共查询到9条相似文献,搜索用时 15 毫秒
1.
Magnetic resonance image and blood manganese concentration as indices for manganese content in the brain of rats 总被引:1,自引:0,他引:1
Chaki H Furuta S Matsuda A Yamauchi K Yamamoto K Kokuba Y Fujibayashi Y 《Biological trace element research》2000,74(3):245-257
Neurological disorders similar to parkinsonian syndrome and signal hyperintensity in brain on T1-weighted magnetic resonance (MR) images have been reported in patients receiving long-term total parenteral nutrition (TPN).
These symptoms have been associated with manganese (Mn) depositions in brain. Although alterations of signal intensity on
T1-weighted MR images in brain and of Mn concentration in blood are theoretically considered good indices for estimating Mn
deposition in brain, precise correlations between these parameters have not been demonstrated as yet.
Male Sprague-Dawley rats received TPN with 10-fold the clinical dose of the trace element preparation (TE-5) for 7 d. At 0,
2, 4, 6, and 8 wk post-TPN, the cortex, striatum, midbrain, and cerebellum were evaluated by MR images, and Mn concentration
in blood and Mn content in these brain sites were measured by atomic absorption spectrometry. Immediately after TPN termination,
signal hyperintensity in brain sites and elevated Mn content in blood and brain sites were observed. These values recovered
at 4 wk post-TPN. A positive correlation was observed between either the signal intensity in certain brain sites or Mn content
in blood and the relevant brain sites.
Our observations suggest that the Mn concentration in blood and signal intensity in the brain sites on T1-weighted MR images are reliable indices for monitoring Mn contents in brain. 相似文献
2.
Although manganese (Mn) is an essential element, exposure to excessive levels of Mn and its accumulation in the brain can
cause neurotoxicity and extrapyramidal syndrome. We have investigated the differences in the accumulated levels of Mn, the
degree of lipid peroxidation, and its effects on the levels of trace elements (Fe, Cu, and Zn) in various regions in the brain
of rats having undergone acute Mn exposure. The rats in the dose—effect group were injected intraperitoneally (ip) with MnCl2 (25, 50, or 100 mg MnCl2/kg) once a day for 24 h. The Mn significantly accumulated (p<0.05) in the frontal cortex, corpus callosum, hippocampus, striatum, hypothalamus medulla, cerebellum, and spinal cord in
each case. The rats in the timecourse group were ip injected with MnCl2 (50 mg MnCl2/kg) and then monitored 12, 24, 48, and 72 h after exposure. The Mn accumulated in the frontal cortex, corpus callosum, hippocampus,
striatum hypothalamus, medulla, cerebellum, and spinal cord after these periods of time, In both the dose—effect and time-course
studies, we observed that the concentration of malondialdehyde, an end product of lipid peroxidation, increased significantly
in the frontal cortex, hippocampus, striatum, hypothalamus, medulla, and cerebellum. However, no relationship between the
concentrations of Mn in the brain and the extent of lipid peroxidation was observed. In addition, we found that there was
a significant increase (p<0.05) in the level of Fe in the hippocampus, striatum, hypothalamus, medulla, and cerebellum, but the Cu and Zn levels had
not changed significantly. These findings indicated that Mn induces an increase in the iron level, which provides direct evidence
for Fe-mediated lipid peroxidation in the rats' brains; these phenomena might play important roles in the mechanisms of Mn-induced
neurotoxicology. 相似文献
3.
Hirotaka Chaki Akihiko Matsuda Kenji Yamamoto Yukifumi Kokuba Mikiko Kataoka Yasuhisa Fujibayashi Tsuyoshi Matsuda Kazutaka Yamamoto 《Biological trace element research》1998,63(1):37-50
In this study, we report on the influence of trace elements (TE) on signal intensities of nuclear magnetic resonance images
(MRI), both in vivo and in vitro. Optimal parameters for the assessment of Mn concentration in the brain of rats on total
parenteral nutrition were established.
For the in vitro study, Mn and trace element solutions, one containing Zn, Cu, Fe, and I (TE-4) and another containing the
above elements plus Mn (TE-5), were diluted with physiological saline or with rat brain homogenate and used to measure signal
intensities in MRI. Concentration-dependent signal hyperintensity was observed in both cases in the Mn and the TE-5 solutions,
but no effect was observed with the TE-4 solution. The signal increase was greater for brain tissue homogenates.
In the in vivo study, the experimental animals were maintained under total parenteral nutrition (TPN) with a standard clinical
dose of TE-5 and/or with 10-fold the clinical dose of TE-4 and TE-5 for 1 wk. Only rats that were receiving the increased
TE-5 dose showed signal hyperintensity on MRI. Positive correlations were observed among the signal hyperintensity, the blood
Mn concentrations, and that of the rat brain.
