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R S Burns

Publications and source records attributed to R S Burns.

At least 19 recordsLinked to original sources
PubMed1999

NMSP binding to dopamine and serotonin receptors in MPTP-induced parkinsonism: relation to dopa therapy.

We tested the hypothesis that N-methylspiperone binding to dopamine D2 receptors must be reduced when L-dopa therapy of parkinsonism augments the binding of dopamine to the receptors and improves the clinical state expressed by the Hoehn & Yahr stage. A patient with MPTP-induced parkinsonism underwent two positron emission tomographic studies of the D2-like dopamine receptors with N-[11C]methylspiperone (NMSP). The first study took place 3 days after cessation of the L-dopa medication, the second 5 days after its resumption. Noticeable clinical deterioration occurred during both studies, consistent with significant dopamine receptor blockade by NMSP and elevated NMSP binding in both scans. The dopa treatment did not reduce the NMSP binding. On the contrary, the rate of binding of NMSP (k3) was increased on-dopa, compared to off-dopa. The increase was consistent with the slightly greater dopamine receptor density estimated after resumption of the dopa therapy. The NMSP binding to serotonin receptors suggested lower synaptic serotonin on-dopa than off-dopa. The results are consistent with negative correlation between the Hoehn & Yahr stage and the amount of dopamine bound to dopamine D2 receptors. Low synaptic serotonin may explain the depression seen in some patients on dopa for Parkinson's disease.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1998

Clinical presentation and pharmacological therapy in corticobasal degeneration.

BACKGROUND: To date, to our knowledge, there is no systematic presentation of treatment outcome in large series of patients clinically diagnosed as having corticobasal degeneration. OBJECTIVE: To evaluate the clinical presentation and treatment outcome of patients clinically diagnosed as having corticobasal degeneration. SUBJECTS: We gathered case patients seen in 8 major movement disorder clinics during the last 5 years who were diagnosed as having corticobasal ganglionic degeneration. METHODS: Using a chart review method, we recorded the clinical presentation, medications used, response to medications, and adverse effects. RESULTS: A total of 147 case patients were reviewed, 7 were autopsy proven. Parkinsonian features were present in all, other movement disorders in 89%, and higher cortical dysfunction in 93%. The most common parkinsonian sign was rigidity (92%), followed by bradykinesia (80%), gait disorder (80%), and tremor (55%). Other movement disorders were dystonia in 71% and myoclonus in 55%. Higher cortical dysfunction included dyspraxia (82%), alien limb (42%), cortical sensory loss (33%), and dementia (25%). Ninety-two percent of the case patients received dopaminergic drugs, which resulted in a beneficial effect for 24%. Parkinsonian signs were the elements improving the most and levodopa was the most effective drug. Benzodiazepines, primarily clonazepam, were administered to 47 case patients, which resulted in improvement of myoclonus in 23% and dystonia in 9%. The most frequent disabling adverse effects of drug trials in these case patients were somnolence (n = 24), gastrointestinal complaints (n = 23), confusion (n = 16), dizziness (n =12), hallucinations (n = 5), and dry mouth (n = 5). CONCLUSIONS: Pharmacological intervention was largely ineffective in the management of corticobasal degeneration, and new treatments are needed for ameliorating the symptoms of this syndrome.

Antiparkinson Agents↗
PubMed1997

Effect of tolcapone on plasma levodopa concentrations after coadministration with levodopa/carbidopa to healthy volunteers.

Tolcapone (Ro 40-7592) is a novel inhibitor of catechol-O-methyltransferase that is being developed for clinical use in the treatment of Parkinson's disease as add-on therapy to a combination of levodopa and a peripheral amino acid decarboxylase inhibitor (benserazide or carbidopa). The current single-blind, randomized study was designed to evaluate the effect of tolcapone compared with placebo on plasma levodopa concentrations in healthy volunteers concomitantly receiving 25 mg of carbidopa and 100 mg of levodopa (Sinemet 25-100) and to assess the tolerability and safety of this combination. Placebo or tolcapone at doses of 5, 10, 25, 50, 100, 200, 400, and 800 mg was coadministered orally with Sinemet 25-100. Each dose was tested in a crossover fashion in a new group of six participants who each received active drug on one occasion and placebo on the other. Tolcapone increased the area under the plasma concentration-time curve and half-life of levodopa approximately twofold, without appreciably increasing the peak concentration. The maximum effect on levodopa half-life was observed with the 200-mg dose. Adverse effects were minor at all doses.

