Development of new levodopa treatment strategies in Parkinson's disease-from bedside to bench to bedside

This review will illustrate the process of moving from an idea through preclinical research and Galenic developments into clinical investigations and finally to approval by regulatory agencies within the European Union. The two new treatment strategies described, levodopa/carbidopa intestinal gel and levodopa/carbidopa microtablets, for advanced Parkinson's disease, have been developed in collaborative research within departments at Uppsala University. With this historical approach, reference priority is given to reports considered to be of special importance for this more than two decades long process 'from bedside to bench to bedside'.

Levodopa/carbidopa microtablets in Parkinson's disease: a study of pharmacokinetics and blinded motor assessment

Background

Motor function assessments with rating scales in relation to the pharmacokinetics of levodopa may increase the understanding of how to individualize and fine-tune treatments.

Objectives

This study aimed to investigate the pharmacokinetic profiles of levodopa-carbidopa and the motor function following a single-dose microtablet administration in Parkinson’s disease.

Methods

This was a single-center, open-label, single-dose study in 19 patients experiencing motor fluctuations. Patients received 150% of their individual levodopa equivalent morning dose in levodopa-carbidopa microtablets. Blood samples were collected at pre-specified time points. Patients were video recorded and motor function was assessed with six UPDRS part III motor items, dyskinesia score, and the treatment response scale (TRS), rated by three blinded movement disorder specialists.

Results

AUC_0–4/dose and C_max/dose for levodopa was found to be higher in Parkinson’s disease patients compared with healthy subjects from a previous study, (p = 0.0008 and p = 0.026, respectively). The mean time to maximum improvement in sum of six UPDRS items score was 78 min (±59) (n = 16), and the mean time to TRS score maximum effect was 54 min (±51) (n = 15). Mean time to onset of dyskinesia was 41 min (±38) (n = 13).

Conclusions

In the PD population, following levodopa/carbidopa microtablet administration in fasting state, the C_max and AUC_0–4/dose were found to be higher compared with results from a previous study in young, healthy subjects. A large between subject variability in response and duration of effect was observed, highlighting the importance of a continuous and individual assessment of motor function in order to optimize treatment effect.

Peripheral blood RNA expression profiling in illicit methcathinone users reveals effect on immune system

Methcathinone (ephedrone) is relatively easily accessible for abuse. Its users develop an extrapyramidal syndrome and it is not known if this is caused by methcathinone itself, by side-ingredients (manganese), or both. In the present study we aimed to clarify molecular mechanisms underlying this condition. We used microarrays to analyze whole-genome gene expression patterns of peripheral blood from 20 methcathinone users and 20 matched controls. Gene expression profile data were analyzed by Bayesian modeling and functional annotation. Of 28,869 genes on the microarrays, 326 showed statistically significant differential expression with FDR adjusted p-values below 0.05. Quantitative real-time PCR confirmed differential expression for the most of the genes selected for validation. Functional annotation and network analysis indicated activation of a gene network that included immunological disease, cellular movement, and cardiovascular disease functions (enrichment score 42). As HIV and HCV infections were confounding factors, we performed additional stratification of subjects. A similar functional activation of the “immunological disease” category was evident when we compared subjects according to injection status (past versus current users, balanced for HIV and HCV infection). However, this difference was not large therefore the major effect was related to the HIV status of the subjects. Mn–methcathinone abusers have blood RNA expression patterns that mostly reflect their HIV and HCV infections.

Manganese-Induced Parkinsonism due to Ephedrone Abuse

During recent years, a syndrome of hypokinesia, dysarthria, dystonia, and postural impairment, related to intravenous use of a "designer" psychostimulant derived from pseudoephedrine using potassium permanganate as the oxidant, has been observed in drug addicts in several countries in Eastern Europe with some cases also in Western countries. A levodopa unresponsive Parkinsonian syndrome occurs within a few months of abusing the homemade drug mixture containing ephedrone (methcathinone) and manganese. The development of this neurological syndrome has been attributed to toxic effects of manganese, but the role of the psychostimulant ephedrone is unclear. This paper describes the clinical syndrome, results of neuroimaging, and therapeutic attempts.

Evidence for astrocytosis in ALS demonstrated by [11C](L)-deprenyl-D2 PET

OBJECTIVE

To use deuterium-substituted [11C](L)-deprenyl PET to depict astrocytosis in vivo in patients with amyotrophic lateral sclerosis (ALS).

BACKGROUND

In human brain, the enzyme MAO-B is primarily located in astrocytes. L-deprenyl binds to MAO-B and autoradiography with 3H-L-deprenyl has been used to map astrocytosis in vitro. Motor neuron loss in ALS is accompanied by astrocytosis and astrocytes may play an active role in the neurodegenerative process. Deuterium-substituted [11C](L)-deprenyl PET provides an opportunity to localize astrocytosis in vivo in the brain of patients with ALS.

