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1.
The transport of vanadium across placenta and milk rats was studied by iv injection of low doses of 48V-labeled pentavanadate (0.1 micrograms V/rat) to pregnant and nursing rats. Significant concentrations of vanadium were found in the liver, intestine, and kidneys of the fetuses, showing that vanadium is capable to pass the placental barrier and, thus, being metabolized in the fetuses. Two days after injection of 0.1 micrograms V/rat as 48V-labeled vanadate to nursing rats, 34 ng V/g milk were found, decreasing to 4 ng V/g at the d 12 after dosing. The corresponding suckling rats showed a significant absorption of vanadium taken up by the milk, as suggested by the presence in their intestine, where 48V is easily absorbed in form of low molecular weight components. Vanadium in milk may be transported in the form of a biocomplex with lactoferrin, since at 12 d after injection, the 48V in the rat milk was mainly found in fractions corresponding to proteins. In weanling rats, 7 d postlactation and 18 d after administration of vanadium to the mother, only very small amounts of 48V were still present in the organs. Excretion studies on weanling rats for 7 d showed that vanadium is rapidly released mainly via feces when earlier taken up by the milk of iv injected mothers and having the same elimination pattern as the milk, which lost about 80% of its vanadium concentration after 12 d. 相似文献
2.
Vanadium was determined by radiochemical neutron activation analysis (RNAA) with proven accuracy in urine of workers occupationally
exposed to vanadium-rich dust in a vanadium pentoxide production plant, and values in the range of 3.02–762 ng/mL (median
33.0 ng/mL) were found. In a control group consisting of administrative workers of the plant, urinary vanadium levels were
found in the range of 1.05–53.4 ng/mL (median 2.53 ng/mL), whereas in an another control group of occupationally nonexposed
persons, these values amounted to 0.066–0.489 ng/mL (median 0.212 ng/mL).
Accuracy of the results was tested by analysis of reference material IAEA A-13 Animal Blood and NIST SRM-1515 Apple Leaves,
and very good agreement was found with literature and the NIST certified values, respectively. Unlike urine, no significant
differences were found for cystine levels in fingernails and hair of exposed and control persons. 相似文献
3.
Maria C. Apella Silvia N. González Enrique J. Baran 《Biological trace element research》1988,18(1):123-130
The inhibitory effect of vanadate species on the enzymatic activity of bovine copper-zinc superoxide dismutase has been investigated
at different pH values and vanadium concentrations. A definite inhibitory effect, clearly related to the main negative charge
of each of the vanadate solutions, has been found. The results suggest that the origin of the inhibitory effect may be similar
to that found for the phosphate ion, i.e., a diminution of the effectiveness of the substrate electronic guidance mechanism
by partial neutralization of the charges close to the active site. Under physiological conditions, the inhibitory effect of
vanadate is somewhat smaller than the phosphate. 相似文献
4.
Multivariate statistical analysis has been applied to time series measurements of aerosol elemental composition from PIXE
analysis of filter samples, and principal components have been resolved that represent distinct particle types in an external
mixture in the atmosphere. In this study, it is argued that a combination of chemical and statistical analyses of the data
may be more powerful in determining chemical species in atmospheric aerosols than studies that employ mainly direct chemical
analysis of chemical species in unresolved mixtures of aerosol particle samples. Sulfur is generally associated with mineral
dust elements. It is reasoned that the association may represent sulfuric acid coatings on particles that can lead to mineral
dissolution and solubilization of significant amounts of aluminum, iron, and other metals.
Upon wet or dry deposition to the surface, the fluxes of these metals in biologically-available form may be sufficient to
affect primary productivity in the world ocean and cause ecological damage in lakes. As a consequence, the fluxes of biogenic
trace gases to the atmosphere may be changed, possibly leading to changes in the tropospheric concentration of ozone. The
inputs to lakes of soluble aluminum, which is toxic to fish, may be partly by deposition directly from the atmosphere, thus
not limited to leaching of soils by acid deposition. Human inhalation of soluble aluminum and other solulilized mineral metals
may account, in part, for the observed geographic pattern of deaths attributed to chronic obstructive pulmonary disease (COPD)
that show high rates in cities of the Western US and the southeast region, but low in most of the midwest and northeast. 相似文献
5.
The phosphorus NMR profile of normal and vanadium-treated chick muscle was obtained in vivo. The data show that the differentiation
of breast and thigh muscles in terms of pH, lipid related metabolites, and bioenergetic parameters can be readily followed.
Although the vanadium-treated chicks showed substantial retardation of growth, the only NMR parameter that was significanty
affected by dietary vanadium was the pH of breast muscle, which was substantially more acidic in the vanadium-treated animals. 相似文献
6.
