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Biomedical subjects

N Amir

Publications and source records attributed to N Amir.

At least 55 records · Page 3Linked to original sources
PubMed1989

[Organic aciduria in Canavan disease].

3 male and 2 female infants with Canavan disease proven in some by brain biopsy, whose symptoms appeared within the first 4 months of life, are presented. Urinary organic acids were analyzed by gas chromatography/mass spectrometry. All excreted large amounts of N-acetylaspartic acid, probably secondary to decreased activity of its hydrolase. The pathogenetic mechanism is not well understood. Analysis of urinary organic acids can replace brain biopsy in the diagnosis of this condition, and the diagnosis can now be made prenatally.

Acids↗
PubMed1989

Segmentation of EEG during sleep using time-varying autoregressive modeling.

Time-varying AR modeling is applied to sleep EEG signal, in order to perform parameter estimation and detect changes in the signal characteristics (segmentation). Several types of basis functions have been analyzed to determine how closely they can approximate parameter changes characteristic of the EEG signal. The TV-AR model was applied to a large number of simulated signal segments, in order to examine the behaviour of the estimation under various conditions such as variations in the EEG parameters and in the location of segment boundaries, and different orders of the basis functions. The set of functions that is the basis for the Discrete Cosine Transform (DCT), and the Walsh functions were found to be the most efficient in the estimation of the model parameters. A segmentation algorithm based on an "Identification function" calculated from the estimated model parameters is suggested.

Algorithms↗
PubMed1989

Glutaric aciduria type I: enzymatic and neuroradiologic investigations of two kindreds.

Two kindreds with glutaric aciduria type I were investigated. Of 20 family members who underwent neurologic examination and organic acid analysis of urine, 18 had glutaryl-coenzyme A dehydrogenase (GDH) activity determined in cultured skin fibroblasts and 12 had computed tomographic brain scans. Six homozygotes were identified who had undetectable GDH activity and identical biochemical profiles (consisting of glutaric and 3-hydroxyglutaric aciduria, reduced serum carnitine concentrations, and frontotemporal atrophy). Serial computed tomographic brain scans of one homozygous infant demonstrated the sequential postnatal development of this atrophy during 3 years before the development of clinical manifestations. In three of the six homozygotes, including the father in one kindred, there were no clinical manifestations of glutaric aciduria type I. These findings raise questions about the value of prenatal diagnosis in predicting clinical manifestations in homozygous newborn infants.

Adult↗
PubMed1988

Developmental dyscalculia.

We conducted a neurobehavioral evaluation on eleven children with developmental dyscalculia in order to determine which aspects of arithmetic processes are affected in this disorder. Our results indicate that memorization of numerical facts in these children was poor or virtually non-existent and the ability to solve simple arithmetic exercises impaired. By contrast, comprehension and production of number functions were intact. Although all children had been referred for evaluation of selective deficits in arithmetic skills, they also displayed a mild degree of dyslexia, dysgraphia, anomia, and grapho-motor dysfunction. We conclude that cognitive mechanisms underlying arithmetic ability can be dissociated developmentally and suggest that remediation programs be designed only after detailed analyses of arithmetic and associated cognitive skills.

Adolescent↗
PubMed1988

Arachnoid cysts: unusual aspects and management.

Several unusual aspects of primary cerebral arachnoid cysts are presented. The optimal management of these lesions is discussed. Attempts at craniotomy and excision of these cysts is not always effective in eliminating the lesion and may provoke intracranial catastrophies. Huge and bilateral cysts are best treated by cystoperitoneal shunting. In general shunting may be preferable to craniotomy and resection of the cyst. An anti-siphon device is recommended to avoid overdrainage of cerebrospinal fluid.

Adult↗
PubMed1987

Glutaric aciduria type I: clinical heterogeneity and neuroradiologic features.

We present four patients, two pairs of siblings, with glutaric aciduria type I (GA I). All four had undetectable glutaryl-CoA dehydrogenase activity on fibroblast culture and massive urinary excretion of glutaric acid. All had serum carnitine deficiency at time of diagnosis except one patient who was diagnosed neonatally. All had a unique pattern of frontotemporal atrophy on CT. Remarkably, in both sibling pairs, one child was asymptomatic. This suggests that the biochemical markers hitherto identified with GA I do not encompass the entire scope of the metabolic or enzymatic abnormalities. Alternatively, as yet unidentified mechanisms might spare or delay the destructive process.

Atrophy↗
PubMed1987

Mucolipidosis type IV: clinical spectrum and natural history.

The clinical spectrum and developmental features of mucolipidosis type IV, a recessive lysosomal storage disorder, are presented. The evaluation was based on information from the clinical charts and information obtained from the families of 20 patients between the ages of 2 to 17 years. The clinical manifestations of the disease, profound psychomotor retardation and visual impairment, appear during the first year of life. Definitive diagnosis is made by electron microscopy which reveals storage organelles typical of the mucolipidoses. This study details, for the first time, the heterogeneity of the ophthalmologic features, specifically as pertains to the age of onset, degree and clinical course of the corneal opacities, and the retinal involvement. Although the top developmental level was found to be 12 to 15 months in language and motor function, the course of the disease is protracted for some children, who show only a slight improvement, and others, little if any deterioration despite the early infantile onset of the disease. This presentation provides guidelines for the clinical diagnosis of mucolipidosis type IV.

Adolescent↗
PubMed1986

Valproic acid in neonatal status convulsivus.

Valproic acid infused rectally was successful in controlling seizures in two neonates who failed to respond to conventional anti-convulsive therapy. We suggest that this drug may be a useful adjuvant in difficult cases of status convulsivus in neonates.

Humans↗
PubMed1986

Gowers' sign in discitis in childhood.

Three cases of discitis in early childhood presented with acute refusal to walk or change in gait pattern without neurologic deficits. In all three, a Gowers' sign was observed, although none had muscular weakness. The diagnosis of discitis was confirmed by the characteristic radiographic findings on survey lumbosacral films and/or by a hot spot at the L3 level on technetium bone scan.

Child, Preschool↗
PubMed1986

Sleep patterns in the Lennox-Gastaut syndrome.

Serial polysomnograms were performed on 11 children with primary Lennox-Gastaut syndrome (LGS), 6 control children with other seizure disorders, and 12 who were developmentally normal. Five LGS children had abnormal polysomnograms with either complete absence or marked reduction of REM sleep; the other six LGS children had only a mild reduction of REM sleep. The percentage of REM in LGS children was less than in the controls with other seizure disorders (p less than 0.05) or the normal children (p less than 0.005). The scatter of REM percentages in LGS may imply heterogeneity of the syndrome, perhaps related to the severity of brainstem dysfunction or neurochemical derangement.

Adolescent↗
PubMed1985

Interictal electroencephalography in night terrors and somnambulism.

Night terrors and somnambulism (NTS) are defined as disorders of arousal occurring in children during Stage 3 to 4 of NREM (non-rapid eye movement) sleep. In this study, the interictal EEG recordings in 35 neurologically normal children with clinical NTS were studied. Sixteen children (47%) had disturbed records including: localized slow, spike or sharp wave activity; generalized bursts of high voltage, sharp waves, spikes and slow delta activity or spike and wave complexes; and episodic high-voltage delta activity during wakeful rest. This percentage represents half the incidence of interictal EEG abnormalities in childhood epilepsy, but far greater than the 10 to 15% found in healthy children.

Adolescent↗