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PubMed1985

The distribution of indium in the central and peripheral nervous system of the young rat.

A subtoxic quantity of radioactive 111indium and stable indium was injected once into young rats. Subsequently pairs of these rats were killed at intervals of 15 minutes to 3 days after the injection. Tissues from the central (CNS) and peripheral nervous system (PNS) and blood were removed from each rat and the amount of 111indium was measured in the tissues. Cryostat sections of the cerebrum, cerebellum, spinal cord, sciatic nerve, a blood smear and a kidney control from each rat were examined with an analytical ion microscope (secondary ion mass spectrometry analysis) and the presence of 113 and 115 indium was localized in the tissues. These observations show that indium penetrates all neural tissues and that the brain resists the entry of indium - a very toxic element - much more effectively than the sciatic nerve.

Animals↗

PubMed1997

Radiation risk estimation in human populations: lessons from the radiological accident in Brazil.

The development of radiological and nuclear technologies and the deployment of nuclear weapons have made ionizing radiation one of the most studied human mutagens. Exposure to ionizing radiation produces DNA damage which can result in mutation and cancer, making the risk associated with human exposure a critical issue. In this paper we estimate the risk associated with radiation exposure for individuals exposed to 137Cs during the 1987 Goiânia radiological accident. Using combined regression slopes from both the in vivo hprt mutant frequency and micronucleus frequency data we estimated a doubling dose of 173 (+/-47) cGy for these two endpoints. This is in close agreement with the published estimates for low dose rate and chronic exposure to low-LET radiation. We obtained risk estimates of about 24-fold increase in dominant disorders in the post-exposure generation of the directly exposed population. No detectable increase was found in the population at large. The risk of carcinogenesis in the directly exposed population was found to be increased by a factor in the range of 1.4 to 1.5. The small sample size in this study requires a large element of caution with respect to risk estimates interpretation. Moreover, the doubling dose estimates prepared here are derived from lymphocytes. This somatic data may require additional considerations for both cancer and certainly germ-line events. Nevertheless, the risk of carcinogenesis and genetic harm for this population are good indicators of the potential genetic damage imposed by ionizing radiation to the Goiânia population.

Air Pollution, Radioactive↗

PubMed2001

Identification of nonessential Helicobacter pylori genes using random mutagenesis and loop amplification.

Analysis of the published genome sequences of Helicobacter pylori revealed that approximately 40% of the predicted open reading frames (ORFs) were of unknown function. We have developed the random mutagenesis and loop amplification (RMLA) strategy, and used this approach both to characterize individual virulence factors and to collectively screen comparatively large numbers of H. pylori mutants to identify genes that are not essential for viability in vitro. The mini-Tn3-Km transposon was used to generate a random mutant library in H. pylori strain G27. By screening the library of mutants we were able to demonstrate that the transposon integrated randomly into the chromosome of H. pylori and that RMLA was able to identify mutants in known virulence genes (urease and catalase). To test whether this strategy could be used as a high-throughput approach for the simultaneous identification of a series of nonessential genes of H. pylori, the transposon-chromosomal junctions of a pool of mutants were amplified by inverse PCR using circular fragments of genomic DNA obtained after chromosomal DNA extracted from the pool of mutants had been digested with HindIII and self-ligated. The amplification products were radioactively labelled and hybridized to a high density macroarray membrane containing a duplicated target sequence for every gene of H. pylori strain 26695. For the positive ORFs the precise site of transposon insertion was confirmed by PCR mapping. In total 78 H. pylori genes were unambiguously identified as nonessential for viability in vitro, including 20 with orthologues of unknown function in other species and 21 which were H. pylori-specific.

DNA Transposable Elements↗

PubMed1986

Organization, nucleotide sequence, and transcription of the chicken HSP70 gene.

We have isolated a gene encoding a 70,000-Da heat shock protein (HSP70) from a chicken genomic library. The recombinant clone C411 was isolated by hybridization to a radioactively labeled plasmid containing Drosophila HSP70 gene sequences. The identity was established by hybrid selected translation using a subcloned restriction fragment, pC1.8, and total cytoplasmic RNA from chicken cells. The selected mRNA translated in vitro a product which co-migrates with in vivo synthesized chicken HSP70 by SDS-polyacrylamide gel electrophoresis. By Northern blot analysis of poly(A)+ mRNA from heat-shocked cells, we detected a 2.6-kilobase pair mRNA homologous to pC1.8. The nucleotide sequences within pC1.8 and a flanking 2.0-kilobase pair HindIII fragment contain a single contiguous open reading frame of 1905 nucleotides that corresponds to a protein of predicted size 70,000 daltons. Upstream of the initiator methionine codon, ATG, lie sequences homologous to the canonical transcription elements TATA, CCAAT, and SP1 binding site, and two overlapping heat shock elements. The order and spacing of these sequences share many features in common with the promoter for the human HSP70 gene.