METHODS

Deuterium-substituted [11C](L)-deprenyl PET was performed in seven patients with ALS and seven healthy control subjects.

RESULTS

Increased uptake rate of [11C](L)-deprenyl was demonstrated in ALS in pons and white matter.

CONCLUSION

This study provides evidence that astrocytosis may be detected in vivo in ALS by the use of deuterium-substituted [11C](L)-deprenyl PET though further studies are needed to determine whether deuterium-substituted [11C](L)-deprenyl binding tracks disease progression and reflects astrocytosis.

Focused Proteomics in Post-Mortem Human Spinal Cord

With a highly sensitive electrospray ionization-Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR MS) system, proteins were identified in minimal amounts of spinal cord from patients with the neurodegenerative disease amyotrophic lateral sclerosis (ALS) and compared to proteins in spinal cord from control subjects. The results show 18 versus 16 significantly identified (p < 0.05) proteins, respectively, all known to be found in the central nervous system. The most abundant protein in both groups was the glial fibrillary acidic protein, GFAP. Other proteins were, for example, hemoglobin alpha- and beta chain, myelin basic protein, thioredoxin, alpha enolase, and choline acetyltransferase. This study also includes the technique of laser microdissection in combination with pressure catapulting (LMPC) for the dissection of samples and specific neurons. Furthermore, complementary experiments with nanoLC-matrix assisted laser desorption ionization time-of-flight tandem mass spectrometry (MALDI-TOF-TOF MS) confirmed the results of the ESI-FTICR MS screening and provided additional results of further identified proteins.

[Conformationally altered proteins cause neurodegenerative diseases]

Brain aggregates of conformationally altered proteins are key features of neurodegeneration and are believed to directly cause or contribute to disease development. Mechanisms underlying the dysregulation of proteins in Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis and other neurodegenerative disorders are now being characterized, due to the discovery of genes causing rare disease forms. As of today, only symptomatic pharmacotherapies are available, but new insights into the underlying molecular mechanisms are providing strategies to prevent or even cure these devastating disorders.

Objective assessment of cervical dystonia: a pilot study

OBJECTIVES

The aims were to characterize the movements in cervical dystonia (CD) by using an estimate of the mechanical power and work involved in the movements and to describe this through a movement energy index (MEI).

MATERIALS AND METHODS

The subjects (patients n = 6, controls n = 6) were seated in front of a screen with a laser pointer attached to a headband while they performed standardized movements. A three-dimensional motion capture system was used and a test-retest was performed.

RESULTS

The mean value of MEI was significantly higher for the patients than for the controls. There was no significant difference between MEI from test to retest for the patients but there was a significant difference between MEI from test to retest for the controls.

CONCLUSION

This study suggests that MEI could be a useful measure for the quantification of movement dysfunction in CD and thus an objective outcome measure in comparison of different therapies.

Cerebrospinal fluid protein patterns in neurodegenerative disease revealed by liquid chromatography-Fourier transform ion cyclotron resonance mass spectrometry

This study demonstrates the power of a novel proteomic approach developed for the detection and identification of biological markers in body fluids. The goal was to observe alterations in the protein patterns of cerebrospinal fluid (CSF) related to amyotrophic lateral sclerosis (ALS), a neurodegenerative disorder with unknown etiology. In the experiments, tryptic digests of CSF from patients and healthy controls were analyzed by on-line capillary liquid chromatography-Fourier transform ion cyclotron resonance mass spectrometry. (FT-ICR MS) Typically, around 4000 peptides were detected in one such experiment, and a pattern recognition program was constructed for the data analysis to distinguish mass chromatograms from patients and controls. This strategy was evaluated comparing the peptide patterns of CSF spiked in vitro with a biomarker, with control CSF. The patterns were clearly separated and the tryptic peptides of the biomarker were successfully selected as characteristic peaks. Hence, the method was applied to compare mass chromatograms of CSF from 12 ALS-patients and 10 matched healthy controls. While no biomarker alone could be identified from the characteristic peaks, we were able to assign 4 out of 5 unknown samples correctly (i.e., 80% correctly diagnosed, 20% false-negative), and it would be 100% if we reject a possible outlier believed to be caused by an occlusion in the spinal CSF compartment. These findings are very promising, although the clinical relevance is not fully established due to the low number of unknown samples analyzed. In addition to the diagnostic potential, these results may be important steps towards understanding the neurodegenerative process.

