A Panel of Oxidative Stress Markers in Parkinson's Disease.

BACKGROUND: Oxidative stress may be the cause or effect of several pathogenetic processes such as neurodegenerative diseases. The aim of this paper was to evaluate the diagnostic efficacy in Parkinson's disease (PKD) of a panel of oxidative stress markers selected from the many proposed by the most recent literature. METHODS: 23 molecules including both plasma and urinary oxidative markers such total radical oxygen species, homocysteine, biological antioxidant potential, glutathione, superoxide dismutase, uric acid, total bilirubin, iron, ferritin, coenzyme Q10, 3-nitrotyrosine, total lipoperoxides, 4-hydroxy-nonenal, and 8-hydroxy-deoxy-guanosine were determined both in PKD and aged control subjects. For each analyte and group, the respective reference intervals were determined. Statistical analysis was used to assess the existence of significant differences between intervals in order to indicate which markers can better characterize PKD and distinguish it from the control population. RESULTS: Some parameters were different in both groups when compared to those observed in younger subjects, supporting the hypothesis that aging is associated with an increase of oxidative stress. A peculiar increase of oxidative damage on nucleic acids was found in PKD, as well as a less efficient turnover of the DNA and an increase of protein peroxidation. CONCLUSIONS: Our results demonstrate that in PKD there is an increase of oxidative attack on nucleic acids and that the protein nitration is a characteristic phenomenon. These observations are in good agreement with the hypothesis that in PKD oxidative damage occurs that counter-regulatory systems attempt to balance, but inefficiently.

Plasma and urinary HPLC-ED determination of the ratio of 8-OHdG/2-dG in Parkinson's disease.

BACKGROUND: Oxidative stress may be directly or indirectly involved in the pathogenesis of Parkinson's disease (PD). 8-hydroxy-2'deoxyguanosine (8-OHdG) is the major product of DNA oxidative damage but its determination in plasma or urine may have controversial significance. The concentration of 8-OHdG not only depends on its oxidation rate but also on the efficacy of the DNA repairing systems. METHODS: We studied the ratio between 8-OHdG and 2-dG (the corresponding not hydroxylated base 2'-deoxyguanosine) in plasma and urine as a marker of oxydative stress in PD. This enabled the determination of the real DNA damage in terms of oxidation rate regardless of the efficacy of the DNA repairing mechanisms. RESULTS: We optimized two different analytical methods: one for 8-OHdG and the other for 2-dG, both based on a common preliminary solid-phase extraction step (SPE) followed by two different HPLC analytical separations with electrochemical detection (HPLC-ED). The reliability of these methods was confirmed by analysing plasma and urine samples collected in parkinsonian patients and in age-matched healthy control subjects. CONCLUSIONS: In urine samples, the measurement of 8-OHdG alone as well as the ratio 8-OHdG/2-dG were significantly different in healthy controls and PD patients. In plasma samples, only the ratio 8-OHdG/2-dG was significantly higher in PD compared to healthy controls showing that the ratio 8-OHdG/2-dG is a reliable diagnostic tool in studies on DNA oxydative damage.

Biochemistry of neuromodulation in primary headaches: focus on anomalies of tyrosine metabolism.

Recent studies have suggested that abnormalities of dopamine and trace amines (tyramine, octopamine, and synephrine), products of tyrosine metabolism, may constitute the metabolic events that predispose to the occurrence of cluster headache (CH) and migraine attacks. This hypothesis is supported by the following evidences: the discovery of trace amine associated receptors (TAARs), expressed on the olfactory epithelium, amigdala, hypothalamus, periacqueductal gray, and the biochemical anomalies of dopamine and trace amines. The possible effects of these biochemical abnormalities on TAARs and dopamine receptors, located in different areas of CNS, may explain the behaviour (restlessness, anxiety and, at times, hypersexuality) and the autonomic signs during the painful attacks of CH, and the premonitory symptoms of migraine crisis (thirst, craving, yawning, alteration of smell, depression etc.).

Treatment of aura: solving the puzzle.

