Bilateral caudate and putamen grafts of embryonic mesencephalic tissue treated with lazaroids in Parkinson's disease

Five parkinsonian patients were transplanted bilaterally into the putamen and caudate nucleus with human embryonic mesencephalic tissue from between seven and nine donors. To increase graft survival, the lipid peroxidation inhibitor tirilazad mesylate was administered to the tissue before implantation and intravenously to the patients for 3 days thereafter. During the second postoperative year, the mean daily L-dopa dose was reduced by 54% and the UPDRS (Unified Parkinson's Disease Rating Scale) motor score in 'off' phase was reduced by a mean of 40%. At 10-23 months after grafting, PET showed a mean 61% increase of 6-L-[(18)F]fluorodopa uptake in the putamen, and 24% increase in the caudate nucleus, compared with preoperative values. No obvious differences in the pattern of motor recovery were observed between these and other previously studied cases with putamen grafts alone. The amount of mesencephalic tissue implanted in each putamen and caudate nucleus was 42 and 50% lower, respectively, compared with previously transplanted patients from our centre. Despite this reduction in grafted tissue, the magnitudes of symptomatic relief and graft survival were very similar. These findings suggest that tirilazad mesylate may improve survival of grafted dopamine neurons in patients, which is in agreement with observations in experimental animals.

The catechol-O-methyltransferase (COMT) inhibitor entacapone enhances the pharmacokinetic and clinical response to Sinemet CR in Parkinson's disease

OBJECTIVES

Entacapone is a specific, potent, peripherally acting catechol-O-methyltransferase (COMT) inhibitor. It has been shown to improve the bioavailability of plasma levodopa and extend its clinical effect when used as an adjunct to standard levodopa preparations, but there is little experience of the effect of entacapone on controlled release levodopa preparations.

METHODS

A double blind, placebo controlled, single dose, randomised, cross over trial was performed in 14 patients with Parkinson's disease with motor fluctuations to investigate the clinical effect of a single dose of entacapone (200 mg) when administered with either standard levodopa-carbidopa (Sinemet) or controlled release levodopa-carbidopa preparations (Sinemet CR).

RESULTS

When entacapone was administered with standard Sinemet the duration of the clinical response to standard Sinemet was longer in comparison with the response after placebo (p=0.02). Moreover, in the same patients, entacapone significantly increased the duration of the clinical response to Sinemet CR (p=0.05) without prolonging the latency of response or enhancing dyskinesias.

CONCLUSIONS

These data confirm the clinical efficacy of entacapone-standard Sinemet combination. They also indicate that adding entacapone to controlled release levodopa preparations might provide a useful treatment option in patients with Parkinson's disease with motor fluctuations. A double blind clinical trial with a chronically administered entacapone-Sinemet CR combination is, however, required to verify this viewpoint.

Neuroimaging of dyskinesia

Dyskinesias are observed in the majority of Parkinson's disease (PD) patients who have been chronically exposed to levodopa, and these may result from supersensitivity of postsynaptic striatal dopamine D1 and D2 receptors following loss of nigral dopaminergic projections. Dyskinetic and nondyskinetic PD patients were studied using 11C-SCH23390 and 11C-raclopride positron emission tomography (PET). No difference in mean putamen or caudate D1 or D2 receptor binding between the two patient subgroups was found, suggesting that dyskinesias are unlikely to arise from a primary disturbance of dopamine receptor availability. When dyskinetic and nondyskinetic patients were studied with 11C-diprenorphine PET, the former showed a significant reduction (p < 0.05) in striatal and thalamic opioid site availability, compatible with the presence of raised levels of endogenous opioid peptides. H2(15)O PET activation studies of patients with focal limb dyskinesias showed that resting levels of regional cerebral blood flow after oral levodopa were increased during dyskinesias in lentiform nuclei, motor, premotor and dorsal prefrontal cortex. These results suggest that dyskinesias are associated with derangement of basal ganglia opioid transmission, resulting in overactivity of basal ganglia-frontal projections.