Amino Acid Sequence↗

PubMed1981

Studies on the sorption of elemental mercury vapor by soils.

Mercury vapor sorption by soil increased curvilinearly with the increase of soil moisture content until a maximum was reached. A further increase of moisture content caused a decline in mercury sorption. The percent moisture contents which gave maximal increase of 203Hg vapor sorption in these soils coincide quite closely with their water-holding capacity values at 1/3 bar. Soil microorganisms may play a part in moist soil for the increase of elemental mercury vapor sorption and subsequent transformation to mercuric form. Mercury vapor diffused into both dry and moist soil columns and the diffusion profile can be described by an exponential function of the form, y = ae-bx, where "a" is the adsorption characteristics of the soil, "b" is the diffusivity coefficient and x is the depth of soil. The diffusivity coefficient for mercury vapor varied with the soil type and its moisture content.

Gases↗

PubMed1999

[Concentration of heavy elements and their compounds in the cells from BALF and pulmonary tumors in radiation-exposed subjects].

AIM: Measurement of heavy elements in alveolar macrophages (AM) of bronchoalveolar lavage (BAL) and pulmonary tumor tissue (PTT); investigation of spacial distribution of the heavy particles in the tissues. MATERIALS AND METHODS: Laser mass-spectrometry estimated quantitative and qualitative characteristics of heavy elements (Mn, Fe, Co, Cu, Zr, etc.) in diagnostic and therapeutic BAL of 6 patients exposed to radiation after the Chernobyl accident and in pulmonary tumor tissue of patients operated for central small-cell and peripheral bronchoalveolar cancer who also had been exposed to radiation after the Chernobyl. RESULTS: Heavy elements concentration in the secondary BAL was less than in the primary one. This shows effectiveness of the procedures aimed at removal of heavy particles from the respiratory organs. Heavy elements content was quite different in two histologically different tumors. CONCLUSION: Laser mass-spectrometry proved its usefulness in simultaneous study of the quantity and quality of heavy elements in AM of BAL and tumors in radiation-exposed subjects, in investigation of the elements distribution in the pulmonary tissues and changes of elements composition in the tissues in the course of tumors development.

Adenocarcinoma, Bronchiolo-Alveolar↗

PubMed1989

Translation in Xenopus laevis oocytes of hybrid selected LEW rat RT1.B alpha- and beta-chain transcripts results in serologically discrete class II polypeptide chain complexes.

Using the non-crossreactive mAb MRC-OX3 and MRC-OX6, two serologically distinct RT1.B-specific (I-A equivalent) alpha, beta heterodimers have previously been described by us as residing at the cell surface of LEW rat spleen cells. The two-chain elements were suggested to represent stable conformation isomers, diverged by dissociation of the mature gamma-chain from a mAb MRC-OX6 reactive biosynthetic intermediate, composed of terminally glycosylated alpha-, beta- and gamma-chains. In this study we addressed the question of whether or not the presence of terminally glycosylated invariant gamma-chain was obligatory for the formation of the two MRC-OX3 and MRC-OX6 reactive two-chain complexes. The synthesis of RT1.B-specific alpha, beta heterodimers was therefore initiated, in the absence of accompanying invariant gamma-chains, by microinjecting hybrid-selected RT1.B alpha- and beta-specific mRNA into oocytes of Xenopus laevis for translation. Class II molecules produced were analyzed by affinity chromatography of radioactive-labeled oocyte detergent lysates using the appropriate monoclonal immunoadsorbents for identification. Although rat gamma-chain mRNA was excluded in this assay system, distinct MRC-OX3 and MRC-OX6 reactive two-chain complexes were detected by two-dimensional gel electrophoresis. These findings clearly indicate that the formation of the two RT1.B-specific alpha, beta heterodimers is independent of the presence of the rat invariant gamma-chain.

Animals↗

PubMed2004

Elemental analysis of Egyptian phosphate fertilizer components.