Migraine with aura (MwA) sufferers, at times, need specific treatments. This is the case when the auras are frequent, prolonged and cause anxiety and distress. Abnormal release of glutamate, which may trigger auras, and abnormal platelet behaviour, which constitutes a possible predisposing factor to MwA, are possible targets for MwA-specific prophylactic therapy. Here we present results obtained using lamotrigine (two open trials), an agent known to inhibit glutamate release, and picotamide, an antiplatelet drug, in the prophylactic treatment of MwA sufferers. Lamotrigine significantly reduced the frequency of MwA attacks, and picotamide together with lamotrigine reduced the duration and/or the occurrence of auras. In comparison to lamotrigine, the therapy with picotamide may have some advantages such as the use of the therapeutic dose from the first day of treatment (lamotrigine needs one month or more to reach such a dose) and the possibility to prevent cerebral ischaemic events and migraine stroke, a rare but severe complication of MwA attacks.

Comparative analysis of visual and semi-quantitative assessment of striatal [123I]FP-CIT-SPET binding in Parkinson's disease.

We used qualitative visual assessment and semiquantitative measures of striatal DAT binding using [(123)I]FP-CIT-SPET in 85 patients with Parkinson's disease (PD). We compared these two assessments and their correlation with PD clinical progression. SPET imaging was visually classified by a nuclear medicine physician as normal or abnormal pattern grade I, II and III, in relation to a different degree of radioligand reduction uptake. Nineteen patients presented abnormal grade I (group 1), 53 grade II (group 2) and 13 grade III (group 3). The UPDRS III motor score, the H-Y score, the rigidity and bradykinesia subscores were significantly different among the three groups. Post hoc analysis showed that all values of these clinical parameters were higher in group 3 than in 2 and 1. All clinical indices were also significantly higher in group 2 than in group 1. This means that groups 3 and 2 were clinically more severely affected. No significant differences among the 3 groups were observed for age or duration of disease. Values of the mean striatum uptake were also significantly different among the three groups. Post hoc analysis revealed significantly lower values of the mean striatum uptake in group 3 with respect to groups 2 and 1; values were also significantly lower in group 2 than in group 1. We conclude that our findings of good consistency between visual and semi-quantitative assessment may help simplify the evaluation of striatal DAT binding in PD in a clinical routine setting.

Contributions of biochemistry to the pathogenesis of primary headaches.

We briefly summarise biochemical anomalies of serotonin, norepinephrine, glutamic and aspartic acids, the main neurotransmitters of inhibitory and excitatory neuronal circuitries, found in primary headaches and their relationship with pathogenesis of migraine and cluster headache (CH). In addition, the high levels of circulating tyramine, octopamine and synephrine (elusive amines), recently reported in both migraine types and CH, are discussed in relation to the other "classic" amines findings. In particular it is suggested how abnormal levels of elusive amines may participate in the pathophysiology of migraine and CH acting through their specific trace amine receptors and alpha and beta receptors. The possible hypothesis that emerges from the analysis of these biochemical findings is that an imbalance of systems, with opposite neurophysiological functions related to the pain and other yet unknown functions, may constitute the biochemical phenotype of migraine with and without aura, and CH.

Entacapone improves the pharmacokinetic and therapeutic response of controlled release levodopa/carbidopa in Parkinson's patients.

The aim of this trial was to evaluate the effects of the COMT inhibitor entacapone on both the pharmacokinetic profile and clinical efficacy of controlled release levodopa in Parkinson's disease (PD) patients. Twelve PD patients experiencing "end-of-dose" type motor fluctuations were evaluated in this single-blind, randomized cross-over study. A single dose of either entacapone (200 mg) or placebo was co-administered with controlled release levodopa. Blood samples were taken every 30 minutes for 3 hours, and in 6 patients, sampling was continued for a further 3 hours. The clinical response to treatment was evaluated using the Unified Parkinson's Disease Rating Scale motor score. Addition of entacapone to levodopa treatment prolonged the "on" phase of the PD patients by 37% (p<0.05). This increased duration of 'on' time was concomitant with a significant increase in levodopa bioavailability (AUC). These data confirm the ability of entacapone to enhance the clinical efficacy of controlled release levodopa formulations, and provide further evidence that entacapone is of value in extending the benefits of levodopa in PD patients experiencing motor fluctuations.

Sleep disorders in Parkinson's disease.