Our results suggest that Mn in TE preparations may be the cause of signal hyperintensity on MRI in a concentration-dependent
fashion, and that MRI and measurement of blood Mn may be used to estimate Mn accumulation in brain tissue. 相似文献
4.
Peter R. Shepherd Clint Elwood Paul D. Buckley Leonard F. Blackwell 《Biological trace element research》1992,32(1-3):109-113
The nature of the dietary component responsible for adipocytes having the ability to respond to Glucose Tolerance Factor (GTF)
was investigated. Rats were raised on either a control diet or one of three diets differing only in the protein source (torula
yeast, brewer's yeast, or casein). Only in adipocytes from rats fed the torula yeast diet did a GTF fraction prepared from
brewer's yeast potentiate the action of suboptimal concentrations of insulin in the incorporation of label fromd-[1-14C]-glucose andd-[U-14C]-glucose into CO2 and fatty acids. It was concluded that this potentiation was not the result of a deficiency of GTF activity in torula yeast,
because a GTF fraction prepared from torula yeast had similar insulin potentiating activity. Differences in response among
diets were not owing to differences in levels of amino acids or owing to concentrations of 22 (Al, As, B, Ca, Cd, Co, Cr,
Cu, Fe, K, Mg, Mo, Na, Ni, P, Pb S, Se, Si, Sn, Sr, Zn) of the 23 trace elements investigated. The level of Mn, was low in
all diets, but particularly low in the torula yeast diet. Mn deficiencies have previously been implicated in perturbations
of glucose metabolism, so that it is possible that this deficiency may be responsible for the effects attributed to the torula
yeast diet. 相似文献
5.
Malthankar GV White BK Bhushan A Daniels CK Rodnick KJ Lai JC 《Neurochemical research》2004,29(4):709-717
Manganese (Mn) is a trace metal required for normal growth and development. Manganese neurotoxicity is rare and usually associated with occupational exposures. However, the cellular and molecular mechanisms underlying Mn toxicity are still elusive. In rats chronically exposed to Mn, their brain regional Mn levels increase in a dose-related manner. Brain Mn preferentially accumulates in mitochondria; this accumulation is further enhanced with Mn treatment in vivo. Exposure of mitochondria to Mn in vitro leads to uncoupling of oxidative phosphorylation. These observations prompted us to investigate the hypothesis that Mn induces alterations in energy metabolism in neural cells by interfering with the activities of various glycolytic and TCA cycle enzymes using human neuroblastoma (SK-N-SH) and astrocytoma (U87) cells. Treatments of SK-N-SH and U87 cells with MnCl2 induced cell death in these cells, in a concentration- and time-dependent manner, as determined by MTT assays. In parallel with the Mn-induced, dose-dependent decrease in cell survival, treatment of these cells with 0.01 to 4.0 mM MnCl2 for 48 h also induced dose-related decreases in their activities of hexokinase, pyruvate kinase, lactate dehydrogenase, citrate synthase, and malate dehydrogenase. Hexokinase in SK-N-SH cells was the most affected by Mn treatments, even at the lower range of concentrations. Mn treatment of SK-N-SH cells affected pyruvate kinase and citrate synthase to a lesser extent as compared to its effect on other enzymes investigated. However, citrate synthase and pyruvate kinase in U87 cells were more vulnerable than other enzymes investigated to the effects of Mn. The results suggest the two cell types exhibited differential susceptibility toward the Mn-induced effects. Additionally, the results may have significant implications in flux control because HK is the first and highly regulated enzyme in brain glycolysis. Thus these results are consistent with our hypothesis and may have pathophysiological implications in the mechanisms underlying Mn neurotoxicity. 相似文献
6.
A particle-induced X-ray emission (PIXE) analysis method is presented, which allows measurement of eight elements (i.e., K,
Ca, Mn, Fe, Cu, Zn, Se, and Rb) in human brain samples of only a few mg dry weight. The precision and accuracy of the method
were investigated by analyzing animal brain matter with both PIXE and instrumental neutron activation analysis (INAA). The
method was applied to measure the 8 elements in 46 different regions of 3 human brains. The sections analyzed originated from
either the left or the right cerebral hemisphere, brain stem, and cerebellum. For one of the brains, sections were also analyzed
from 26 corresponding regions of both hemispheres. For all elements, similar concentrations were found in the corresponding
areas of the left and right sides of the brain. The concentrations (in μg/g dry weight) of the elements K, Fe, Cu, Zn, Se,
and Rb were consistently higher in cortical structures than in white matter. Deep nuclei and brain stem, which have a mixed
composition, showed intermediate values for K, Zn, Se, and Rb. A hierarchical cluster analysis indicated that the various
brain regions clustered into two large groups, one comprising gray and mixed matter regions and the other, white and mixed
matter brain areas. 相似文献
7.
