Response to levodopa treatment in dopa-responsive dystonia.

Background: Dopa-responsive dystonia (DRD) is similar to Parkinson disease in that both disorders have impaired dopamine synthesis and respond to levodopa treatment. Dopa-responsive dystonia differs in that dopamine storage is intact in contrast to Parkinson disease in which it is markedly reduced.

Objective: To examine the short- and long-duration responses to levodopa dosing in subjects with DRD.

The effects of different repeated doses of entacapone on the pharmacokinetics of L-Dopa and on the clinical response to L-Dopa in Parkinson's disease.

We performed a double-blind, placebo-controlled, randomized, crossover, multiple-dose study on entacapone in 25 patients with Parkinson's disease with levodopa (L-Dopa) treatment-related fluctuations. A run-in period was followed by four 2-week treatment periods during which the patients took 4 to 6 daily doses of L-Dopa concomitantly with 100, 200, or 400 mg of entacapone or with placebo. The effects were assessed at the end of each period; the inhibition of soluble catechol-O-methyltransferase (S-COMT) activity in red blood cells and the plasma concentrations of entacapone, L-Dopa, and 3-O-methyldopa (3-OMD) were measured and clinical effects assessed on an 18-hour home diary.

DBS and diathermy interaction induces severe CNS damage.

Pulse-modulated radiofrequency diathermy treatment to the maxilla produced permanent diencephalic and brainstem lesions and a vegetative state in a patient with PD with implanted subthalamic electrodes for deep brain stimulation.

Parkinson's disease, CYP2D6 polymorphism, and age.

Objective: PD may be caused by genetic susceptibility to neurotoxins. CYP2D6 is a candidate gene for PD because it regulates drug and toxin metabolism, but association studies have been inconsistent. The aim of this study was to test if the CYP2D6*4 allele (poor metabolizer phenotype) is associated with earlier age at onset.

Exacerbated physical fatigue and mental fatigue in Parkinson's disease.

Objective: To characterize fatigue in Parkinson's disease (PD).

Background: Fatigue is a recognized problem in PD. Fatigue can be in the physical realm or in the mental realm.

Induction by dopamine D1 receptor agonist ABT-431 of dyskinesia similar to levodopa in patients with Parkinson disease.

Background: Dyskinesias are a frequent adverse effect of long-term levodopa therapy. The relative contribution of dopamine D(1) and D(2) receptor function to the pathophysiology of levodopa-induced dyskinesias remains a matter of controversy.

Objective: To establish whether a selective D(1) dopamine agonist induces more or less dyskinesia than levodopa in primed dyskinetic patients with Parkinson disease.

Effect of COMT inhibition on the pharmacokinetics and pharmacodynamics of levodopa in parkinsonian patients.

Catechol-O-methyl transferase (COMT) is one of the principal levodopa-metabolizing enzymes, particularly when aromatic amino acid decarboxylase (AAAD) is partially inhibited by carbidopa or benserazide. This paper examines the pharmacology of COMT inhibitors such as tolcapone and entacapone, and considers the effects of these drugs on the pharmacolinetics of levodopa. Both agents extend the elimination half-life and plasma area under the curve of levodopa without affecting the maximal plasma concentration of levodopa (Cmax) or the time until an oral dose of levodopa reaches its peak plasma concentration (Tmax).

Centrally initiated postural adjustments in parkinsonian patients on and off levodopa.

This study investigates the effects of parkinsonism and dopamine replacement therapy (levodopa) on centrally initiated postural activity preceding rising onto the toes. The electromyographic (EMG) and force magnitude, scaling, sequencing, and postural stabilization were compared when rising-to-toes under two conditions, slow/low versus fast/high, for parkinsonian patients and elderly control subjects. Parkinsonian subjects were tested after withholding their levodopa medication for 12-16 h and again 1 h after taking their medication when parkinsonian signs were diminished.

Continuous dopamine-receptor stimulation in advanced Parkinson's disease.

Intermittent or pulsatile dopamine-receptor stimulation is postulated to induce plastic changes in motor systems that are responsible for the development of the motor fluctuations and dyskinesia that complicate long-term L-dopa therapy of Parkinson's disease. As a corollary to this hypothesis, continuous dopamine-receptor stimulation can avoid or reverse these complications. Such continuous stimulation is unlikely to mimic completely the normal function of the dopaminergic system, but should avoid the supra-physiological swings in extracellular dopamine that accompany intermittent L-dopa dosing.

