Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0030567 (Parkinson's disease)
 63,064 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Motor fluctuations after long-term administration of levodopa may be due to central pharmacodynamic mechanisms such as reduced striatal synthesis and storage of dopamine from exogenous levodopa and subsensitization of postsynaptic dopaminergic receptors. Peripheral pharmacokinetic mechanisms may be equally important, particularly in motor fluctuations of the "delayed on" (increased time latencies from dose intake to start-up of clinical benefit) and "no-on" (complete failure of a levodopa dose to exert an "on" response) types. Levodopa itself has a very poor solubility. In addition, there is delayed gastric emptying in many advanced patients. Therefore, an oral dose of levodopa may remain in the stomach for long periods of time before it passes into the duodenum where there is immediate absorption. Consequently, in order to overcome response fluctuations caused by impaired pharmacokinetic mechanisms and to improve its absorption, we recommend that levodopa be taken in multiple small doses, on an empty stomach, preferably crushed and mixed with a lot of liquid. Protein intake should be minimized. Prokinetic drugs such as prepulsid (Cisaprid) could be used to facilitate gastric motility and levodopa transit time. Administration of crushed levodopa through nasoduodenal or gastrojejunostomy tubes may be helpful in certain circumstances. Bypassing the stomach with subcutaneous injections of apomorphine may provide dramatic rescue from difficult "off" situations. Oral and s.c. administration of novel, extremely soluble prodrugs of levodopa, e.g., levodopa ethylester, may offer a new approach to overcome difficulties in levodopa absorption. Addition of dopamine agonists, MAO-B inhibitors, COMT inhibitors and controlled release levodopa preparations may be helpful in prolonging the duration of efficacy of each single levodopa dose. Levodopa, administered orally, usually combined with peripheral dopa decarboxylase inhibitors, continues to be the most widely-used and most effective pharmacological treatment for Parkinson's disease (Melamed, 1987). Undoubtedly, the outstanding therapeutic success of levodopa represents a dramatic and revolutionary breakthrough in medicine, in general, and in neurology, in particular. Although, since the introduction of levodopa, there have been many additional pharmacological and even surgical anti-parkinsonian strategies, it still stands out as a mandatory axis of treatment in the majority of patients (Steigler and Quinn, 1992). Indeed, levodopa therapy improves, sometimes markedly, the motor signs and symptoms of the illness, the functional capacity and quality of life and perhaps also life expectancy of the afflicted patients. It is therefore unfortunate that after an initial problem-free period of successful, smooth and stable clinical benefit from levodopa that lasts about two to five years, the responsiveness of many patients worsens with the emergence of a variety of complications (Marsden et al., 1982; Hardie et al., 1984). These adverse reactions include dyskinesias and dystonias, psychotic problems and, particularly, the troublesome motor fluctuations (Marsden and Parkes, 1977; Marsden, 1994). The latter phenomenon may be particularly complex, limiting and disabling. It is believed that most patients on long-term levodopa therapy will, sooner or later, develop response fluctuations of varying types and severity (Riley and Lang, 1993). Because of the serious impact of these phenomena on the quality of life and function of the patients, many efforts are now being undertaken to identify the responsible mechanisms and to devise preventive and therapeutic measures.
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PMID:Current management of motor fluctuations in patients with advanced Parkinson's disease treated chronically with levodopa. 1037 Sep 11

Catechol-O-methyltransferase (COMT, EC 2.1.1.6) is a ubiquitous enzyme that is crucial to the metabolism of carcinogenic catechols and catecholamines. Regulation of human COMT gene expression may be important in the pathophysiology of various human disorders including estrogen-induced cancers, Parkinson's disease, depression, and hypertension. The gender difference in human COMT activity and variations in rat COMT activity during the estrous cycle led us to explore whether estrogen can regulate human COMT gene transcription. Our Northern analyses showed that physiological concentrations of 17-beta-estradiol (10(-9)-10(-7) M) could decrease human 1. 3-kilobase COMT mRNA levels in MCF-7 cells in a time- and dose-dependent manner through an estrogen receptor-dependent mechanism. Two DNA fragments immediately 5' to the published human COMT gene proximal and distal promoters were cloned. Sequence analyses revealed several half-palindromic estrogen response elements and CCAAT/enhancer binding protein sites. By cotransfecting COMT promoter-chloramphenicol acetyltransferase reporter genes with human estrogen receptor cDNA and pSV-beta-galactosidase plasmids into COS-7 cells, we showed that 17-beta-estradiol could down-regulate chloramphenicol acetyltransferase activities, and COMT promoter activities dose-dependently. Functional deletion analyses of COMT promoters also showed that this estrogenic effect was mediated by a 280 base pair fragment with two putative half-palindromic estrogen response elements in the proximal promoter and a 323-base pair fragment with two putative CCAAT/enhancer binding protein sites in the distal promoter. Our findings provide the first evidence and molecular mechanism for estrogen to inhibit COMT gene transcription, which may shed new insight into the role of estrogen in the pathophysiology of different human disorders.
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PMID:Characterization and implications of estrogenic down-regulation of human catechol-O-methyltransferase gene transcription. 1038 81

