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)

Oxidative stress plays a crucial role in the manifestations of maneb (MB) and paraquat (PQ)-induced toxicity including MB+PQ-induced Parkinson's disease (PD). Polymorphonuclear leukocytes (PMNs) actively participate in the oxidative stress-mediated inflammation and organ toxicity. The present study was undertaken to investigate the MB- and/or PQ-induced alterations in the indices of oxidative stress in rat PMNs. Animals were treated with or without MB and/or PQ in an exposure time dependent manner. In some sets of experiments, the animals were pre-treated with NOS inhibitors N(G)-nitro-L-arginine methyl ester (L-NAME) and aminoguanidine (AG) along with respective controls. A significant increase in myeloperoxidase (MPO), superoxide dismutase (SOD), nitric oxide, iNOS expression and lipid peroxidation (LPO) was observed in PMNs of MB- and/or PQ-treated animals, while catalase and glutathione S-transferase (GST) activities were attenuated. L-NAME and AG significantly reduced the augmented nitrite content, iNOS expression and MPO activity to control level in MB and PQ exposed animals. Although the augmented LPO was also reduced significantly in L-NAME and AG treated rat PMNs, the level was still higher as compared with controls. Alterations induced in SOD and GST activities were not affected by NOS inhibitors. The results thus suggest that MB and/or PQ induce iNOS-mediated nitric oxide production, which in turn increases MPO activity and lipid peroxidation, thereby oxidative stress.
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PMID:The involvement of nitric oxide in maneb- and paraquat-induced oxidative stress in rat polymorphonuclear leukocytes. 1898 85

Nitric oxide (NO), which is produced from L-arginine by the nitric oxide synthase (NOS) family of enzymes, is an important second-messenger molecule that regulates several physiological functions. In endothelial cells, it relaxes smooth muscle, which decreases blood pressure. Macrophage cells produce NO as an immune defense system to destroy pathogens and microorganisms. In neuronal cells, NO controls the release of neurotransmitters and is involved in synaptogenesis, synaptic plasticity, memory function, and neuroendocrine secretion. NO is a free radical that is commonly thought to contribute to oxidative damage and molecule and tissue destruction, and thus it is somewhat surprising that it has so many significant beneficial physiological effects. However, the cell is generally protected from NO's toxic effects, except under certain pathological conditions in which excessive NO is produced. In that case, tissue damage and oxidative stress can result, leading to a wide variety of diseases, including rheumatoid arthritis, Alzheimer's disease, and Parkinson's disease, among others. In this Account, we describe research aimed at identifying small molecules that can selectively inhibit only the neuronal isozyme of NOS, nNOS. By targeting only nNOS, we attained the beneficial effects of lowering excess NO in the brain without the detrimental effects of inhibition of the two isozymes found elsewhere in the body (eNOS and iNOS). Initially, in pursuit of this goal, we sought to identify differences in the second sphere of amino acids in the active site of the isozymes. From this study, the first class of dual nNOS-selective inhibitors was identified. The moieties important for selectivity in the best lead compound were determined by structure modification. Enhancement provided highly potent, nNOS-selective dipeptide amides and peptidomimetics, which were active in a rabbit model for fetal neurodegeneration. Crystal structures of these compounds bound to NOS isozymes showed a one-amino-acid difference between nNOS and eNOS in the second sphere of amino acids; this was the difference that we were searching for from the beginning of this project. With the aid of these crystal structures, we developed a new fragment-based de novo design method called "fragment hopping", which allowed the design of a new class of nonpeptide nNOS-selective inhibitors. These compounds were modified to give low nanomolar, highly dual-selective nNOS inhibitors, which we recently showed are active in a rabbit model for the prevention of neurobehavioral symptoms of cerebral palsy. These compounds could also have general application in other neurodegenerative diseases for which excess NO is responsible.
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PMID:Design of selective neuronal nitric oxide synthase inhibitors for the prevention and treatment of neurodegenerative diseases. 1915 46

Chronic L-DOPA pharmacotherapy in Parkinson's disease is often accompanied by the development of abnormal and excessive movements known as L-DOPA-induced dyskinesia. Rats with 6-hydroxydopamine lesion of dopaminergic neurons chronically treated with L-DOPA develop a rodent analog of this dyskinesia characterized by severe axial, limb, locomotor and orofacial abnormal involuntary movements. While the mechanisms by which these effects occur are not clear, they may involve the nitric oxide system. In the present study we investigate if nitric oxide synthase inhibitors can prevent dyskinesias induced by repeated administration of L-DOPA in rats with unilateral 6-hydroxydopamine lesion. Chronic L-DOPA (high fixed dose, 100 mg/kg; low escalating dose, 10-30 mg/kg) treatment induced progressive dyskinesia changes. Two nitric oxide synthase inhibitors, 7-nitroindazole (1-30 mg/kg) and NG-nitro-L-arginine (50 mg/kg), given 30 min before L-DOPA, attenuate dyskinesia. 7-Nitroindazolee also improved motor performance of these animals in the rota-rod test. These results suggest the possibility that nitric oxide synthase inhibitors may be useful to treat L-DOPA-induced dyskinesia.
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PMID:Nitric oxide synthase inhibition attenuates L-DOPA-induced dyskinesias in a rodent model of Parkinson's disease. 1930 33