Levodopa motor complications in Parkinson's disease.

Parkinson's disease (PD) is an age-related neurodegenerative disorder with an average onset age of 60 years. In the United States, approximately one million persons suffer from PD, and there are 60,000 newly diagnosed cases every year. The estimated cost of PD to society is $27 billion per year.

Determinants of tapping speed in normal control subjects and subjects with Parkinson's disease: differing effects of brief and continued practice.

Background: Alternate tapping speed is widely used as a measure of bradykinesia in Parkinson's disease (PD). Tapping speed in normal control subjects and factors that might influence tapping speed have not been systematically examined.

Objective: To examine the effects of age, hand dominance, and gender on tapping speed in normal control subjects and to compare the effects of practice on tapping speed in normal and PD control subjects.

Clinical pharmacology of levodopa-induced dyskinesia.

Levodopa-induced dyskinesia (LID) is a major impediment to the successful therapy of Parkinson's disease. The development of LID is facilitated by dopaminergic denervation but may not require denervation. Repeated levodopa dosing is necessary to induce dyskinesia, implying the development of sensitization to levodopa.

Apomorphine can sustain the long-duration response to L-DOPA in fluctuating PD.

The authors investigated the ability of daytime infusions of apomorphine, a D-1 and D-2 dopamine agonist, to sustain the long-duration response (LDR) in seven subjects with fluctuating PD in whom L-DOPA was discontinued for 3 days. Apomorphine maintained the LDR to the extent that it kept the subjects "on" during the day. This observation suggests that the LDR can be a postsynaptic effect, independent of dopamine storage.

Exclusion of dominant mutations within the FTDP-17 locus on chromosome 17 for Parkinson's disease.

Parkinson's disease (PD) is a prevalent movement disorder, and 10-30% of PD is familial. Several neurodegenerative disorders which are collectively called frontotemporal dementia and parkinsonism have been mapped to chromosome 17q and mutations in tau have been identified. The clinical and pathological overlap suggests that these related conditions may be due to mutations in tau.

A novel nonsense mutation in CACNA1A causes episodic ataxia and hemiplegia.

Objective: To identify the disease-causing mutation and to characterize penetrance and phenotypic variability in a large pedigree with episodic ataxia type 2 (EA-2) previously linked to chromosome 19.

Background: Mutations in the CACNA1A gene on chromosome 19 encoding a calcium channel subunit cause EA-2, which is characterized by recurrent attacks of imbalance with interictal eye movement abnormalities.

Methods: The authors used single-strand conformation polymorphism (SSCP) analysis to screen for point mutations, and direct sequencing to identify mutations in CACNA1A.

ABT-431, a D1 receptor agonist prodrug, has efficacy in Parkinson's disease.

Studies in animal models show a selective D1 receptor agonist with full functional efficacy compared with dopamine to have antiparkinsonian efficacy of similar magnitude to levodopa, without the same propensity for inducing dyskinesia. To date, no such agent has been tested in humans. ABT-431 is the prodrug of A-86929, a full, selective D1 receptor agonist.

Verbal fluency task affects gait in Parkinson's disease with motor freezing.

We examined the effects of a simultaneous verbal fluency task on walking in Parkinson's disease (PD) patients with freezing of gait (PD-F) compared to nonfreezing patients (PD-NF) or control subjects (C). Effects of antiparkinsonian medications on gait in PD-F were examined. PD-F patients exhibited a greater increase in the number of steps to complete the walk with verbal fluency, even when the effect of medication was taken into account (mean increase +/- SD): PD-F = 4.

Matrix metalloproteinase-1 is induced by epidermal growth factor in human bladder tumour cell lines and is detectable in urine of patients with bladder tumours.

The matrix metalloproteinases are a family of enzymes that degrade the extracellular matrix and are considered to be important in tumour invasion and metastasis. The effect of epidermal growth factor (EGF) on matrix metalloproteinase-1 (MMP1) production in two human bladder tumour cell lines, RT112 and RT4, has been investigated. In the RT112 cell line, an increase in MMP1 mRNA levels was found after a 6-h incubation with EGF, and this further increased to 20-fold that of control levels at 24- and 48-h treatment with 50 ng ml(-1) of EGF.