Several new methods for the treatment of patients suffering from Parkinson's disease have been introduced during the last few years. COMT inhibitors are available in addition to levodopa with a decarboxylase inhibitor. COMT inhibitors enhance and prolong the effect of single levodopa doses. Severe side effects have been mentioned in connection with the COMT inhibitor tolcapone in recent months. Several new dopaminergic agonists now provide efficacious monotherapy in the early stages of the disease. This brings about a reduction in late problems of treatment such as dyskinesias and fluctuations. Stereotaxic operations in the pallidum and the subthalamic afford relief for these late complications of treatment in selected patients.
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PMID:[Modern therapeutic possibilities in Parkinson disease]. 1040 49

Despite new medical and surgical therapy, mortality rates for Parkinson's disease remain unchanged. Nevertheless, symptom progression can be slowed and quality of life improved with current methods of treatment. Levodopa is the most effective drug for Parkinson's disease, but its long-term use is associated with significant motor complications. Dopamine agonists hold promise because of more sustained stimulation of dopamine receptors and possibly an antioxidant effect. Selegiline, amantadine, and anticholinergics are still used but must be employed with caution in the elderly. COMT inhibitors may be useful adjuncts to levodopa therapy but are plagued with serious adverse effects. Goals of therapy in patients less than 60 years of age include sparing levodopa therapy and providing neuroprotection. For patients 60 years and older, goals include maintaining cognitive status and treating symptoms. Surgical treatment includes globus pallidus internal-segment pallidotomy, deep brain stimulation, and fetal nigral transplantation. These hold promise for the future.
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PMID:Medical and surgical treatment of Parkinson's disease. Strategies to slow symptom progression and improve quality of life. 1045 38

Inhibition of catechol-O-methyltransferase (COMT; EC 2.1.1.6) is a new therapeutic strategy in the treatment of Parkinson's disease. However, nothing is known about the effects of COMT inhibition on levodopa (L-dopa)-induced toxicity in dopamine (DA) neurons. Therefore we evaluated the effects of the selective COMT inhibitors Ro 41-0960, OR-486, and tolcapone alone and in combination with L-dopa in primary mesencephalic cultures from rat. Neither COMT inhibitor affected the growth of tyrosine hydroxylase immunoreactive (THir) cells with concentrations up to 10 microM when studied alone. However, Ro 41-0960 reduced the L-dopa-induced THir cell loss after 24 h in a dose-dependent manner, shifting the TD(50) value from 21 microM in the absence to 71 microM in the presence of 1 microM Ro 41-0960 (P <.01) without affecting survival of non-DA neurons. OR-486 and the clinically used COMT inhibitor tolcapone showed similar effects. In contrast, toxicity induced by D-dopa was not altered by COMT inhibitors. Furthermore, the primary metabolite of L-dopa formed by COMT, 3-O-methyldopa, and the methyl group donor S-adenosyl-L-methionine used by COMT did not alter THir neuron survival and L-dopa-induced toxicity, respectively, with concentrations up to 100 microM. These data demonstrate that COMT inhibition attenuates L-dopa toxicity toward DA neurons in vitro, but probably not by preventing 3-O-methyldopa production or cellular S-adenosyl-L-methionine depletion.
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PMID:Catechol-O-methyltransferase inhibition attenuates levodopa toxicity in mesencephalic dopamine neurons. 1069

Motor fluctuations complicate therapy in Parkinson's disease (PD). The mechanisms responsible for motor fluctuations such as the on-off type, are poorly understood. Differences of activity of various enzymes, such as Catechol-O-Methyltransferase (COMT, E.C.2.1.1.6.) may influence the appearance of motor fluctuations and the quantity of metabolic products of levodopa. Aim of this study was to compare erythrocyte COMT-activity in Parkinsonian patients without and with motor fluctuations from the on-off type. No significant differences in COMT-activity appeared in both groups. We conclude that activity differences in COMT-activity do not contribute to the appearance of motor fluctuations in Parkinson's disease.
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PMID:The activity of catechol-O-methyltransferase in parkinsonian patients with "on-off fluctuations". 1080 8