Adolescent↗
PubMed1995

A stereological study of substantia nigra in young and old rhesus monkeys.

The number of pigmented and non-pigmented neurons in the substantia nigra (SN) of 10 old and six young female Macaca mulatta monkeys and in three old alpha male monkeys were estimated using new stereological cell counting methods. No systematic right-left differences were noted, nor were old animals different from young ones with respect to SN volume (68.9 mm3 vs. 62.8 mm3) or absolute number of nerve cells (320,000 vs. 312,000). However, the total number of pigmented neurons was about eight times higher in old animals compared with young ones (166,000 vs. 21,400) while the total number of non-pigmented SN neurons was less than half in old animals compared with young ones (139,000 vs. 285,000). These differences create difficulties in generalizing experimental results from the rhesus animal model to man. It seems unlikely that a simple correlation can be made between pigmented and tyrosine hydroxylase (TH) positive neurons in SN in monkeys. Instead of estimating the total number of pigmented and non-pigmented cells, only SN neurons positive for TH using immunohistochemical techniques might be used an indicator of the total number of dopaminergic neurons in SN in monkeys.

Age Factors↗
PubMed1995

Effects of tolcapone in Parkinson's patients taking L-dihydroxyphenylalanine/carbidopa and selegiline.

A double-blind, placebo-controlled, crossover trial of tolcapone (RO 40-7592), a potent reversible inhibitor of catechol-O-methyltransferase (COMT), was performed in 10 Parkinson's disease (PD) patients to determine single-dose safety and efficacy. All subjects were chronically treated with stable doses of selegiline and L-dihydroxyphenylalanine (L-DOPA)/carbidopa. Tolcapone was administered in four single ascending doses (50-800 mg) randomly paired with placebo. Motor ratings were performed every 30 min for 6 h. At higher doses (400 mg and 800 mg), tolcapone prolonged the antiparkinson response of L-DOPA. Nausea was the most common adverse effect of the tolcapone-L-DOPA/carbidopa-selegiline combination. Adverse cardiovascular effects were not seen. The acute inhibition of amino acid decarboxylase, monoamine oxidase-B, and COMT is well tolerated and prolongs the L-DOPA response in PD patients. Tolcapone may be a safe and useful adjunct to L-DOPA/carbidopa in PD patients taking selegiline.

Aged↗
PubMed1995

Acute effects of COMT inhibition on L-DOPA pharmacokinetics in patients treated with carbidopa and selegiline.

The effects of acute catechol-O-methyltransferase (COMT) inhibition on L-DOPA pharmacokinetics were studied in 10 parkinsonian subjects on stable doses of L-DOPA/carbidopa and selegiline. Tolcapone, a reversible COMT inhibitor, was administered in four single ascending doses (50-800 mg) randomly paired with placebo. Serial plasma concentrations of L-DOPA and its metabolites were measured, and patient diaries and clinical ratings of dyskinesia were completed every 30 min for 6 h. Tolcapone increased the area under the curve of the plasma L-DOPA concentration versus time curve and decreased the accumulation of homovanillic acid. COMT inhibition increased "on" time and the duration of dyskinesia without affecting the maximal amplitude of dyskinesia. Tolcapone may be a useful adjunct to L-DOPA/carbidopa.

Aged↗
PubMed1995

Clonazepam-sensitive intermittent dystonic tremor.

We report three cases and a literature review describing a syndrome of intermittent idiopathic focal or segmental dystonic tremor dramatically responsive to clonazepam. All patients were young men who had intermittent symptoms. After magnetic resonance imaging of the brain and laboratory analysis of blood, each patient was treated with clonazepam and clinically observed for 1 year. In all three cases clonazepam produced full abatement of the tremor. None of the patients displayed progression of symptoms, and all have remained tremor free with stable doses of clonazepam. Clonazepam-sensitive intermittent dystonic tremor may represent a benign syndrome occurring in young men.

