Manganese-induced parkinsonism in methcathinone abusers: bio-markers of exposure and follow-up.

BACKGROUND AND PURPOSE: Methcathinone abuse is a new cause of manganism. The psychostimulant is prepared from pseudoephedrine using potassium permanganate as an oxidant. We describe the clinical, biological, neuroimaging characteristics and follow-up results in a large Estonian cohort of intravenous methcathinone users. METHODS: During 2006-2012 we studied 38 methcathinone abusers with a mean age of 33 years. Subjects were rated by the Unified Parkinson's Disease Rating Scale (UPDRS), Hoehn and Yahr (HY), and Schwab and England (SE) rating scales. Twenty-four cases were reassessed 9-70 (20 ±â€…15) months after the initial evaluation. Manganese (Mn) in plasma and hair was analysed by inductively coupled plasma-atom emission spectrometry. Magnetic resonance imaging (MRI) was performed in 11, and single-photon emission computed tomography (SPECT) with iodobenzamide (IBZM) in eight subjects. RESULTS: The average total UPDRS score was 43 ±â€…21. The most severely affected domains in UPDRS Part III were speech and postural stability, the least affected domain was resting tremor. At follow-up there was worsening of HY and SE rating scales. Subjects had a higher mean level of Mn in hair (2.9 ±â€…3.8 ppm) than controls (0.82 ±â€…1.02 ppm), P = 0.02. Plasma Mn concentrations were higher (11.5 ±â€…6.2 ppb) in active than in former users (5.6 ±â€…1.8 ppb), P = 0.006. Active methcathinone users had increased MRI T1-signal intensity in the globus pallidus, substantia nigra and periaquaductal gray matter. IBZM-SPECT showed normal symmetric tracer uptake in striatum. CONCLUSION: Methcathinone abusers develop a distinctive hypokinetic syndrome. Though the biomarkers of Mn exposure are characteristic only of recent abuse, the syndrome is not reversible.

Frequent administration of levodopa/carbidopa microtablets vs levodopa/carbidopa/entacapone in healthy volunteers.

OBJECTIVES: An oral dispersible microtablet formulation of levodopa/carbidopa 5/1.25 mg (LC-5) was developed for individualized repeated dosing. The aim was to compare pharmacokinetic profiles of LC-5 and levodopa/carbidopa/entacapone (LCE). MATERIALS AND METHODS: A randomized, crossover study was carried out in 11 healthy subjects. Plasma concentrations of levodopa, carbidopa and 3-O-methyldopa were determined after intake of 300 mg levodopa during the day, either as three intakes of 100/25/200 mg LCE or as a morning dose of 75/18.25 mg followed by five repeated doses of 45/11.25 mg LC-5. RESULTS: Repeated dosing (2.4-hourly) with LC-5 microtablets compared to LCE (6-hourly) avoided long periods with low plasma levodopa levels. Time to maximum plasma concentrations was significantly shorter for LC-5. LC-5 showed lower fluctuation index (FI) in plasma compared to LCE (ANOVA P = 0.0028). FI for dose 2-5 was on average 1.26 for levodopa in LC-5, and 2.23 for dose 1-2 of LCE. The ratio between the two mean FI:s is 0.565; that is, LC-5 gave nearly half the FI as compared to LCE. CONCLUSIONS: Fractionation of levodopa with LC-5 into small, frequent administrations as compared to standard administrations of LCE decreased the FI in plasma for both levodopa and carbidopa by nearly half.

Clinical, neuroimaging and neurophysiological features in addicts with manganese-ephedrone exposure.

OBJECTIVE: To identify biomarkers supporting the clinical diagnosis of manganism in patients several years after exposure to manganese (Mn). METHODS: Neurophysiological examinations, magnetic resonance imaging (MRI), single-photon emission computed tomography and fluorodeoxyglycose (FDG) positron emission tomography were performed in four former ephedrone addicts with extrapyramidal symptoms. RESULTS: Peripheral nervous system was not affected. No patients had reduced uptake of (123)I Ioflupane in the striatum. MRI signal intensities were slightly changed in the basal ganglia. All patients showed a widespread, but not uniform, pathological pattern of FDG uptake with changes mainly located to the central part of the brain including the basal ganglia and the surrounding white matter. CONCLUSIONS: Presynaptic neurons in the nigrostriatal pathway are intact in Mn-induced parkinsonism after prolonged abstinence from ephedrone. The diagnosis is principally based on clinical signs and the history of drug abuse.

Impact of dystonia on quality of life and health in a Swedish population.

