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1.
Giorgio Brandi Giuditta F. Schiavano A. Albano Flaminio Cattabeni Orazio Cantoni 《Biological trace element research》1989,21(1):271-275
Treatment with 16 μM K2Cr2O7 results is a time-dependent loss of the clonogenicity ofE. coli cells. Under the same experimental conditions, optical density values do not change significantly, since cells have the ability
to replicate but not to septate. In fact, microscopic analysis of samples taken over 240 min of exposure to the toxin has
revealed the formation of filaments. The filamentous response appears similar to that generated by mitomycin C. 相似文献
2.
Nickel is a potent carcinogen and, at high concentrations, is toxic to mammalian cells. The effects associated with nickel
exposure are well-documented but its mechanism of action in the cell has not yet been fully described. In order to understand
the metabolic fate of nickel in mammalian cells, a variant cell population has been selected that continues to grow and divide
in the presence of nickel chloride concentrations that are toxic to the parental cell line (Balb/c-3T3 mouse fibroblasts).
Nickel resistance is not caused by altered uptake of nickel from the medium or increased clearance from the cells and is not
associated with changes in metallothionein expression. Compared to the normal cells, the nickel resistant cells have a decreased
number of chromosomes and numerous centromeric fusions. The expression of some proteins and the distribution of nickel bound
by various proteins are altered in the nickel resistant cells. Preliminary results indicate that the nickel resistant phenotype
may be transferred by genomic DNA-mediated transfection into a recipient NIH-3T3 cell line. Current investigations are directed
at identifying a gene responsible for nickel resistance. 相似文献
3.
The transformation of a rat liver epithelial cell line under a wide range of doses of chromium was determined by anchorage-independent
growth and tumor formation in syngeneic animals. Chronic exposure to low concentrations and brief exposure to high concentrations
of hexavalent chromium (K2CrO4) transformed the cells, but one dose (1 mM K2CrO4, 2h) was clearly optimal in this regard. The cytotoxicity, effects on cell cycle, rates of chromium uptake, and mutagenic
activity under the different treatment conditions were evaluated. The results showed that cells could adapt to the presence
of chromium under certain treatment conditions, but this was not the case for the optimal transforming dose. Cells treated
with chromium above the optimal transforming dose showed evidence of a transient G2 arrest, whereas all lower levels of treatment
did not. A low level continuous exposure to chromate was mutagenic, whereas high level short exposures, including the optimal
transforming dose, were not. An increase in the amount of protein complexed with isolated nucleic acids was detected in cells
following treatment with the optimal transforming dose of chromate. The results indicate that the effects of chromium on this
in vitro system vary with dose; and the identification of those events relevant to metal carcinogenesis will require consideration
of treatment conditions. 相似文献
4.
Nickel ions produce selective damage in heterochromatic regions of chromosomes. Male Chinese hamster embryo cells, which have
heterochromatin along the entire long arm of the X-chromosome, exhibit an unusually high incidence of nickel-induced transformation
compared with female cells of the same species. However, 3-methylcholanthrene, a carcinogen that produces a random distribution
of chromosome damage, transforms female and male cells equally. Other species that do not have as much heterochromatin on
the X-chromosome exhibit similar incidences of nickel-induced tumors in males and females. Four out of five of the male nickel-transformed
Chinese hamster cell lines exhibit a deletion of the heterochromatic long arm of the X-chromosome as the only common karyotypic
aberration. This result indicates that a deletion of a heterochromatic chromosomal region may be an important feature of the
nickel-induced carcinogenic process. All of the male nickel transformed cells lines are able to form tumors in athymic nude
mice. 相似文献
5.
6.
The accumulation of Cd in the kidneys is enhanced markedly if chelating agents that contain SH-groups like 2,3 dimercaptopropanol
(BAL) are injected immediately after the metal. This is not a transient effect but persists for more than 3 d. It is less
pronounced at higher chelate doses or when the pH of urine is increased. Our experiments indicate that chelating agents, which
form unstable complexes at acid pH and are able to pass through the cell membrane, will cause metal accumulation in the kidneys. 相似文献
7.