Adolescent↗
PubMed1991

Levels of pros-methylimidazoleacetic acid: correlation with severity of Parkinson's disease in CSF of patients and with the depletion of striatal dopamine and its metabolites in MPTP-treated mice.

The cerebrospinal fluid (CSF) levels of pros-methylimidazoleacetic acid (p-MIAA) in thirteen medication-free patients with mild to moderate Parkinson's disease were highly correlated (Spearman's rho = 0.749, p less than 0.005) with the severity of signs of the disease as scored on the Columbia University Rating Scale. Levels of p-MIAA in males (n = 8) and females (n = 5) were each significantly correlated with scores of severity (rho = 0.78, p less than 0.05 and rho = 1.0, p less than 0.05, respectively). In C57BL/6 mice treated with 1-methyl-4-phenyl-1,2,3,6-tetra-hydropyridine (MPTP), levels of p-MIAA were significantly correlated with the depleted levels of dopamine (r = 0.85, p less than 0.01), homovanillic acid (r = 0.79, p less than 0.02), 3,4-dihydroxyphenylacetic acid (r = 0.84, p less than 0.01) and norepinephrine (r = 0.91, p less than 0.002) in striatum, but not in cortex of the same mice. No such correlations were observed in either striatum or cortex of saline-treated control mice. Mean levels of p-MIAA in CSF did not differ significantly between patients and age-matched controls; and mean levels of p-MIAA in striatum did not differ between MPTP-treated mice and controls. The simplest hypothesis to account for these strong correlations in the absence of differences in mean levels of p-MIAA is that accumulation of p-MIAA [or process(es) that govern its accumulation] influences a failing nigrostriatal system. It is also possible (in analogy with findings in other diseases and with other drugs) that measurements of the putative metabolite(s) of p-MIAA may distinguish the patients and the MPTP-treated mice from their respective controls. Elucidation of the processes that regulate formation and disposition of p-MIAA in brain and information on the neural effects of p-MIAA, its precursors and its putative metabolites may yield insight into factors that regulate the progression of Parkinson's disease, and may shed additional light on the cause(s) of this disease.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1991

Subclinical damage to the nigrostriatal dopamine system by MPTP as a model of preclinical Parkinson's disease: a review.

The study of subtle changes in motor and cognitive function after exposure to MPTP might serve as a guide to the very earliest stages of Parkinson's disease. Studies in nonhuman primates and man exposed to MPTP who remained asymptomatic or recovered completely are reviewed. The question of the relationship between the degree and extent of damage to the nigrostriatal dopamine system and changes in motor and cognitive (behavioral) function is addressed. What guidance they provide in the study of subclinical or preclinical Parkinson's disease is discussed.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1990

Alterations in prealbumin concentration after adrenal autotransplantation for Parkinson's disease.

The cerebrospinal fluid of eight patients with Parkinson's disease who underwent adrenal medullary autotransplantation was analyzed using SDS-polyacrylamide gel electrophoresis. A protein, subsequently identified as prealbumin, was noted to change in concentration over the intraoperative to 18-month postoperative time course. The qualitative changes observed on visual inspection were confirmed and quantified using laser densitometry. The concentration of prealbumin increased by an average of 90% when the intraoperative and 12-month samples were compared. This increase persisted at 18 months. The ratio of prealbumin to albumin also increased from intraoperative to 12 months by an average of 56%. This suggests that the increases in PA are the result of choroid plexus activation rather than a nonspecific breakdown of the blood-brain barrier. Given the association of prealbumin with other nervous system diseases, as well as its known ability to bind multiple substances, these findings may have important implications. Alterations in prealbumin may be responsible for the improvement seen in some patients who receive adrenal medullary autotransplants. Alternatively, prealbumin may be implicated in the pathophysiology of Parkinson's disease.

Adrenal Medulla↗
PubMed1990

Decreased efficacy of levodopa with carbidopa in parkinsonian patients after adrenal-to-caudate implants.

