Multielement determination in rice,wheat, and barley by instrumental neutron activation analysis

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.     

Charged-particle activation analysis of biological material

Charged-particle activation analysis offers a number of interesting possibilities for the determination of trace elements in biological material. It allows the determination of those elements that are difficult or impossible to determine by neutron activation, such as Li, B, Al, Si, V, Cr, Ni, Cd, Sn, Tl, and Pb. Up to now, protons have been successfully applied to samples of both vegetale and human origin. A number of difficulties have to be overcome, one of which is excessive heating of the samples owing to the limited range of the charged particles, thus giving rise to a high energy deposition in a small volume. Moreover, the sample composition has to be known to allow the calculation of the range of the particles. an interesting alternative has been proposed using an internal standard together with a standard additions procedure. Proton activation analysis was tested on a wide variety of reference materials, giving evidence that accurate results can be obtained for many trace elements, even when applying a purely instrumental method. Thus, the method can also be applied in the certification of reference materials, since nuclear methods are independent of chemical properties of the sample.     

Electron microscopy, electron diffraction, and element analysis of wet biological specimens

Temperature controlled differentially pumped environmental chambers now allow more routine examination of wet specimens in the electron microscope. A sensitive test of their efficiency is the ability to provide high resolution electron diffraction patterns from wet, unfixed protein microcrystals. Fortunately, wet specimens can be prepared with only a few tens of nanometers thickness of remaining water, so extraneous electron scattering by liquid water can be kept to a minimum. It still remains to be determined whether microprobe analysis (X-ray or electron energy-loss spectroscopy) using wet specimens gives better element localization in cells than the current freezing methods. More extensive comparisons are also required of the ultrastructural preservation and visibility of macromolecules immersed in a thin layer of water vs immersion in a thin layer of amorphous ice. However, the recent introduction of commercial forms of the necessary equipment now make these comparisons more feasible.     

Enhancement of the kidney Cd burden by SH-containing chelating agents

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.     

Trace elemental content of biological materials

The advantages and disadvantages of neutron activation analysis (NAA) and inductively coupled plasma-source mass spectrometry (ICP-MS) for the analysis of biological materials is reviewed. Comparison is made between NAA (instrumental) and ICP-MS (conventional pneumatic solution nebulization and laser ablation) analysis of the biological reference material National Bureau of Standards (NBS) SRM 1577 Bovine Liver. Relatively good agreement is achieved between the results for the 18 elements analyzed by both techniques and those either certified or reported in the literature. Elemental concentrations for Li, Mg, Al, Ca, Cr, Mn, Fe, Cu, Zn, Br, Rb, and Cs are also reported for IAEA Mixed Human Diet (H9), NBS SRM 909 Human Serum, and NBS SRM 1577a Bovine Liver, analyzed by solution nebulization ICP-MS.     

Identifying sources of groundwater pollution using trace element signatures

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.     

Determination of selenium in duplicate diets of residents of Pinhel,Portugal, by neutron activation

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.     

Cell orientation induced by extracellular signals

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.     

Soluble metals in the atmosphere and their biological implications

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.     

A new technique for the study of erythrocyte survival by double labeling and use of a well-type Ge detector

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.     

Interaction of dietary calcium,manganese, and manganese source (Mn oxide or Mn methionine complex) on chick performance and manganese utilization

