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Biomedical subjects

I Rapin

Publications and source records attributed to I Rapin.

At least 109 records · Page 6Linked to original sources
PubMed1975

GM2-gangliosidosis, AB variant: clinico-pathological study of a case.

Clinical and neuropathological studies of a case of AB variant GM2-gangliosidosis have been presented. The patient was a 14 months old black female infant who had "black cherry spot" in the retinas. The total activities of beta-galactosidase and N-acetyl-beta-hexosaminidase, as well as the proportion of hexosaminidase A and B components in her serum and leukocytes were normal when the assays were carried out with artificial fluorogenic substrate. Diagnosis of GM2-gangliosidosis AB variant was established by an abnormal increase of GM2-ganglioside in the biopsied brain tissue, similar to classical Tay-Sachs disease. Her clinical manifestation appeared to be similar but somewhat milder than those of classical Tay-Sachs disease. Light microscopic features of the cerebral biopsy were also closely similar to Tay-Sachs disease and Sandhoff disease but gliosis and neuronal loss were less pronounced. Electron microscopic study revealed numerous membranous cytoplasmic bodies (MCB) and zebra bodies in neurons. In addition, varieties of large intracytoplasmic inclusions in astrocytes, a feature distinctly different from classical Tay-Sachs disease, were observed. Numerous cytoplasmic inclusions were also present in oligodendroglia, pericytes and microglial cells.

Acetylglucosaminidase↗
PubMed1975

Ceroid lipofuscinosis.

Seven of ten patients with ceroid lipofuscinosis, including infantile, late infantile, juvenile, and atypical variants, presented with visual acuity loss. In the infantile case visual acuity loss was early and severe. Two patients with atypical variants did not develop ocular abnormalities. Children presenting with macular degeneration may have more extensive retinal involvement on electrophysiologic testing; neurologic evaluation may rule out the prodromal stages of lipofuscinosis.

Adolescent↗
PubMed1975

Cortical evoked potentials elicited by real speech words and human sounds.

Averaged evoked potentials were recorded from PZ and left and right temporo-parietal electodes to real speech words and human sounds in 8 right-handed subjects. Stimuli were presented in a "no task" condition where the subject was instructed to listen attentively, and a vigilance condition where the subject responded to a particular word or sound during a run of such stimuli. The vigilance condition produced two classes of stimuli:signals and non-signals. Evoked potentials to physically identical words or sounds were examined when they were "no task", non-signal and signal stimuli. P300 amplitude increased significantly as a function of increasing task demands going from "no task" to non-signal to signal. When a strict statistical criterion for multiple comparisons (Bonferroni test) was applied in looking for asymmetries between hemispheres, only 2 isolated left greater than right differences turned out to be significant. Review of the literature concerning evoked potential correlates of differential hemispheric processing pointed up flaws in design, statistical technique, and inconsistencies in reported findings which suggested that while evoked potentials may sometimes reflect differences in hemispheric functioning, this effect is marginal at best.

Adult↗
PubMed1975

The late positive component (P300) and information processing in sentences.

Averaged visual evoked potentials to sequentially flashed words comprising a sentence were recorded from vertex and left and right temporoparietal electrodes in 8 right-handed subjects. In condition 1 the sentence took the form: The -eel is on the shoe, in which the first grapheme was omitted from the second word, so that the subject did not know the meaning of the second word until he viewed the last word. In condition 2, the sentence took the form: The heel is on the shoe, in which the second word was given and the last word provided no further information. P300 latency to words which delivered information (last word of condition 1, second word of condition 2) were significantly longer than P300 latency to any of the other words in the sentence, as well as to the same position word in the other condition. Comparisons of P300 latencies to redundant words (the, is, on) within and between conditions showed no significant differences. P300 amplitude to the last word was significantly larger than P300 amplitude to any of the other words within the sentence, even in condition 2 where the second word delivered information. The major effect of information delivery was on P300 latency, while "syntactic closure" had its major effect on P300 amplitude. The fact that evoked potentials to all words had P300 components was attributed to the engagement of the P300 system whenever task-related language stimuli are used.

Adolescent↗
PubMed1975

Neuropsychologic function of children with severe hearing impairment.