The accumulation of certain elements in vitally important media such as water, soil, and food is undesirable from the medical point of view. It is clear that the fertilizers vary widely in their heavy metals and uranium content. A shielded high purity germanium HPGe detector has been used to measure the natural concentration of 238U, 232Th, and 40K activities in the phosphate fertilizer and its components collected from Abu-Zaabal fertilizers and chemical industries in Egypt. The concentration ranges were 134.97-681.11 Bq kg(-1), 125.23-239.26 Bq kg(-1), and 446.11-882.45 Bq kg(-1) for 238U, 232Th, and 40K, respectively. The absorbed dose rate and external hazard index were found to be from 177.14 to 445.90 nGy h(-1) and 1.03 to 2.71 nGy y(-1), respectively. The concentrations of 22 elements (Be, Na, Mg, Si, P, S, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Zr, Mo, Cd, Ba) in the samples under investigation were determined by inductively coupled plasma optical-emission spectrometry (ICP-OES). The results for the input raw materials (rock phosphate, limestone and sulfur) and the output product as final fertilizer are presented and discussed.

Egypt↗

PubMed1992

LDEF radiation measurements: preliminary results.

The Long Duration Exposure Facility (LDEF), retrieved by the Space Shuttle mission STS-32 after nearly 6 yr in orbit, is the focus of a broad-based study of the radiation environment in low Earth orbit (LEO) and its effects on materials. A combination of passive techniques has been used to study this environment via detectors which were contained in experiments aboard the LDEF spacecraft and through analysis of induced radioactivities. Preliminary results for absorbed dose measurements and for induced activities in various materials are presented. A number of effects have been observed which reflect the anisotropy of the charged particle flux in low Earth orbit. Quantitative results from these measurements should provide an accurate means of confirming environmental flux models and techniques for predicting radiation encountered in future LEO missions, particularly those of extended duration.

Activation Analysis↗

PubMed2002

A general approach to transform a lake model for one radionuclide (radiocesium) to another (radiostrontium) and critical model tests using data for four Ural lakes contaminated by the fallout from the Kyshtym accident in 1957.

This paper presents results of a model test carried out within the framework of the COMETES project (EU). The aim of the work was to change the structure of the MOIRA lake model for radiocesium so that it can be applied more generally for, in principle, all types of radionuclides and heavy metals. This general lake model is used within the MOIRA decision support system (DSS; MOIRA and COMETES are acronyms for EU-projects). The model is based on a set of differential equations and a specific modelling structure. It incorporates all important fluxes to, from and within lakes in a general manner. Yet the model is driven by a minimum of variables accessible from standard maps and monitoring programs. The model can be separated into two parts, a general part with equations applicable for all types of water pollutants and a substance-specific part. This model has previously been validated for 137Cs from many lakes covering a wide domain and yielded excellent predictive power. The alterations discussed in this work are meant to be general and radiostrontium is used as a typical element. Radiostrontium is known to be more mobile than radiocesium and all abiotic parts of the model handling fixation and mobility have been altered. The new model for 90Sr has been critically tested using data from four lakes heavily contaminated with 90Sr from the Kyshtym accident in the Southern Urals, Russia, using empirical data from a period from 1958 to 1995 for 90Sr in fish (here goldfish), water and sediments.

Cesium Radioisotopes↗

PubMed1976

Biochemical changes in rat kidney on exposure to elemental mercury vapor: effect on biosynthesis of metallothionein.

Evidence is presented that exposure of rats to elemental mercury vapor results in increased amounts of a metallothionein-like protein in kidney tissue but not in liver. After three or more daily exposures, each of 2 h duration, to elemental mercury vapor, more than 50% of the mercury in kidney tissue is bound to a protein having a molecular weight (mol. wt.) of about 10 000 as determined by Sephadex G-75 gel filtration chromatography. Cystine is incorporated into a 10 000 mol. wt. protein fraction from kidneys of rats which were injected with [U-14C] cystine after five daily 2-h exposures to mercury vapor. In contrast, no significant incorporation of [U-14C] cystine into this protein fraction was observed in kidneys of control rats or in livers of both control and mercury vapor-exposed rats. The in vivo incorporation of 109Cd into the fraction followed the same pattern as that of [14C] cystine in rats injected with tracer doses of CdCl2 labeled with radioactive 109Cd isotope. This 10 000 mol. wt. protein, newly synthesized in response to repeated exposures to mercury vapor, exhibited identical properties to metallothionein, namely in its subcellular localization, molecular weight, heat stability and isoelectric points. A significant incorporation of [U-14C]-cystine into this protein in rat kidney alone on exposure to mercury vapor confirms its induced biosynthesis in the kidney.

Animals↗

PubMed2005

Radiocesium contamination behavior and its effect on potassium absorption in tropical or subtropical plants.