Diurnal motor variations to repeated doses of levodopa in Parkinson's disease

Patients with Parkinson's disease (PD) in long-term levodopa therapy often complain of worsening of motor symptoms in the afternoon and evening. The pathophysiology of this phenomenon is not known. We evaluated the motor response to repeated doses of levodopa during a 12-hour period in 52 parkinsonian patients (19 de novo, 20 stable, and 13 wearing-off). On the day of the study, all patients received standard doses of levodopa/carbidopa at 8:00 a.m., 12:00 noon, and 4:00 p.m. Motor measurements such as tapping test, walking time, and tremor score, and blood samples for levodopa and 3-O-methyldopa (3OMD) plasma analysis, were performed hourly. Mean motor scores and pharmacokinetic data, evaluated for a period of 3 hours after each levodopa dose, were compared. In de novo patients, we did not observe diurnal changes in motor score, whereas a progressive daytime worsening was visible in stable and wearing-off patients. No significant difference in levodopa pharmacokinetics after each levodopa dose was observed within each patient group, whereas 3OMD plasma levels significant increased with repeated levodopa administrations. However, no significant correlation between motor scores and 3OMD plasma levels was observed, suggesting that the diminishing motor response to afternoon and evening doses of levodopa in patients in long-term levodopa therapy does not relate to the pharmacokinetics of the drug. It is possible that this phenomenon may be an expression of the occurrence of tolerance to repeated doses of levodopa.

Dopamine release from nigral transplants visualized in vivo in a Parkinson's patient

Synaptic dopamine release from embryonic nigral transplants has been monitored in the striatum of a patient with Parkinson's disease using [11C]-raclopride positron emission tomography to measure dopamine D2 receptor occupancy by the endogenous transmitter. In this patient, who had received a transplant in the right putamen 10 years earlier, grafts had restored both basal and drug-induced dopamine release to normal levels. This was associated with sustained, marked clinical benefit and normalized levels of dopamine storage in the grafted putamen. Despite an ongoing disease process, grafted neurons can thus continue for a decade to store and release dopamine and give rise to substantial symptomatic relief.

Sequential bilateral transplantation in Parkinson's disease: effects of the second graft

Five parkinsonian patients who had received implants of human embryonic mesencephalic tissue unilaterally in the striatum 10-56 months earlier were grafted with tissue from four to eight donors into the putamen (four patients) or the putamen plus the caudate nucleus (one patient) on the other side, and were followed for 18-24 months. After 12-18 months, PET showed a mean 85% increase in 6-L-[18F]fluorodopa uptake in the putamen with the second graft, whereas there was no significant further change in the previously transplanted putamen. Two patients exhibited marked additional improvements after their second graft: 'on-off' fluctuations virtually disappeared, movement speed increased, and L-dopa could be withdrawn in one patient and reduced by 70% in the other. The improvement in one patient was moderate. Two patients with atypical features, who responded poorly to the first graft, worsened following the second transplantation. These findings indicate that sequential transplantation in patients does not compromise the survival and function of either the first or the second graft. Moreover, putamen grafts that restore fluorodopa uptake to normal levels can give improvements of major therapeutic value.

The role of inheritance in sporadic Parkinson's disease: evidence from a longitudinal study of dopaminergic function in twins

Despite the major finding of a genetic defect being responsible for the Parkinson's disease (PD) phenotype in some kindreds with dominantly transmitted PD, the role of inheritance in the cause of the more widespread sporadic form of the disease is still unclear. Twin studies are a classic tool for assessing the influence of hereditary factors in diseases; however, the application of this approach to late-onset illnesses, like PD, poses some problems because of the identification of subclinical cases. In the present longitudinal study we have used [18F]dopa and positron emission tomography to study dopaminergic function in twin pairs at baseline clinically discordant for PD. At baseline, the concordance for subclinical striatal dopaminergic dysfunction was found to be significantly higher in 18 monozygotic than in 16 dizygotic twin pairs (55% vs 18%, respectively). The asymptomatic monozygotic cotwins all showed progressive loss of dopaminergic function over 7 years and 4 developed clinical PD. None of the dizygotic twin pairs became clinically concordant. At follow-up, the combined concordance levels for subclinical dopaminergic dysfunction and clinical PD were 75% in the 12 monozygotic and 22% in the 9 dizygotic twin pairs evaluated twice. Our findings suggest a substantial role for inheritance in sporadic PD.