Seema Mathur 《Biological trace element research》1994,41(3):201-215
An ayurvedic medicine, Liv-52, was studied as a prophylactic agent against beryllium-induced toxicity in rats. Administration
of berylliumper se caused severe degenerative and necrotic changes in kidneys, liver, and uterus. Beryllium exposure also reduced glycogen content,
activities of alkaline phosphatase, succinate-dehydrogenase, and adenosine-triphosphatase in these organs. On the contrary,
activities of acid phosphatase and glucose-6-phosphatase showed marginal increase. Liv-52-primed rats exhibited comparatively
less marked toxic effects. 相似文献
8.
U. Nannmark G. Blomqvist M. Braide B. R. Johansson U. Bagge 《Cell biochemistry and biophysics》1990,17(2):153-161
Earlier studies have shown a lower degree of lodgement and early survival of tumor cells in muscle than in liver after infusion
via the femoral artery and portal vein, respectively. A possible explanation to this difference might be that the tumor cells
are mechanically destroyed, and thus die more rapidly in muscle because they enter this capillary network at a much higher
flow velocity. In the present study, the effect on early tumor cell (rat fibrosarcoma) survival of a high and a low flow velocity/deformation
rate was evaluated in micropore (5 μm) filters, using isotope (Cr51) technique. These experiments were combined with scanning electron microscopic (SEM) analyses. The filter experiments showed
no significant differences in the rate of cell death in the filters between tumor cells subjected to high or low deformation
rates, and there were no qualitative differences in tumor cell appearance in the SEM study. It is, therefore, concluded that
the difference in tumor cell lodgement and survival between muscle and liver is not primarily caused by differences in the
rate of cell deformation upon entry of the organ capillary network. 相似文献
9.
This article describes the technique of immobilized metal ion affinity chromatography (1MAC). The IMAC stationary phases are
designed to chelate certain metal ions that have selectivity for specific groups in peptides and on protein surfaces. The
number of stationary phases that can be synthesized for efficient chclation of metal ions is unlimited, but the critical consideration
is that there is enough exposure of the metal ion to interact with the proteins, preferably in a biospecific manner. The versatility
of IMAC is one of its greatest assets. An important contribution to the correct use of IMAC for protein purification is a
simplified presentation of the various sample elution procedures. 相似文献
10.
11.
Ralf Kemkemer Cornelia Neidlinger-Wilke Lutz Claes Hans Gruler 《Cell biochemistry and biophysics》1999,30(2):167-192
Cells like fibroblasts and osteoblasts are oriented by different extracellular guiding signals like an electric field, a bent surface, and a periodically stretched surface. An automatic controller is responsible for the cell alignment. The controller contains both a deterministic and a stochastic signal. The following machine properties were determined: (1) The angle dependence of the cellular signal transformer is cos 2(psi 0 - psi). (2) The set point of the automatic controller is psi 0 = +/- 90 degrees. The cells like to orient their long axis perpendicular to the direction of the applied guiding signal. (3) The signal transformer measures the extracellular signal in a quadratic fashion. The cells cannot register the sign of the guiding field. (4) The stochastic signal in the automatic controller can be quantified by a characteristic time (approximately 130 min for fibroblasts). (5) The extracellular signal is registered in cell-made standards (ratio of the deterministic and stochastic signal equals one): 0.3 +/- 0.05 V/mm for human fibroblasts (electric field) and 85 +/- 3 microns for human fibroblasts and osteoblasts (cyclindrically bent surface). (6) The lag-time in the signal transduction system of fibroblasts is approximately 4 min. 相似文献
12.
Bode Peter de Bruin Marcel Oldenburg Siewart van der Wiel Albert Wolterbeek Bert 《Biological trace element research》1990,(1):111-118
A double label procedure with57Co and58Co has been developed for detailed in vivo studies of erythrocyte survival. A well-type Ge detector is used in the measurements.
