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PubMed1989

In-vivo uptake of human growth hormone in male rat liver.

125I-Labelled human GH (hGH) was injected i.v. to male rats and its subcellular distribution in the hepatocyte was examined using fractionation techniques. Uptake into liver homogenates was maximal by 15 min after injection and represented 24% of the injected radioactivity; it was markedly inhibited by coinjection of native hGH. 125I-Labelled hGH taken up by the liver underwent a time-dependent translocation process. The peak of specific labelling of plasma membranes occurred at 3 min whereas later on the radioactivity was concentrated in low-density structures present in Golgi-endosome fractions. To characterize the ligand-associated structures better, endosome-enriched fractions were prepared from a microsomal fraction by isopycnic centrifugation in a sucrose gradient and a Nycodenz gradient. The radioactivity was in one peak with a median density of 1.096 g/cm3 in the Nycodenz gradient fractions. The peak of radioactivity was distinct from that of galactosyltransferase activity which appeared at a median density of 1.114 g/cm3. The labelled material eluted from the various subcellular fractions appeared as intact hGH. Upon in-vivo interaction with male rat hepatocytes, 125I-Labelled hGH was internalized with a sequential association with plasma membranes and endocytic structures distinct from Golgi elements.

Animals↗

PubMed2003

Long-term stewardship of the environmental legacy at restored sites within the Department of Energy nuclear weapons complex.

It is readily apparent, as the Department of Energy Office of Environmental Management proceeds in remediating its vast network of contaminated nuclear weapons facilities, that final cleanup at many facilities will not be performed to a level allowing unrestricted use of the facility. Instead, these facilities must rely on engineering, administrative, and institutional controls to ensure the level of cleanup performed at the site remains adequately protective of public health and the environment. In order for these controls to remain effective, however, a plan for long-term stewardship of these sites must be developed that is approved by the U.S. Congress. Although this sounds simple enough for the present, serious questions remain regarding how best to implement a program of stewardship to ensure its effectiveness over time, particularly for sites with residual contamination of radionuclides with half-lives on the order of thousands of years. Individual facilities have attempted to answer these questions at the site-specific level. However, the complexities of the issues require federal support and oversight to ensure the programs implemented at each of the facilities are consistent and effective. The Department of Energy recently submitted a report to Congress outlining the extent of long-term stewardship needs at each of its facilities. As a result, the time is ripe for forward thinking Congressional action to address the relevant issues and ensure the remedy of long-term stewardship successfully carries out its intended purpose and remains protective of public health and the environment. The regulatory elements necessary for the stewardship program to succeed can only be implemented through the plenary powers of the U.S. Congress.

Decontamination↗

PubMedDate not supplied

[Dynamic study of the cytogenetic effects in blood lymphocytes from humans living in the Chernobyl Atomic Energy Station exclusion zone without permission].

The cytogenetic examination of a group of people, self-residing in ChNPP Exclusion Zone with soil contamination density 137Cs 74-477 kBq/m2, 90Sr 33-289 kBq/m2, 238, 239 + 240Pu 1.5-10.0 kBq/m2, was conducted in 1998-1999 and also 2001. It is shown, that after 12-15 years of the accident the level of chromosome damages in Zone self-residents' lymphocytes detected by a routine analysis is higher then at the residents of control Yagotin district, Kiev region and comes to a plateau. Lymphocytes with multiple chromosome damages are detected. The probability of its transuranium elements induction which are present in the Zone is discussed at present.

Adult↗

PubMed1986

The range of high LET effects from 125I decays.

Track structure techniques are applied to calculate energy depositions in cylindrical targets 20 A in diameter (simulating the DNA duplex) containing, or near, 125I decays. Two problems are examined: (1) The possible effects of incorporated versus nonincorporated 125I are evaluated; (2) the extent of the radiological damage along the DNA is described and discussed for individual decays taking place in the DNA. The results of three different calculations are presented: (1) The distribution of the total energy deposited in the target per decay: Here it is shown that the 125I decays deposit considerably more energy than 5-MeV alpha particles when the decay occurs on the central axis of the cylinder. When the decay occurs at 40 A from the axis, the energy depositions are small and infrequent, showing that the iodine decay must occur within this distance to produce a high LET-like effect. (2) The distribution of average energy depositions around a curved cylinder simulating the DNA duplex encircling the nucleosome: There is a rapid decrease in the energy deposited in elements (of size resembling a base pair) away from the location of the decay. At approximately 17 A (approximately 5 bp) from the decay the mean energy deposited in an element is reduced by a factor of 10. (3) The energy deposited in individual elements of the cylinder is presented for single decays: The smooth decrease in average energy depositions with distance from the decay ((2) above) is not reflected in individual decays.