OBJECTIVES: Dystonia is often disabling and disfiguring. The aim of the study was to identify factors influencing the impact of dystonia on self-reported quality of life and health. MATERIAL AND METHODS: Members of the Swedish Dystonia Patient Association participated in a survey covering demographic variables, satisfaction with treatment, physiotherapy and physical activity. Quality of life and health were assessed by the Craniocervical Dystonia Questionnaire and the Cervical Dystonia Impact Profile, respectively. Of 378 questionnaires, 76% were analysed. Multiple linear regression analyses were performed to evaluate associations of the above variables with quality of life and health. RESULTS: Level of physical activity and satisfaction with treatment showed the highest association with quality of life and health. No significant relationship was found between form of dystonia and quality of life. CONCLUSIONS: The study indicates a need for health care professionals to encourage physical activity and to question dystonia patients about satisfaction with treatment. Further investigations with prospective controlled trials are necessary to evaluate the value of physiotherapy and physical activity in patients with dystonia.

What has PET told us about Parkinson's disease?

From 1983, when dopaminergic structures were visualized for the first time in the human brain by positron emission tomography (PET) and onwards about 120 PET studies on Parkinsons disease have been listed in MEDLINE. With 18F-fluorodopa presynaptic dopamine insufficiency can be demonstrated in PD. By using 11C-nomifensine the dopamine reuptake sites can be visualized with PET. These results indicate that the striatal dopaminergic terminals are relatively preserved in PD as compared to the extreme reductions of dopamine in this region post mortem. Radiolabelled D2-agonists indicate a slight increase in these binding sites in de novo PD and no marked reduction in more advanced disease. 11C-selegiline have been used to demonstrate the intracerebral MAO-B inhibition by therapeutic doses of this drug. 11C-L-dopa and PET have demonstrat the rapid striatal decarboxylation of therapeutic doses of L-dopa also in advanced PD and a rough estimate of the striatal dopamine concentration inducing an "on-response" has been obtained. These contributions of PET to PD research are discussed in the article.

Brain dopaminergic mechanisms in Parkinson's disease evaluated by positron emission tomography.

The meso-striatal dopamine neurons, essential for the automated control of movements, are primarily affected in patients with P.D. Direct study of the role of this pathway in states of disease has not been possible until recently and the application of PET for the in vivo investigation of dopaminergic mechanisms may serve to demonstrate the potential of the technique. One basic idea has been to work out methods to investigate multiple aspects of dopaminergic function, i.e. presynaptic mechanisms such as re-uptake sites and synthesis of neurotransmitter as well as postsynaptic such as receptor properties. Furthermore, efforts have been made to evaluate dopamine degradating enzymes. Preclinical PET-investigations have regularly been performed in Rhesus monkeys and the hemiparkinsonian model produced by infusing MPTP into one internal carotid artery has been of great value to characterize new 11C-labelled tracers. Today 11C--(+)-nomifensine is used to give a measure of dopamine re-uptake sites, probably reflecting nerve terminals. 11C-labelled L-dopa has now been introduced and can be expected to replace 18F-L-fluorodopa as a physiological tracer for precursor transport and transmitter synthesis. Several ligands are available for the quantitation of dopamine receptors--11C-N-methylspiperone and 11C-raclopride have been used in our studies. 11C-L-selegiline and its "inactive" D-form have been used in clinical PET-studies aimed to evaluate the enzyme MAO-B. A summary of in vivo information of dopaminergic mechanisms in P.D. obtained using the above-mentioned tracers and PET is presented.

Biochemical changes in dementia disorders of Alzheimer type (AD/SDAT).

In postmortem investigations of patients with dementia of Alzheimer type (AD/SDAT) (n = 14) the brain weight was significantly reduced when compared to controls (n = 16). In four AD/SDAT-brain parts investigated the concentrations of 5-hydroxy-tryptamine and noradrenaline were significantly reduced while 3-methoxy-4-hydroxyphenylglycol was significantly increased. In the caudate nucleus of the AD/SDAT-brains the concentrations of dopamine and homovanillic acid were significantly reduced. The activity of monoamine oxidase B was increased suggesting a proliferation of extra neuronal tissue in the AD/SDAT-brains. The activity of choline acetyl transferase was reduced in the four brain parts investigated, showing a general reduction in the acetylcholine system in the AD/SDAT-brains. The ganglioside concentration was significantly reduced suggesting a reduced density of nerve endings in the demented brains. The AD/SDAT-group was according to rating scales severely demented. Patients with an early onset of the dementia disease were more severely intellectually reduced and had more pronounced biochemical disturbances than those with a late onset of the dementia.

Choline therapy in Huntington chorea.

Choline chloride was administered orally (3 to 15 gm per day) to five patients with Huntington chorea. A long-lasting dose-dependent elevation of the concentration of free choline in plasma was obtained and the highest plasma concentrations (25 to 30 mumol per liter) were of the same magnitude as those that increase brain acetylcholine content in the rat. However, the choline treatment did not conclusively alter the involuntary movements of these patients.

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.

Monoamine oxidase-B in motor cortex: changes in amyotrophic lateral sclerosis.

