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1.
d-penicillamine (β,β-dimethylcysteine) promotes the incorporation of iron into isolated rat hepatocytes. The mechanism for
doing this remains unknown. No differences in iron distribution between control and treated cells has been observed. Ferritin
appears as the main destination of internalized iron in both cases. Therefore, increasing iron storage may appear as a side
effect of the use ofd-penicillamine as a therapeutic agent for several diseases. 相似文献
2.
Eva Kot Robin Miller-Catchpole Anatoly Bezkorovainy 《Biological trace element research》1993,38(1):1-12
Protoplasts ofBifidobacterium thermophilum were prepared by a combination of lysozyme and protease digestion, and ferrous iron uptake studies were carried out. Little,
if any, iron was internalized by the protoplasts, although large amounts of iron were bound to the protoplast surface. This
binding was much greater than that of intact cells, which prefer to internalize iron by an energy-dependent process. It was
also found that the binding of iron by protoplasts of cells grown in an iron-deficient medium was much more extensive than
that of cells grown in an iron-sufficient medium. Soluble and particulate fractions of protoplasts were prepared by grinding
them in a glass homogenizer, and the particulate fraction was also subjected to iron binding studies. The amount of iron bound
was the same as that in intact protoplasts, indicating that the particulate fraction membrane fragments bound iron on their
outer surface only. Nevertheless, when iron-preloaded cells were protoplasted and their surface cleared of iron, their particulate
fraction contained considerable amounts of iron, indicating that the inner surface of the membranes is capable of binding
iron as long as the cell is intact. The amount of iron so bound was dose-dependent on the amount of iron entering the cell.
The failure of the outer and inner surface iron pools to mix was confirmed by the fact that when iron-preloaded protoplasts
were incubated with additional iron, only the latter (surface-bound) was elutable with nonradioactive 2 mM FeSO4. It is concluded that increasing bifidobacterial iron load increases the amount of iron bound to the inner surface of the
membrane; the procedure, which is effective in forming bifidobacterial protoplasts, destroys their iron transport mechanism
while uncovering surface iron-binding sites; and that such iron-binding sites may be of significance in the cellular iron
metabolism processes. 相似文献
3.
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
4.
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
5.
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
6.
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
7.
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
8.
9.
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
10.
Yan G. Zorbas Youri F. Federenko Konstantin A. Naexu 《Biological trace element research》1994,41(3):253-267
The objective of this investigation was to determine the effect of daily intake of fluid and salt supplementation (FSS) on
increased urinary losses of microelements that developed during hypokinesia (decreased number of walking steps/d). The studies
were performed on 30 endurance-trained male volunteers aged 23–26 yr, with an averaged maximum oxygen uptake of 65 mL/kg/min
during 364 d of hypokinesia (HK). All volunteers were divided into three equal groups: Ten volunteers were placed continuously
under an average of 10,000 running steps/d (14.2 km/d) (control subjects), ten volunteers subjected continuously to HK without
the use of FSS (hypokinetic subjects), and ten volunteers were continuously submitted to HK and consumed daily FSS (hyperhydrated
subjects). For the simulation of the hypokinetic effect the hypokinetic and hyperhydrated volunteers were kept under an average
of 3,000 walking steps/d (2.7 km/d) for 364 d. Prior to their exposure to HK the volunteers were on an average of 10,000 running
steps/d (14.2 km/d). During the prehypokinetic period of 60 d and during the hypokinetic period of 364 d were determined renal
excretion of microelements responses of endurance-trained volunteers. In the hyperhydrated volunteers urinary excretion of
iron, zinc, copper, manganese, cobalt, nickel, lead, tin, chromium, aluminum, molybdenum, and vanadium decreased, whereas
in the hypokinetic volunteers it increased significantly. It was concluded that chronic hyperhydration may be used to attenuate
urinary excretion of microelements in endurance-trained volunteers during prolonged restriction of muscular activity. 相似文献
11.
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
12.
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
13.
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
14.
Vimal Kishore 《Biological trace element research》1990,25(2):123-135
Concentrations of copper, zinc, and iron were analyzed and compared in a number of tissues of adjuvant arthritic rats following 22 d of chronic treatment (per os) with either vehicle, aspirin or copper aspirinate, at doses of 100 mg/kg, 200 mg/kg, or 400 mg/kg. Such chronic treatment resulted in a negative balance in copper, zinc, and iron in many tissues. Among the tissues examined, liver and kidney exhibited the greatest changes in metal concentrations; brain and skeletal muscle exhibited the least. Arthritis-induced changes in the concentrations of all three metals in the liver were reversed upon treatment with aspirin. Treatment with copper aspirinate, on the other hand, resulted in an extremely high accumulation of copper in the liver. Arthritis-induced changes in copper, zinc, and iron concentrations in the pancreas and copper concentration in the plasma were generally not reversed upon treatment with either aspirin or copper aspirinate. Among the three metals examined, the degree of change observed as a result of drug treatments was greatest for iron and least for zinc. Finally, it appeared that the effects of aspirin and copper aspirinate on tissue metal concentrations were independent of the antiarthritic effects of these compounds. 相似文献
15.
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
16.
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
17.
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
18.
19.
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
20.
A simple receptor modeling approach has been applied to groundwater pollution studies and has shown that maker trace elements
can be used effectively in source identification and apportionment. Groundwater and source materials from one coal-fired and
five oil-fired power plants, and one coal-tar deposit site have been analyzed by instrumental neutron activation analysis
for more than 20 minor and trace elements. In one of the oil-fired power plants, trace element patterns indicated a leak from
the hazardous waste surface impoundments owing to the failure of a hypolon liner. Also, the extent and spatial distribution
of groundwater contamination have been determined in a coal-tar deposit site. 相似文献