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1.
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
2.
Inhibition of the methylation of arsenic in rabbits by ip injection of periodate-oxidized adenosine (PAD) prior to an iv injection
of74As-arsenate (AsV; 0.4 mg As/kg body wt) caused a marked increase in the retention of74As in both the cellular organelles and the soluble fractions of liver and kidney. One day after exposure, almost 30% of the
arsenic in the liver and about 40% of the arsenic in the kidney was recovered in the nuclear fraction. In the liver nuclei,
the inhibition of the methylation increased the74As content of the insoluble fraction and most of this arsenic was protein-bound. The major part of the soluble intranuclear74As was in the form of AsIII, formed by reduction of the administered AsV. In the liver, PAD also caused a pronounced increase
in the74As content of the microsomal fraction. In the kidneys, where most of the arsenic was present as AsV, there was a marked accumulation
of arsenic in the mitochondria. 相似文献
3.
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
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.
We investigated the carbon isotope ratios and the diurnal pattern of malate accumulation in leaves and aerial roots of eight
species of Phalaenopsis grown in greenhouses. The leaves of all the species showed carbon isotope ratios and the diurnal patterns of malate content
typical of CAM plants. However, the aerial roots exhibited a large variation in the diurnal pattern of malate content among
species and even among plants within the same species, although carbon isotope ratios were always CAM-like values. Some aerial
roots showed the typical diurnal pattern of CAM, but others maintained high or low malate contents during a day without fluctuation.
In order to characterize more strictly the nature of the malate variation in the aerial roots, we further investigated a possible
variation of the diurnal pattern of malate among different aerial roots within an individual for Phalaenopsis amabilis and P. cornu-cervi. The diurnal pattern of malate content was varied even among different aerial roots within the same plant. Thus the photosynthetic
carbon metabolism in aerial roots of orchids is fairly complex. 相似文献
6.
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
7.
8.
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
9.
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
10.
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
11.
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
12.
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
13.
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
14.
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
15.
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
16.
17.
K. Kostial D. Dekanić S. Telišman M. Blanuša S. Duvančić D. Prpić-Majić J. Pongračić 《Biological trace element research》1991,28(3):181-185
Nutritional factors are known to influence metabolism and toxicity of several metals in animal experiments, but relevant human data are scarce and inconclusive. In this work, we tested the hypothesis that dietary calcium influences lead metabolism in humans. Blood lead concentrations were used as indicators of lead exposure and metabolism. Two groups of peasant women living in similar conditions in two different regions in Yugoslavia (100 in each) were chosen as subjects for this purpose. In region A, the dietary calcium intake was about 940 mg, and in region B about two times lower, i.e., 450 mg/day. The average blood lead concentration was significantly lower in women from region A (69 micrograms/L) than from region B (83 micrograms/L). Our results support the assumption that adequate calcium intake might be one of the preventive measures for decreasing lead absorption. This new evidence, sought for some time by nutritionists and toxicologists, needs further international confirmation. 相似文献
18.
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. |
19.
Nigel R. Burns Jacqueline E. M. Gilmour Susan M. Kingsman Alan J. Kingsman Sally E. Adams 《Molecular biotechnology》1994,1(2):137-145
This article describes how pure Ty-VLPs (virus-like particles) can be prepared from hybrid Ty-VLPs. Many different hybrid
Ty-VLPs have been produced and may be easily purified. Since the sedimentation properties of different hybrid Ty-VLPs are
similar, a simple purification process can be used for any VLP. This fast, versatile, and easy process allows for the production
of a variety of recombinant proteins. 相似文献
20.
Oral administration of different concentrations of Strontium chloride to laboratory bred mice in vivo induced chromosomal aberrations in bone marrow cell metaphase preparations. The degree of clastogenicity was directly proportional to concentration used at 6, 12, and 24 h of treatment. Duration of treatment could only be related positively in the lower doses. The females showed greater susceptibility than the males at all concentrations used. 相似文献