Levodopa-induced dyskinesias are a common complication of long-term therapy in Parkinson's disease. Although both pre- and post-synaptic mechanisms seem to be implicated in their development, the precise physiopathology of these disabling involuntary movements remains to be fully elucidated. Abnormalities in glutamate transmission (over expression and phosphorylation of N-methyl-D-aspartate rec...

The effect of chronic levodopa administration on the functional activity of the basal ganglia and its output regions was evaluated by means of the 2-deoxyglucose (2-DG) autoradiographic technique in rats with a unilateral 6-hydroxydopamine lesion of the nigrostriatal pathway. The rates of local cerebral glucose utilization were studied under basal conditions as well as in response to challenge ...

RATIONALE Synaptic dopamine (DA) release induced by amphetamine or other experimental manipulations can displace [ (11)C]raclopride (RAC*) from dopamine D2-like receptors. We hypothesized that exogenous levodopa might increase dopamine release at striatal synapses under some conditions but not others, allowing a more naturalistic assessment of presynaptic dopaminergic function. Presynaptic dopa...

Deficits in velocity generation and movement accuracy occur in Parkinson's disease and are postulated to contribute to the characteristic bradykinesia. In the present study, we attempted to clarify the relationship between the deficits in velocity generation and movement accuracy. Patients with Parkinson's disease and normal controls tracked visually displayed sinusoidal and step targets with t...

OBJECTIVES To determine the possible interactions between levodopa therapy and plasma levels of B vitamins in patients with advanced idiopathic Parkinson's disease (IPD) in the context of either oral levodopa therapy or levodopa/carbidopa intestinal gel (LCIG). Secondly, to determine the prevalence of neuropathy and its relation to plasma levels of B vitamins and homocysteine. METHODS Medicat...

In patients with early, mild Parkinson disease (PD), does the long-term effectiveness of levodopa alone differ from that of levodopa plus selegiline or initial bromocriptine mono-therapy? Randomized {allocation concealed*} †, blinded {data safety and monitoring commit-tee} †,* controlled trial with a mean 9.2-year follow-up. P a t i e n t s 782 patients with a clinical diagnosis of PD. Exclusio...

An automated multi-pumping flow system is proposed for the simultaneous chemiluminometric determination of benserazide and levodopa using multivariate calibration methods. The developed methodology is based on chemiluminescence (CL) emission generated by the reaction of benserazide with luminol, and on a concurrent inhibiting effect of levodopa on this reaction. A multi-pumping flow system comp...

A pathological study of 21 patients with Parkinson's disease of asymmetrical onset revealed significant asymmetry of degeneration of the substantia nigra with greater neuronal loss contralateral to the initially affected body side. It has previously been suggested that decline in duration of effectiveness of levodopa doses in Parkinsonian patients with motor oscillations is caused by loss of ni...

Parkinson’s disease (PD) is characterized by motor and neuropsychiatric features. Within the latter, conditions such as psychosis, obsessive compulsive disorder (OCD), levodopa addiction and pathologic gambling are considered as secondary to the use of dopamimetic drugs. We present four patients with PD who developed clinical criteria for levodopa and pathologic gambling addiction, generalized ...

The rationale for sustained release oral levodopa preparations is to deliver levodopa in the areas of maximal intestinal absorption in a slow and predictable way, leading to stable plasma levodopa levels and brain dopamine levels, therefore resulting in a lengthened duration of action. Sinemet CR is the prototype of such preparations, with demonstrated efficacy in decreasing periods of akinesia...