The accumulation and long-term decline of radiocesium contamination in tropical plant species was studied through measurements of gamma-ray spectra from pomegranate (Punica granatum) and chili pepper (Capsicum fructescens) trees. The plants were originally grown at a (137)Cs contaminated site (where a radiological accident occurred in the city of Goiânia, Brazil, in 1987), and transplanted to uncontaminated soil, so that the main source of contamination of the new leaves and fruits would be the fraction of the available radiocesium in the body of the plants. Measurements of (137)Cs and (40)K concentrations along the roots, main trunk, twigs, leaves and fruits before and after the transplant process of both plant species indicated a direct competition between Cs and K ions, suggesting that these elements could have a common accumulation mechanism. Cesium transfer factors from soil to pomegranate, green and red chili pepper fruits were evaluated as 0.4 +/- 0.1, 0.06 +/- 0.01 and 0.05 +/- 0.01, respectively. Biological half-life values due to (137)Cs translocation from the tree reservoir (BHL(T)) were calculated as 0.30 years for pomegranate, 0.12 years and 0.07 years for red and green peppers, respectively.

Capsicum↗

PubMed2001

Comparison of two micro-analytical methods for detecting the spatial distribution of sorbed Pu on geologic materials.

Subsurface transport of groundwater contaminants is greatly influenced by chemical speciation, precipitation and sorption processes at the mineral-water interface. The retardation of contaminants is often greatest at boundaries between minerals and in fractures and pore spaces. The investigation of the spatial distribution of sorbed contaminants along these boundaries requires micro-analytical techniques. The sorption of dissolved Pu(V) on a natural zeolitic tuff from Yucca Mountain (NV, USA) was examined using microautoradiography (MAR), X-ray diffraction (XRD), electron microprobe (EM) techniques, and synchrotron-based micro-X-ray fluorescence (micro-SXRF). The tuff contained a heterogeneous distribution of zeolites and trace quantities of smectites, Fe oxides (hematite), and Mn oxides (rancieite), which are present as fracture fill and pore space materials. Micro-SXRF studies showed that Pu is mostly associated with bodies of smectite plus Mn oxides, which were typically elevated in Ce, Ga, Nb, Pb, Y, Ca, Ti, and Zn. Sorbed Pu was not associated with Fe-rich bodies, which were enriched in Cl and Rb. Results of the MAR studies were complementary to that of the micro-SXRF studies in that Pu was associated with similar elements in the tuff. Indirect detection of Pu by EM or micro-SXRF (by analyzing Ag developed on the MAR photoemulsion) was a more sensitive method for detecting lower levels of sorbed Pu than the direct detection of sorbed Pu via micro-SXRF in the absence of the photoemulsion.

Adsorption↗

PubMed2007

A generic-tee-plenum mixing system for application to single point aerosol sampling in stacks and ducts.

The ANSI/HPS-N13.1-1999 standard is based on the concept of obtaining a single point representative sample from a location where the velocity and contaminant profiles are relatively uniform. It is difficult to predict the level of mixing in an arbitrary stack or duct without experimental data to meet the ANSI/HPS N13.1-1999 requirements. The goal of this study was to develop experimental data for a range of conditions in "S" (S-shaped configuration) duct systems with different mixing elements and "S" systems having one or two mixing elements. Results were presented in terms of the coefficients of variation (COVs) for velocity, tracer gas, and 10-mum aerodynamic diameter (AD) aerosol particle profiles at different downstream locations for each mixing element. Five mixing elements were tested, including a 90 degrees elbow, a commercial static mixer, a Small-Horizontal Generic-Tee-Plenum (SH-GTP), a Small-Vertical Generic-Tee-Plenum (SV-GTP), and a Large-Horizontal Generic-Tee-Plenum (LH-GTP) system. The COVs for velocity, gas concentration, and aerosol particles for the three GTP systems were all determined to be less than 8%. Tests with two different sizes of GTPs were conducted, and the results showed the performance of the GTPs was relatively unaffected by either size or velocity as reflected by the Reynolds number. The pressure coefficients were 0.59, 0.57, and 0.65, respectively, for the SH-GTP, SV-GTP, and LH-GTP. The pressure drop for the GTPs was approximately twice that of the round elbow, but a factor of 5 less than a Type IV Air Blender. The GTP was developed to provide a sampling location less than 4-duct diameters downstream of a mixing element with low pressure drop condition. The object of the developmental effort was to provide a system that could be employed in new stack; however, the concept of GTPs could also be retrofitted onto existing system applications as well. Results from these tests show that the system performance is well within the ANSI/HPS N13.1-1999 mixing criteria--the COVs for velocity, tracer gas, and 10-microm AD aerosol particles are less than the 20% criteria levels.

