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

Glutamate receptor antagonists with selective action at the N-methyl-D-aspartate (NMDA) receptor are promising agents for the neuroprotective and symptomatic pharmacotherapy of various neuropsychiatric disorders. Although NMDA receptor antagonists of the phencyclidine (PCP) type are precluded from clinical use because of their psychotomimetic properties, amantadine and memantine have been administered to human patients with idiopathic Parkinson's disease and spasticity for many years without serious adverse effects. The mechanisms underlying these differences in psychotogenicity of different NMDA receptor antagonist are currently being discussed. Different affinity to the PCP binding site of the NMDA receptor, region-specific pharmacology, as well as different binding profiles to neurotransmitter receptors other than the NMDA type glutamate receptor, most likely play a role in determining whether an NMDA receptor antagonist drug will be tolerated clinically or not.
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PMID:[New therapeutic possibilities with low-affinity NMDA receptor antagonists]. 867 93

Incubation of highly enriched neurons from rat cerebral cortex with the human immunodeficiency virus type 1 (HIV-1) coat protein gp120 for 18 h results in fragmentation of DNA at internucleosomal linkers, a feature of apoptosis. We report that neurons respond to exposure to gp120 with an increased release of arachidonic acid via activation of phospholipase A2. This process is not inhibited by antagonists of the N-methyl-D-aspartate (NMDA) receptor channels. To investigate the influence of arachidonic acid on the sensitivity of NMDA receptor towards its against, low concentrations of NMDA were coadministered with arachidonic acid. Under these conditions the NMDA-mediated cytotoxicity was enhanced. We conclude that gp120 causes an activation of phospholipase A2, resulting in an increased release of arachidonic acid which in turn sensitizes the NMDA receptor. Two compounds were found to act cytoprotectively against the deleterious effect caused by gp120 on neurons: Memantine [1-amino-3,5-dimethyladamantane] and Flupirtine [2-amino-3-ethoxycarbonylamino-6-(4-fluoro-benzyl-amino)-pyridine maleate]. Both compounds have been found to display a potent cytoprotective effect on neurons treated with the excitatory amino acid NMDA or with the human immunodeficiency virus type 1 (HIV-1) coat protein gp120. The NMDA antagonist Memantine, a drug currently used in the therapy of spasticity and Parkinson's disease, prevented the effects of gp120 at micromolar concentrations. Flupirtine was previously found to be a centrally acting, nonopiate analgesic agent which additionally possesses anticonvulsant and muscle-relaxant activity at doses similar to those producing analgesia. The cytoprotective effect of Flupirtine in vitro was significant (above 10 microM). Considering the fact that both Memantine and Flupirtine display almost no clinical side effects, these drugs may prove useful both in preventing primary infection of brain cells with the HIV virus, as well as in treating the neurological disorders often associated with the immunodeficiency syndrome such as AIDS-related dementia.
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PMID:Neurotoxicity in rat cortical cells caused by N-methyl-D-aspartate (NMDA) and gp120 of HIV-1: induction and pharmacological intervention. 882 91

The development of neuroprotective agents for the prevention of neuronal loss in acute conditions such as stroke and epilepsy or chronic neurodegenerative disorders including Parkinson's disease, Alzheimer's disease, Huntington's chorea, and motor neuron disease is currently focusing on drugs that inhibit excitatory amino acid neurotransmission or exhibit antioxidant properties. Unfortunately, potent antagonists at the N-methyl-D-aspartate (NMDA) type glutamate receptor, which is thought to mediate excitotoxic neuronal injury, e.g., MK-801 or phencyclidine (PCP), share a high probability of inducing psychotomimetic side effects. Further, these drugs have been associated with acute neurotoxicity in vitro and in vivo, precluding their clinical use. In contrast, low affinity NMDA receptor antagonists like amantadine and its dimethyl derivative, memantine, have been administered clinically for the management of Parkinson's disease, dementia, neuroleptic drug-induced side effects, and spasticity. These agents have only rarely induced significant psychotomimetic side effects. Recent pharmacologic advances have helped to elucidate how high drug affinity for the PCP binding site of the NMDA receptor may enhance psychotogenicity. Low affinity and associated fast voltage-dependent channel unblocking kinetics are likely to be responsible for the better tolerance of amantadine and memantine compared with MK-801 and PCP. Further factors apparently modulating psychotogenicity of glutamate receptor antagonists include differential actions on neuronal populations in various brain regions and interactions with neurotransmitter receptors other than the NMDA type glutamate receptor.
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PMID:Psychotogenicity and N-methyl-D-aspartate receptor antagonism: implications for neuroprotective pharmacotherapy. 901 83