Acute and chronic effects of clozapine in essential tremor

Patients with essential tremor (ET) may not respond to commonly used drugs. Clozapine, an atypical neuroleptic drug, has been reported to improve postural Parkinson's disease tremor clinically resembling ET. The effects of a single dose of 12.5 mg clozapine and placebo were evaluated in a randomized, double-blind, crossover study in 15 drug-resistant patients with ET. Patient responders with more than 50% improvement after a single dose of clozapine subsequently received the drug (39+/-9 mg up to 50 mg) unblinded for a period of 15.8+/-7.7 months. Tremor was effectively reduced by a single dose of clozapine in 13 of 15 patients (p <0.01). Sedation was the only side effect reported during the clozapine test; however, the time course of sedation and of the antitremor effect were not coincident. A significant reduction of tremor was reported with chronic clozapine treatment (p <0.01) with no tolerance to drug antitremor effect, whereas sedation markedly decreased after 6-7 weeks of therapy. No clozapine-induced hematologic side effects were observed in our cohort of patients during long-term treatment. Our results suggest that in selected drug-resistant ET cases, clozapine should be considered before resorting to neurosurgical options.

The role of inheritance in sporadic Parkinson's disease: evidence from a longitudinal study of dopaminergic function in twins

Despite the major finding of a genetic defect being responsible for the Parkinson's disease (PD) phenotype in some kindreds with dominantly transmitted PD, the role of inheritance in the cause of the more widespread sporadic form of the disease is still unclear. Twin studies are a classic tool for assessing the influence of hereditary factors in diseases; however, the application of this approach to late-onset illnesses, like PD, poses some problems because of the identification of subclinical cases. In the present longitudinal study we have used [18F]dopa and positron emission tomography to study dopaminergic function in twin pairs at baseline clinically discordant for PD. At baseline, the concordance for subclinical striatal dopaminergic dysfunction was found to be significantly higher in 18 monozygotic than in 16 dizygotic twin pairs (55% vs 18%, respectively). The asymptomatic monozygotic cotwins all showed progressive loss of dopaminergic function over 7 years and 4 developed clinical PD. None of the dizygotic twin pairs became clinically concordant. At follow-up, the combined concordance levels for subclinical dopaminergic dysfunction and clinical PD were 75% in the 12 monozygotic and 22% in the 9 dizygotic twin pairs evaluated twice. Our findings suggest a substantial role for inheritance in sporadic PD.

Alterations in opioid receptor binding in Parkinson's disease patients with levodopa-induced dyskinesias

Levodopa-induced dyskinesias remain a major challenge in the therapeutic management of Parkinson's disease (PD). Their etiology is unknown although dysfunction of striatal opioid transmission has been implicated in experimental models of PD. To determine whether the opioid system is involved in human dyskinetic PD, we measured in vivo opioid receptor binding in PD patients with and without levodopa-induced dyskinesias, using positron emission tomography (PET) and the opioid receptor ligand [11C]diprenorphine. Striatal and thalamic/occipital uptake ratios were calculated using a region of interest (ROI) approach. In addition, we used statistical parametric mapping (SPM) and images reflecting the volume of distribution of [11C]diprenorphine to assess changes in cerebral receptor binding on a voxel-by-voxel basis. By using the ROI approach, we found significantly reduced striatal and thalamic opioid binding in dyskinetic, but not in nondyskinetic, PD patients. The SPM approach confirmed reduced availability in these areas and, in addition, showed decreased cingulate and increased prefrontal opioid receptor binding in the dyskinetic patients. Our findings confirm that altered opioid transmission is part of the pathophysiology of levodopa-induced dyskinesias in PD and support further investigation into the role of opioid agents in the management of these involuntary movements.