DNA↗

PubMedDate not supplied

[Study of the possibility of identifying the structural elements of the phenylalanyl-tRNA-synthetase active center by affinity labeling].

The possibility of localization of active sites structural components by affinity labelling was investigated. The modification of E. coli MRE-600 phenylalanyl-tRNA synthetase (E.C.6.1.1.20) (alpha 2 beta 2-type) by the phosphorylating analog of ATP-- [14C]adenosine-5'-trimetaphosphate results in the labelling of both heavy (beta) and light (alpha) enzyme subunits. Analysis of the peptide maps of the tryptic enzyme hydrolysate reveals a great number of peptides containing [14C]radioactivity. The decrease of covalent binding at low concentration of the analog did not abolish the plural labelling. The data permit to consider this kind of analogs as unperspective for localization of specific peptides. Modification of phenylalanyl-tRNA synthetase by tRNAPhe containing the photoreactive group (--CH2CONHC6H5N3) at eighth position of molecule (S8U) results in the labelling of only heavy beta-subunits. These data correspond to the previous results which testify to the disposition of tRNA binding sites on beta-subunits of phenylalanyl-tRNA synthetase. After hydrolysis of the modified phenylalanyl-tRNA synthetase by trypsin six peptides covalently bound with tRNAPhe were revealed. This quantity of modified peptides is higher than the number of tRNA binding sites. Hence the method of affinity labelling has definite limitations for localization of peptides of enzyme active sites.

Affinity Labels↗

PubMed1976

Electron microscopic evidence for a transsynaptic migration of tetanus toxin in spinal cord motoneurons: an autoradiographic and morphometric study.

Adult rats were injected intramuscularly (musculus deltoideus) with 125I-labeled tetanus toxin. First signs of tetanic rigidity became visible 12-13 h after injection: death occurred 1-2 h later. Electron microscopic autoradiography of the ventrolateral spinal cord gray matter showed a large part of the radioactivity to be located in motoneurons (perikaryon, axon and dendrites) at 7 and 14 h after injection. A great majority of the rest of the label was found over synaptic terminals, most of them were afferent to motoneurons. The percentage of labeled nerve terminals increased significantly (P less than 0.05) between 7 h and 14 h after injection. Glial elements surrounding the motoneurons were mostly unlabeled. These observations strongly favor the assumption of a transsynaptic migration of tetanus toxin. Dorsal root, dorsal horn and cell bodies of spinal cord interneurons were free of label.

Animals↗

PubMed1999

Distribution coefficients (Kd's) for use in risk assessment models of the Kara Sea.

As a prerequisite for most evaluations of radionuclide transport pathways in marine systems, it is necessary to obtain basic information on the sorption potential of contaminants onto particulate matter. Kd values for use in modeling radionuclide dispersion in the Kara Sea have been determined as part of several international programs addressing the problem of radioactive debris residing in Arctic Seas. Field and laboratory Kd experiments were conducted for the following radionuclides associated with nuclear waste: americium, europium, plutonium, cobalt, cesium and strontium. Emphasis has been placed on two regions in the Kara Sea: (i) the Novaya Zemlya Trough (NZT) and (ii) the mixing zones of the Ob and Yenisey Rivers (RMZ). Short-term batch Kd experiments were performed at-sea on ambient water column samples and on samples prepared both at-sea and in the laboratory by mixing filtered bottom water with small amounts of surficial bottom sediments (particle concentrations in samples = 1-30 mg/l). Within both regions, Kd values for individual radionuclides vary over two to three orders of magnitude. The relative particle affinities for radionuclides in the two regions are americium approximately equal to europium > plutonium > cobalt > cesium > strontium. The values determined in this study agree with minimum values given in the IAEA Technical Report [IAEA, 1985. Sediment Kd's and Concentration Factors for Radionuclides in the Marine Environment. Technical Report No. 247. International Atomic Energy Agency, Vienna.]. Given the importance of Kd's in assessments of critical transport pathways for radionuclide contaminants, we recommend that Kd ranges of values for specific elements rather than single mean values be incorporated into model simulations of radionuclide dispersion.

Americium↗

PubMed1999

GABA(B) receptor isoforms GBR1a and GBR1b, appear to be associated with pre- and post-synaptic elements respectively in rat and human cerebellum.

