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C W Olanow

Publications and source records attributed to C W Olanow.

At least 55 records · Page 3Linked to original sources
PubMed1999

Apoptosis in neurodegenerative diseases: the role of mitochondria.

Nerve cell death is the central feature of the human neurodegenerative diseases. It has long been thought that nerve cell death in these disorders occurs by way of necrosis, a process characterized by massive transmembrane ion currents, compromise of mitochondrial ATP production, and the formation of high levels of reactive oxygen species combining to induce rapid disruption of organelles, cell swelling, and plasma membrane rupture with a secondary inflammatory response. Nuclear DNA is relatively preserved. Recent evidence now indicates that the process of apoptosis rather than necrosis primarily contributes to nerve cell death in neurodegeneration. This has opened up new avenues for understanding the pathogenesis of neurodegeneration and may lead to new and more effective therapeutic approaches to these diseases.

Apoptosis↗
PubMed1999

Long-term evaluation of bilateral fetal nigral transplantation in Parkinson disease.

BACKGROUND: Parkinson disease (PD) is associated with a progressive loss of nigrostriatal dopamine neurons. Medication therapy provides adequate control of symptoms for several years, but long-term treatment is complicated by progressive disability and the development of motor fluctuations and dyskinesias. In animal models of PD, fetal nigral transplants have been shown to survive grafting into the striatum, provide extensive striatal reinnervation, and improve motor function. In patients with PD, cell survival and clinical benefit have been observed following fetal nigral grafting, but results have been inconsistent. OBJECTIVE: To evaluate the safety and efficacy of bilateral fetal nigral transplantation into the postcommissural putamen in patients with advanced PD complicated by motor fluctuations and dyskinesias. PATIENTS AND METHODS: Six patients with advanced PD underwent bilateral fetal nigral transplantation. Each patient received solid grafts derived from donors aged 6 1/2 to 9 weeks after conception stereotactically implanted into the postcommissural putamen using 3 to 4 donors per side. Cyclosporine was administered for approximately 6 months to provide immune suppression. Clinical evaluations included the Unified Parkinson's Disease Rating Scale (UPDRS), Schwab-England Activities of Daily Living Scale, and timed tests of motor function conducted during both the "off' and "on" states at baseline and at 1, 3, 6, 9, 12, 18, and 24 months following transplantation. Percentage of time off and percentage of time on with and without dyskinesia were recorded at half-hour intervals using home diaries during the week prior to each evaluation. 18F-fluorodopa positron emission tomographic scans were performed at baseline, and at 6 months and 1 year following transplantation. RESULTS: Patients have been followed up for a mean+/-SD of 20.5+/-5.5 months. Complications related to surgery were mild and transient. Activities of daily living, motor, and total (activities of daily living plus motor) UPDRS scores during the off state improved significantly (P<.05, Wilcoxon signed rank test) at final visit in comparison with baseline. Mean total UPDRS off score improved 32%, and each patient experienced at least a 19% improvement. Mean percentage of time on without dyskinesia during the waking day improved from 22% to 60% (P<.05). Mean putamenal fluorodopa uptake on positron emission tomography increased significantly at 6 and 12 months in comparison with baseline (P<.001, 2-tailed t test). This increase correlated with clinical improvement. Two patients died 18 months after transplantation from causes unrelated to the surgical procedure. In both cases, histopathological examination showed robust survival of tyrosine hydroxylase immunoreactive cells and abundant reinnervation of the postcommissural putamen. CONCLUSIONS: Fetal nigral tissue can be transplanted into the postcommissural putamen bilaterally in patients with advanced PD safely and with little morbidity. In this open-label pilot study we observed consistent long-term clinical benefit and increased fluorodopa uptake on positron emission tomography. Clinical improvement appears to be related to the survival and function of transplanted fetal tissue.

Adult↗
PubMed1999

Glial cells mediate toxicity in glutathione-depleted mesencephalic cultures.