Pathological amyloid deposits are mixtures of polypeptides and non-proteinaceous species including heparan sulfate proteoglycans and glycosaminoglycans (GAGs). We describe a procedure in which a (13)C-labelled N-acetyl derivative of the GAG heparin ([(13)C-CH(3)]NAcHep) serves as a useful probe for the analysis of GAG-protein interactions in amyloid using solid-state nuclear magnetic resonance (SSNMR) spectroscopy. NAcHep emulates heparin by enhancing aggregation and altering the fibril morphology of Abeta(1-40), one of the beta-amyloid polypeptides associated with Alzheimer's disease, and alpha-synuclein, the major protein component of Lewy bodies associated with Parkinson's disease. (13)C SSNMR spectra confirm the presence of [(13)C-CH(3)]NAcHep in Abeta(1-40) fibril deposits and detect dipolar couplings between the glycan and arginine R(5) at the Abeta(1-40) N-terminus, suggesting that the two species are intimately mixed at the molecular level. This procedure provides a foundation for further extensive investigations of polypeptide-glycan interactions within amyloid fibrils.
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PMID:Exploiting a (13)C-labelled heparin analogue for in situ solid-state NMR investigations of peptide-glycan interactions within amyloid fibrils. 1946 52

Parkinson's disease has been long linked to environmental factors, such as transition metals and recently to alpha-synuclein, a presynaptic protein. Using tryptophan-containing peptides, we identified the minimal Cu(II)-binding sequence to be within the first four residues, MDV(F/W), anchored by the alpha-amino terminus. In addition, mutant peptide 1-10 (Lys --> Arg) verified that neither Lys6 nor Lys10 are necessary for Cu(II) binding. Interestingly, Trp4 excited-state decay kinetics measured for peptides and proteins reveal two quenching modes, possibly arising from two distinct Cu(II)-polypeptide structures.
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PMID:Identification of the minimal copper(II)-binding alpha-synuclein sequence. 1978 Jun 17

The dopamine transporter (DAT) operates via facilitated diffusion, harnessing an inward Na(+) gradient to drive dopamine from the extracellular synaptic cleft to the neuron interior. The DAT is relevant to central nervous system disorders such as Parkinson disease and attention-deficit hyperactivity disorder and is the primary site of action for the abused psychostimulants cocaine and amphetamines. Crystallization of a DAT homolog, the bacterial leucine transporter LeuT, provided the first reliable 3-D DAT template. Here, the LeuT crystal structure and the DAT molecular model have been combined with their respective substrates, leucine and dopamine, in lipid bilayer molecular dynamics simulations toward tracking substrate movement along the protein's substrate/ion permeation pathway. Specifically, movement of residue pairs that comprise the "external gate" was followed as a function of substrate presence. The transmembrane (TM) 1 arginine-TM 10 aspartate strut formed less readily in DAT compared with LeuT, with or without substrate present. For LeuT but not DAT, the addition of substrate enhanced the chances of forming the TM 1-10 bridge. Also, movement of the fourth extracellular loop EL-4 in the presence of substrate was more pronounced for DAT, the EL-4 unwinding to a degree. The overall similarity between the LeuT and DAT molecular dynamics simulations indicated that LeuT was a legitimate model to guide DAT structure-function predictions. There were, nevertheless, differences significant enough to allow for DAT-unique insights, which may include how cocaine, methylphenidate (Ritalin, NIDA Drug Supply, Rockville, MD), and other DAT blockers are not recognized as substrates even though they can access the primary substrate binding pocket. Proteins 2010. (c) 2009 Wiley-Liss, Inc.
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PMID:Molecular dynamics of leucine and dopamine transporter proteins in a model cell membrane lipid bilayer. 1989 68

The intramembrane receptor-receptor interactions among GPCRs demonstrated in the beginning of the 80s in the CNS probably reflect the existence of allosteric mechanisms in receptor heteromers, and the postulated assemblies of multiple GPCRs coined 'receptor mosaics' in the early 80s probably represent higher order receptor heteromers, recently demonstrated with novel biophysical techniques in living cells. The receptor interface in the GPCR heteromers is beginning to be characterized and in adenosine A(2A)-dopamine D(2)-like heteromers the electrostatic arginine-phosphate salt bridge seems to be a hot spot in the interface with covalent-like stability, possibly participating in the allosteric interactions and making possible integration of heteromer receptor function. We discuss the possible relevance of some putative D(2) receptor heteromers in the treatment of Parkinson's disease and schizophrenia, respectively.
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PMID:Molecular integration via allosteric interactions in receptor heteromers. A working hypothesis. 1994 81