1. Metabotropic gamma-aminobutyric acid (GABA) receptors, GABA(B), are coupled through G-proteins to K+ and Ca2+ channels in neuronal membranes. Cloning of the GABAB receptor has not uncovered receptor subtypes, but demonstrated two isoforms, designated GBR1a and GBR1b, which differ in their N terminal regions. In the rodent cerebellum GABA(B) receptors are localized to a greater extent in the molecular layer, and are reported to exist on granule cell parallel fibre terminals and Purkinje cell (PC) dendrites, which may represent pre- and post-synaptic receptors. 2. The objective of this study was to localize the mRNA splice variants, GBR1a and GBR1b for GABA(B) receptors in rat cerebellum, for comparison with the localization in human cerebellum using in situ hybridization. 3. Receptor autoradiography was performed utilizing [3H]-CGP62349 to localize GABA(B) receptors in rat and human cerebellum. Radioactively labelled oligonucleotide probes were used to localize GBR1a and GBR1b, and by dipping slides in photographic emulsion, silver grain images were obtained for quantification at the cellular level. 4. Binding of 0.5 nM [3H]-CGP62349 demonstrated significantly higher binding to GABA(B) receptors in the molecular layer than the granule cell (GC) layer of rat cerebellum (molecular layer binding 200+/-11% of GC layer; P<0.0001). GBR1a mRNA expression was found to be predominantly in the GC layer (PC layer grains 6+/-6% of GC layer grains; P<0.05), and GBR1b expression predominantly in PCs (PC layer grains 818+/-14% of GC layer grains; P<0.0001). 5. The differential distribution of GBR1a and GBR1b mRNA splice variants for GABA(B) receptors suggests a possible association of GBR1a and GBR1b with pre- and post-synaptic elements respectively.

Aged↗

PubMed1987

[Characteristics of the complex formation of L-DOPA with chromatin elements from brain cells].

It was found that L-DOPA interacts with brain cell chromatin. The life-time of the chromatin-L-DOPA complex is the greatest at 24 degrees C, while at 37 degrees C the destruction of the complex is observed. The specific binding is about 40% at pH 7.4-7.6. The Kd value calculated by the method of Scatchard is equal to 35.10(-9) M. Treatment of the chromatin-L-DOPA complex with DNAase I decreases the chromatin radioactivity by 15-20%. At the same time pronase treatment decreases the chromatin radioactivity by 80%. NaCl (0.2 and 0.4 M) causes the extraction of more than 70% of 3H-DOPA in the complex with chromatin proteins. Thus, L-DOPA interacts predominantly with chromatin proteins.

Animals↗

PubMedDate not supplied

[Incorporation of 3H-estradiol into elements of the tanycytic and ciliated ependyma of the 3d cerebral ventricle in experiments in vitro].

The label incorporation into the arcuate nucleus neurons, the tanicytic and ciliary ependyma of the mediobasal hypotahalamus, and also into the underlying nerve tissue after in vitro incubation of male Wistar rats hypothalamic tissue in the presence of 3H-estradiol was studied autoradiographically. After incubation at 37 degrees C, along with the nuclear localization of the label in the neutrons of the arcuate nucleus, characteristic of estradiol, high radioactivity was revealed in tanicytes; the label incorporation into beta-tanicytes was always higher than into the alpha2-tanicytes. Subsequent incubation of the tissue with nonlabeled estradiol led to reduction of beta-tanicytes radioactivity; as to ciliary ependyma and alpha2-tanicytes radioactivity--it rose. Reduction of incubation temperature to 22 degrees C failed to alter the character of the label incorporation into tanicytes. The data obtained confirmed the possibility of participation of the mediobasal hypothalamus tanicytes in the realization of the estradiol action of the hypothalamus.

Animals↗

PubMed1981

Albumin secreted by rat liver bypasses Golgi apparatus cisternae.

Albumin was isolated immunologically from various subcellular fractions from livers of adult male rats receiving an intraperitoneal injection of [3H]leucine to investigate the kinetics and pathway of subcellular transfer of newly synthesized albumin during secretion. At appropriate time intervals, livers were excised and fractionated into endoplasmic reticulum and Golgi apparatus. Golgi apparatus were further subfractionated into cisternae and secretory vesicles. In endoplasmic reticulum fractions labeled albumin appeared within 7.5 min of injection of isotope, followed by a rapid decline in specific activity. Albumin in Golgi apparatus was labeled and concentrated in secretory vesicles over 25 min. The radioactivity in albumin per mg total protein was highest in secretory vesicles and insignificant in the cisternal fraction. Labeled albumin was present in serum by 30 min and radioactivity in serum albumin reached a plateau within 60-90 min after injection of isotope. Results provide evidence for the migration of albumin from its site of synthesis on endoplasmic reticulum membrane-bound polyribosomes to its site of secretion into the circulation via the Golgi apparatus. The pathway of albumin transport to secretory vesicles is suggested to involve peripheral elements of the Golgi apparatus. Secretory vesicle formation and maturation required 20 to 30 min for completion, via a mechanism whereby the inner spaces of the central saccules may be bypassed.