We have examined the role of glial cells in the toxicity that results from inhibition of reduced glutathione (GSH) synthesis by L-buthionine sulfoximine (BSO) in mesencephalic cell cultures. We show that GSH depletion, to levels that cause total cell loss in cultures containing neurons and glial cells, has no effect on cell viability in enriched neuronal cultures. An increase in the plating cell density sensitizes glia-containing cultures to GSH depletion-induced toxicity. This suggests that cell death in this model is the consequence of events that are induced by GSH depletion and are mediated by glial cells. The antioxidant ascorbic acid and the lipoxygenase (LOX) inhibitor nordihydroguaiaretic acid (1-10 microM) provide full protection from BSO toxicity, indicating that arachidonic acid metabolism through the LOX pathway and the generation of reactive oxygen species play a role in the loss of cell viability. In contrast, inhibition of nitric oxide (NO) synthase affords only partial protection from BSO toxicity, suggesting that increased NO production cannot entirely account for cell death in this model. Our data provide evidence that GSH depletion in the presence of glial cells leads to neuronal degeneration that can be prevented by inhibition of LOX. This may have relevance to the pathogenesis of Parkinson's disease, where glial activation and depletion of GSH have been found in the substantia nigra pars compacta.

Animals↗
PubMed1999

Etiology and pathogenesis of Parkinson's disease.

Parkinson's disease (PD) is an age-related neurodegenerative disorder that affects approximately 1 million persons in the United States. It is characterized by resting tremor, rigidity, bradykinesia or slowness, gait disturbance, and postural instability. Pathological features include degeneration of dopaminergic neurons in the substantia nigra pars compacta coupled with intracytoplasmic inclusions known as Lewy bodies. Neurodegeneration and Lewy bodies can also be found in the locus ceruleus, nucleus basalis, hypothalamus, cerebral cortex, cranial nerve motor nuclei, and central and peripheral components of the autonomic nervous system. Current treatment consists of a dopamine replacement strategy using primarily the dopamine precursor levodopa. While levodopa provides benefit to virtually all PD patients, after 5-10 years of treatment the majority of patients develop adverse events in the form of dyskinesia (involuntary movements) and fluctuations in motor response. Further, disease progression is associated with the development of dementia, autonomic dysfunction, and postural instability, which do not respond to levodopa therapy. Accordingly, research efforts have been directed toward understanding the etiology and pathogenesis of PD in the hope of developing a more effective therapy that will slow or halt the natural progression of PD. This paper reviews recent advances.

Apoptosis↗
PubMed1998

Alzheimer's disease and Parkinson's disease: distinct entities or extremes of a spectrum of neurodegeneration?

Alzheimer's disease (AD) and Parkinson's disease (PD) are generally considered to be separate and distinct disease entities. However, a considerable amount of evidence demonstrates that these disorders share common clinical and neuropathologic features and that overlap between the two conditions is extensive. For example, a significant percentage of AD patients exhibit extrapyramidal features, and many PD patients develop dementia. Similarly, at autopsy many AD patients not only exhibit the neuropathologic features of that disorder but also exhibit nigral pathology, including Lewy bodies. The vast majority of demented PD patients show widespread neurofibrillary tangles and senile plaques as well as Lewy body formation and nigral degeneration. The extent of such overlap is far greater than one would anticipate by chance alone. We argue that such overlap reflects a common pathogenic mechanism for the neurodegeneration encountered within specific vulnerable neuronal populations. Furthermore, we suggest that the current nosologic approach, which attempts to separate AD from PD, fails to properly deal with the issue of overlap and that a new classification of the neurodegenerative disorders should be considered.

Alzheimer Disease↗
PubMed1998

Understanding cell death in Parkinson's disease.

Current concepts of the cause of Parkinson's disease (PD) suggest a role for both genetic and environmental influences. Common to a variety of potential causes of nigral cell degeneration in PD is the involvement of oxidative stress. Postmortem analysis shows increased levels of iron, decreased complex I activity, and a decrease in reduced glutathione (GSH) levels. The decrease in GSH levels may be a particularly important component of the cascade of events leading to cell death because it occurs in the presymptomatic stage of PD and may directly induce nigral cell degeneration or render neurons susceptible to the actions of toxins. There is evidence suggesting that oxidative stress might originate in glial cells rather than in neurons, and alterations in glial function may be an important contributor to the pathologic process that occurs in PD. Oxidative damage occurs in the brain in PD, as shown by increased lipid peroxidation and DNA damage in the substantia nigra. Increased protein oxidation is also apparent, but this occurs in many areas of the brain and raises the specter of a more widespread pathologic process occurring in PD to which the substantia nigra is particularly vulnerable. The inability of the substantia nigra to handle damaged or mutant (eg, alpha-synuclein) proteins may lead to their aggregation and deposition and to the formation of Lewy bodies. Indeed, Lewy bodies stain for both alpha-synuclein and nitrated proteins. Current evidence enables us to hypothesize that a failure to process structurally modified proteins in regions of the brain exhibiting oxidative stress is a cause of both familial and sporadic PD.