The activities necessary for these experiments are very low, and the associated dose received by the test persons can be neglected. 相似文献
13.
Arsenic compounds are known carcinogens. Although many carcinogens are also mutagens, we have previously shown that sodium
arsenite is not mutagenic at either the Na+/K+ ATPase orhprt locus in Chinese hamster V79 cells. It can, however, enhance UV-mutagenesis. We now confirm the nonmutagenicity of sodium
arsenite in line G12, a pSV2gpt-transformed V79 (hprt
−) cell line, which is able to detect multilocus deletions in addition to point mutations and small deletions. The lack of
arsenic mutagenicity has led to studies emphasizing its comutagenicity. Sodium arsenite at relatively nontoxic concentrations
(5 μM for 24 h or 10 μM for 3 h) is comutagenic withN-methyl-N-nitrosourea (MMU) at thehprt locus in V79 cells. Using a nick translation assay, which measures DNA strand breaks by incorporating radioactive deoxyribonucleoside
monophosphate at their 3′OH ends in permeabilized cells, we found that much more incorporation was seen in cells treated with
MNU (4 mM, 15 min) followed by 3-h incubation with 10 μM sodium arsenite compared with cells exposed to the same MNU treatment followed by 3-h incubation without sodium arsenite.
This result shows that in the presence of arsenite, strand breaks resulting from MNU or its repair accumulate over a 3-h period.
We suggest that the repair of MNU-induced DNA lesions may be inhibited by arsenite either by affecting the incorporation of
dNMPs into the MNU-damaged DNA template or by interfering with the ligation step. 相似文献
14.
A rapid cyclic instrumental neutron activation analysis (CINAA) method has been used to determine the selenium content of
27 duplicate diet samples from each of the 27 districts surrounding Pinhel, Portugal. The accuracy and precision of the CINAA
method have been evaluated by analyzing certified reference materials and observed to be within ±5–10% for samples containing
at least 40 ppb of selenium. The detection limit has been found to vary between 26–42 ppb selenium depending on the sample
composition. The average daily dietary intake has been calculated as 37 μg of selenium per day. 相似文献
15.
We studied in the rat the effects of the drug etretinate (Tigason), given at three doses 3, 10, and 30 mg/kg body wt for 1 mo, on the concentrations of Na, K, Ca, Mg, Fe, S, P, Cu, and Zn in the plasma, brain, thymus, heart, liver, lung, kidney, testicle, muscle, and bone. The elements were simultaneously determined in tissues after nitric acid dissolution by inductively coupled plasma emission spectrometry using a JY 48 instrument. At the dose of 3 mg/kg, etretinate did not induce any statistically significant modifications of the element distribution. At the dose of 10 mg/kg, the main observed modifications were in plasma an increase of copper (+38%) and a decrease of zinc (-25%). At the highest dose of 30 mg/kg, some variations of the concentrations of elements in tissues were observed. But, on no account did retinoids induce an alteration of the mineral composition of bone, despite obvious macroscopic bone alterations. 相似文献
16.
Most of the cancer cells arrested in the microcirculation during hematogenous metastasis are rapidly killed; one major mechanism is surface-membrane rupture, associated with the mechanical deformation of cancer cells in capillaries. The feasibility of increasing the susceptibility of cancer cells to lethal, deformation-associated trauma by doxorubicin, was tested in an in vitro mechanical model system, by filtering suspensions of L1210 leukemia cells through 8-μm pore-size Nuclepore® membranes, with or without prior incubation with 10-7M doxorubicin. The results showed that mechanically-induced loss of cancer cells immediately after filtration was increased from 18 to 55% in cells previously exposed to doxorubicin for 48 h. The results indicate the feasibility of chemotherapeutic enhancement of the mechanical killing-action of the microvasculature as a potential rate-regulator of hematogenous metastasis. 相似文献
17.