A neuropsychologic and medical study was carried out on a selected sample of 34 hearing-impaired children aged seven to 10 years at the onset of the study. In 16 children the cause of the hearing loss was thought to be exogenous. Eight of these had evidence for organic brain dysfunction. Nine children were thought to have genetic etiologies, and in nine no cause could be determined (sporadic hearing loss). Medical examination revealed several unsuspected abnormalities, particularly visual ones. Motor and visual motor deficits were frequent among hearing-impaired children with brain damage. The Performance Scale of the Wechsler Intelligence Scale for Children, and Raven's Coloured Progressive Matrices, as well as the Paper Folding item of the Hiskey-Nebraska Test of Learning Aptitude appeared sensitive to the presence of brain damage. The mean score for the WISC Performance Scale fell within the average range for hearing children, supporting previous findings of cognitive competence of the deaf. In this sample, Hiskey-Nebraska scores tended to be lower than WISC scores. Reasons for this discrepancy were suggested and did not appear to be accounted for by brain damage. Deficits in items requiring visual memory, sequencing, and categorization were relatively prevalent but showed no etiologic predilection. They were thought to be related to the consequence of hearing loss rather than to brain damage. Difficulty with stereognosis highlighted the problem of deciding why a hearing-impaired child might fail a particular task. This difficulty suggested that failure might not indicate a deficit in the function the task was designed to measure, but rather, reliance on an inefficient strategy for success.

Audiometry↗
PubMed1975

Dylexia in children and young adults: three independent neuropsychological syndromes.

In an attempt to delineate causal factors in dyslexia, 113 children and young adults (age-range eight to 18 years) were divided into three groups: those with brain damage who could read (n=31), those with brain damage who were dyslexic (n=53), and those without brain damage who were dyslexic (n=29). A battery of neuropsychological tests was presented to each participant. No significant differences were found between the two dyslexic groups. Three syndromes--language disorder, articulation and graphomotor dysco-ordination, and visuo-perceptual disorder--were found among the great majority of those with dyslexia. The results support a model of dyslexia as being caused by multiple independent defects in higher cortical functioning, as opposed to the theory of a single causal defect. A clinical description of each syndrome is given and models of dyslexia are discussed. The authors stress the desirability of including brain-damaged readers as a control group in any future study on causal factors in dyslexia.

Adolescent↗
PubMed1975

Improving evoked response audiometry. Results of normative studies for machine scoring.

Normative studies were carried out with 8 adult subjects whose averaged evoked responses to auditory stimuli were scored visually and by a number of differently defined quantitative methods (machine scoring). In order to compare different scoring methods a common signal-to-noise ratio measure was introduced based on a model where noise is distributed normally and signal is additive. Visual and machine scoring proved to be approximately equally sensitive, but the latter lends itself to a superior testing procedure which takes only one-third as long for equivalent results and is not contaminated by subjective error. The authors believe that the greatest promise for improving evoked response audiometry lies in the exploration of the new techniques proposed earlier. Progress in proving out one of these techniques, fast periodic stimulation, is reported.

Acoustic Stimulation↗
PubMed1973

Peroxisomal and mitochondrial defects in the cerebro-hepato-renal syndrome.

The cerebro-hepato-renal syndrome is a rare familial malady with cerebral, renal, and skeletal abnormalities, severe hypotonia, cirrhosis, iron and lipid storage, and death within 6 months. Correlated electron microscopic, histochemical, and biochemical studies demonstrate defects in two oxidative organelles. Peroxisomes cannot be found in hepatocytes and renal proximal tubules. In hepatocytes and cortical astrocytes, mitochondria are distorted in their appearance and glycogen stores are increased. Oxygen consumnption of brain and liver mitochondrial preparations with succinate and with substrates reducing nicotinamide adenine dinucleotide is markedly diminished, but the consumption is normal with ascorbate and tetramethylphenylenediamine, which suggests a defect in electron transport prior to the cytochromes. Histochemical studies of mitochondrial oxidation point to a defect between the succinate dehydrogenase flavoprotein and coenzyme Q, possibly in the region of nonheme iron protein.

Acidosis↗