Cell Death↗
PubMed1998

A fluorescent double-labeling method to detect and confirm apoptotic nuclei in Parkinson's disease.

In situ end-labeling (ISEL) has become a widely used method to determine whether cells die via apoptosis by detecting double-stranded DNA breaks that are the result of endonuclease digestion. The enzyme terminal deoxynucleotidyl transferase can be used to label the digested 3'-OH ends of DNA with biotin-, digoxigenin-, or fluorescent probe-conjugated nucleotides. However, both single-stranded and double-stranded DNA breaks can be labeled by this method and therefore ISEL cannot unequivocally demonstrate apoptosis when used alone. We have developed a fluorescent double-labeling method using ISEL combined with the cyanine dye YOYO-1 that binds to DNA. When combined with confocal laser microscopy and deconvolution analysis, YOYO-1 can demonstrate the presence or absence of nuclear chromatin condensation and thus confirm that ISEL-positive nuclei are indeed apoptotic. Preliminary findings indicate that dopaminergic neurons in the substantia nigra compacta die via apoptosis in Parkinson's disease.

Apoptosis↗
PubMed1998

Dopamine agonists and neuroprotection in Parkinson's disease.

There is increasing interest in the potential of dopamine agonists to provide a neuroprotective effect and to alter the natural course of levodopa-treated Parkinson's disease (PD). Theoretically, such a protective effect might derive from (a) a levodopa sparing effect, (b) stimulation dopamine autoreceptors resulting in decreased dopamine synthesis, release, and turnover, (c) direct anti-oxidant effects, and (d) restoration of dopaminergic tone to the dopamine-denervated brain so as to restore inhibition to the subthalamic nucleus and thereby diminish STN-mediated excitotoxicity. Preclinical studies have demonstrated that dopamine agonists reduce dopamine formation in comparison to levodopa, protect cultured dopaminergic neurons from a variety of toxins including levodopa, and protect dopaminergic neurons from toxins and age-related degeneration in some rodent models of parkinsonism. Based on these findings, several clinical trials have been initiated in patients with early PD to test the effect of dopamine agonists on clinical and neuroimaging markers of disease progression.

Animals↗
PubMed1998

Subthalamic nucleus-mediated excitotoxicity in Parkinson's disease: a target for neuroprotection.

Dopamine deficiency causes disinhibition and overactivity of the subthalamic nucleus (STN). Output neurons from the STN are excitatory and use glutamate as a neurotransmitter. They project to the external and internal segments of the globus pallidum (GPe and GPi), the substantia nigra pars reticulata (SNr), and the pedunculopontine nucleus (PPN). In addition, STN neurons provide excitatory innervation to dopaminergic (DA) neurons in the substantia nigra pars compacta (SNc) that contain glutamate receptors. Stimulation of the STN induces bursting activity in SNc dopaminergic neurons. This raises the possibility that the disinhibition of STN neurons that occurs as a result of a dopamine lesion might induce excitotoxic damage in target structures, including the SNc. In addition, the reduction in complex I activity found in the nigra in Parkinson's disease (PD) may cause mitochondrial dysfunction and make SNc dopaminergic neurons vulnerable to even physiologic concentrations of glutamate. We postulate that the dopamine loss that occurs in PD produces augmented STN activity which, in turn, causes further damage to vulnerable dopaminergic neurons, thereby creating a scenario for an increasing cycle of neuronal loss in the SNc. In addition, STN overactivity could, in theory, cause damage to the GPi, SNr, and PPN and thereby account for the development of parkinsonian features that do not respond to levodopa in patients with advanced disease. This hypothesis suggests that pharmacologic or surgical therapies that reduce STN neuronal overactivity or block glutamate receptors in the SNc and other target structures might be neuroprotective and might slow or halt the progression of neurodegeneration in PD.

Cell Death↗
PubMed1998

The causes of Parkinson's disease are being unraveled and rational neuroprotective therapy is close to reality.

