6,628 research outputs found
Effects of EGb 761® Ginkgo biloba extract on mitochondrial function and oxidative stress
As major sources of reactive oxygen species (ROS), mitochondrial structures are exposed to high concentrations of ROS and may therefore be particularly susceptible to oxidative damage. Mitochondrial damage could play a pivotal role in the cell death decision. A decrease in mitochondrial energy charge and redox state, loss of transmembrane potential (depolarization), mitochondrial respiratory chain impairment, and release of substances such as calcium and cytochrome c all contribute to apoptosis. These mitochondrial abnormalities may constitute a part of the spectrum of chronic oxidative stress in Alzheimer's disease. Accumulation of amyloid beta (Abeta) in form of senile plaques is also thought to play a central role in the pathogenesis of Alzheimer's disease mediated by oxidative stress. In addition, increasing evidence shows that Abeta generates free radicals in vitro, which mediate the toxicity of this peptide. In our study, PC12 cells were used to examine the protective features of EGb 761(definition see editorial) on mitochondria stressed with hydrogen peroxide and antimycin, an inhibitor of complex III. In addition, we investigated the efficacy of EGb 761 in Abeta-induced MTT reduction in PC12 cells. Moreover, we examined the effects of EGb 761 on ROS levels and ROS-induced apoptosis in lymphocytes from aged mice after in vivo administration. Here, we will report that EGb 761 was able to protect mitochondria from the attack of hydrogen peroxide, antimycin and Abeta. Furthermore, EGb 761 reduced ROS levels and ROS-induced apoptosis in lymphocytes from aged mice treated orally with EGb 761 for 2 weeks. Our data further emphasize neuroprotective properties of EGb 761, such as protection against Abeta-toxicity, and antiapoptotic properties, which are probably due to its preventive effects on mitochondria
Apollo 15 rake sample microbreccias and non-mare rocks: Bulk rock, mineral and glass electron microprobe analyses
Quantitative electron microprobe data of Apollo 15 nonmare rake samples are presented. Bulk analyses of lithic fragments in the nomare rocks (expressed in oxide weight-percent) and the corresponding CIPW molecular norms are given. The mineralogy of the rocks and lithic fragments are also given; structural formulae for complete analyses and molecular end-members for all mineral analyses are included. The mineral analyses include pyroxene, olivine, plagioclase, barian K-feldspar, spinel and ilmenite, cobaltian metallic nickel-iron as well as SiO2-K2O-rich residual glass. Electron micropobe analyses (oxide weight percent) of glasses in loose fines and microbreccia samples and their CIPW molecular norms are presented along with electron microprobe data on bulk, mineral, and matrix glass from chondrules
XMM-Newton observation of the ULIRG NGC 6240: The physical nature of the complex Fe K line emission
We report on an XMM-Newton observation of the ultraluminous infrared galaxy
NGC 6240. The 0.3-10 keV spectrum can be successfully modelled with: (i) three
collisionally ionized plasma components with temperatures of about 0.7, 1.4,
and 5.5 keV; (ii) a highly absorbed direct power-law component; and (iii) a
neutral Fe K_alpha and K_beta line. We detect a significant neutral column
density gradient which is correlated with the temperature of the three plasma
components. Combining the XMM-Newton spectral model with the high spatial
resolution Chandra image we find that the temperatures and the column densities
increase towards the center.
With high significance, the Fe K line complex is resolved into three distinct
narrow lines: (i) the neutral Fe K_alpha line at 6.4 keV; (ii) an ionized line
at about 6.7 keV; and (iii) a higher ionized line at 7.0 keV (a blend of the Fe
XXVI and the Fe K_beta line). While the neutral Fe K line is most probably due
to reflection from optically thick material, the Fe XXV and Fe XXVI emission
arises from the highest temperature ionized plasma component.
We have compared the plasma parameters of the ultraluminous infrared galaxy
NGC 6240 with those found in the local starburst galaxy NGC 253. We find a
striking similarity in the plasma temperatures and column density gradients,
suggesting a similar underlying physical process at work in both galaxies.Comment: 8 pages including 9 figures. Accepted for publication in A&
The Role of Copper in Hemoglobin Regeneration
During the past few years a considerable amount of investigation has been devoted to the part played by copper in hemoglobin formation. Hart, Steenbock, Waddell, and Elvehjem were the first to show that in nutritional anemia regeneration of hemoglobin does not occur when pure iron salts are administered, but if a small amount of copper as copper sulphate be added along with the iron salt regeneration is very rapid
Studies on Regeneration of Hemoglobin
Many investigators in the past few years have been interested in the problem of the relation of iron to anemia. This problem originated in connection with studies involving a comparison of inorganic versus organic iron, which later led to studies on the relation of solubility of iron compounds to regeneration of hemoglobin and the treatment of anemia
An extended equation of state for core-collapse simulations
In stellar core-collapse events matter is heated and compressed to densities
above nuclear matter saturation density. For progenitors stars with masses
above about 25 solar masses, which eventually form a black hole, the
temperatures and densities reached during the collapse are so high that a
traditional description in terms of electrons, nuclei, and nucleons is no
longer adequate. We present here an improved equation of state which contains
in addition pions and hyperons. They become abundant in the high temperature
and density regime. We study the different constraints on such an equation of
state, coming from both hyperonic data and observations of neutron star
properties. In order to test the zero-temperature versions, we perform
numerical simulations of the collapse of a neutron star with such additional
particles to a black hole. We discuss the influence of the additional particles
on the thermodynamic properties within the hot versions of the equation of
state and we show that in regimes relevant to core-collapse and black hole
formation, the effects of pions and hyperons on pressure, internal energy and
sound speed are not negligible.Comment: 20 page
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