Cortical control of movement in Huntington's disease. A PET activation study

Regional cerebral blood flow was measured with H2(15)O PET in seven patients with choreic Huntington's disease and seven age-matched control subjects. Subjects were scanned at rest and when performing paced joystick movements, in freely chosen directions, with the dominant arm. During movement, the patients showed impaired activation of contralateral primary motor, medial premotor, bilateral parietal and bilateral prefrontal areas along with increased activation of bilateral insular areas. The underactivity of frontal areas in Huntington's disease is similar to the pattern of impaired activation in Parkinson's disease and is likely to result from degeneration of basal ganglia to frontal projections. Primary motor underactivity may explain the bradykinesia that these patients exhibit and, if inhibitory neurons are involved, also their chorea.

11C-diprenorphine binding in Huntington's disease: a comparison of region of interest analysis with statistical parametric mapping

We compare region of interest (ROI) analytical approaches with statistical parametric mapping (SPM) of 11C-diprenorphine positron emission tomography findings in five patients with Huntington's disease (HD) and nine age-matched controls. The ROI were placed on caudate, putamen, and an occipital reference area. Ratios of striatal-occipital uptake from averaged static images centered at 60 minutes showed a mean 20% reduction in caudate (P = 0.034) and 15% reduction in putamen (P = 0.095) receptor binding in the HD patients. Dynamic data from caudate and putamen ROI, together with a plasma tracer input function, were analyzed using spectral analysis to give regional impulse response functions. Regional data at 60 minutes after impulse showed a mean 29% decrease in caudate (P = 0.006) and 23% decrease in putamen (P = 0.029) opioid binding in the HD cohort. Parametric images of tracer binding also were produced with spectral analysis on a voxel basis. The images of the unit impulse response function at 60 minutes showed a mean 31% decrease in caudate (P = 0.005) and a 26% decrease in putamen binding (P = 0.011) in HD. The voxel-based parametric images were transformed into standard stereotactic space, and a between-group comparison (patient versus controls) was performed with SPM. This approach revealed symmetrical decreases in caudate (peak 40% decrease, z score = 4.38) and putamen opioid binding (peak 24% decrease, z score = 4.686) with additional nonhypothesized changes in cingulate, prefrontal, and thalamic areas. The significance and precision of changes measured with spectral analysis applied to dynamic data sets were superior to ROI-based ratio analysis on static images. The SPM replicated the striatal reductions in opioid binding in HD and detected additional nonpredicted changes. This study suggests that SPM is a valid alternative to conventional ROI analytical approaches for determining binding changes with positron emission tomography and may have advantages over region-based analyses in exploratory studies.

Dopaminergic function in familial Parkinson's disease: a clinical and 18F-dopa positron emission tomography study

There is increasing evidence for familial aggregation in Parkinson's disease (PD). It is possible that some asymptomatic relatives of PD patients have subclinical nigral Lewy body pathology and their identification could help determine the true prevalence of the disease. We used 18F-dopa positron emission tomography to investigate nigrostriatal dopaminergic terminal function in asymptomatic members of 7 unrelated kindreds in which at least 2 members had parkinsonism. Eight (25%) of the 32 asymptomatic relatives showed abnormal putamen 18F-dopa uptake (2.5 standard deviations below the normal mean). When discriminant function analysis was applied, all of these 8 subjects plus another 3 were classified with high probability as having PD. On neurological examination, 5 of the 32 relatives scanned had an isolated mild postural tremor and 2 of these 5 had reduced putamen uptake. Our findings provide further support for a role of inheritance in the etiology of PD and suggest that the penetrance for nigrostriatal dopaminergic dysfunction in familial clusters of PD is higher than the prevalence of clinical parkinsonism reported in epidemiological surveys.