There has been significant progress in our knowledge of the cause, the pathogenesis, and the nature of the mechanism of cell death in Parkinson's disease (PD). Mutations in single genes have now been shown to be able to cause PD but likely only account for a small number of cases. Alternatively, there is evidence that environmental factors play a large role in the majority of cases of sporadic PD. Most likely, genetic factors predispose patients to develop PD if combined with other gene mutations or environmental toxins. Interest has thus focused on factors that contribute to the pathogenesis of neurodegeneration and the mechanism of cell death in an attempt to design a neuroprotective therapy. Oxidant stress, mitochondrial dysfunction, excitotoxicity with excess nitric oxide formation, and glia and inflammatory processes are all thought to contribute to the cell death process and agents that interfere with these events may be neuroprotective. It is now generally held that the final culmination of these events is the induction of apoptosis in nigral dopaminergic neurons and this too offers opportunities for providing neuroprotection. A rational argument can be made for investigating a large number of different approaches or combination of approaches in the hope of developing a meaningful neuroprotective therapy, using clinically relevant indices and neuroimaging markers of nigral dopaminergic neurons. It is evident that conventional approaches to trials that utilize large numbers of patients in search of small incremental effects are costly and time consuming. As such, it will be virtually impossible to test all of the potentially valuable neuroprotective agents that are now at hand, let alone those that will likely soon emerge. We suggest that it may be more profitable to test a large number of agents in a small number of selected patients in search of a more robust neuroprotective effect. In this way, we will reduce the risk of missing a powerful neuroprotective treatment with a treatment that might not otherwise have been studied because of a lack of time, money, or patients.

Cell Death↗
PubMed1998

Fetal nigral grafts survive and mediate clinical benefit in a patient with Parkinson's disease.

We have previously demonstrated that fetal nigral grafts can survive, reinnervate the striatum, and mediate clinically relevant recovery in a patient with Parkinson's disease (PD). Most previous autopsy cases have failed to identify meaningful numbers of viable grafted cells suggesting that differences in critical transplant variables determine graft viability. The present study evaluated the structural and functional correlates of fetal nigral transplantation in a second PD patient who received fetal nigral grafts according to our previously published transplant protocol. A 61-year-old woman with severe PD received bilateral fetal nigral grafts to the postcommissural putamen from seven donor fetuses (four right side and three left side) aged 6.5-9 weeks postconception. This patient died 19 months after surgery from a cause unrelated to the transplant surgery. Her postoperative clinical course was characterized by improved motor and activities of daily living scores during "off time," reduced "off time," and increased "on" time without dyskinesia. Positron emission tomography (PET) scans revealed a bilateral and progressive increase in fluorodopa (FD) uptake within the grafted putamen. Postmortem examination of the right hemisphere revealed large oval-shaped grafts containing more than 138,000 tyrosine-hydroxylase-immunoreactive (TH-ir) neurons. Grafted cells formed a seamless border with the host and provided dense TH-ir innervation to 78% of the host postcommissural putamen. Graft-mediated sprouting of host fibers was not observed. These data provide essential confirmation that, under appropriate transplant conditions, grafted nigral neurons can survive, reinnervate the host striatum, and provide clinical benefit to PD patients. These findings also support the concept that improved motor function and striatal FD uptake on PET after nigral grafting in PD are the result of the viability of grafted neurons and graft-derived reinnervation of the host striatum.

Brain Tissue Transplantation↗
PubMed1998

Protein nitration in Parkinson's disease.

Oxidative stress has been proposed as a pathogenetic mechanism in Parkinson's disease (PD). One mechanism of oxidative cellular injury is the nitration of protein tyrosine residues, mediated by peroxynitrite, a reaction product of nitric oxide and superoxide radicals. We demonstrate here the presence of nitrotyrosine immunoreactivity in Lewy bodies within melanized neurons and in amorphous deposits associated with intact and degenerating neurons. The core of the Lewy body was frequently intensely immunolabeled, while the rim was lightly labeled or unlabeled. This likely reflects the fact that tyrosine residues of neurofilament proteins are primarily localized to Lewy body cores, and suggests that nitrotyrosine is present in neurofilament protein itself. Although these observations are as yet unable to provide a definitive link between oxidative stress and neuronal dysfunction, they demonstrate that oxidative stress has occurred within the vulnerable neurons of PD, leaving a permanent marker of oxidative modification of neuronal proteins within the target cells of neurodegeneration. In addition, these observations provide a potential link between excitotoxicity and oxidative stress within the vulnerable neurons of PD and represent a pathogenetic mechanism in common with the 2 other major age-related neurodegenerative diseases, Alzheimer disease and amyotrophic lateral sclerosis.

Adult↗
PubMed1998

Effect of selegiline on mortality in patients with Parkinson's disease: a meta-analysis.