Levodopa Infusion Therapy in Parkinson Disease

Orally administered levodopa, in combination with a decarboxylase inhibitor, is the gold standard therapy for Parkinson disease (PD). The problems in management of motor fluctuations in the advanced stages of the disorder are due to the close relationship between plasma levodopa levels and availability of dopamine at striatal receptor sites. The fluctuating levodopa concentrations are mainly explained by the fact that levodopa absorption only occurs in the proximal small intestine. The patient's motor function thus depends on gastric emptying, which is erratic and may even be delayed in PD. Oral therapy with sustained-release formulations and COMT inhibitors have not solved the problems satisfactorily. Therefore, infusions of levodopa by intravenous and enteral (duodenal/jejunal) routes of administration have been studied. In this review of the literature on clinically relevant levodopa infusion studies, it is shown that improvements regarding fluctuations in both plasma levodopa levels and motor performance have been repeatedly reported. The results acquired so far suggest that levodopa infusion is a safe and efficacious therapy. Recent drug delivery development and long-term studies have shown that infusion is a clinically feasible alternative to treat advanced PD.

Wireless real-time electronic data capture for self-assessment of motor function and quality of life in Parkinson's disease

Frequent assessment of the symptoms in Parkinson's disease (PD) is important in both clinical and experimental settings, especially when motor fluctuations are present. Patient diaries are increasingly used in studies, allowing patients to stay in their home environments. However, traditional paper diaries may not reflect reality because of a lack in compliance or retrospective data entries. This study presents a comparison between paper diaries and a new method, real-time data capture with a hand-held computer (electronic diary). Twenty patients with PD diagnosed at least 5 years previously were randomly assigned to use either a paper diary or an electronic diary on 8 days during 1 month. Questions were answered every 2 hours over a 12-hour period on each day. Median compliance was 88% with the electronic diary and 98% with the paper diary, although strict compliance to the scheduled times by patients using the paper diary was 78%. Neither age nor earlier experience with computers affected the patient's ability to use the electronic diary. Electronic diaries can be used for self-assessment of PD symptoms. The real-time feature provides fast access to clean data with knowledge of true compliance.

[A national curriculum in neurology for medical education]

The knowledge within medicine is growing rapidly. It has become more and more difficult to decide what knowledge that has to be taught to medical students during their University Medical Degree (MD) education and what has to be omitted from their study plans. As help for teachers and students, a core curriculum of the education defines what is of importance for all students. However, there is a risk of "curriculum overload" with too much information being put into a short time interval. To avoid this and to define what is really the "core" of a course, a national consensus decision may be useful. As an example of this approach, we here report a new joint Swedish core curriculum in neurology for medical students. Teachers responsible for neurological education at all six universities giving University MD education in Sweden have in January 2003 agreed upon the core curriculum that we present. It is our hope that this method can be useful also for other clinical specialities.

The increased utilisation of dopamine agonists and the introduction of COMT inhibitors have not reduced levodopa consumption--a nation-wide perspective in Sweden

OBJECTIVE

To study the impact of the new pharmacological treatment strategies in Parkinson's disease by analysis of the sales of dopaminergic drugs in Sweden 1990-2001.

METHODS

Invoice statistics and statistics on prescription sales of dopaminergic drugs 1990-2001 were obtained from the 906 public pharmacies and the 89 hospital pharmacies in Sweden. The Swedish Diagnosis and therapy survey was used to study the diagnosis the drugs were prescribed for.

RESULTS

During the period the sales expressed in DDD/1000 inhabitants and day increased from 1.75 to 1.86 (6%) for levodopa and from 0.04 to 0.27 (575%) for dopamine agonists. The increase in sales of dopamine agonists occurred after 1997 and consisted entirely of the sales of the new agonists, cabergoline, pramipexole and ropinirole. In Swedish crowns the total sales of dopaminergic drugs increased with 126% during the period. The cost for the dopamine agonists was 8% of the total cost for dopaminergic drugs in 1990 and 23% in 2001. The prescription sales figures of levodopa and dopamine agonists for the different Swedish counties in 2001 varied between 1.52 and 2.44 and 0.13 and 0.74 DDD/1000 inhabitants and day, respectively. There was no correlation, whether positive or negative, between the sales of dopamine agonists, levodopa and COMT inhibitors or between the sales and the densities of neurologists.

CONCLUSION

The consumption of levodopa in Sweden continues to increase in spite of a dramatic increase in the utilisation of dopamine agonists and the introduction of COMT-inhibitors.

Optimizing levodopa pharmacokinetics: intestinal infusion versus oral sustained-release tablets

Continuous duodenal infusion of carbidopa/levodopa has been shown to control motor fluctuations in advanced Parkinson's disease (PD). The authors compared the pharmacokinetics of levodopa and 3-O-methyldopa in patients with advanced PD after administration of an oral sustained-release levodopa preparation and after continuous intestinal levodopa infusion with a new formulation as a gel suspension. A randomized crossover trial was carried out in 12 patients. Carbidopa/levodopa was administered as an oral sustained-release tablet and by nasoduodenal continuous infusion for 3-week periods for each treatment. Plasma levodopa concentrations and motor performance were evaluated every 30 minutes during 3 test days of each treatment period. The average intraindividual coefficient of variation for the plasma levodopa concentrations after oral therapy was 34% and was significantly lower (14%, p < 0.01) during continuous infusion. Hourly video evaluations showed a significant increase in ON time during infusion and a significant decrease in OFF time and dyskinesia. Continuous intraduodenal delivery of a new carbidopa/levodopa formulation offers a means for markedly improved control of motor fluctuations in late stages of PD.

