1,329 research outputs found
Quinone formation as dopaminergic neuron-specific oxidative stress in the pathogenesis of sporadic Parkinson's disease and neurotoxin-induced parkinsonism.
Parkinson's disease (PD) is a progressive neurodegenerative disease characterized by dopaminergic neuron-specific degeneration in the substantia nigra. A number of gene mutations and deletions have been reported to play a role in the pathogenesis of familial PD. Moreover, a number of pathological and pharmacological studies on sporadic PD and dopaminergic neurotoxin-induced parkinsonism have hypothesized that mitochondrial dysfunction, inflammation, oxidative stress, and dysfunction of the ubiquitin-proteasome system all play important roles in the pathogenesis and progress of PD. However, these hypotheses do not yet fully explain the mechanisms of dopaminergic neuron-specific cell loss in PD. Recently, the neurotoxicity of dopamine quinone formation by auto-oxidation of dopamine has been shown to cause specific cell death of dopaminergic neurons in the pathogenesis of sporadic PD and dopaminergic neurotoxin-induced parkinsonism. Furthermore, this quinone formation is closely linked to other representative hypotheses in the pathogenesis of PD. In this article, we mainly review recent studies on the neurotoxicity of quinone formation as a dopaminergic neuron-specific oxidative stress and its role in the etiology of PD, in addition to several neuroprotective approaches against dopamine quinone-induced toxicity.</p
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Optimum Object Analysis Of Islands Activities On South China Sea By DNB On VIIRS
A data processing and analyzing system was designed and made operational with free software to process the big data over the South China Sea (SCS), which are provided by the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi National Polar-orbiting Partnership (Suomi-NPP) to monitor the light distributions in the night. The VIIRS data are processed from the raw data (level-0) to geophysical data (level-3) using the International Polar Orbiter Processing Package (IPOPP), which are freely available from NASA. The Day Night Band (DNB) of VIIRS is extracted from the level-3 data and is geospatially projected for our region of interest (ROI) on the SCS. For those ingested data, an optimum object analysis in geographic domain was proposed to estimate the reclamation activities on coral reefs in the SCS using GDAL. A pixel base analysis of DNB data is possible to estimate the island activities independently among dredgers, support vessels, or buildings on coral reefs, but not appropriate to analyze the activities for as an integrated system or for the changes in the ROI. Although there is a difficulty to determine the scale of objects on the analysis of DNB data for the reclamation activities, the optimum object scale was empirically determined for different size of coral reefs and was applied for this study. The optimum object analysis determines the reclamation activities with including lights not only from buildings but also dredgers and supporting vessels around coral reefs
A database of water and heat observations over grassland in the north-east of Japan
A highly valuable database of long-term hydrometeorological measurements is
presented, containing in situ observations for a period of 37 years from a
well-maintained grassland in the north-east of Japan. The observations
include shortwave radiation, net radiation, air and dew point temperatures at
three elevations, soil temperature at four depths, sensible heat flux, soil
heat flux, wind speed, relative humidity, air pressure and precipitation. The
heights of measurements are 1.6, 12.5 and 29.5 m above ground, with the
soil-layer observations at depths of 0.02, 0.1, 0.5 and 1 m. This
high-quality database includes four temporal resolutions of 10 s, 0.5 h,
1 h and 24 h, with the hourly data
presented here. Monthly and annual statistics are presented at the database
web page of the Center for Research in Isotopes and Environmental Dynamics
and Prediction of the University of Tsukuba,
http://doi.org/10.24575/0001.198108. We validated the data by comparing
them with published data from the local meteorological agency in Tateno operated
by the Japan Metrological Agency, including the average, maximum and minimum
values of air temperature, shortwave radiation, wind speed, relative
humidity and precipitation. We have generated a daily downward longwave
radiation time series with a method developed by Kondo and Xu (1997) based on
the observations from the database. This constructed time series agrees well
with observations collected between 2002 and 2006, as evaluated based on the
values of the Nash–Sutcliffe efficiency (=0.947) and percent bias (=1.486). For the whole database, annually averaged values show a positive
trend in precipitation, air temperature, shortwave radiation, net radiation
and sensible heat flux over the past 37 years, with a negative trend detected
for wind speed, soil heat flux and soil temperature.</p
Strongly residual coordinates over A[x]
For a domain A of characteristic zero, a polynomial f over A[x] is called a
strongly residual coordinate if f becomes a coordinate (over A) upon going
modulo x, and f becomes a coordinate upon inverting x. We study the question of
when a strongly residual coordinate is a coordinate, a question closely related
to the Dolgachev-Weisfeiler conjecture. It is known that all strongly residual
coordinates are coordinates for n=2 . We show that a large class of strongly
