinical manifestations of this syndrome and the classical form of infantile spinal muscular atrophy (SMA type 1) as well as other congenital hereditary neuropathies is discussed.

Atrophy↗
PubMed1988

Brain glucose utilization in childhood Huntington's disease studied with positron emission tomography (PET).

Brain glucose metabolism was measured in two children with early-onset Huntington's disease, using positron emission tomography with fluorodeoxyglucose (FDG) as the tracer. A marked (48%) hypometabolism was found at the level of the caudate nuclei, but other areas of the brain, particularly the cerebral cortex, were not significantly affected. Despite its different clinical presentation, Huntington's disease in children is characterized by brain metabolic alterations similar to those found in adult patients.

Adolescent↗
PubMed1986

Wernicke's aphasia in a 10-year-old boy.

We report the case of a ten-year-old boy, who, after herpes simplex encephalitis, presented a sensory aphasia having much in common with Wernicke's aphasia in adults. The genesis of neologisms appeared very similar to the mechanisms described by Buckingham and Kertesz (1974, Brain and Language, 1, 43-61). The findings are discussed in the light of theories of hemispheric specialization and of age-related semiologies.

Aphasia↗