Levodopa pharmacokinetics and motor performance during activities of daily living in patients with Parkinson's disease on individual drug combinations

Pharmacokinetics and pharmacodynamics of levodopa were evaluated at a high-resolution level in a heterogeneous group of 10 patients with idiopathic Parkinson's disease during their normal daily activity. A physician and a nurse spent 10 hours with each patient from the first morning dose of levodopa during daily activities at home and at work. Plasma samples were obtained every 20 minutes for analysis of levodopa and 3-O-methyldopa by high-performance liquid chromatography. To assess clinical response, mobility was rated on every test occasion by patients and by investigators. Food and fluid intake and physical activity were also monitored. There was a large intra- and interindividual variability in the pharmacokinetics of levodopa regardless of the different drug combinations used. Mean plasma levodopa concentration ranged between 0.45 to 7.07 microg/mL and peak concentrations between 0.95 to 13.75 microg/mL. In 44 of 58 dosing events, an oral dose of levodopa was related to a peak in plasma concentration. Assessment of the clinical effects was more sensitive when given by patients than when given by the investigators. The fluctuations of the levodopa concentration in plasma had a clear effect on the clinical parameters assessed, even during early disease stages. Variation in levodopa concentration is the determining factor for motor fluctuations also in patients on clinically optimized combinations with dopamine agonists and enzyme inhibitors.

Duodenal levodopa infusion in Parkinson's disease--long-term experience

Motor fluctuations in parkinsonian patients can be reduced by intraduodenal infusion of levodopa. Between 1991 and 1998 continuous daytime administration of levodopa through a transabdominal port has been used in 28 very advanced patients over a total period of 1045 months. A stable suspension of levodopa and carbidopa (Duodopa) has been developed. Patients were characterized by early onset, long history of disease and levodopa therapy. The reason for infusion was in all cases related to on-off fluctuations. All patients experienced a general improvement after the introduction of continuous treatment. There have been no severe complications. Six patients have taken the decision to curtail their treatment. The mean daily levodopa consumption has been slightly reduced on infusion as compared to oral therapy. Nine of the first group of patients participating in the new therapy have been regularly evaluated by means of rating scales and movement analyses. Short-term results have already been published and a follow-up showing continued positive effect after 4-7 years of continuous duodenal infusion is presented.

Amyotrophic lateral sclerosis: evidence for intact hepatocyte growth factor/met signalling axis

Hepatocyte growth factor (HGF) is a secreted cytokine which is expressed in the central nervous system (CNS) together with its specific receptor MET. Since HGF exerts strong neurotrophic activity including motoneurons, we have further analysed whether the HGF/MET axis is defective in patients with amyotrophic lateral sclerosis (ALS). Intrathecal HGF-secretion was measured in cerebrospinal fluid (CSF) from patients with amyotrophic lateral sclerosis and in controls without neurological diseases using a specific sandwich immunoassay (ELISA). MET-expression was analysed by immunohistology in spinal cord cross-sections of ALS patients and unaffected controls. The HGF concentrations in CSF were moderately but significantly increased in ALS patients compared to healthy controls (580 pg/ml vs 348 pg/ml). MET-protein was detectable in spinal cord motoneurons of patients with ALS as well as unaffected controls. The data demonstrate that ALS does not show a lack of the trophic signalling axis, HGF/MET, suggesting that the signalling system itself is not affected. The moderate increase in HGF-secretion may represent a compensatory effect.

High 3H-vesamicol binding in ALS motor neurons--autoradiographic visulalization of hyperactivities?

OBJECTIVES

To evaluate if increased metabolic demand in remaining motor neurons in ALS spinal cord sections can be visualized by 3H-vesamicol binding.

MATERIAL AND METHODS

As a presumed marker of the vesicular acetylcholine transporter, 3H-vesamicol was applied in quantitative autoradiography in cervical spinal cord sections from 11 ALS patients and 4 control cases. The regional binding was compared to that of the muscarinic ligand 3H-QNB.

RESULTS

Our results demonstrate the same magnitude of H-vesamicol binding in the ventral horn of ALS spinal cord as compared to controls, despite the profound loss of motor neurons in that specific area in ALS. The specificity of 3H-vesamicol binding for the cholinergic transporter is high in the motor neuron area, and sigma-sites constitute a minor proportion.

