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Biomedical subjects

Y D Lapierre

Publications and source records attributed to Y D Lapierre.

At least 145 records · Page 8Linked to original sources
PubMed1977

Alterations in brain 5-hydroxytryptamine metabolism during the 'withdrawal' phase after chronic treatment with diazepam and bromazepam.

1 Daily administration of diazepam or bromazepam (10 mg/kg) for 22 days significantly increased the activity of mid-brain tryptophan hydroxylase by 36% and 39%, respectively. The concentration of tryptophan was also enhanced in the mid-brain region of rats subjected to benzodiazepine treatment.2 Chronic therapy with either of the two anti-anxiety agents enhanced the endogenous levels of 5-hydroxytryptamine and 5-hydroxyindoleacetic acid in cerebral cortex, hypothalamus, pons-medulla, mid-brain and striatum.3 Whereas diazepam treatment decreased (13%) the activity of monoamine oxidase in mid-brain, bromazepam failed to exert any effect, suggesting that the observed elevation in 5-hydroxy-indoleacetic acid levels is not associated with enhanced deamination of 5-hydroxytryptamine.4 Discontinuation of treatment for 48 h significantly decreased the activity of mid-brain tryptophan hydroxylase to levels that were significantly lower than those seen for benzodiazepine-treated and normal rats. The concentrations of mid-brain tryptophan and 5-hydroxytryptamine were also reduced in various brain regions examined.5 Withdrawal from diazepam or bromazepam therapy further augmented the levels of brain 5-hydroxyindoleacetic acid.6 The results demonstrate that the depressant effects on behaviour of these agents are accompanied by increased metabolism of 5-hydroxytryptamine in the brain. Withdrawal from these minor tranquillizers, on the other hand, reduces the synthesis of this indoleamine.

Animals↗
PubMed1976

Control of lithium tremor with propranolol.

Lithium tremor is an irregular, nonrhythmic tremor of the distal extremities, variable in both intensity and frequency. It is clinically differentiated from essential tremor and tremors due to anxiety and neuroleptics. The pathophysiologic mechanisms are hypothesized to be of perpheral origin. Five patients were successfully treated with propranolol. In general, the dosage of propranolol must be individually adjusted and is usually from 30 to 40 mg daily in divided doses. This blocker of beta-adrenergic receptors remains effective with long-term administration and increases in dosage are not required.

Adult↗
PubMed1975

The effect of methylphenidate on sensory perception in varying degrees of hyperkinetic behaviour.

In a double-blind study of methylphenidate, hyperkinetic children of varying levels of age and degree of hyperactivity were assessed on subtests of the Illinois Test of Psycholinguistic Ability (ITPA). The ITPA was supplemented with a combination of monosensory, bisensory, and trisensory stimuli presentations. Methylphenidate improved the ITPA's visual, auditory and tactile age scores of children who exhibited a more marked degree of hyperkinetic behaviour. That improvement was also observed in the recognition of sensory stimuli presented in a monosensory fashion. Similarly, the children with a more marked degree of hyperkinesis improved their stimuli recognition rate significantly on methylphenidate when stimuli were presented to bisensory and trisensory perceptual modalities simultaneously. It was concluded that drug improvement on sensory perception seemed to be more related to the degree of hyperkinetic behavior manifested than to chronological age. Further research of degree of hyperkinesis, age-level, sensory modality and drug administration was suggested.

Adolescent↗
PubMed1975

The effect of methylphenidate on cardiovascular sensory differentiation on the hyperkinetic syndrome.

In the present study, the action of methylphenidate on mean heart rate was studied while hyperkinetic children were attending to monosensory, bisensory and trisensory stimuli presentations. Neither children receiving methylphenidate nor those receiving placebo exhibited a significant shift in tonic heart rate during relaxation periods. While attending to sensory stimuli, heart rates were higher for children receiving placebo than for those receiving methylphenidate in all experimental conditions for the high and moderate degrees of hyperkinetic behavior. A drug reversal effect was demonstrated in mildly hyperkinetic children.

Acoustic Stimulation↗
PubMed1975

Clinical and physiological assessment of chlorazepate, diazepam and placebo in anxious neurotics.

A 28-day double-blind assessment of chlorazepate dipotassium, diazepam and placebo was done on 30 outpatient neurotics with a primary symptom of anxiety. Acute, sub-acute and more chronic effects of the drug were assessed after 3 hours, 14 days and 28 days of drug administration. A battery of psychiatric ratings as well as physiological and psychophysiological assessments were done at each period. The psychometric assessments showed a trend for diazepam to be the most anxiolytic of the three drugs, followed by chlorazepate and then placebo. These measurements did not reach uniform statistically significant differences. Psychological measurements demonstrated the same trends, but some of these reached statistically significant levels. These parameters also indicate a slightly different mode of action of the two drugs at equimolecular doses. Diazepam would depress baseline and stimulation arousal, whereas chlorazepate would decrease baseline CNS arousal, but facilitate CNS response upon stimulation.

Adolescent↗