Striatal D1 and D2 dopamine receptor loss in asymptomatic mutation carriers of Huntington's disease

We have investigated striatal dopamine D1 and D2 receptor binding in asymptomatic subjects from Huntington's disease (HD) families using positron emission tomography. Nineteen adult subjects at risk of developing HD were scanned with 11C-SCH 23390 and 11C-raclopride to calculate the D1 and D2 receptor binding potential, respectively. Eight of the 19 were shown to have the HD mutation; of these, 4 subjects had significant reductions in striatal dopamine receptor binding. Abnormalities were more common in older subjects and were not correlated with the size of the HD mutation. There was a strong coefficient of correlation between individual levels of striatal D1 and D2 binding in subjects with the mutation. Of 6 other cases with a 50% risk of carrying the HD gene, 1 showed subclinical loss of caudate and putamen D2 binding. Our study suggests that both striatal D1 and D2 dopamine receptors are lost in parallel from both caudate and putamen in presymptomatic HD and that dopamine receptor binding provides a sensitive means of detecting subclinical striatal dysfunction.

Transcranial Doppler ultrasound in migraine and tension-type headache after apomorphine administration: double-blind crossover versus placebo study

The effect of the dopaminergic agonist apomorphine on blood velocity in the middle cerebral artery has been studied in patients with migraine, tension-type headaches, and healthy subjects by means of transcranial Doppler monitoring. Following the administration of apomorphine, systolic velocity and mean velocity significantly increased and pulsatility index significantly decreased in migraineurs compared to placebo and to the other groups of subjects. These changes were dose-dependent and showed a time-curved compatible with the pharmacokinetic profile of the drug. The different effect of apomorphine in migraineurs compared with controls and tension-type headache patients implies that migraineurs have increased sensitivity to dopaminergic stimuli and suggests that transcranial Doppler monitoring after apomorphine administration could be a useful tool in the evaluation of migraineurs.

White matter hyperintensities in Parkinson's disease. Clinical correlations

OBJECTIVES

To verify recent preliminary data indicating that white matter hyperintensities on magnetic resonance imaging are more abundant in patients with Parkinson's disease (PD) than in healthy subjects and to examine possible correlation between these abnormalities and clinical features of PD.

DESIGN

Magnetic resonance imaging data on patients with PD and normal subjects were compared as to frequency, extent, and topographic location of white matter hyperintensities; moreover, in the PD group, we studied the possible correlation of white matter hyperintensities with clinical features such as severity, disease duration, and therapy.

SETTING

The outpatient clinic of the Institute of Clinical Neurology and the Neuroradiology Unit of the University of Pisa (Italy).

PATIENTS

We studied 102 nondemented patients with idiopathic PD and 68 sex- and age-matched healthy controls, all screened for absence of cerebrovascular risk factors.

OUTCOME MEASURES

White matter hyperintensities were classified as periventricular hyperintensities and deep hyperintensities. Frequency, extent, and topographic location of both periventricular and deep hyperintensities were evaluated. The clinical parameters examined were disease duration, treatment type, and disease severity (using Hoehn and Yahr staging and the Unified Parkinson's Disease Rating Scale), as well as disease progression index (ratio between Hoehn and Yahr stage and disease duration).

RESULTS

The frequency and the extent of periventricular hyperintensities were significantly higher in patients with PD than in healthy subjects. Moreover, within the PD group, the patients who had periventricular hyperintensities had significantly shorter disease duration and greater disease severity, ie, a higher disease progression index, than those who did not.

CONCLUSION

These data suggest that periventricular hyperintensities may represent a marker for a clinical subtype of PD characterized by a more rapid neurodegenerative process.