CONCLUSION

The lack of decrease in 3H-vesamicol binding in postmortem ALS spinal cord sections probably reflects an upregulated synthesis of vesicular membranes in remaining and hyperactive motor neurons in vivo.

A comparative study of methionine adenosyltransferase activity and regional distribution in mammalian spinal cord

To provide a background for future studies on neurodegenerative changes in the spinal cord, the present study analysed the distribution of the activity of methionine adenosyltransferase (ATP:L-methionine S-adenosyltransferase, EC 2.5.1.6, MAT), an enzyme that catalyses the synthesis of the biological methyl group donor S-adenosylmethionine (AdoMet), in spinal cords from bovine and pig, and compared the results with those from human spinal cord. The enzyme activity was estimated by a radiochemical method measuring the rate of formation of [(3)H]AdoMet from L-[methyl-(3)H]methionine and ATP. The MAT activity (V(max)) was quite homogeneously distributed between spinal regions and species investigated (19-50 pmol [(3)H]AdoMet/mg protein/minute), with the highest level found in the male bovine group. The bovine group (both males and females) also presented a 20% higher enzymatic activity in the dorsal horn as compared to the ventral horn and white matter areas. In the pig spinal cord, the highest level of activity was found in the white matter. The lowest affinity for methionine (highest K(m)) was found in the human spinal cord. Whole spinal cords of one cat and one rhesus monkey were also analysed and the levels of MAT activity were similar to that of humans and bovine females, respectively. Studies of MAT stability in the rat spinal cord (post-mortem time 0-72 hr) showed a significant decrease in enzyme activity during the interval of 0-8 hr (23 degrees ). From this time point on and up to 72 hr (4 degrees ), the significant decrease in the activity remained at 60% of the initial value.

Gender differences in Parkinson's disease symptom profile

Gender symptom differences were studied in 948 subjects with Parkinson's disease (PD) using a questionnaire covering the most common symptoms associated with PD at debut (SP-1) and at present (SP-2). The symptoms most frequently reported by both genders were: tremor, fumblingness, writing problems, rigidity and fatigue. At SP-1 females reported neck-pain and low back pain more frequently than males. At SP-2 subjects reported an increased number of symptoms. The following symptoms were more frequent among males than females: writing difficulties, fumblingness, gait problems, speech problems, increased flow of saliva, lack of initiative. Sleep problems were common in both sexes with inability to turn in bed and calf muscle cramps in a high percentage. A majority of female subjects find their symptoms (e.g. depression) constantly distressing. Although depression is not one of primary reported symptoms (36%) attention is called for, due to the problem with compliance to treatment regimes. About 30% do not report having tremor and rigidity. This study indicates the usefulness of a symptom profile instrument capable of capturing the many symptoms involved in PD. Such an instrument could be used to detect apparent mistakes in medication and thereby increase the function and quality of life for the individual.

Palmar and axillary hyperhidrosis treated with botulinum toxin: one-year clinical follow-up

Focal hyperhidrosis is a common and sometimes handicapping condition for which the presently most effective treatment, sympathectomy, often leads to irreversible side-effects. We aimed to study effectiveness and tolerability of an alternative treatment with botulinum toxin injections over a period of one year for this condition. Twenty-eight patients with palmar (n = 19) and/or axillary (n = 13) hyperhidrosis were treated with intracutaneous injections of botulinum toxin (Botox(R)) 2 U/4 cm2. Sweat function was studied clinically and by objective measurements after treatment of one side. Treated and untreated sides, and pre- and post-treatment skin areas were compared. Subjective evaluation was performed after treatment of one side and 2-5 months after treatment of both sides. Duration of effect was controlled by a one-year follow-up. Sweating disappeared in eight out of 13 patients with axillary and in five out of 19 with palmar hyperhidrosis, and was reduced markedly in another five out of 13 and 10 out of 19 patients. Two-thirds of those treated for hand sweat noticed a slight and transient reduction of power of finger grip. No side-effects were noticed after treatment of axillary hyperhidrosis. We find intracutaneous injections of botulinum toxin with this technique safe and effective, and due to the relatively long duration of effect the treatment should be recommended before sympathectomy for focal hyperhidrosis.

Upregulation of Bax protein and increased DNA degradation in ALS spinal cord motor neurons

OBJECTIVES

To investigate if degeneration of motor neurons in amyotrophic lateral sclerosis (ALS) is related to altered levels of the apoptosis regulating proteins Bcl-2 and Bax. In addition, immunoreactivity of the cysteine protease ICH-IL and detection of motor neurons with DNA fragmentation, indicative of apoptosis, was also studied.