This article will review those electrophysiological investigations which have addressed the neuronal mechanisms underlying impaired gait. The aims of the review are to provide further insights to the underlying pathophysiology of impaired gait and also towards the selection of an appropriate treatment. From the patients' point of view the first indication of a central motor system lesion is an impairment of movement, most notably locomotion. These symptoms are characteristic in cases of spasticity, cerebellar lesion or Parkinson's disease. Clinical examination reveals typical changes in tendon tap reflexes and muscle tone which were believed to account for the movement disorder presented. However, we now know that there is only a weak relationship between the physical symptoms observed during clinical examination under passive motor conditions and the altered neuronal mechanisms underlying the impairment during active motion. By recording and analysing electrophysiological and biomechanical parameters during functional movements such as locomotion, the significance of impaired reflex behaviour or the pathophysiology of muscle tone and its contribution to the movement disorder can be reliably assessed. Consequently, the treatment should not be cosmetic, i.e. the correction of an isolated clinical parameter, but should be based on the pathophysiology and significance of those mechanisms underlying the impairment of the patients' movements. Data from electrophysiological and biomechanical investigations of locomotion of patients with spasticity, cerebellar disorder or Parkinson's disease are discussed in this review. The neuronal mechanisms, which are essentially central programs and afferent input, involved in disorders of gait are evaluated on the basis of their function in healthy subjects. The impact of this analysis in deciding an appropriate treatment are discussed with respect to the pathophysiology underlying the gait disorder (spasticity, cerebellar disorder or Parkinson's disease). At the present time we have only a basic understanding of the essential receptor systems, such as leg extensor load receptors, and their interaction with other systems involved in postural control. In the future, the knowledge gained from gait analysis may help in the selection of the appropriate pharmacological and physical treatment required even though the patient may only be at an early stage of motor impairment.
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PMID:Neurophysiology of gait disorders: present and future applications. 930 81

Excessive accumulation of glutamate or other excitatory amino acids and the subsequent overactivity of NMDA receptors is currently thought to lead to neuronal injury in cerebral ischemia. Therefore, antagonists of the NMDA receptor may offer an approach for the treatment of ischemic brain injury. Dizocilpine (MK-801), an NMDA receptor-associated channel blocker, protects neurons in several rodent stroke models. However, this drug has numerous side effects and causes apoptosis of neonatal neurons. Recently, another NMDA receptor-associated channel blocker, memantine, has been shown to ameliorate NMDA-receptor mediated neurotoxicity in neuronal cell cultures and in focal cerebral ischemia models in adult rats without substantial side effects. Memantine has been used clinically in the treatment of Parkinson's disease and spasticity for a number of years. Here we tested the effects of memantine on focal stroke caused by photochemical thrombosis in neonatal rats and demonstrated a neuroprotective effect of memantine in this model. We also found excellent correlation between infarct size determined by magnetic resonance imaging (MRI) and histopathological analysis in the same animals. A single pre-ischemic dose of memantine (20 mg/kg) given 15 min prior to induction of stroke reduced the infarct size by 36.3% when compared to control animals treated with normal saline (P < 0.0001). At this dosage, memantine manifests few, if any, neurobehavioral side effects. Thus memantine appears to be both safe and effective in neonatal as well as adult animal models of stroke.
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PMID:Neuroprotection by the NMDA receptor-associated open-channel blocker memantine in a photothrombotic model of cerebral focal ischemia in neonatal rat. 1044 69

The achievements of Indian neurosurgeons in different fields of stereotactic surgery over the past decades have been discussed. This covers diverse areas like Parkinson's disease, abnormal movements, cerebral palsy, spasticity, pain relief, and sedative and functional neurosurgery. Recently, technological advances have made stereotactic surgery useful in many fields like deep biopsies, minimally invasive surgery and radiosurgery. Apart from these areas, there is still a big scope for revival of surgery on deep structures of the brain, as was practised earlier. This will lead to newer knowledge about brain function and also give relief to many patients. The future is bright, provided Indian neurosurgeons show a paradigm shift in their thinking and bring out new ideas. Interaction with other scientific disciplines is necessary in the future if new knowledge has to be added or new techniques have to be devised.
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PMID:Stereotactic surgery in India: the past, present and the future. 1075 7