residual coordinates that are generated by elementaries upon inverting x are in
fact coordinates for arbitrary n, with a stronger result in the n=3 case. As an
application, we show that all Venereau-type polynomials are 1-stable
coordinates.Comment: 15 pages. Some minor clarifications and notational improvements from
the first versio
Transplantation of melanocytes obtained from the skin ameliorates apomorphine-induced abnormal behavior in rodent hemi-parkinsonian models
Tyrosinase, which catalyzes both the hydroxylation of tyrosine and consequent oxidation of L-DOPA to form melanin in melanocytes, is also expressed in the brain, and oxidizes L-DOPA and dopamine. Replacement of dopamine synthesis by tyrosinase was reported in tyrosine hydroxylase null mice. To examine the potential benefits of autograft cell transplantation for patients with Parkinson's disease, tyrosinase-producing cells including melanocytes, were transplanted into the striatum of hemi-parkinsonian model rats or mice lesioned with 6-hydroxydopamine. Marked improvement in apomorphine-induced rotation was noted at day 40 after intrastriatal melanoma cell transplantation. Transplantation of tyrosinase cDNA-transfected hepatoma cells, which constitutively produce L-DOPA, resulted in marked amelioration of the asymmetric apomorphine-induced rotation in hemi-parkinsonian mice and the effect was present up to 2 months. Moreover, parkinsonian mice transplanted with melanocytes from the back skin of black newborn mice, but not from albino mice, showed marked improvement in the apomorphine-induced rotation behavior up to 3 months after the transplantation. Dopamine-positive signals were seen around the surviving transplants in these experiments. Taken together with previous studies showing dopamine synthesis and metabolism by tyrosinase, these results highlight therapeutic potential of intrastriatal autograft cell transplantation of melanocytes in patients with Parkinson's disease
Chapter IV: Atmosphere-surface Interaction
Measuring atmospheric heating of landsurface using shimmer ......85Heat transport from the ground to the atmosphere estimated by airplane data ......86Soil moisture estimated from satellite data ......8
A novel class of CoA-transferase involved in short-chain fatty acid metabolism in butyrate-producing human colonic bacteria
Peer reviewedPublisher PD
Probing the physiology of ASH neuron in Caenorhabditis elegans using electric current stimulation
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98694/1/ApplPhysLett_99_053702.pd
Imaging Oxygen Defects and their Motion at a Manganite Surface
Manganites are technologically important materials, used widely as solid
oxide fuel cell cathodes: they have also been shown to exhibit
electroresistance. Oxygen bulk diffusion and surface exchange processes are
critical for catalytic action, and numerous studies of manganites have linked
electroresistance to electrochemical oxygen migration. Direct imaging of
individual oxygen defects is needed to underpin understanding of these
important processes. It is not currently possible to collect the required
images in the bulk, but scanning tunnelling microscopy could provide such data
for surfaces. Here we show the first atomic resolution images of oxygen defects
at a manganite surface. Our experiments also reveal defect dynamics, including
oxygen adatom migration, vacancy-adatom recombination and adatom bistability.
Beyond providing an experimental basis for testing models describing the
microscopics of oxygen migration at transition metal oxide interfaces, our work
resolves the long-standing puzzle of why scanning tunnelling microscopy is more
challenging for layered manganites than for cuprates.Comment: 7 figure
Scaling Microseismic Cloud Shape During Hydraulic Stimulation Using In Situ Stress and Permeability
Forecasting microseismic cloud shape as a proxy of stimulated rock volume may improve the design of an energy extraction system. The microseismic cloud created during hydraulic stimulation of geothermal reservoirs is known empirically to extend in the general direction of the maximum principal stress. However, this empirical relationship is often inconsistent with reported results, and the cloud growth process remains poorly understood. This study investigates microseismic cloud growth using data obtained from a hydraulic stimulation project in Basel, Switzerland, and explores its correlation with measured in situ stress. We applied principal component analysis to a time series of microseismicity for macroscopic characterization of microseismic cloud growth in two- and three-dimensional space. The microseismic cloud, in addition to extending in the general direction of maximum principal stress, expanded in the direction of intermediate principal stress. The orientation of the least microseismic cloud growth was stable and almost identical to the minimum principal stress direction. Further, microseismic cloud shape ratios showed good agreement when compared with in situ stress magnitude ratios. The permeability tensor estimated from microseismicity also provided a good correlation in terms of direction and magnitude with the microseismic cloud growth. We show that in situ stress plays a dominant role by controlling the permeability of each existing fracture in the reservoir fracture system. Consequently, microseismic cloud growth can be scaled by in situ stress as a first-order approximation if there is sufficient variation in the orientation of existing faults
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