The occurrence of monoamine oxidase-B in cerebral cortex and white matter in brains from three patients with the diagnosis of amyotrophic lateral sclerosis and three controls was quantified by means of an autoradiographical method. [3H]L-Deprenyl, an irreversible and selective monoamine oxidase-B inhibitor, was used as ligand and the autoradiographs were analysed by computer-assisted densitometry. In both amyotrophic lateral sclerosis and control cerebral cortex, lamina I showed the highest, laminae II and III intermediate, laminae IV, V and VI the lowest [3H]L-deprenyl binding. White matter showed about one-third of the binding in the cortex. Amyotrophic lateral sclerosis cases showed significantly higher binding of [3H]L-deprenyl in all the cortex laminae of the pre- and postcentral gyri. There was no difference in the binding between the amyotrophic lateral sclerosis cases and the controls in area 7 of the occipital cortex, an area which is relatively spared in amyotrophic lateral sclerosis.

Clinical pharmacokinetics of cholinesterase inhibitors.

This review deals mainly with the pharmacokinetics of the reversible quaternary cholinesterase inhibitors neostigmine, pyridostigmine and edrophonium, which are mainly used to antagonise non-depolarising neuromuscular blockade in general anaesthesia and in the symptomatic treatment of myasthenia gravis. Only in the last few years, since the introduction of highly sensitive and selective analytical procedures based on gas and liquid chromatography, have proper pharmacokinetic studies of these drugs become possible. Rapid cooling and addition of internal standard to samples before freezing are important precautions in view of the poor stability of the cholinesterase inhibitors in plasma and blood. Plasma clearances of the reversible quaternary cholinesterase inhibitors are in the range 0.5 to 1.0 L/h/kg and their apparent volumes of distribution range from 0.5 to 1.7 L/kg. Accordingly, the drugs have short plasma elimination half-lives, in the order of 30 to 90 minutes. One to two hours after oral administration of 60 mg pyridostigmine, peak plasma concentrations of 40 to 60 micrograms/L are observed, whereas the plasma concentrations of neostigmine after a 30 mg oral dose are only 1 to 5 micrograms/L. The oral bioavailability of these hydrophilic ionised compounds is low: that of pyridostigmine is approximately 10% and the value for neostigmine is even lower. In spite of the short elimination half-life of pyridostigmine, intraindividual variations in plasma concentration during a dose interval are small in myasthenic patients receiving oral maintenance therapy, probably as a result of slow absorption from the gastrointestinal tract. Severely impaired renal function has been shown to prolong the elimination of neostigmine and pyridostigmine, while methylcellulose has been reported to inhibit the absorption of the latter drug completely. Other pharmacokinetic drug interactions suggested so far do not seem to be of clinical significance. Although a positive correlation has been demonstrated between the plasma concentrations of these drugs and their pharmacological effects as measured by a decrement in muscle response to repetitive nerve stimulation in a single muscle, this relationship is less clear when a global evaluation of muscular function in myasthenia gravis is used. Pharmacokinetic studies of the tertiary reversible cholinesterase inhibitor physostigmine, an important tool in experimental cholinergic neuropharmacology, are still in their initial stages. This drug too is characterised by a short plasma elimination half-life of 20 to 30 minutes.(ABSTRACT TRUNCATED AT 400 WORDS)

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.

Muscarinic binding sites in small homogenates and in autoradiographic sections from rat and human spinal cord.

Binding of labelled L- quinuclidinylbenzylate was studied in cryosections and homogenates of human and rat spinal cord. For the cryosections an autoradiographic method was used. With both techniques a higher density of muscarinic binding sites was found in rat than in human spinal cord. In the autoradiographs very high densities of muscarinic binding sites were observed in the motor neurone area and in the apical part of the dorsal horn. The latter high density region was not always found in homogenates from dissected tissue samples. The autoradiographic technique has a better resolution for detecting discrete regional variations in the receptor content of the spinal cord.

Topographical localization of choline acetyltransferase within the human spinal cord and a comparison with some other species.

Choline acetyltransferase (ChAT), which is known to be a specific marker of cholinergic structures, was assayed in small tissue samples punched out from cryosections of human, bovine, cat and rat spinal cords. The relative distribution patterns of spinal ChAT were similar between the different species. An area of high activity in the ventrolateral part of the ventral horn was found. This activity is probably located in the motor neurons, as it could be traced into the ventral root region. In addition, in the dorsal horn of the cord from man and cow another area with high ChAT activity was found. Subcellular studies suggest that this activity is mainly located at nerve terminals.

Choline acetyltransferase and substance P-like immuno-reactivity in the human spinal cord: changes in amyotrophic lateral sclerosis.