MATERIAL AND METHODS

The immunoreactivity of Bcl-2, Bax and ICH-1L were compared in ALS and control spinal cord motor neurons by immunohistochemical analysis and motor neurons with DNA fragmentation were identified by the TUNEL-method.

RESULTS

The results demonstrate an increased expression of Bax in the ALS material as compared to controls but no change in Bcl-2 and ICH-1L expressions. Moreover, a larger proportion of motor neurons stained positive for TUNEL in ALS spinal cords.

CONCLUSION

Present study suggest an upregulation of the cell death promoting protein Bax and increased DNA degradation, indicative of apoptosis, in spinal motor neurons of ALS patients.

Methionine adenosyltransferase activity in erythrocytes and spinal cord of patients with sporadic amyotrophic lateral sclerosis

The role of transmethylation mechanisms in the etiology of amyotrophic lateral sclerosis (ALS) is hitherto unexplored. The activity of L-methionine S-adenosyltransferase (MAT), a regulatory enzyme of S-adenosylmethionine biosynthesis, was investigated in erythrocytes of 21 patients with ALS, spinal cord specimens of 7 ALS patients, and matched controls. In ALS patients the activity of MAT in erythrocytes was sex-dependent. In comparison with controls, the male group presented a 33% higher V(max) (P < 0.05) and a 41% decrease in the affinity of MAT for methionine (K(m), P < 0.05). The type of ALS onset (limb or bulbar), age, or duration of the disease did not influence erythrocyte MAT activity. In the spinal cord, the activity of MAT was homogeneously distributed through dorsal horn, ventral horn, and white matter. Comparisons between data from controls and ALS patients and analysis of sex effect showed no significant differences. The kinetic difference of erythrocyte MAT in the male group of ALS patients might be interesting to explore since it is well known that there is a male predominance of 1.5 to 2. 5:1 in ALS.

Absorption of L-DOPA from the proximal small intestine studied in the rhesus monkey by positron emission tomography

Positron emission tomography (PET) seems to be a valuable method for the understanding of intestinal absorption mechanisms, for simultaneous quantitation of absorption rate and distribution kinetics to the tissues of interest after oral drug delivery. PET was evaluated in three Rhesus monkeys for quantitation of the absorption rate from the gastrointestinal tract and the distribution kinetics into different organs. To obtain optimal standardized conditions for the measurement of absorption the drug was administered via a naso-duodenal catheter directly to the absorption site in the proximal small intestine. l-DOPA was used as study drug given in a suspension together with carbidopa and the radiomarker l-[beta-11C]DOPA. The l-DOPA suspension was given into the duodenum without and after administration of a suspension of six l-amino acids (120 mM) in order to investigate any interaction on the intestinal absorption and distribution of l-DOPA into the liver and brain tissue. Intestinal absorption was in general minor during the first study period and higher together with administered l-amino acids. The somewhat contradictory result with increased absorption when amino acids were present in the intestinal lumen, may be a consequence of increased intestinal motility initiated by the nutrient load.

Increased expression of glial cell line-derived neurotrophic factor mRNA in muscle biopsies from patients with amyotrophic lateral sclerosis

The expression of glial cell line-derived neurotrophic factor (GDNF) mRNA and brain-derived neurotrophic factor (BDNF) mRNA were studied in muscle biopsies from five patients with amyotrophic lateral sclerosis (ALS), six patients with other neuromuscular diseases and eight healthy control persons. All five patients with ALS had higher GDNF mRNA expressions in their biopsies than the healthy control group (almost a three fold increase). Among the other patients only one, who had a rapidly progressing toxic polyneuropathy, showed a GDNF mRNA expression above those of the controls. The BDNF mRNA expressions in the biopsies from the ALS patients were in the same range as those from the healthy controls, although the mean value of the ALS patients was higher. The only biopsy that showed a markedly higher BDNF mRNA expression was taken from one patient with progressive muscular atrophy. These results suggest that increased GDNF mRNA expression in muscle is an unspecific response to ongoing denervation and that this response is maintained in ALS, at least temporarily. If increased GDNF mRNA in muscle proves to be a constant finding in ALS the rationale for the use of GDNF as a therapeutic agent in ALS must be questioned.

Long-term intraduodenal infusion of a water based levodopa-carbidopa dispersion in very advanced Parkinson's disease

OBJECTIVE

To evaluate the effects of continuous duodenal infusion of levodopa over time on the disabling fluctuations in motor performance in advanced parkinsonian patients. It has earlier been demonstrated that these fluctuations can be reduced by keeping the plasma concentration of levodopa constant.

MATERIAL AND METHODS

In view of the low water solubility of levodopa a stable dispersion of the drug was developed and used for continuous intraduodenal infusion in patients with advanced Parkinson's disease. Nine patients were evaluated with respect to an optimal oral treatment, during nasoduodenal infusion by a portable pump and then followed for 6 months to 2 1/2 years when treated via transabdominal infusion. Upon each test occasion, over 2 non-consecutive days, objective movement analysis by means of an opto-electronic system was applied every 15-20 min and video recordings performed twice every h. On several test occasions plasma levodopa concentrations were analysed every 15 min.