We studied a 27-year-old woman who died after a 6-year history of progressive dementia, dystonia, ataxia, apraxia, spasticity, choreoathetosis, visual and auditory hallucinations, and optic atrophy. Magnetic resonance imaging showed decreased intensity in the globus pallidus, substantia nigra, and dentate nuclei in T2-weighted images, supporting the clinical diagnosis of neurodegeneration with brain iron accumulation type 1 (NBIA-1; formerly known as Hallervorden-Spatz syndrome). At autopsy the brain showed mild frontotemporal atrophy and discoloration of the globus pallidus and the substantia nigra pars reticularis. Histologically, features typical of NBIA-1 were found including widespread axonal spheroids and large deposits of iron pigment in the discolored regions. Additionally, excessive numbers of Lewy bodies (LBs) were found throughout all examined brain stem and cortical regions. LBs of both types, as well as Lewy neurites in this case of NBIA-1, were strongly labeled by antibodies against alpha-synuclein. These findings give further evidence that accumulation of alpha-synuclein is generally associated with LB formation, i.e., in Parkinson's disease, dementia with Lewy bodies and NBIA-1. The case presented here is particularly notable for its high number of LBs in all areas of the cerebral cortex.
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PMID:Alpha-synuclein accumulation in a case of neurodegeneration with brain iron accumulation type 1 (NBIA-1, formerly Hallervorden-Spatz syndrome) with widespread cortical and brainstem-type Lewy bodies. 1104 80

Glutamate is the major excitatory neurotransmitter of the central nervous system. Besides its importance in many physiological processes, increased glutamate release and subsequent excessive stimulation of the various glutamate receptors are thought to play critical roles in the pathophysiological mechanisms underlying many neurologic diseases. Experimental data suggest that blockade of glutamate receptors or inhibition of glutamate release has positive effects in many disease models. Glutamate antagonists are already in clinical use for the treatment of Parkinson's disease, epilepsy, spasticity, and neuropathic pain. Overall, glutamate antagonists have not been found clinically effective for neuroprotective treatment of cerebral ischemia or chronic neurodegenerative diseases, with one exception. Side effects of glutamate antagonists can be mainly attributed to central mechanisms and include psychosis, agitation, and disorientation. It is to be hoped that further development of new glutamate antagonists that block disease-relevant subtypes of glutamate receptors will lead to more effective drugs with fewer side effects.
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PMID:[Glutamate antagonists in neurology]. 1143 98

Kufor-Rakeb syndrome is an autosomal recessive nigro-striatal-pallidal-pyramidal neurodegeneration. The onset is in the teenage years with clinical features of Parkinson's disease plus spasticity, supranuclear upgaze paresis, and dementia. Brain scans show atrophy of the globus pallidus and pyramids and, later, widespread cerebral atrophy. We report linkage in Kufor-Rakeb syndrome to a 9 cM region of chromosome 1p36 delineated by the markers D1S436 and D1S2843, with a maximum multipoint lod score of 3.6.
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PMID:Kufor-Rakeb syndrome, pallido-pyramidal degeneration with supranuclear upgaze paresis and dementia, maps to 1p36. 1158 46

Using criteria of the classification recently described by Nutt et al., we examined gait disorder in five patients with normal pressure hydrocephalus (NPH). Their cerebrospinal fluid (CSF) pressures were in the normal range, and trials of CSF removal produced temporary improvement of symptoms. Surgical procedures to relieve hydrocephalus improved gait disorders in all patients. No patient showed spasticity, sensory ataxia, cerebellar ataxia, extrapyramidal signs, or limb apraxia. All walked slowly with a wide base and a short stride. The arm swing normally associated with walking was preserved. In standing, patients were unsteady and fell easily when pushed. Four patients showed hesitation in initiating walking and in turning. These clinical features fit Nutt's criteria for frontal gait disorder and frontal disequilibrium. Unlike findings in Parkinson's disease, where similar gait disorders may occur, other extrapyramidal signs, Myerson's sign, and upper limb dysfunction were absent in NPH, and arm swing while walking was preserved. We suspect that ventricular dilatation disturbs neuronal connections between the supplementary motor area and the globus pallidus in NPH patients.
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PMID:Gait disturbance in patients with low pressure hydrocephalus. 1174 14


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