7.
The first successful freezing of early embryos to −196°C in 1972 required that they be cooled slowly at ∼1°C/min to about
−70°C. Subsequent observations and physical/chemical analyses indicate that embryos cooled at that rate dehydrate sufficiently
to maintain the chemical potential of their intracellular water close to that of the water in the partly frozen extracellular
solution. Consequently, such slow freezing is referred to as equilibrium freezing. In 1972 and since, a number of investigators
have studied the responses of embryos to departures from equilibrium freezing. When disequilibrium is achieved by the use
of higher constant cooling rates to −70°C, the result is usually intracellular ice formation and embryo death. That result
is quantitatively in accord with the predictions of the physical/chemical analysis of the kinetics of water loss as a function
of cooling rate. However, other procedures involving rapid nonequilibrium cooling do not result in high mortality. One common
element in these other nonequilibrium procedures is that, before the temperature has dropped to a level that permits intracellular
ice formation, the embryo water content is reduced to the point at which the subsequent rapid nonequilibrium cooling results
in either the formation of small innocuous intracellular ice crystals or the conversion of the intracellular solution into
a glass. In both cases, high survival requires that subsequent warming be rapid, to prevent recrystallization or devitrification.
The physical/ chemical analysis developed for initially nondehydrated cells appears generally applicable to these other nonequilibrium
procedures as well. 相似文献
8.
Yan G. Zorbas Mitsui A. Sokiguchi Olav A. Johanson Youri F. Federenko 《Biological trace element research》1995,48(2):185-196
The objective of this study was to evaluate the effects of hypokinesia (HK) and fluid- and salt supplementation (FSS) on zinc
metabolism in endurance-trained volunteers (ETV) for a period of 364 d. Thirty long-distance runners aged 22–25 yr with a
peak VO2 of 67 mL/min/kg with an average 13.8 km/d running distance were chosen as subjects. They were equally divided into three
groups:
Throughout the duration of the study, groups 2. and 3. were maintained under an average running distance of 2.7 km/d, whereas
group 1. did not experience any modifications to their normal training routines and diets. Prior to and during the experimental
period, plasma volume, hemoglobin, sodium, potasium, hematocrit, osmolality, and protein concentrations were determined along
with the concentrations and urinary excretions of zinc, magnesium, calcium, and phosphorous. During the HK period, plasma
concentrations of these minerals increased significantly when compared to the HK+FSS and control groups. The same was observed
for the remaining parameters, which led us to conclude that during prolonged restriction of muscular activity, (PRMA) the
body of the HK+FSS volunteers acquire an apparent tendency to retain zinc, whereas in the HK group the opposite is observed. 相似文献
1. | Controls; |
2. | HK subjects; and |
3. | HK+FSS subjects. |
9.
Roles of iron in neoplasia 总被引:5,自引:0,他引:5
Eugene D. Weinberg 《Biological trace element research》1992,34(2):123-140
Research and clinical observations during the past six decades have shown that: 1. Iron promotes cancer cell growth; 2. Hosts attempt to withhold or withdraw iron from cancer cells; and 3. Iron is a factor in prevention and in therapy of neoplastic disease. Although normal and neoplastic cells have similar qualitative requirements for iron, the neoplastic cells have more flexibility in acquisition of the metal. Excessive iron levels in animals and humans are associated with enhanced neoplastic cell growth. In invaded hosts, cytokine-activated macrophages increase intracellular ferritin retention of the metal, scavenge iron in areas of tumor growth, and secrete reactive nitrogen intermediates to effect efflux of nonheme iron from tumor cells. Procedures associated with lowering host intake of excess iron can assist in prevention and in management of neoplastic disease. Chemical methods for prevention of iron assimilation by neoplastic cells are being developed in experimental and clinical protocols. The antineoplastic activity of a considerable variety of chemicals, as well as of radiation, is modulated by iron. The present article focuses on recent findings and suggests directions for further cancer-iron research. 相似文献
10.
Theodor Günther Jürgen Vormann Jamaledin Ghaida 《Biological trace element research》1989,20(3):243-249
Application of salicylate increased the concentration of metallothionein (MT) in liver of pregnant rats as well as of adult male rats, whereas in fetal liver, MT was reduced by salicylate. Induction of MT synthesis by salicylate is an indirect effect because in cultured hepatocytes salicylate did not induce MT synthesis. Salicylate increased MT also in adrenalectomized rats. Indomethacin induced the same concentration of MT in maternal liver as salicylate. However, indomethacin had no effect on MT in fetal liver. Induction of MT in adult liver by salicylate and indomethacin was independent of zinc. 相似文献
11.