RESULTS

The patients showed improvement and decreased variance of their motor function. In the 2 patients followed over a period of 2 1/2 years levodopa plasma concentration showed reduced fluctuations on infusion and the levodopa consumption as well as mean levodopa plasma concentration decreased.

CONCLUSION

Continuous duodenal infusion of levodopa is an alternative treatment strategy for patients with advanced Parkinson's disease when conventional therapy has failed.

Reversible chorea in primary antiphospholipid syndrome

A 20-year-old woman with acute chorea induced by primary antiphospholipid syndrome was studied by using fluorodeoxyglucose and positron emission tomography (PET). PET sessions were conducted during an episode of severe chorea and after recovery. The symptoms predominantly affected the right side of her face and body, and PET demonstrated a corresponding increase in lentiform and caudate nucleus metabolism prevailing on the left side. After recovery, PET showed normal values in the regions previously studied. This study adds further evidence to support the theory that acute choreas are somehow the result of striatal hypermetabolism.

Levels of L-methionine S-adenosyltransferase activity in erythrocytes and concentrations of S-adenosylmethionine and S-adenosylhomocysteine in whole blood of patients with Parkinson's disease

In the present study, levels of S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) in whole blood as well as L-methionine S-adenosyltransferase (MAT) activity in erythrocytes were assayed in a series of 20 patients with Parkinson's disease and 12 healthy control subjects. A significant difference was found with regard to SAM levels between patients and controls, with the detected levels being 383.1 +/- 41.5 nM for the parkinsonian patients and 680.6 +/- 30.9 nM for the controls. With regard to SAH, we found no difference between the groups. The catalytic activity of MAT was increased by 30% in patients compared to controls, with the Vmax for methionine being 17.9 +/- 3.7 and 13.9 +/- 2.2 pmol/mg/h, respectively.

Levodopa-induced changes in synaptic dopamine in patients with Parkinson's disease as measured by [11C]raclopride displacement and PET

Changes in striatal binding of [11C]raclopride, a dopamine D2 receptor antagonist, induced by acute levodopa administration, were evaluated with PET in 10 patients with idiopathic Parkinson's disease (PD). The patients were scanned on two occasions: drug-free and 15 minutes after a 5-minute intravenous infusion of 3 mg/kg levodopa. Levodopa administration produced reductions in striatal [11C]raclopride uptake index with a rostrocaudal gradient. The most pronounced reduction was found in the posterior putamen (to 82% of baseline), followed by the anterior putamen (to 88% of baseline) and the caudate nucleus (to 94% of baseline). The magnitude of [11C]raclopride uptake index reduction correlated with drug-free disability. Moreover, in four hemiparkinsonian patients, a reduction in [11C]raclopride uptake index was measured in the putamen contralateral to the parkinsonian symptoms. The present results demonstrate a positive correlation between striatal dopaminergic nerve-terminal deficiency and the capacity for levodopa to increase synaptic dopamine and displace [11C]raclopride binding, which corresponds to an accelerated amine turnover in dopamine-depleted striatal tissue. We therefore suggest that dopaminergic degeneration in PD is paralleled by a progressive acceleration of amine turnover. This mechanistic consequence of nigrostriatal degeneration, the selective restoration of synaptic dopaminergic neurotransmission in denervated striatal subregions, may explain the effectiveness of levodopa in producing symptomatic benefits in early PD. However, we also suggest that in the vastly denervated striatum, as in advanced PD, an excessive acceleration of amine turnover results in swings in levodopa-induced synaptic dopamine levels that are far beyond normal. This phenomenon most likely plays a key role in the pathogenesis underlying the development of motor-response complications in PD.

Neurological Wilson's disease studied with magnetic resonance imaging and with positron emission tomography using dopaminergic markers

Four patients with neurological Wilson's disease were investigated using magnetic resonance imaging (MRI) and positron emission tomography (PET). All patients had dystonia as their major clinical manifestation but also had dysarthria and at the presentation of the disease had choreoathetoid movements in at least one limb. A multitracer approach with PET was used to visualize various aspects of dopaminergic function; [11C]-(+)-nomifensine (NMF), [11C]raclopride (RAC) and [11C]-L-DOPA (one patient). Correlation analysis of RAC and NMF binding as well as putamen/caudate uptake ratios showed corresponding reductions. The patient investigated with [11C]-L-DOPA had a normal striatal uptake. Generally, structural changes as shown by MRI corresponded to reductions both in NMF and RAC binding. There was no evident correspondence between PET findings and the severity of clinical symptoms seen in the individual patient. In two patients with discrete neurological impairment at the time of investigation, PET showed serious presynaptic dopaminergic lesions in the putamen. Our data suggest that the striatal degeneration seen in Wilson's disease comprises a complex pathology involving both afferent and efferent projections. The discrete neurological impairment seen in some patients with gross striatal pathology might be due to concomitant lesions in functionally counteracting basal ganglia circuits.

