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Biomedical subjects

B Garreau

Publications and source records attributed to B Garreau.

At least 55 records · Page 3Linked to original sources
PubMed1984

Are there sex differences in averaged evoked responses produced by coupling sound and light in children and adults?

Averaged evoked response (AER) amplitudes have been reported to be larger in women than in men. The aim of this study was to determine whether AER changes produced by coupling sound and light differed between males and females (adults and children). Given the 3:1 male-female ratio in early infantile autism, we reasoned that information about sex-related differences in normal subjects might be important in interpreting the results in autism. We observed the characteristic AER changes when coupling sound and light: increased response amplitude over the occiput for both adults and children, decreased response amplitude over the vertex for adults and N1 decreased and P2 increased response amplitude over the vertex for children. Differences appeared as a function of sex in adults: the number and the amplitudes of AERs recorded in women were greater than in men with the exception of the P2 peak recorded over the occiput which was similar for males and females. The sex-related differences observed in the number and amplitudes of AERs are reduced when coupling sound and light.

Acoustic Stimulation↗
PubMed1984

[Relation between auditory evoked potentials (presence, amplitude) during sound and light conditioning and levels of dopamine derivatives in infantile autism].

The aim of this study was to study the relationships between conditioned AEPs and homovanillic acid (HVA) levels in autistic children (A, 9 boys, average age 6.3) compared to normal children (9 boys, average age 6.5) and to mentally retarded children (MR, 9 boys, average age 6.1) without any autistic behavior. AEPs were recorded at Cz and Oz during two sessions. The auditory stimulus (S) was first presented alone (habituation); the visual stimulus (L) was then presented 800 msec after S (conditioning). S was again presented alone (extinction). Urinary HVA dosage was performed on samples of urine taken after a 48-h tyrosine-free diet. Conditioning induced enhancement of AEPs. Latencies and amplitudes were smaller in autistic children. AEP presence was smaller in patients than in normal children and smaller in MR than in A children. Urinary HVA level was higher in patients and higher in the MR group than in the A group. A negative correlation between HVA level and Cz AEP presence was observed. Results showing higher Cz AEP variability and higher HVA level in MR than in autistic children tend to lead us to consider that both syndromes are related to common neurological dysfunctionings rather than indicating autistic syndrome behavioral specificity.

Attention Deficit Disorder with Hyperactivity↗
PubMed1984

[Brain stem auditory evoked potentials in the normal and autistic child].

From a neurophysiological viewpoint a hypothesis for the etiology of early infantile autism suggests that the symptoms are a result of abnormalities in processing sensory input at the level of the brain-stem. The methods for recording auditory evoked responses (BAERs) seemed particularly well suited to study a failure at this level. BAERs to brief monaural and binaural stimulation were studied in 17 autistic children ranging in age from 3 to 9 years (mean = 6.1). They were age and sex matched to normal controls. Electrodes were placed at the vertex and at the mastoid ipsilateral to the stimulation. Signals were amplified 10(5) using an amplifier with bandpass filters set at 160 Hz and 3 kHz. Stimuli were clicks (120 microsec) delivered to subjects through earphones at 2 intensities: 70 and 90 dB. Stimuli were presented in blocks of 3000 clicks (1500 clicks for each intensity) with a rate of 10/sec. No sedative medication was used. There was no difference between autistic and normal children for the latencies of peak I. Latencies of peaks II, III, IV and V were found to be shorter in autistic than in normal children. The I-II and II-III interpeak transmission times were significantly decreased in the autistic group, but not III-V interpeak transmission time. Autistic children showed V-VN amplitude greater than normal children. Our findings suggest that in the autistic syndrome, there is a defect of the modulation processing input related to intensity at brain-stem level.

Autistic Disorder↗
PubMed1983

Auditory brain stem responses and cortical auditory-evoked potentials in difficult-to-test children.

Brain-stem-evoked responses (BERs) and cortical auditory-evoked potentials (AEP) were recorded in 24 children showing severe behavioral disorders. BER testing always requires sedation if not general anesthesia. This allowed us to perform precise acoustic impedance measurements, and thus to find 3 glue ears. The electrophysiological tests revealed whether there was sensorineural deafness, which was cared for if necessary. Finally, when the BERs were normal, we evaluated the modifications in the cortical AEP, in relation to a clinical classification closely related to that of the DSM III of the American Academy of Psychiatry.

Adolescent↗
PubMed1983

[Monoamine and monoamine enzyme abnormalities in childhood autism].

According to monoaminergic hypothesis of psychosis, several symptoms observed in child autism may be related to anomalies of cerebral amines and/or synaptic dysfunctioning. The main amines concerned are serotonin and dopamine which are synthetized and catabolized following similar schemes. Methyl-indolamines production, mentioned in adult schizophrenia, has not been observed in child autism. Similarly, monoaminoxydase diminution has been observed in adults and not in children. Hyperserotoninemia does exist in some cases of child autism. Results concerning dopaminergic systems are more promising. The autistic behavioral syndrome suggests a dopaminergic dysfunctioning. Enhancement of homovanillic acid, the main metabolite of dopamine, has been found both in cerebrospinal fluid and in urines of some autistic children. Moreover, modifications of dopamine-beta-hydroxylase, an enzyme that changes dopamine into noradrenaline, have been mentioned in some cases of autism. A better definition of the autistic clinical syndromes associated with a more systematic study of monoamines plasmatic and urinary derivates will allow, in the near future, a better understanding of child autism and a clearer definition of therapeutic indications.