We studied 6 parkinsonian patients 6 weeks after unilateral adrenal-to-caudate implants. We withheld medications the night before each of 2 study days and gave the patients a single test dose of either a combination of levodopa and carbidopa, or levodopa alone in double-blind random order. We administered the modified Columbia scale, objective measurements of rigidity and movement velocity, and the pegboard test at regular intervals after the single test dose. The results revealed that the improvements in performance recorded by the Columbia scale and the pegboard test were significantly less on the side contralateral to the operation when patients received carbidopa, whereas there was no significant difference in performance between the 2 observations on the ipsilateral side. Carbidopa apparently crossed the disrupted blood-brain barrier and lowered the efficacy of levodopa.

Adrenal Medulla↗
PubMed1989

Adrenal medullary transplantation to the caudate nucleus in Parkinson's disease. Initial clinical results in 18 patients.

Results from a pilot study of adrenal medullary autotransplantation for Parkinson's disease are presented. Eighteen patients were studied; 12 were followed up for 1 year, and 6 were followed up for 6 months. Four of 12 patients showed distinct improvement in the signs and symptoms of their disease, as assessed using the Columbia Rating Scale, at 1 year; none showed distinct deterioration. The 6 patients who were followed up for only 6 months were an average of 20 years older and generally more severely affected. None distinctly improved. Morbidity was considered to be minor and transient among the first 12 patients, while 4 of the last 6 patients experienced alteration in mental status lasting as long as several months. This problem has led us to conclude that older patients with preexisting cognitive impairment should not be included in future studies until the benefits are more clearly established. However, we believe that the distinct and persistent improvement seen in some of the younger patients warrants the initiation of a well-designed, randomized, and controlled trial of adrenal medullary autotransplantation for the purpose of confirming these results and assessing the effect of the procedure on the natural progression of Parkinson's disease.

Adrenal Medulla↗
PubMed1989

Diurnal fluctuation in levels of histamine metabolites in cerebrospinal fluid of rhesus monkey.

In samples of ventricular cerebrospinal fluid (CSF) that were collected from a conscious, restrained rhesus monkey at intervals of 30 90 min, levels of the histamine metabolites, tele-methylhistamine (t-MH) and tele-methylimidazoleacetic acid (t-MIAA), were determined by gas chromatography-mass spectrometry. Levels of t-MH and t-MIAA each showed time-related fluctuations. Peak and trough concentrations of t-MIAA, the product of t-MH, paralleled, but lagged about 2 h behind, the levels of t-MH. Within the first 3 h of illumination, metabolite levels increased more than 3-fold; they fell sharply within the first 3 h of darkness. Mean levels of t-MH and t-MIAA were significantly higher during periods of illumination than of darkness. Fluctuations in the levels of pros-methylimidazoleacetic acid (p-MIAA), an endogenous isomer of t-MIAA that is not a histamine metabolite, were markedly different from those of t-MH or t-MIAA; p-MIAA levels peaked only at the middle of the dark period. The time-related fluctuations in levels of t-MH and t-MIAA, but not p-MIAA, are similar to the daily rhythmic changes observed in monkey CSF for the levels of other central neurotransmitters and peptide neurohormones.

Animals↗
PubMed1989

Ultrastructural alterations induced by 1-methyl-4-phenylpyridinium (MPP+) in canine substantia nigra and rat mesencephalon in vitro.

Explants of canine substantia nigra (SN) and rat mesencephalon (MES), grown in organotypic culture, were incubated with 1-methyl-4-phenylpyridinium (MPP+) and examined for ultrastructural changes. Prolonged exposure (3 days) to doses ranging from 0.1 nM to 10 microM MPP+ resulted in total destruction of all constituents (neuronal and glial) of canine SN cultures. No association was noted between MPP+-induced toxicity and age of canine SN cultures. The first ultrastructural change observed in canine SN cultures incubated with 0.1 nM MPP+ was at 3 h. Grossly swollen mitochondria were noted in large nerve cells. Swollen mitochondria were present in all cells of canine SN cultures by 8 h of incubation with MPP+. Only those rat MES cultures with relatively high preincubation levels of homovanillac acid, determined as an index of viable dopaminergic neurons, incubated with MPP+ (10 microM) for up to 8 days exhibited ultrastructural changes, namely, a swelling of mitochondria within the cytoplasm of large nerve cells. These findings suggest that continual exposure to MPP+ in vitro results in a generalized, nonspecific toxicity in those species known to be susceptible to the parent compound 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine in vivo. However, the initial ultrastructural change, i.e., a swelling of mitochondria, may be the same in all species regardless of sensitivity suggesting that the ultimate mechanism underlying MPP+-toxicity relates to mitochondrial function.