Insulin-like growth factor-1 receptors in human spinal cord: changes in amyotrophic lateral sclerosis

Neurotrophic factors are important for neuronal survival and maintenance in the adult nervous system. The regional distribution of insulin-like growth factor-1 (IGF-1) receptors in human spinal cords from controls and amyotrophic lateral sclerosis (ALS) patients was studied by immunohistochemistry and quantitative autoradiography. When comparing 125I-IGF-1 binding in the different spinal levels of normal spinal cord the same distribution pattern was found in which the binding was highest in the central canal > dorsal horn > ventral horn > white matter. In the ALS cases although a general upregulation of IGF-1 receptors was observed throughout the spinal cord, significant increases were observed in the cervical and sacral segments compared to controls. IGF-1 receptor immunoreactivity showed a similar pattern to that for 125I-IGF-1 binding, with immunoreactivity being found in the gray matter of the spinal cord and enhanced immunoreactivity occuring in ALS patients compared to controls. In agreement with the distribution of IGF-1 receptors, IGF-1 immunoreactivity was found within the gray matter of the spinal cord. The cartography of IGF-1 receptors in the normal spinal cord as well as the change of these receptors in diseased spinal cord may be of importance in future treatment strategies of ALS.

Double blind cross over trial with deprenyl in amyotrophic lateral sclerosis

In this paper we present results from a double blind cross over trial with deprenyl, a selective and irreversible monoamine oxidase-B (MAO-B) inhibitor, in 10 patients suffering from amyotrophic lateral sclerosis. The patients were randomised in such a way that half of the patients started with the active drug and half with the placebo treatment. Each patient was given 10 mg deprenyl (eldepryl, 10 mg tablets) per day for 12 weeks and then placebo for the same length of time. There was a drug free period of 12 weeks between the courses. The neurological status of the patients were evaluated every six weeks by using Norris, spinal and bulbar scores and it was observed that all cases deteriorated in their clinical status during the 36 weeks of the controlled study. MAO-B activity in blood platelets was completely inhibited during treatment with deprenyl. In the preliminary analysis performed so far, no obvious retardation in the progress of the disease could be observed with deprenyl treatment.

Reactive gliosis and monoamine oxidase B

A double-staining method was applied to cryosections of human spinal cord from patients who died with amyotrophic lateral sclerosis (ALS) and corresponding controls in order to investigate cellular content of monoamine oxidase B (MAO-B). 3H-L-Deprenyl emulsion autoradiography was used in combination with histochemical methods for the detection of astrocytes and monocytes/microglia. In the ALS spinal cords an increased number of astrocytes as well as an increased content of MAO-B in reactive species of astrocytes was demonstrated. No significant 3H-L-deprenyl binding was observed in cells derived from the mesoderm, e.g. monocytes or microglia. Furthermore, a sub-population of reactive astrocytes that contained low levels of MAO-B was observed in spinal sections. These findings were further substantiated by studies performed on primary astrocyte cultures.

Monoamine oxidase-B in motor cortex and spinal cord in amyotrophic lateral sclerosis studied by quantitative autoradiography

The distribution of MAO-B was studied by using an in vitro quantitative autoradiographical method in the post-mortem spinal cord and motor cortex from control and ALS cases. 3H-L-deprenyl was used as a radiotracer. Sections stained with thionine were used to count glial cells. In both control and ALS spinal cords, high density of 3H-L deprenyl binding was observed around the central canal, in the substantia gelatinosa and other grey matter regions. In the ALS cases a pronounced and statistically significant increase of MAO-B was observed in the corticospinal tract, the motor neuron areas and in the ventral white matter. An increase in the number of glial cells in spinal cords from ALS cases was also evident. Moreover, the concentration of MAO-B was highly correlated with glial cell counts in thionine stained sections in various regions of the spinal cord, both in controls and ALS cases. An elevated level of 3H-L-deprenyl binding, in ALS cases, was observed in all the individual laminae of the pre- and post-central gyri of the cerebral cortex. There was no difference in MAO-B concentration between the two groups in the occipital cortex. A substantial increase in the concentration of MAO-B was observed in the white matter of ALS cases. Reactive gliosis has been shown to be associated with neurodegenerative disorders and experimental lesions in animals. The most likely explanation for the increase of MAO-B in ALS and in other neurodegenerative disorders seems to be that the increase is a consequence of the reactive gliosis associated with these disorders.