INTRODUCTION: The Parkinson's Disease Research Group of the United Kingdom (PDRG-UK) reported increased mortality in PD patients treated with levodopa plus selegiline compared with those treated with levodopa alone. METHODS: We performed a meta-analysis on five long-term, prospective, randomized trials of selegiline in patients with untreated PD. Included in the analysis were four randomized, double-blind, placebo-controlled studies and one randomized, double-blind, placebo-controlled study of 2 years' duration followed by long-term, open follow-up. RESULTS: The mean duration of follow-up was 4.1 +/- 1.8 years. There were 14 deaths in 297 selegiline-treated patients (4.7%) and 17 deaths in 292 non-selegiline-treated patients (5.8%). The hazard ratio for mortality was 1.02 (95% CI 0.44 to 2.37; p = 0.96). An analysis restricted to patients receiving only levodopa with or without selegiline noted 11 deaths in 257 levodopa/selegiline-treated patients (4.3%) and 11 deaths in 254 patients treated with levodopa alone (4.3%). The hazard ratio was 1.06 (95% CI 0.44 to 2.55; p = 0.90). Death rate per 1,000 patient years was 11.4 in the selegiline group and 14.2 in the nonselegiline group. Kaplan-Meier survival curves reflecting pooled survival data showed no significant difference in duration of survival. The hazard ratio was 0.84 (95% CI 0.41 to 1.70; p = 0.63) for selegiline- versus non-selegiline-treated patients and 1.05 (95% CI 0.46 to 2.43; p = 0.91) for selegiline/levodopa- versus levodopa-treated patients. CONCLUSION: These results contrast with those of the PDRG-UK study and demonstrate no increase in mortality associated with selegiline treatment whether or not patients also received levodopa.

Aged↗
PubMed1998

A multicenter trial of ropinirole as adjunct treatment for Parkinson's disease. Ropinirole Study Group.

OBJECTIVE: To evaluate the nonergot dopamine agonist ropinirole as an adjunct to L-dopa in a randomized, double-blind trial in PD patients with motor fluctuations. BACKGROUND: L-dopa in the treatment of PD is associated with motor fluctuations, dyskinesia, and other adverse effects. The use of dopamine agonists in the treatment of PD delays recourse to L-dopa and thus delays the possibility of adverse effect onset. METHODS: Ropinirole (n = 95) or placebo (n = 54) was added to L-dopa, and L-dopa was then reduced in a planned manner during the 6-month trial. RESULTS: A significantly greater number of ropinirole patients were able to achieve a 20% or greater reduction in both L-dopa dose and in percent time spent "off" compared with placebo (35.0% versus 13.0%; p = 0.003). The mean daily L-dopa dose was reduced significantly with ropinirole treatment (242 mg versus 51 mg; p < 0.001) as was the percent awake time spent "off" (11.7% versus 5.1%; p = 0.039). There was no difference in the percent of patients who withdrew because of adverse effects (15.8% on ropinirole versus 16.7% on placebo). CONCLUSIONS: Ropinirole permits a reduction in L-dopa dose with enhanced clinical benefit for PD patients with motor fluctuations.

Antiparkinson Agents↗
PubMed1998

Deprenyl and desmethylselegiline protect mesencephalic neurons from toxicity induced by glutathione depletion.

Oxidative stress is thought to play an important role in the pathogenesis of Parkinson's disease (PD). Glutathione (GSH), a major cellular antioxidant, is decreased in the substantia nigra pars compacta of PD patients. The aim of the present study was to investigate whether deprenyl and its desmethyl metabolite, putative neuroprotective agents in the treatment of PD, could protect cultured rat mesencephalic neurons from cell death caused by GSH depletion due to treatment with L-buthionine-(S,R)-sulfoximine (BSO). BSO (10 microM) caused extensive cell death after 48 hr, as demonstrated by disruption of cellular integrity and release of lactate dehydrogenase into the culture medium. Both deprenyl and desmethylselegiline, at concentrations of 5 and 50 microM, significantly protected dopaminergic neurons from toxicity without preventing the BSO-induced loss in GSH. Protection was not associated with monoamine oxidase type B inhibition in that pargyline, a potent MAO inhibitor, was ineffective and pretreatment with pargyline did not prevent the protective effects of deprenyl. Protection was not associated with inhibition of dopamine uptake by deprenyl because the dopamine uptake inhibitor mazindol did not diminish BSO toxicity. The antioxidant ascorbic acid (200 microM) also protected against BSO-induced cell death, suggesting that oxidative events were involved. This study demonstrates that deprenyl and its desmethyl metabolite can diminish cell death associated with GSH depletion.

Amphetamines↗