While many treatments for mitochondrial electron transport (respiratory) chain disorders have been suggested, relatively few have undergone controlled clinical trials. This review focuses on the recent history of clinical trials of dichloroacetate (DCA), arginine, coenzyme Q(10), idebenone, and exercise in both primary (congenital) disorders and secondary (degenerative) disorders. Despite prior clinical impressions that DCA had a positive effect on mitochondrial disorders, two trials of diverse subjects failed to demonstrate a clinically significant benefit, and a trial of DCA in MELAS found a major negative effect of neuropathy. Arginine also has been used to treat MELAS with promising effects, although a controlled trial is still needed for this potentially toxic agent. The anti-oxidant coenzyme Q(10) is very widely used for primary mitochondrial disorders but has not yet undergone a controlled clinical trial; such a trial is now underway, as well as trials of the co-Q analogue idebenone for MELAS and LHON. Greater experience has accumulated with multi-center trials of coenzyme Q(10) treatment to prevent the progression of Parkinson disease. Although initial smaller trials indicated a benefit, this has not yet been confirmed in subsequent trials with higher doses; a larger Phase III trial is now underway. Similarly, a series of trials of idebenone for Friedreich ataxia have shown some benefit in slowing the progression of cardiomyopathy, and controlled clinical trials are now underway to determine if there is significant neurological protection. Uncontrolled trials of exercise showed an increase of exercise tolerance in patients with disorders of mitochondrial DNA, but did not selectively increase the percentage of normal mtDNA; a larger partially controlled trial is now underway to evaluate this possible benefit. In summary, none of the controlled trials so far has conclusively shown a benefit of treatment with the agents tested, but some promising therapies are currently being evaluated in a controlled manner. These experiences underscore the importance of controlled clinical trials for evaluation of benefits and risks of recommended therapies. Application of such clinical trials to future more effective therapies for mitochondrial disorders will require multi-center collaboration, organization, leadership, and financial and advocacy support.
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PMID:Treatment of mitochondrial electron transport chain disorders: a review of clinical trials over the past decade. 2006 Mar 49

The morphological and chemical changes associated with the exposure of melanosomes to methyl iodide are assessed by a variety of analytical, imaging and spectroscopic methods. Scanning electron microscopy, light scattering and N(2) adsorption measurements all indicate significant changes in the morphology of the pigment following methylation. Solid-state nuclear magnetic resonance (SS-NMR) spectroscopy and chemical degradation analysis reveals the methylation results in the introduction of ester groups into the pigment structures. Amino acid analysis further reveals that Arg, Cys, His, Ser and Tyr undergo methylation; the SS-NMR data provide additional evidence for the methylation of the sulfur of Cys. Methylation results in increased solubility of the melanosome; the absorption properties of the dissolved material are characterized by an absorption maximum at 225 nm, with a long tail throughout the UV-A and UV-B, indicating that the solubilized material is a combination of protein and pigment. The methylation-induced decomposition of the melanosomes provides new insights into both the observed increase in O-methyl derivatives of the indolic precursor to eumelanin in the urine of melanoma patients and how increased levels of biologic methylating agents in the brain induce symptoms that resemble Parkinson's disease.
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PMID:Imaging, chemical and spectroscopic studies of the methylation-induced decomposition of melanosomes. 2033 25

Toxicity of human alpha-synuclein when expressed in simple organisms can be suppressed by overexpression of endoplasmic reticulum (ER)-to-Golgi transport machinery, suggesting that inhibition of constitutive secretion represents a fundamental cause of the toxicity. Whether similar inhibition in mammals represents a cause of familial Parkinson's disease has not been established. We tested elements of this hypothesis by expressing human alpha-synuclein in mammalian kidney and neuroendocrine cells and assessing ER-to-Golgi transport. Overexpression of wild type or the familial disease-associated A53T mutant alpha-synuclein delayed transport by up to 50%; however, A53T inhibited more potently. The secretory delay occurred at low expression levels and was not accompanied by insoluble alpha-synuclein aggregates or mistargeting of transport machinery, suggesting a direct action of soluble alpha-synuclein on trafficking proteins. Co-overexpression of ER/Golgi arginine soluble N-ethylmaleimide-sensitive factor attachment protein receptors (R-SNAREs) specifically rescued transport, indicating that alpha-synuclein antagonizes SNARE function. Ykt6 reversed alpha-synuclein inhibition much more effectively than sec22b, suggesting a possible neuroprotective role for the enigmatic high expression of ykt6 in neurons. In in vitro reconstitutions, purified alpha-synuclein A53T protein specifically inhibited COPII vesicle docking and fusion at a pre-Golgi step. Finally, soluble alpha-synuclein A53T directly bound ER/Golgi SNAREs and inhibited SNARE complex assembly, providing a potential mechanism for toxic effects in the early secretory pathway.
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PMID:Alpha-synuclein delays endoplasmic reticulum (ER)-to-Golgi transport in mammalian cells by antagonizing ER/Golgi SNAREs. 2039 39


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