Ojo J. O. Oluwole A. F. Durosinmi M. A. Asubiojo O. I. Akanle O. A. Spyrou N. M. 《Biological trace element research》1994,(1):453-459
Elemental concentrations in head hair and blood (whole-blood, erythrocytes and plasma) of 28 Nigerian subjects were determined
using instrumental neutron activation analysis (INAA) and proton-induced X-ray emission (PIXE) techniques. Correlations found
between different elements in hair and blood are reported. Hair levels of both zinc and chlorine were found to be significantly
correlated with their levels in erythrocytes. 相似文献
12.
The mode of action of nerve growth factor in PC12 cells 总被引:9,自引:0,他引:9
This review deals with the mechanism of nerve growth factor action. In view of the many and diversified effects of this growth factor, and since it could utilize different mechanism(s) in distinct types of cells, we have confined our analysis to the best characterized and more extensively studied target, the clonal cell line PC12. When exposed to NGF in vitro, these neoplastic cells recapitulate the last major steps of neuronal differentiation, i.e., the commitment to become a neuron and the acquisition of the neuronal phenotype. This is characterized by electrically excitable neurites, a display of a highly organized cytoskeleton, and the specific chemical and molecular neuronal properties. These effects are elicited upon the interaction of NGF with a receptor whose gene has been cloned and whose kinetic properties are now relatively well characterized. It is not yet clear, on the contrary, if and which of the several potential second messengers (cAMP, Ca, or phosphoinositides) that undergo marked fluctuations following NGF binding, transduce and amplify the NGF message. Among both the early and late effects of NGF is the modulation of expression of several genes. Some of the products of these genes are mainly restricted to nerve cells and others appear to play a crucial role in regulating the proper assembly of cytoskeletal elements. It is hypothesized that this complex array of chemical, molecular, and ultrastructural changes is triggered by NGF, not through activation of a single pathway, but more likely via combinatorial processes whereby several intracellular signals interplay before the irreversible commitment of becoming a neuron is undertaken. 相似文献
13.
Changes of concentrations of the elements Co,Cr, Sb,and Sc in tissues of persons with joint implants
Schnabel C. Herpers U. Michel R. Löer F. Buchhorn G. Willert H. -G. 《Biological trace element research》1994,(1):389-395
Elevated levels of Co and Cr were found in several organs of deceased implant bearers (CoCr-alloy/polyethylene joint prostheses)
by means of instrumental and radiochemical neutron activation analysis as compared to normal persons. For comparative purposes,
concentrations of the elements Co, Cr, Sb, and Sc were measured in heart, kidney, liver, and spleen of the patients and normal
persons. For Cr determination, a new radiochemical separation technique with sufficiently low determination limit was employed.
The importance of such investigations for studying possible carcinogenic effects of corrosion products and wear particles
of metallic prostheses is mentioned. 相似文献
14.
Temporal changes in tissue glutathione in response to chemical form,dose, and duration of selenium treatment 总被引:1,自引:0,他引:1
Selenium has been reported to affect glutathione (GSH) concentrations in short-term animal-feeding experiments. Given the central role that this tripeptide plays in maintaining cellular homeostasis, it was hypothesized that perturbations in glutathione metabolism induced by selenium might account for its cancer chemopreventive activity. In the present study, four experiments were conducted in which the effect of acute, short-, or long-term exposure to selenium was assessed. Selenium was provided as either sodium selenite or D,L-selenomethionine. Selenite was observed to induce a biphasic response in total liver GSH. Injected selenium caused an acute reduction in GSH, whereas short-term feeding (up to 8 wk) increased both total GSH and oxidized glutathione (GSSH), an effect that gradually diminished in magnitude with prolonged feeding. Our data suggest that such changes are unlikely to account for the chemopreventive activity of selenium for the following reasons: Perturbations in glutathione metabolism occurred only at doses of selenite that approached toxicity. These doses are higher than what would be required for producing cancer chemoprevention. The transient nature of these changes also contrasts with the need for a continuous supplementation of selenite in suppression of tumorigenesis. Furthermore, selenomethionine was found to have little activity in altering glutathione metabolism, even though it compares favorably with selenite as a cancer chemopreventive agent. Nonetheless, these findings do not discount the possibility that sulfhydryl compounds, such as glutathione, might be used to modify the toxicity and/or enhance the cancer prophylactic activity of selenium compounds. 相似文献
15.