The topographic location of the enzyme choline acetyltransferase (ChAT) has recently been determined within the human spinal cord. ChAT, which is regarded as a specific marker of cholinergic structures in nervous tissue, showed an area of high activity in the ventrolateral part of the ventral horn, probably related to motor neurons. In addition, an area of high ChAT activity was found in the apical part of the dorsal horn. As amyotrophic lateral sclerosis (ALS) is characterized by progressive degeneration of the cortico-spinal tracts and the lower motor neurons, we considered it of value to investigate the involvement of spinal cholinergic structures in this disorder. Substance P is regarded as the transmitter of incoming pain signals to the dorsal horn of the spinal cord, a subject recently reviewed by Marx. As disturbed sensation of pain is not a symptom of ALS, there seemed reason to correlate the spinal concentration of this peptide with the activities of ChAT in ALS.

Unilateral MPTP lesion in a rhesus monkey: effects on the striatal dopaminergic system measured in vivo with PET using various novel tracers.

We have produced in one monkey a unilateral lesion of the dopaminergic nigrostriatal pathway by slowly infusing 1-methyl-4-phenyl-1.2.3.6-tetrahydropyridine (MPTP) into the right internal carotid artery, resulting in contralateral hemiparkinsonism. This procedure was combined with a series of positron emission tomography scans before and after the lesion, using several dopaminergic tracers in parallel. We show that specific binding of [11C]nomifensine in the lesioned striatum disappears to a large extent (80-90%) as a result of the lesion, indicating a corresponding loss of striatal dopamine re-uptake binding sites and thus of the dopamine nerve terminal pool. The uptake of radioactivity in the striatum contralateral to the lesion remained unchanged. In parallel, an early increase in ipsilateral [11C]raclopride binding, indicating upregulation of dopamine D2 receptors, was seen following the presynaptic lesion. [11C]Deprenyl uptake, indicating monoamine oxidase type B enzyme concentration, did not change after the lesion.

Quantitative localization of human brain monoamine oxidase B by large section autoradiography using L-[3H]deprenyl.

The distribution of monoamine oxidase B (MAO-B) in the human brain was studied by quantitative autoradiography using L-[3H]deprenyl as a ligand. Two postmortem brains from patients without any known neurological diseases were used in this study. Cryosections of 100 microns thickness were taken on tape/paper and transferred to gelatinized glass plates. The sections were incubated with 10 nM L-[3H]deprenyl for 1 h and exposed to a film at 4 degrees C for 4 weeks. The autoradiograms were analyzed by computerized densitometry. High L-[3H]deprenyl binding was observed in caudate nucleus, putamen, cingulate gyrus and insula cortex. Moderate to low binding was seen in globus pallidus, temporal and parietal cortex and in various thalamus nuclei. Occipital cortex showed the lowest binding among the cortex regions and white matter the lowest among all the regions studied. All the regions in case 2 (aged 67) showed higher degree of binding when compared with case 1 (aged 58), which is in agreement with previous results showing an increase in MAO-B activity with age. When the specific binding of L-[3H]deprenyl was plotted against the MAO-B activities estimated biochemically in punches from the same areas, a high positive correlation was found.

Autoradiographic distribution of [3H]acetylcholine binding sites in the cervical spinal cord of man and some other species.

The distribution of [3H]acetylcholine ([3H]ACh) and [3H]ACh co-incubated with 1-mM nicotine (muscarinic receptor), and [3H]ACh co-incubated with 1.5 microM atropine (nicotinic receptor) binding sites were studied in man and compared to monkey, cat and rat using quantitative in vitro autoradiography. The highest density of total [3H]ACh binding sites was found in laminae II-III, IX (motor neuron areas) and X close to the central canal. The distribution pattern of the muscarinic cholinergic binding sites was similar to that of the total cholinergic binding. In general the number of nicotinic binding sites in the spinal cord was relatively small. The largest number of such binding sites was found in laminae II-III of the dorsal horn and in laminae X around the central canal. It is evident that the spinal cord has a 2-3 times higher number of muscarinic than of nicotinic cholinergic receptors.

In vivo and in vitro receptor autoradiography of the human brain using an 11C-labelled benzodiazepine analogue.

In vitro autoradiography of an 11C-labelled ligand, Ro 15-1788, has been used to visualize benzodiazepine binding sites in large human brain cryo-sections. In parallel, using the same radioligand, an in vivo study of a human healthy volunteer was performed, by means of positron emission tomography (PET). The in vitro and in vivo mapping of the ligand demonstrated a very similar binding pattern, although the poor resolution of PET precluded a full discrimination of fine details. The 11C-autoradiograms showed good spatial resolution, even with distinction of different layers in the cerebral and cerebellar cortex. In a separate experiment, the spatial resolution of 11C-autoradiography was found to be 180 microns, using 80-microns-thick cryo-sections. It is emphasized that in vitro and in vivo studies of the same radioligand give complementary information, which is valuable in the assessment of PET images.

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.