Albumins↗

PubMed1990

High-performance liquid chromatographic separation of inositol phosphate isomers employing a reversed-phase column and a micellar mobile phase.

Surfactants have been employed in high-performance liquid chromatography (HPLC) for the separation of ionic and non-ionic compounds. We have developed a method employing a reversed-phase column and a mobile phase containing a surfactant, hexadecyltrimethylammonium hydroxide (HDTMA+OH-), for the separation of several inositol phosphate positional isomers. Various parameters were studied for their effect on the chromatographic capacity factor (k'). They included the concentration of HDTMA+OH-, the pH of the bulk micellar suspension and the addition of inorganic salts to the mobile phase. Resolution of the inositol monophosphates was controlled by a mixed mechanism, where the predominant elements were electrostatic forces and the formation of micelles. The elution of the inositol polyphosphate isomers was obtained by increasing the amount of a non-polar solvent, in agreement with an ion-pairing process. This method represents an alternative to ion-exchange HPLC. If offers a practical advantage when detection of radiolabeled samples by in-line radioactive flow detectors is required, because low-quenching solvents with good miscibility with scintillant fluids are employed. The analysis of various chromatographic conditions, the system reproducibility and its application to the analysis of biological samples are described.

Chromatography, High Pressure Liquid↗

PubMed1980

Fibronectin-mediated uptake of gelatin-coated latex particles by peritoneal macrophages.

The present study demonstrates the ability of plasma fibronectin or cold-insoluble globulin (Clg) to promote the uptake of 125I-labeled, gelatin-coated latex beads (g-Ltx*) by monolayers of peritoneal macrophages (PM). The uptake of g-Ltx* by PM was enhanced by Clg in a concentration-dependent fashion and required the presence of heparin (10 U/ml) as an obligatory cofactor for maximal particle uptake. Treatment of PM monolayers with trypsin (1 mg/ml) for 15 min at 37 degrees C after particle uptake removed less than 15% of the radioactivity incorporated by the monolayers. However, a similar trypsin treatment of the monolayers before the addition of latex particles depressed Clg-dependent uptake by greater than 75%. Pretreatment of PM monolayers with inhibitors of glycolysis effectively reduced the Clg-dependent uptake of latex. Similarly, pretreatment of monolayers with either inhibitors of protein synthesis or agents that disrupt cytoskeletal elements also significantly depressed Clg-dependent particle uptake. Phagocytosis of g-Ltx* by PM in the presence of Clg and heparin was confirmed by electron microscopy. Finally, g-Ltx* could also be effectively opsonized with Clg at 37 degrees C before their addition to the monolayers. These studies suggest that the recognition of g-Ltx* in the presence of Clg required cell surface protein(s) and that subsequent phagocytosis of these particles by PM was energy dependent and required intact intracellular cytoskeleton elements. Thus, PM monolayers provide a suitable system for further studies on the function of Clg in the recognition and phagocytosis of gelatin-coated particles by phagocytic cells.

Animals↗

PubMed1972

Molecular studies on entry exclusion in Escherichia coli minicells.

Minicells produced by abnormal cell division in a strain of Escherichia coli (K-12) have been employed here to investigate the phenomenon of "entry exclusion." When purified minicells from strains containing F' or R factors, or both, are mated with radioactive thymidine-labeled Hfr or R(+) donors, the recipient minicells can be conveniently separated from normal-sized donors following mating, and the products of conjugation can be analyzed in the absence of donors and of further growth of the recipients. Transmissible plasmids or episomes are transferred less efficiently to purified minicells derived from strains carrying similar or related elements than to strains without them. Measurement of deoxyribonucleic acid (DNA) degradation and determination of weight-average molecular weights following transfer indicate that degradation of transferred DNA or transfer of smaller pieces cannot account for the comparative reduction in transfer to entry-excluding recipients. Therefore, we conclude that entry exclusion operates to prevent the physical entry of DNA into recipients expressing the exclusion phenotype. The R-produced repressor (product of the drd(+) gene), which represses fertility (i.e., ability to act as donor), reduces exclusion mediated by R or F factor, or both, in matings between strains carrying homologous elements. Furthermore, the data suggest that the presence of the F pilus or F-like R pilus on recipient cells ensures maximum expression of the exclusion phenotype but is not essential for its expression. In contrast to previous suggestions, we found no evidence for a reduction of entry exclusion attributable to the DNA temperature-sensitive chromosomal mutation dnaB(TS).

