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Biomedical subjects

G M Stern

Publications and source records attributed to G M Stern.

12 recordsLinked to original sources

Tiapride in levodopa-induced involuntary movements.

Tiapride, a substituted benzamide derivative closely related to metoclopramide, reduced levodopa-induced peak dose involuntary movements in 16 patients with idiopathic Parkinson's disease. However, an unacceptable increase in disability from Parkinsonism with aggravation of end-of-dose akinesia led to its cessation in 14 patients. Tiapride had no effect on levodopa-induced early morning of "off-period" segmental dystonia. These results fail to support the notion that levodopa-induced dyskinesias are caused by overstimulation of a separate group of dopamine receptors.

Aged

Chip fractures of the os triquetrum: the mechanism of injury.

Studies derived from analyses of radiographs and dissections of cadaveric wrists have been directed at testing and disproving the commonly held theories that link chip fractures of the os triquetrum with avulsion. The authors found that the mechanism of such injuries involved a chisel action of the ulnar styloid upon the dorsum of the os triquetrum; furthermore, the impact of a fall on the outstretched arm with the hand rigidly held in strong dorsiflexion and ulnar deviation could be forceful enough to fracture the body of the os triquetrum as well. In all cases a striking prolongation of the ulnar styloid, beyond the surface of the ulnar head, was consistently noted.

Carpal Bones

Deprenyl administration in man: a selective monoamine oxidase B inhibitor without the 'cheese effect'.

After pretreatment with the selective monoamine oxidase B inhibitor, (-)-deprenyl, in doses sufficient for complete inhibition of the platelet enzyme, 4 normal and 6 parkinsoniam volunteers (2 receiving levodopa and 2 levodopa plus carbidopa) suffered no adverse pressor reaction ('cheese effect') after challenge with oral tyramine in amounts considerably greater than those likely to be encountered in a normal diet. Nor did the levodopa-deprenyl combination itself result in a pressor response. Normal human intestinal mucosa was shown predominantly to contain the deprenyl-insensitive A form of the enzyme, which presumably degraded administered tyramine in the deprenyl-treated volunteers; even those receiving the drug for prolonged periods manifested no 'cheese effect', suggesting that the A form remained uninhibited. Intestinal monoamine oxidase A was able to oxidise dopamine, whereas in human platelet or striatum the amine is a monoamine oxidase B substrate. Like tyramine, oral phenylethylamine challenge with amounts greater than those known to be present in a normal diet similarly gave rise to no adverse reaction in (-)-deprenyl-treated subjects; the reasons for this remain to be determined.

Adult

Endocrine aspects of bromocriptine therapy in Parkinsonism.

Plasma growth hormone (GH) concentrations in Parkinsonian patients following 3 months optimum therapy with bromocriptine showed no significant change from pretreatment values, whilst plasma prolactin concentrations were uniformly suppressed. Pretreatment GH and prolactin levels were unrelated to clinical disability, and no correlation between hormonal changes and therapeutic response was found. These results suggest the presence of different dopaminergic receptor mechanisms for GH and prolactin release as well as between the extrapyramidal and neuroendocrine systems.

Bromocriptine

Baclofen in Parkinson's disease.

In a controlled trial, baclofen (mean dose 45 mg daily) signficantly increased disability from Parkinsonism in 12 patients with the long-term levodopa syndrome. Peak dose choreoathetosis was not improved but benefit was observed in all four patients with "off period dystonia." Adverse side effects were common and severe, and included visual hallucinations, vomiting, and dizziness.

Aged

Deprenyl in Parkinson's disease.

In a double-blind crossover trial, (-)-deprenyl, a fast-acting selective monoamine-oxidase-B inhibitor without a "cheese effect", was given to 41 patients with idiopathic Parkinson's disease who were receiving maximum tolerated doses of levodopa either alone or combined with carbidopa ("Sinemet"). In a dose of 10 mg, daily or on alternate days, (-)-deprenyl prolonged the therapeutic effect of levodopa and was effective in mild "on-off" disabilities with end-of-dose akinesia; the majority of patients with nocturnal and early-morning akinesia also improved. No statistically significant improvement occurred in diurnal akinesia, and there was no improvement in patients with severe on-off disabilities with freezing and rapid oscillations ("yo-yo" effect). Levodopa-induced dyskinesias were aggravated in 14 patients. In 5 previously untreated patients, (-)-deprenyl alone gave no benefit, but when it was used with levodopa and carbidopa a mean dosage reduction of 200 mg levodopa daily was possible. Depression, present in 15 patients, was unchanged. (-)-Deprenyl in combination with smaller total daily doses of levodopa and a peripheral decarboxylase inhibitor may prove useful in reducing the frequency and severity of some types of on-off effect with overall benefit comparable to that obtained with larger doses of levodopa.

Adult