Amino Acids↗
PubMed1981

Effects of pyridoxine and magnesium on autistic symptoms--initial observations.

In an open trial, a heterogeneous group of 44 children with autistic symptoms were treated with large doses of vitamin B6 and magnesium. Clinical improvement with worsening on termination of the trial was observed in 15 children. Thirteen responders and 8 nonresponders were retested in a 2-week, crossover, double-blind trial, and the responses to the open trial were confirmed.

Adolescent↗
PubMed1981

HVA and MHPG in urine of premature infants.

Higher levels of homovanillic acid (HVA) and 3-methoxy-4-hydroxyphenylglycol (MHPG) were observed in urines of 12 premature infants than in older children. An examination of the influence of age, sex, size, and head circumference revealed that the smaller the infants, the higher the HVA and MHPG values. Recently several investigators have reported an increased titer of urinary HVA in autistic children. It has been hypothesized that the increased levels of catecholamine metabolites (notable HVA and MHPG) could reflect accelerated catecholamine turnover. The elevated urinary HVA titers in infants as well as in autistic children may be due to an immaturity of the dopaminergic receptors.

Cephalometry↗
PubMed1981

Effects of vitamin B6 on averaged evoked potentials in infantile autism.

In autistic children, averaged evoked potentials have been reported to have lower amplitudes and shorter latencies than those of normal children. Also, moderate clinical improvement has been observed in some autistic children after treatment with vitamin B6 and magnesium. We have studied biochemical and electrophysiological effects of vitamin B6 and magnesium in 12 autistic children and in 11 normal children. During treatment of the autistic children with B6, an increase of amplitude of middle-latency evoked potentials and a decrease of urinary homovanillic acid were found. The reverse was noted in the normal subjects.

Autistic Disorder↗
PubMed1979

[Measurement of homovanillic acid in urine of newborns and in older children].

In this study, the urinary H.V.A. of new borns and of older children was measured. The urinary H.V.A. titer of the new borns was found to be significantly greater than in older children. Moreover the increase is more pronounced when those infants are born prematurely. Former studies have shown that the metabolism of central nervous system catecholamine reflected by the urinary titers of H.V.A. is as accurate as titers measured in the CSF. Recently several authors have found increased titers of urinary H.V.A. in autistic children. It is therefore possible that the elevated urinary H.V.A. titers in the new born are due to an immaturity of the dopaminergic structures. Blocking these structures provokes an accelerated catecholamine turnover, thereby increasing the levels of catecholamines metabolites (most notably H.V.A.).

Adolescent↗
PubMed1978

[Modifications in urinary homovanillic acid after ingestion of vitamin B6; functional study in autistic children (author's transl)].

Basing their study on the investigations which led to the dopaminergic theory of the psychoses, the authors studied homovanillic acid (principal derivative from dopamine) levels in the urines of 37 autistic children, and 11 normal children acting as controls. The favourable action of vitamin B6 on autism, reported by anglosaxon authors, was confirmed in 15 of the children. Furthermore, vitamin B6 reduces homovanillic acid levels in 33 autistic chilren and increases them in all the control group children.

Autistic Disorder↗
PubMedDate not supplied

Cortical evoked potentials as indicators of auditory-visual cross-modal association in young adults.

Auditory evoked potentials (AEPs) were studied from scalp locations Cz and Oz on 37 adults aged 20-22 years during sensori-sensorial association of a weak sound (S) and a strong flash of light (L). After sound alone repetition (habituation), S-L association modified AEP: first, it caused a generalized orienting response expressed as increasing of Cz and Oz amplitude AEPs. Then, this pattern gave way to an activation limited to the Oz lead: the increase of amplitude was then concomitant with shortened latencies when compared to sound-alone-habituated responses. Inter-individual differences were observed since these occipital modifications were recorded only on 26 subjects. The other 11 subjects did not exhibit any occipital modifications following S-L association. For them, the main modification was a strong decrease of Cz AEP induced by S-L association. These two groups also differed in their capacity to ignore irrelevant stimuli which is higher in the first group (AEP amplitude habituation with sound-alone repetition) than in the second one (no AEP habituation).

Adult↗
PubMedDate not supplied

The physicochemical and biological properties of alpha-fetoprotein depend of its ligand environment.

The majority of studies have concentrated on the endocrine and immunological roles of alpha-fetoprotein (AFP). These studies have been strongly orientated and sustained by research showing that rat and mouse AFPs competitively bind estrogen and non-esterified fatty acids. AFPs of other species, such as humans, are not estrogenophilic but all those studied to date bind NEFAs tightly. Endogenous ligands can greatly influence the conformation of the protein and consequently its biological activity. AFP may have three possible mechanisms of action: a) Murine AFP may be a modulatory element of estrogen expression which determines, under the control of NEFAs the concentration of the active free steroid. b) The protein could be transformed by bound ligands, so enhancing or inhibiting its binding to a target cell receptor, and consequently modifying its biological activity. AFP per se, can be the regulatory element. c) AFPs of all species can work as fatty acid binding proteins and modulate the availability of free NEFAs (not bound to protein). These free NEFAs can, in turn, act positively or negatively on various proteins involved in the pathways of the transfer of the steroid and peptide informations leading to cell multiplication or differentiation.

Animals↗