Summary Solution calcium concentrations required for the growth of a range of plant species, including both monocotyledons and dicotyledons,
were determined in two experiments in which plants were grown in flowing solution culture at constantly maintained calcium
concentrations ranging from 0.5 to 3000 μM. Calcium chloride was used as the calcium source in the first experiment, calcium sulphate was used in the second.
At calcium concentrations of 10 μM and below, all species developed calcium deficiency symptoms. The severity of the deficiency was more pronounced in the dicotyledons
than in the monocotyledons. However, cassava was much more tolerant than all other dicotyledons and equally as tolerant as
rice, the most tolerant monocotyledon.
Solution calcium concentrations required for 90% of maximum yield were generally lower for monocotyledons (3 to 20 μM) than for dicotyledons (7 to 720μM) when calcium chloride was used as the calcium source. When calcium sulphate was used, 7 out of 11 species, including 3 monocotyledons,
required external calcium concentrations of 1200 μM and above. The results are discussed in relation to effects of solution composition and the choice of counter-ions on plant
response to calcium and other macronutrient cations. It is concluded that yield depressions due to toxicity of excesses of
chloride, and possibly other counter-ions, can lead to serious underestimation of limiting external cation concentrations
for plant growth. 相似文献
8.
Laurent Noël Céline Huynh-Delerme Thierry Guérin Hélène Huet Jean-Marc Frémy Martine Kolf-Clauw 《Biometals》2006,19(5):473-481
The influence of long-term exposure to cadmium (Cd) on essential minerals was investigated using a Caco-2 TC7 cells and a
multi-analytical tool: microwave digestion and inductively coupled plasma mass spectrometry. Intracellular levels, effects
on cadmium accumulation, distribution, and reference concentration ranges of the following elements were determined: Na, Mg,
Ca, Cr, Fe, Mn, Co, Ni, Cu, Zn, Mo, and Cd. Results showed that Caco-2 TC7 cells incubated long-term with cadmium concentrations
ranging from 0 to 10 μmol Cd/l for 5 weeks exhibited a significant increase in cadmium accumulation. Furthermore, this accumulation was more marked
in cells exposed long-term to cadmium compared with controls, and that this exposure resulted in a significant accumulation
of copper and zinc but not of the other elements measured. Interactions of Cd with three elements: zinc, copper, and manganese
were particularly studied. Exposed to 30 μmol/l of the element, manganese showed the highest inhibition and copper the lowest on cadmium intracellular accumulation
but Zn, Cu, and Mn behave differently in terms of their mutual competition with Cd. Indeed, increasing cadmium in the culture
medium resulted in a gradual and significant increase in the accumulation of zinc. There was a significant decrease in manganese
from 5 μmol Cd/l exposure, and no variation was observed with copper. 相似文献
9.
The influence of dietary copper, iron, and ascorbic acid on iron utilization was examined in a 2×2×2 factorial experiment.
Male Sprague-Dawley weanling rats were fed copper-deficient (Cu-, 0.42 μg Cu/g) or copper-adequate (Cu+, 5.74 μg Cu/g) diets
that contained one of two levels of iron (38 or 191μg Fe/g) and ascorbic acid (0 or 1% of the diet). These eight diets were
fed for 20 d, and rats received an oral dose of 4 μCi iron-59 on d 15. Compared to Cu+ rats, the Cu− rats had 27% lower hemoglobin
levels with 45, 59, and 65% lower cytochrome c oxidase (CCO) activities in the liver, heart, and bone marrow, respectively
(p<0.0001). High dietary iron or ascorbic acid did not alter hemoglobin in Cu+ rats. However, hemoglobin was 23% lower in Cu−
rats fed the highest, rather than the lowest levels of iron and ascorbic acid. Liver CCO was decreased (p<0.02) in Cu− rats fed high iron. Among Cu− rats, ascorbic acid did not influence CCO but decreased hemoglobin by 17% (p<0.001), reduced the percentage of absorbed iron-59 in the erythrocytes by 91% (p<0.05) and depressed the percentage apparent absorption of iron (p<0.05). These results suggest that the effects of elevated dietary iron and ascorbic acid on iron utilization are influenced
by copper status. 相似文献