The nature of sleep is one of the major sources of dissatisfaction with the quality of life among patients with Parkinson's disease (PD). Difficult sleep maintenance (light and fragmented sleep) and difficulties with sleep initiation are the earliest and most frequent sleep disorders observed in these patients. Sleep disorders are also common in the normal elderly population, suggesting that normal aging may play a role in the etiology of sleep disorders in PD. Factor et al. examined the frequency of various sleep disorders in PD and compared them to those of normal elderly subjects. Sleep fragmentation and spontaneous daytime dozing occurred much more frequently in PD patients than in controls. Sleep fragmentation in PD may be due to an increased skeletal muscle activity, disturbed breathing and REM/non-REM variations of the dopaminergic receptor sensitivity. In parkinsonian patients who developed motor fluctuations (on-off phenomenon, wearing-off) during the day, other common sleep-related motor complaints including nocturnal akinesia, dystonia and painful cramps are observed. In a double-blind cross-over study, we compared the efficacy of a single dose of a chronic release formulation of levodopa/carbidopa (Sinemet CR) with that of a placebo in improving sleep-related motor disturbances in a group of 40 fluctuating PD patients. Sinemet CR significantly improved nocturnal akinesia and increased the hours of sleep in this group of patients. Initiation and maintenance of sleep are problems that may not be solved with antiparkinsonian treatment.

Determination of apomorphine in human plasma by alumina extraction and high-performance liquid chromatography with electrochemical detection.

Apomorphine is a powerful agonist of dopaminergic receptors which several years ago was introduced into the therapy of Parkinson's Disease. The pharmacological activity of apomorphine already appears significant at low doses. Unfortunately, the difficulty in determining the drug in plasma at low concentrations hampers the completion of accurate pharmacokinetic studies in humans. Considering the analogy of apomorphine with the molecular structure of catecholamines, the extraction of the drug from plasma was optimized by using adsorption on alumina, a technique widely used for noradrenaline and adrenaline analysis in clinical chemistry laboratories. This method proved particularly efficient and selective in apomorphine extraction from plasma prior to high-performance liquid chromatographic analysis. After pretreatment of 200 microliters of plasma sample with 40 mg of alumina and 10 microliters of tris buffer (pH 8.6), the drug was eluted with 200 microliters of an acidic-organic solution. One volume of the supernatant was mixed with two volumes of phosphate buffer (pH 3.6), and 100 microliters of the obtained mixture were injected into the HPLC system. The chromatograph was equipped with a C18 reversed-phase column and with an electrochemical coulometric detector fitted with a high-sensitivity cell (first electrode 0.00 volts, second electrode +0.35 volts). Sensitivity (20 pg of injected drug), precision (CV within assay and between assays of 3.7% and 5.6%, respectively) and accuracy were comparable to more complex analytical procedures. The miniaturisation of the entire sample pretreatment proved very advantageous for pharmacokinetics studies and, in principle, for therapeutic drug monitoring and toxicological investigations.

The long-duration action of levodopa may be due to a postsynaptic effect.

A single dose of levodopa (L-DOPA) reduces motor disability in Parkinson's disease (PD) for a few hours, a short-duration effect. However, there are suggestions that L-DOPA may also produce a long-duration benefit of some days. In the present study, we examined the long-duration action of L-DOPA by observing the time taken to achieve maximum stable benefit after starting a constant dose of sinemet-CR (sinemet-CR) (200 g L-DOPA/50 mg carbidopa) twice daily in nine newly diagnosed patients, and the time taken to deteriorate back to baseline after stopping treatment. A single dose of sinemet-CR (200 mg L-DOPA/50 mg carbidopa) had little obvious short-duration action on the Unified PD Rating Scale (UPDRS) motor scores in the majority of patients, either before starting chronic sinemet-CR therapy (200 mg L-DOPA/50 mg carbidopa, b.i.d.) or after chronic treatment. However, all patients gradually improved on chronic sinemet-CR therapy, taking 9.3 +/- 1.8 days to achieve maximum response. On stopping chronic sinemet-CR treatment, it took 6.8 +/- 3.0 days for the same patients to deteriorate back to baseline motor disability. In similar experiments, the time taken to deteriorate back to baseline after stopping treatment with the directly acting dopamine agonist ropinirole (9-21 mg daily) in eight other de novo patients with PD was found to be 6.2 +/- 1.7 days. The long-duration effect of L-DOPA and ropinirole may, therefore, be due to some slowly evolving postsynaptic pharmacodynamic change in the central nervous system (CNS). Loss of this long-duration action may be responsible for the emergence of motor fluctuations on chronic L-DOPA therapy.