Yongpeng Tong Yongping Zhang Yaoliang Xu Jingyi Rui Minqian Li Cuiying Shen Zhongming Xiao Jinxin Hong 《Biological trace element research》1991,29(1):31-34
Gastric, hepatic, and pulmonary cancer cell lines, and the third passage of normal gastric and pulmonary cell lines were analyzed by proton induced X-ray emission (PIXE) method. The contents of element Sr, Ca, Fe, Zn, P, K, Cu, and As in the cell lines were determined. The Sr, Ca, Fe, Zn, and As contents in cancer cell lines were significantly lower than those in the normal cell lines (p less than 0.05), whereas there were no significant differences for the P, K, and Cu contents (p greater than 0.1). The results suggest that the need of some essential elements has been diminished in cancer cell proliferation. 相似文献
16.
The potential for commercial application of transgenic technologies in domestic animals is discussed in relation to the areas
where a significant impact on agriculture might be expected. These are the endocrine system, novel biochemical pathways, structural
proteins of milk and of textile fibers, and the immune system. Manipulation of the endocrine system has been investigated
for some years and it is clear that very accurate control is needed over gene expression if this approach is to prove commercially
useful. The area most advanced in commercial application is the production of high-value pharmaceutical proteins in the mammary
glands of domestic animals. Other applications that are discussed remain to be proven in larger animals despite being demonstrated
laboratory test animals. These include a functional cysteine biosynthetic pathway and a functional glyoxylate cycle transferred
from bacteria to mice, and alterations to the proteins of hair that change the physical properties of the resultant fibers.
Research is also actively directed toward novel approaches for providing domestic animals with resistance to insects. 相似文献
17.
An existing radiochemical NAA procedure for Cd, Co, and Cu was improved to allow determination of individual radiochemical
yields by the radioisotopic tracer technique, thus eliminating errors owing to variable recovery.109Cd was used as tracer for Cd determination via115Cd/115mIn,57Co for Co via60Co, and potentially for Ni via58Co, whereas as a novelty67Cu, produced by reactor irradiation of ZnO of natural isotopic composition (by the67Zn [n,p]67Cu reaction) was used for Cu via the indicator nuclide64Cu. The simple production and purification of67Cu by anion exchange is described. Results for biological RMs are given and discussed. 相似文献
18.
Cesia Shenberg Miriam Boazi Jacob Cohen Abraham Klein Marcus Kojler Abraham Nyska 《Biological trace element research》1994,40(2):137-149
The effect ofcis-DDP treatment with and without selenite and selenocistamine was studied on kidneys of tumor-bearing mice. The amounts ofcis-DDP, selenite, and selenocistamine injected were chosen so as to be compatible with the treatment of humans. The animals
were sacrificed at 7, 14, and 28 d after treatment. The kidneys were removed and subjected to trace element analysis by a
novel X-ray fluorescence (XRF) method and for pathological assessment. The results show that following treatment withcis-DDP, K, Fe, Cu, and Zn reach a maximum level after 7 d; K, Fe, and Cu levels were significantly reduced by the addition of
selenite. The level of Zn was reduced only in groups treated with selenite whereas that of K and Cu was reduced also in groups
treated with selenocistamine with and withoutcis-DDP. The greatest increase in Pt and Se levels was reached 1 wk after injection withcis-DDP, with and without selenocompounds, and in the case of Pt was partly reduced by addition of selenite. Se returned to control
values 2 wk after injection, although Pt was still high in all groups 2 and 4 wk after injection. The results corroborate
the findings of our previous studies. The effect of selenocistamine incis-DDP treated mice was partly insufficient. The pathological examination of the kidneys did not show any differences in the
effect of various additives during the study. 相似文献
19.
Andrási E. Nádasdi J. Molnar Zs. Bezur L. Ernyei L. 《Biological trace element research》1990,(1):691-698
A study was undertaken to determine the average values for elements in normal human brain (11 individuals, age group 65–75).
Twelve brain parts were selected from both hemispheres. Determinations were carried out by NAA and ICP-AES. The main elements
(Na, K, Mg, Ca, Fe, P, S) and trace elements (Al, B, Co, Cr, Cu, Mn, Ni, Pb, Zn) were investigated. Quality control was ensured
by using NBS Bovine Liver SRM. The results obtained with independent methods were compared, and the data show a good correlation.
On the basis of these investigations, the regional distribution of elements can be given. 相似文献
20.
This paper presents observations made on the behavior of radioactive cesium in laboratory conditions.134Cs-loaded aerosols are generated from UO2 pellets in an electric oven and allowed to deposit on small spruce trees. The transfer of radioactivity to the plants has
been studied. In another series of experiments, trees are submitted to artificial rain contaminated by the radioactive aerosols.
The two modes of contamination are compared. 相似文献