1-Methyl-4-phenylpyridinium↗
PubMed1989

PET studies of parkinsonian patients treated with autologous adrenal implants.

Transplantation of autologous adrenal medulla tissue into the striatum has recently been proposed as a treatment for Parkinson's disease. We report the use of positron emission tomography (PET) to evaluate patients who had adrenal implants placed into the right caudate. 6-[18F] fluoro-L-dopa (6-FD) scans were performed to study the integrity and activity of the implant, and the nigrostriatal dopamine system before and six weeks after transplantation surgery. [68Ga] Gallium-ethylenediaminetetraacetate (Ga) scans were also performed to assess the blood brain barrier. The Ga scans performed on two patients showed increased permeability of the blood brain barrier at the surgical site. 6-FD PET scans in five patients did not show a consistent change in striatal uptake following adrenal medullary implantation after six weeks. Further assessment of implant viability with 6-FD PET scans after longer follow up may provide useful information if the blood-brain barrier becomes re-established with the passage of time.

Adrenal Medulla↗
PubMed1989

The subjective experience of acute pain. An assessment of the utility of 10 indices.

Sixty-nine postoperative patients indicated the severity of their pain using eight measures designed to assess pain intensity and two designed to measure pain affect. The utility and validity of the 10 measures were evaluated according to two criteria: (a) the magnitude of the relationship between each scale and a linear combination of the pain measures, and (b) relative rates of incorrect responding. The results indicate that each of the measures of pain intensity is adequately valid. In addition, this sample of patients failed to differentiate pain intensity and pain affect using the present measures, suggesting the need for additional research to explore the validity of the affective measures employed in the study. The 11-point Box Scale (BS-11) of pain intensity demonstrated the strongest relationship to a linear combination of all of the measures employed and was responded to correctly by each subject in the sample. All else being equal, these results suggest that the BS-11 scale may be the most useful clinical index of pain intensity among postoperative patients.

Acute Disease↗
PubMed1989

Effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine in the dog: effect of pargyline pretreatment.

Adult beagle dogs of either sex were injected with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-HCl (2.5 mg/kg, i.v.) alone or after pretreatment with pargyline (5.0 mg/kg, s.c., twice), with pargyline alone, or were uninjected. Groups were killed 2 h, 3 weeks, or 3 months after injection, and several brain areas were assayed for biogenic amines and their synthetic and degradative enzymes. MPTP caused a massive and permanent loss of striatal dopamine, tyrosine hydroxylase, and 3,4-dihydroxyphenylalanine decarboxylase activities and the loss of cells within the substantia nigra pars compacta. Dopamine and norepinephrine also were depleted to various degrees in cortex, olfactory bulb, and hypothalamus; however, dopamine beta-hydroxylase activity in cortex was normal. There was no cell loss in the ventral tegmental area or locus ceruleus. The activities of monoamine oxidase (MAO)-A and MAO-B in cortex and caudate were not affected by MPTP. Despite a permanent loss of the nigrostriatal system, the dogs exhibited only a transient hypokinesia lasting 1-2 weeks. Pargyline pretreatment prevented the loss of striatal dopamine and cells from the substantia nigra, but did not prevent a prolonged but reversible decrease in the concentration of dopamine metabolites. It is argued that this apparent inhibition of MAO is due not to suicide inactivation of the enzyme by MPTP, but to reversible inhibition by accumulation of the pyridinium metabolite, 1-methyl-4-phenylpyridinium, selectivity in aminergic terminals.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