Apomorphine test for dopaminergic responsiveness: a dose assessment study

The clinical diagnosis of idiopathic Parkinson's disease (IPD) remains difficult and is supported by a favorable response to levodopa, while failure to respond represents an exclusion criterion. Recently, the response to subcutaneous apomorphine has been suggested as a tool in predicting levodopa responsiveness in parkinsonian syndromes. We administered apomorphine at doses of 10, 50, and 100 micrograms/kg subcutaneously against placebo over two consecutive days in 37 patients with parkinsonism and evaluated the motor response for 90 min after each dose. Subsequently, we compared the motor response with the follow-up response to levodopa therapy and to a final diagnosis. Twenty-seven patients of 37 showed a positive response to apomorphine, and 10 had a negative response. All positive responses to the apomorphine test were obtained with 50 or 100 micrograms/kg doses. Because of the high frequency of side effects with the dose of 100 micrograms/kg, 50 micrograms/kg seems more useful. After an adequate period of levodopa/carbidopa therapy (12-month follow-up), 29 patients improved; 25 of these had demonstrated a positive response to the apomorphine test. The final diagnosis of IPD, made on the basis of an exhaustive clinical and neuroradiological evaluation and on the response to chronic levodopa therapy, was in good agreement with the response to the apomorphine test (predictivity of diagnosis, 86.4%). Our data indicate that subcutaneous apomorphine at the dose of 50 micrograms/kg is a useful tool in the differential diagnosis of parkinsonian syndromes.

Apomorphine test in de novo Parkinson's disease

We administered apomorphine, a powerful dopaminergic agonist, subcutaneously to 25 untreated patients with parkinsonian features and evaluated motor response with the aim of discriminating idiopathic Parkinson's disease (IPD) from multiple system atrophy and progressive supranuclear palsy. The response to apomorphine was strongly predictive of responsiveness to subsequent levodopa follow-up and of the final diagnosis, made on the basis of both clinical and instrumental evaluation. Our data confirm that the apomorphine test is helpful in the differential diagnosis of IPD.

Apomorphine in malignant syndrome due to levodopa withdrawal

We report a case of neuroleptic malignant syndrome (NMS) following abrupt reduction of chronic levodopa treatment in a 71 year old female parkinsonian patient. The NMS resolved within 24 hours of the addition of apomorphine to levodopa therapy.

Effects of rotational stress on the effectiveness of cyclophosphamide and razoxane in mice bearing Lewis lung carcinoma

The effects of conventional vs protected housing, and those caused by the periodic application of a psychological stressor (rotational stress, spatial disorientation) on mice kept in a protected housing, with spontaneous tumor metastasis have been determined in mice implanted with Lewis lung carcinoma as a function of tumor inoculum size and response to treatment with cyclophosphamide and razoxane. With a reduced inoculum size, tumor takes do not occur in mice kept in the protected housing, but do occur with spatial disorientation. With a larger inoculum size, tumor takes occur in all untreated mice, and the weight of spontaneous lung metastasis is significantly increased by spatial disorientation. For mice in protected housing, cyclophosphamide results in the absence of macroscopically detectable tumors in all of the treated mice, whereas the use of spatial disorientation abolishes this therapeutic action. The antimetastatic effects of razoxane are also reduced by rotational stress. These results indicate that housing conditions and a psychological stressor can control tumor takes and metastasis formation. They also indicate that host's antitumor resistance effectors, which are susceptible to neuroendocrine modulation by environmental and psychological stressors, participate to determine the effectiveness of the treatment with a cytotoxic (cyclophosphamide) and antimetastatic (razoxane) antitumor drug.

Naloxone partly counteracts apomorphine side effects

The effects of naloxone on side effects provoked by apomorphine (APO) administration in patients with parkinsonian syndrome have been studied. The group under study included eight patients with Parkinson's disease and four with parkinsonism who received 100 micrograms/kg s.c. APO acutely to test dopaminergic responsiveness. All patients were treated with 20 mg domperidone tablets t.i.d. and then for 2 consecutive days (in double blind fashion) were given a 2-hour i.v. saline infusion alone or with naloxone (8 mg) starting 30 min before APO administration. In both groups, naloxone delayed the appearance of sleepiness, and reduced the intensity of yawning, sleepiness, nausea, and vomiting as compared with saline. These findings indicate a potential usefulness of naloxone and other opioid antagonists in preventing acute APO side effects.