Two trials were conducted to determine the utilization of manganese (Mn) as influenced by the level and source of Mn and the level of dietary calcium (Ca) in broiler chickens. Trial One was a 2 x 2 x 3 factorial arrangement of two Mn sources (Mn methionine or manganous oxide), two levels of dietary Ca (1.8 or 1.0), and three levels of supplemental Mn (30, 60, or 200 mg/kg) fed until 4 wk of age. Total phosphorus (available phosphorus) levels were 0.70% (0.48%) during all ages. High levels of dietary Ca caused a slower early rate of growth (0.53 vs. 0.64 kg) for chicks fed 1.8 vs 1.0% Ca, respectively. Chick weight was equivalent for all diets within the Ca-treatment group, except the dietary combination of high Ca and 200 mg/kg Mn as Mn methionine. Bone and liver Mn were significantly increased as the Mn level increased, but were not affected by the Mn source. Chicks fed 1.8% Ca had higher levels of bone Mn (9.28 ppm) than chicks fed 1.0% Ca (7.23 ppm). High levels of dietary Ca and 200 ppm Mn methionine dramatically depressed early growth, feed intake, and bone ash in this trial, raising the question of a diet x environment (heat-stress) effect. Trial Two was a 2 x 2 factorial arrangement of two levels of dietary Ca (1.8 or 1.0%) and two Mn sources (200 mg/kg Mn as Mn methionine or MnO) up to 3 wk of age in a controlled heat-stress environment. No growth depression in the chicks fed high levels of Ca and Mn methionine was observed. In the presence of high levels of dietary Ca, bone Mn was significantly higher when chicks were fed the MnO source. In summary, dietary Ca did not decrease Mn utilization in these trials, and availability of Mn in Mn methionine as a source compared to MnO depended on dietary Ca levels.     

Iron,copper, and zinc status in rats fed supplemental nickel

Literature data concerning the effect of increasing dietary Ni concentrations on Fe, Cu, and Zn status in rats are sparse and, in part, controversial. Therefore, the effects of the addition of either 0, 3, 50, or 100 mg Ni/kg diet on Fe, Cu, and Zn status of rats were investigated in two separate experiments. Purified diets were used that were composed according to the established nutrient requirements of rats. Ni in kidney was increased with increasing Ni intakes. Dietary Ni did not significantly influence Fe concentrations in plasma, liver, kidney, femur, and spleen. Likewise, the addition of Ni to the diet did not alter Cu status. Zn concentrations in femur were significantly decreased after feeding the diets with 100 mg Ni/kg. However, Zn in plasma, liver, kidney, and spleen was not affected. It is concluded that variations in dietary Ni concentrations have no major impact on Fe, Cu, and Zn status in rats.     

Effects of doxorubicin on the sensitivity of L1210 leukemia cells to deformation-associated trauma

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.     

Characterization of a nickel resistant mouse cell line

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.     

A comparison of thermodynamic approaches to predict the adhesion of dairy microorganisms to solid substrata

Four different thermodynamic approaches were compared on their usefulness to predict correctly the adhesion of two fouling microorganisms from dairy processing to various solid substrata. The surface free energies of the interacting surfaces were derived from measured contact angles according to:

Global amplification of cDNA from limiting amounts of tissue. An improved method for gene cloning and analysis

In this study we present an improved polymerase chain reaction (PCR)-based methodology to generate large amounts of high-quality complementary DNA (cDNA) from small amounts of initial total RNA. Global amplification of cDNA makes it possible to simultaneously clone many cDNAs and to construct directional cDNA libraries from a sequence-abundance-normalized cDNA population, and also permits rapid amplification of cDNA ends (RACE), from a limited amount of starting material. The priming of cDNAs with an adapter oligo-deoxythymidine (oligo-dT) primer and the ligation of a modified oligonucleotide to the 3′ end of single-stranded cDNAs, through the use of T4 RNA ligase, generates known sequences on either end of the cDNA population. This helps in the global amplification of cDNAs and in the sequence-abundance normalization of the cDNA population through the use of PCR. Utilization of a long-range PCR enzyme mix to amplify the cDNA population helps to reduce bias toward the preferential amplification of shorter molecules. Incorporation of restriction sites in the PCR primers allows the amplified cDNAs to be directionally cloned into appropriate cloning vectors to generate cDNA libraries. RACE-PCR done with biotinylated primers and streptavidin-coated para-magnetic particles are used for the efficient isolation of either full-length coding or noncoding strands.     

Copper deficiency and hyperlipoproteinemia induced by a tetramine cupruretic agent in rabbits

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.     

Correlations between trace element levels in head hair and blood components of Nigerian subjects

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.     

Production and purification of hybrid Ty-VLPs

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.