Apomorphine was the first dopaminergic drug ever used to treat symptoms of Parkinson's disease. While powerful antiparkinsonian effects had been observed as early as 1951, the potential of treating fluctuating Parkinson's disease by subcutaneous administration of apomorphine has only recently become the subject of systematic study. A number of small scale clinical trials have unequivocally shown that intermittent subcutaneous apomorphine injections produce antiparkinsonian benefit close if not identical to that seen with levodopa and that apomorphine rescue injections can reliably revert off-periods even in patients with complex on-off motor swings. Continuous subcutaneous apomorphine infusions can reduce daily off-time by more than 50% in this group of patients, which appears to be a stronger effect than that generally seen with add-on therapy with oral dopamine agonists or COMT inhibitors. Extended follow-up studies of up to 8 years have demonstrated long-term persistence of apomorphine efficacy. In addition, there is convincing clinical evidence that monotherapy with continuous subcutaneous apomorphine infusions is associated with marked reductions of preexisting levodopa-induced dyskinesias. The main side effects of subcutaneous apomorphine treatment are related to cutaneous tolerability problems, whereas sedation and psychiatric complications play a lesser role. Given the marked degree of efficacy of subcutaneous apomorphine treatment in fluctuating Parkinson's disease, this approach seems to deserve more widespread clinical use.
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PMID:Apomorphine: an underutilized therapy for Parkinson's disease. 1100 81

During the last half of the 20th century, medical treatment for Parkinson's disease (PD) showed remarkable progresses, resulting in marked prolongation of life and self-dependency of patients. In Japan, peak of ages of PD patients visiting all medical institutions was between 75 and 84 years of age(1993), with which course of illness is predicted to exceed twenty years in a large number of patients. As exploration of neuroprotective therapies for PD has not been successful yet, continuous progress in neuronal cell death in the substantia nigra result in loss of efficacy of medication, motor fluctuations and CNS side effects such as dyskinesia and psychosis in the long course of dopaminergic supplementation therapies. Future development of medical therapies for PD is expected in different ways. First, elaboration in controlled-release of DCI/levodopa, utilization of dopamine(DA) receptor agonists with different profiles in affinity to DA receptor subtypes and half-time of blood concentration, and utilization of COMT inhibitors. Second, neuroprotection with MAO-B inbitators or DA receptor agonists. Neuroprotective function is expected in animal studies for these substances but clinical usefulness should be verified with randomised controlled trials. Third, treatment for extra-motor symptoms such as dementia, cognitive disorders, depression, autonomic disturbances such as orthortatic hypotension and bladder disturbances, which is essential for maintenance of quality of life of patients with long course of illness. Gene therapy, neuroprotection before development of symptoms in PD may be attained within the first few decades of the next century. In this respect, establishment of preclinical diagnosis with neuroimaging and sensitive motor and psychological tests is imperative.
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PMID:[A prospect of treatment for Parkinson's disease in the 21st century]. 1106 33

The purpose of the new drugs for Parkinson's disease is control of the long-term levodopa treatment syndromes, especially wearing-off phenomenon and dyskinesia. Therefore, they show long T1/2. Most of them are classified into dopamine agonists. Others are monoamine oxidase B inhibitor and cathecole-o-methyltransferase inhibitor. Marketed dopamine agonists are bromocriptine, pergolide, talipexole, and cabergoline in Japan. Except talipexole, they are all ergot alkaloid derivatives. Their affinity for dopamine receptor is D2 group, and their T1/2 are longer than levodopa. Bromocriptine is an oldest dopamine agonist. Other 3 drugs and bromocriptine had made each other double blinded cross over trial previously. The result of double blinded studies show that their efficacy for PD treatment were equal, 40-50% patients with PD. However, in clinical usage, some difference is observed as described below. Efficacy of pergolide is strong compared with bromocriptine; however, pergolide is easy to arise dyskinesia. Talipexole is strong in the hypnosis effect. As for cabergoline, it takes long time to show medical effect, so that it is expected to control wearing-off phenomenon. Monoamine oxidase B inhibitor, Selegiline, is useful as an economizer effect to levodopa. As for the cathechole-o-methyltransferase inhibitor (COMT-I) will be make double-blinded trial in future. The efficacy for PD treatment of COMT-I is prolonged levodopa effect for PD, so that wearing-off phenomenon will be controlled. To use these drugs successfully is important with the treatment of PD. In the future, the development of the cause therapy in addition to the systematic therapy is wanted.
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PMID:[The new Parkinson's disease drugs]. 1106 48

Parkinson's disease imposes a considerable economic burden on our society. Apart from the direct costs for therapy, the indirect costs of the disease are estimated to be substantially higher. Unfortunately, only the high costs of current medication are usually considered, when financial aspects are discussed. An ideal therapy should ameliorate the symptoms of the disease and achieve a high quality of life. but the prognosis should also be improved. Cost estimates have to be extended throughout the course of the disease. We recommend a treatment schedule which is expected to result in a favorable cost profile when the entire course of the disease, is considered. L-Dopa monotherapy in working patients is obsolete. During the course of the disease dopamine agonists, amantadine, budipine, COMT inhibitors and selegiline will be used.
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PMID:Costs in the treatment of parkinsonism. 1119 15


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