Centrifugation, Density Gradient↗

PubMed1999

A description of factors affecting hazardous waste workers' use of respiratory protective equipment.

This article describes the first phase of a study that was designed to gain an understanding of hazardous waste workers' attitudes and beliefs about the use of respiratory protective equipment. Exploratory, open-ended interviews were conducted among 28 respirator users at a US Department of Energy facility. Subjects were asked to describe their knowledge, attitudes, and beliefs about their risks to hazards at their worksites and to discuss their use of respiratory protective equipment. A detailed content analysis of the interviews resulted in the generation of a taxonomy of issues and concerns which fell into three general categories: 1) Knowledge, Beliefs, and Attitudes, 2) Physical and Psychological Effects, and 3) External Influences. Knowledge, Beliefs, and Attitudes included Training, Fit Testing, Medical Clearance, Work Exposures, Respirator Use, and Vulnerability to Disease. Physical and Psychological Effects included Somatic/Health Effects, Personal Comfort, Visual Effects, Fatigue, Communication, and Anxiety. External Influences included Structural Environment, Quality and Availability of Equipment, Other PPEs, Co-Worker Influence, Supervisor Influence, and Organizational Culture. The findings from this study have important implications to training and education programs. Effective respiratory protection programs depend on a knowledge of the factors that affect workers' use of equipment. This study suggests that efforts to assure equipment comfort and fit, to assist workers who see and hear less well as a result of their equipment, and to develop strategies to allay worker anxiety when wearing equipment should all be components of a program. An organizational culture that supports and abets the appropriate use of equipment is also a critical element in a successful program.

Adult↗

PubMedDate not supplied

[Experimental investigations of 211Am accumulation by macrophytes of the Yenisei River].

Experiments were carried out in which 241Am was added to water samples containing macrophytes of the Yenisei River, and the radionuclide absorption rates and concentration factors were determined for the plants. It has been shown that the water moss (Fontinalis antipyretica) has a higher capacity to accumulate 241Am than the Canadian pondweed (Elodea canadensis) does. The laboratory experiments revealed that the capacity of dead biomass of the Canadian pondweed to accumulate 241Am is twice higher than that of living biomass. In contrast, no significant increase in 241Am accumulation by dead biomass of the water moss has been recorded. The transuranic element 241Am was firmly fixed by the plant biomass and was not released into water in the course of long-duration experiments.

Absorption↗

PubMedDate not supplied

[Cytological characteristics, elemental composition of alveolar macrophages from bronchoalveolar lavage, lung pathology in liquidators of the consequences of the accident at the Chernobyl power plant].

Bronchoalveolar lavage fluid (BALF), broncho- and transbronchial biopsies were examined in Chernobyl wreckers eleven years after the accident. Cytologically and electron-microscopically, there was predominance of alveolar macrophages (AM) with many cytoplasmic foreign bodies containing clear needle-like crystals. Roentgenospectral analysis and laser mass-spectrometry revealed chemical elements which are part of non-active "hot particles" (Al, Si, Ca, Fe) as well as reactor fuel elements and the station constructive materials which are the active part of "hot particles". Programmed BALF allowed to decrease cytosis and the amount of AM containing foreign-body particles as well as concentration of the majority of chemical elements in AM.

Adult↗

PubMed2006

A propolis extract and the labeling of blood constituents with technetium-99m.

Since ancient times propolis has been employed for many human purposes because to their favourable properties. Blood constituents labeled with technetium-99m (99mTc) have been used in nuclear medicine procedures. Some authors have reported that synthetic or natural drugs can interfere with the labeling of blood constituents with 99mTc. The aim of this work was to evaluate the action of a propolis extract on the labeling of blood elements with 99mTc. Samples of whole blood of male Wistar rats were incubated in sequence with an aqueous propolis extract at different concentrations, stannous chloride and 99mTc, as sodium pertechnetate. Blood samples were centrifuged to separate plasma and blood cells, soluble and insoluble fractions of plasma and blood cells were also separated after precipitation in trichloroacetic acid solution and centrifugation. The radioactivity was counted and the percentage of incorporated radioactivity (%ATI) for each fraction was calculated. The data obtained showed that the aqueous propolis extract used decreased significantly the %ATI in plasma proteins at higher concentration studied. Results suggest that at high concentration the constituents of this extract could alter the labeling of plasma proteins competing with same binding sites of the 99mTc on the plasma proteins or acting as antioxidant compounds.

Animals↗