Biogenic amines in the vomeronasal organ.

The vomeronasal organ of frog and mouse was investigated for the presence and content of serotonin and catecholamines by means of high-performance liquid chromatography. Measurable amounts of serotonin, adrenaline and noradrenaline were found in the vomeronasal organ of adult individuals of both species. The amine content varied with sex of adult frogs and mice and sexual maturity of mice. In preliminary experiments, acute exposure to male urine containing pheromone affected the amine content in the vomeronasal organ of adult female mice. These data suggest that functional sex dimorphism is present in the vomeronasal organ, and biochemical changes therein take place according to stage of sexual maturity. The role of biogenic amines in the vomeronasal organ deserves further study.

Strategies for treating patients with advanced Parkinson's disease with disastrous fluctuations and dyskinesias.

Patients with advanced Parkinson's disease often develop severe fluctuations and dyskinesias while receiving long-term levodopa therapy. These complications can prove increasingly difficult to control. Here we review our strategies for coping with such problems. These include establishing the best rational schedule of levodopa treatment, optimizing levodopa absorption, the use of oral dopaminergic agonists, and the use of subcutaneous injections or infusions of apomorphine or lisuride. The problems of severe dyskinesias, sleep disturbances, psychotoxicity, and urinary difficulties also are considered. Finally, the role of new surgical procedures to treat Parkinson's disease is reviewed.

Melperone in the treatment of iatrogenic psychosis in Parkinson's disease.

The pharmacological management of Parkinson's disease (PD) can be complicated by psychiatric disorders induced by antiparkinsonian drugs. The reduction or withdrawal of levodopa (l-dopa) and other drugs commonly used in the treatment of PD may attenuate the psychosis but exacerbate motor impairment and disability. Melperone is an atypical antipsychotic drug showing in vivo a greater relative affinity for the 5-HT2 than the D2 receptors. A two-year study to assess the clinical efficacy and the safety of melperone in the management of iatrogenic psychosis in 30 parkinsonian patients was carried out. Neurological evaluation was performed with patients in the "off" and in the "on" state using the motor examination of the Unified Parkinson's Disease Rating Scale (UPDRS). Time spent in "on" state was evaluated using the self-evaluation diary of daily life. To assess psychiatric disturbances the modified version of the Brief Psychiatric Rating Scale (BPRS) was used. The mean BPRS score was significantly reduced when comparing baseline with individual examinations; no statistically significant differences were found between subsequent examinations. UPDRS motor score and time spent in "on" state during daily life showed no statistically significant differences when comparing baseline with subsequent examinations. Two patients dropped out because of excessive sedation problems but in the remaining 28 patients melperone proved to be optimally tolerated.

Fluctuating parkinsonism: a pilot study of single afternoon dose of levodopa methyl ester.

Thirty-four patients with idiopathic fluctuating Parkinson's disease and early afternoon "delayed on" or severely resistant "off" periods, in spite of long-term antiparkinsonian therapy, were studied. The first afternoon levodopa administration was substituted with an equimolar dosage of the liquid formulation levodopa methyl ester (LDME). The major end-points for efficacy were latency to "on" and duration of "on" periods. The patients were divided into five subgroups according to their baseline treatment and they were evaluated monthly for 6 months using the Unified Parkinson's Disease Rating Scale. The patients completed weekly self-evaluation using an "on-off" chart. LDME was well tolerated by all the patients. A statistically significant reduction in latency to "on" was observed in all patients. The clinical effect of LDME remained stable during the treatment period (repeat measures ANOVA). The more rapid clinical effect of LDME and its stable and predictable antiparkinsonian activity represents a new and useful approach for treating patients with complicated Parkinson's disease.

Treatment of parkinsonian conditions with a controlled-release form of levodopa--preliminary study.

Results obtained in 22 patients with Parkinson's disease in whom treatment with standard Madopar was replaced by Madopar HBS, a CR formulation of the same product, are presented. All the patients presented with dyskinesia and akinesia phenomena related in part to the L-dopa treatment and in part to the disease itself. In 20 patients replacement of the standard agent by HBS led to a distinct improvement in the clinical condition and a significant reduction of the 'on-off' phenomenon. However, with the new formulation the dosage had to be increased by 86% on average as compared with standard Madopar. In 6 of the 22 patients treatment with the HBS formulation has continued for over 6 months and is still giving very good results.