Aerosols↗

PubMed1995

Venus reconsidered.

The Magellan imagery shows that Venus has a crater abundance equivalent to a surface age of 300 million to 500 million years and a crater distribution close to random. Hence, the tectonics of Venus must be quiescent compared to those of Earth in the last few 100 million years. The main debate is whether the decline in tectonic activity on Venus is closer to monotonic or episodic, with enhanced tectonism and volcanism yet to come. The former hypothesis implies that most radioactive heat sources have been differentiated upward; the latter, that they have remained at depth. The low level of activity in the last few 100 million years inferred from imagery favors the monotonic hypothesis; some chemical evidence, particularly the low abundance of radiogenic argon, favors the episodic. A problem for both hypotheses is the rapid decline of thermal and tectonic activity some 300 million to 500 million years ago. The nature of the convective instabilities that caused the decline, and their propagation, are unclear.

Elements↗

PubMed1994

LacZ inducible, antigen/MHC-specific T cell hybrids.

The nuclear factor of activated T cells (NFAT) enhancer element of the IL-2 gene can regulate expression of the Escherichia coli lacZ reporter gene in activated T cells. Based upon this observation, we showed that this inducible NFAT--lacZ construct could be used to measure TCR mediated, ligand-specific activation in single T cells. Here we describe a general approach to obtaining lacZ inducible, T cell hybrids by generating two new fusion partners BWZ.36 and BWZ.36 CD8 alpha derived by transfecting alpha-beta-BW5147 cells with the NFAT--lacZ construct. Using these fusion partners and normal T cells from immunized mice, we obtained T cell hybrids in which lacZ activity is specifically induced in response to antigen/MHC class II or MHC class I complexes. We show that measuring ligand induced T cell activation by the non-radioactive lacZ assay is simpler, faster, and most cost-effective relative to conventional IL-2 assays. Most importantly, the unique ability to detect activation of single T cells by the lacZ assays permits detection of rare antigen presenting cells and thus provides the basis for developing expression cloning strategies for identifying unknown T cell antigens.

Animals↗

PubMed1986

Eicosanoid synthesis by rabbit hydronephrotic cortical interstitial cells in culture.

Rabbit hydronephrotic cortical interstitial cells in primary culture were labeled with [1-14C]arachidonic acid and the eicosanoids released after stimulation with bradykinin or A23187 were studied by reverse-phase high performance liquid chromatography. The major arachidonic acid metabolite formed was prostaglandin (PG)E2, comprising more than 30% of the total radioactivity released. 12-Hydroxyheptadecatrienoic acid, probably representing spontaneous breakdown of the cyclic endoperoxides PGG2 and/or PGH2, made up 10 to 15% of the radioactivity released. Other cyclooxygenase products that were released included PGF2 alpha, PGD2, 6-keto PGF1 alpha and only minute amounts of thromboxane B2. Small quantities of the lipoxygenase products 15-, 12- and 5-hydroxyeicosatetraenoic acids (HETEs) as well as leukotrienes (LT)B4, LTC4 and LTD4 were also identified. Significantly larger quantities of 15- and 5-HETEs were recovered at 2 to 5 min than after longer incubations with A23187, suggesting esterification of these HETEs into cellular phospholipids. The data indicate that interstitial cells of the hydronephrotic kidney synthesize a variety of cyclooxygenase and lipoxygenase products of arachidonic acid, which may contribute to the pathophysiology of hydronephrosis. Moreover, it is suggested that PGG2 and/or PGH2 that are released from these cells may be metabolized further by adjacent kidney cells or circulating blood elements to other eicosanoid products, thus increasing the diversity of eicosanoids synthesized in the hydronephrotic kidney.

Animals↗

PubMed1988

Studies with FtsA-LacZ protein fusions reveal FtsA located inner-outer membrane junctions.

Four FtsA-LacZ translational gene fusions were constructed using a mini-Mu transposon (MudII 1734). FtsA-LacZ fusions and FtsA protein that were radioactively labelled using maxicell technique fractionated identically into membranes and cytoplasm. The FtsA-LacZ fusion proteins were also localized in wild type dividing cells using beta-galactosidase activity. Fractions from a modified sucrose equilibrium gradient exhibited beta-galactosidase activity in fractions corresponding to outer membrane-heavy (OMH) and outer membrane light (OML). The data are consistent with a model in which FtsA protein is incorporated into septal adhesion sites associated with cell division.

Bacterial Proteins↗