Al-Jobori S. M. Shihab K. M. Jalil M. Saad A. Mohsin A. 《Biological trace element research》1990,(1):637-645
INAA has been used for the determination of Na, Mg, Al, Cl, K, Sc, Cr, Mn, Fe, Co, Cu, Zn, As, Se, Br, Rb, Sr, Mo, and W in
grains of rice, wheat, and barley, which were collected from different plant fields in Iraq. Samples and standards were irradiated
in the IRT-5000 reactor, at neutron fluxes of 2 × 1013 cm−2·s−1 and 3.2 × 1011 cm−2·s−1. Interferences of photopeaks with each other were considered, and reaction interferences were calculated and determined experimentally.
Accuracy of our method was assessed by the analysis of IAEA standards Wheat Flour and Bovine liver. A good agreement has been
achieved between the present results and recommended values. The precision and detection limit were determined for all elements
in all types of grain. 相似文献
18.
The effectiveness of a cupruretic agent, N,N'-bis-(2 amino ethyl)-1,3-propanediamine HCl or 2,3,2-tetramine HCl (TETA), in the induction of copper (Cu) deficiency and the ability of a Cu-deficient diet in the maintenance of the depressed Cu status 10 wk after TETA treatment were examined in this study. In the first experiment, 42 male New Zealand White rabbits, 35 d of age, were randomly divided into three dietary treatments: a copper (Cu)-deficient (2.3 mg Cu/kg diet), a Cu-adequate (13.5 mg Cu/kg diet), and a commercial ration (21.6 mg Cu/kg diet) group. A single oral dose of 100 mg of 2,3,2-tetramine HCl TETA/kg body wt/d were administered to half of the rabbits from each treatment group for 10 d while the remaining rabbits were untreated. In the second experiment, 10 similar rabbits were assigned to three treatments: Cu-deficient plus TETA (n = 4); Cu-adequate plus TETA (n = 3); and Cu-adequate alone (n = 3). The rabbits were fed a TETA dose of 100 mg/d for three 4-d periods over 3 wk, and thereafter maintained on the diets for another 10 wk. Rabbits from the first experiment fed Cu-deficient diet and treated with TETA demonstrated cardiac hypertrophy and markedly reduced plasma and liver Cu concentrations that indicated that the animals were Cu-deficient. Significant elevations (twofold) in low density lipoprotein (LDL) protein, cholesterol, triglyceride, and apolipoprotein B (apo B) concentrations were observed in TETA treated rabbits fed Cu-deficient diet. In the second experiment, the plasma LDL protein level remained elevated, the plasma Cu level was reduced 45%, and the Cu level of the heart when expressed as microgram/g dry tissue was reduced, 10 wk post TETA treatment in rabbits maintained on Cu-deficient diet. Thus, Cu deficiency and hyperlipoproteinemia was rapidly induced by TETA and was still evident 10 wk posttreatment in rabbits maintained on a Cu-deficient diet. 相似文献
19.
The neurotoxic effects of Manganese (Mn) are well known, and are usually caused by high occupational exposure over long periods
of time. The effects caused by low doses of this metal have been poorly evaluated. For this reason, we decided to evaluate
neuroendocrinal tests in a group of 14 male workers employed in a ferrousmanganese foundry (exposed to Mn air concentrations
within the TLV-TWA) and in 14 male control subjects, by analyzing FSH, LH, prolactin, and cortisol. The urinary Mn, prolactin,
and cortisol levels were significantly higher in the worker’s group. The preliminary results of this research seem to show
that for exposure below the TLV, Mn can somehow interfere with the neuroendocrine system. In order to confirm the existence
of these effects and to verify their possible correlation with the dopaminergic control system, further studies are necessary. 相似文献
20.
Application of general tracer theory to the problem of estimating fluxes of tracee between the gastrointestinal tract and
the body proper, from observations of the movement of tracer, shows that a number of assumptions must be fulfilled. Two specific
sets of assumptions are discussed and, in both cases, measurement of tracer fluxes yields information on the integrated absorption
of the tracee. 相似文献