Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “BERYLLIUM”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 433 records · Page 24Linked to original sources
PubMed1992

Shear strength of laboratory-processed composite resins bonded to a silane-coated nickel-chromium-beryllium alloy.

The shear bond strengths of three commercial laboratory curing composite resin veneers bonded to a nickel-chromium-beryllium alloy treated with the Silicoater system were evaluated. Two light-cured resins and one heat- and pressure-cured resin were evaluated. No statistically significant difference in bond strengths among the three resins was found. Microscopic analysis of the fracture surfaces indicated that all failures were complex and cohesive in nature within the resin and composite. On the basis of the shear bond strengths measured, any of the composite resin veneers tested appear to be clinically acceptable.

Acrylic Resins↗
PubMed1987

Bronchoalveolar lavage in rats and mice following beryllium sulfate inhalation.

The effects of lung injury in rats and mice exposed to an aerosol of beryllium sulfate for 1 hr through nose-only inhalation were evaluated by the method of bronchoalveolar lavage. The lavage fluid of rats exposed to an aerosol of either 3.3 or 7.0 micrograms Be/liter over a 21-day period following exposure indicated lactate dehydrogenase (LDH) and alkaline phosphatase (Alk Pase) activities to be the most sensitive indicators of lung damage. LDH activity peaked at 8 days postexposure while Alk Pase activity was maximum at Day 5. Both values were 30 times greater than comparable controls at these time points. Acid phosphatase activity and albumin levels also increased over the 21-day period, but not to the same extent. The lung lavage of mice exposed to 7.2 micrograms Be/liter showed LDH activity as the most sensitive indicator of lung damage with a maximum response three times greater than that of controls at Day 5.

Acid Phosphatase↗
PubMed1985

The effect of cyclosporin A on pulmonary fibrosis induced by butylated hydroxytoluene, bleomycin and beryllium sulfate.

Interstitial pulmonary fibrosis is characterized by an abnormal accumulation of fibroblasts with a resultant increase in lung collagen content. Previous research has implied a possible involvement of the T-lymphocyte in this process. We used cyclosporin A (Cy A), a known immunosuppressant, to deplete T-lymphocyte-dependent responses in animals following treatment with agents known to produce fibrosis; butylated hydroxytoluene (BHT), bleomycin and beryllium (Be). BHT-treated mice and bleomycin-treated rats showed significant reduction in total lung hydroxyproline content with Cy A (P less than 0.05). These results suggest a contribution of the T-lymphocyte in the overall process of fibrosis, but do not indicate its role as the sole causative agent.

Animals↗
PubMed1986

Mitogenic effects of beryllium and zirconium salts on mouse splenocytes in vitro.

The beryllium (Be) and zirconium (Zr) salts, BeSO4 and Zr(SO4)2, each exerted a concentration-dependent stimulation of mouse spleen cell proliferation as measured by an increase in [3H]thymidine incorporation into lymphocyte DNA, although the maximal response induced by Zr(SO4)4 (4-5 fold at 100-200 microM) was greater than that by BeSO4 (2-3 fold at 1-5 microM). Preincubation of splenocytes with low concentrations of BeSO4 (less than 1 microM) or a broad range of Zr(SO4)2 concentrations (2-100 microM) was also found to assist subsequent lectin (concanavalin A; ConA)-mediated lymphocyte proliferation. The results indicate that at defined concentrations Be and Zr salts can both act as lymphocyte mitogens and augment the functional responsiveness of immune cells, which may help explain the characteristic induction of delayed hypersensitivity and production of immunological granulomas by these metals in vivo.

Animals↗
PubMed2004

Novel inhibition mechanism of Bacillus cereus sphingomyelinase by beryllium fluoride.

Phosphate analogs have been known to inhibit competitively various phosphatases and phospholipase C and D. We found for the first time that only beryllium fluoride (BeF(x)) among the phosphate analogs studied inhibits Bacillus cereus sphingomyelinase (SMase) activity. The active inhibitory species proved to be not BeF(3)(-) but BeF(2) by the measurement of SMase activity and of (19)F NMR spectroscopy in the presence of a fixed concentration of BeCl(2) and different concentrations of NaF, although both the species have been reported for other kinds of enzymes. The result of kinetic experiment also indicated that the BeF(x) binds in the vicinity of the essential binding site for the substrate and that the Mg(2+) binding to SMase is essential for the binding of BeF(x) to the enzyme.

Bacillus cereus↗
PubMed2004

Partial least-squares regression for the simultaneous determination of aluminum and beryllium in geochemical samples using xylenol orange.

A partial least-squares regression (PLS) was developed for the simultaneous spectrophotometric determination of aluminum and beryllium in geochemical samples by xylenol orange as the chromogenic reagent in water media and in micellar media. The effects of pH, xylenol orange concentration and surfactant concentration on the complexes formation reactions were studied. In the absence of surfactant the complex color development takes place at 2 h after mixing the reagents. By using CTAB as micellar media the complexes formation was improved and the rate of the complexation reactions increased. By using PLS-1 algorithm satisfactory results were obtained. The proposed procedure showed to be useful for prediction of Al and Be values from 0.1 to 1.0 mg L(-1).

Aluminum↗
PubMed1992

Beryllium-induced lung disease in the dog following two exposures to BeO.

We have shown previously that dogs exposed once to aerosols of beryllium oxide (BeO) calcined at 500 or 1000 degrees C developed granulomatous lung lesions as well as Be-specific immune responses in the blood and lung. In this report, we investigate the immunopathologic consequences of exposing dogs twice to aerosols of BeO. Dogs previously exposed to aerosols of 500 or 1000 degrees C calcined BeO to achieve an initial lung burden (ILB) of either 50 or 17 micrograms/kg body wt were exposed a second time to BeO calcined at 500 degrees C, 2.5 years after the first exposure, to achieve an ILB of about 50 micrograms/kg body wt. Immune responses of peripheral blood and lung lymphocytes were measured at 0, 14, 30, 60, 90, 120, 150, 165, 180, and 210 days postexposure (dpe), and dogs were euthanized at 210 dpe. Be-specific immune responses occurred in blood at 30 dpe and again at 150 to 210 dpe. Only sporadic positive responses were seen among lung lymphocytes when cells were cultured in 10% fetal bovine serum. In contrast, samples collected at 165, 180, and 210 dpe and incubated with 10% dog serum showed a large number of positive responses in both blood and lung. Histologic lesions were characterized by perivascular and interstitial infiltrates of lymphocytes and macrophages with progression to patchy granulomatous pneumonia accompanied by focal septal fibrosis. We conclude that Be-induced granulomatous and fibrotic lung lesions are accompanied by Be-specific immune responses within the lung but these changes do not appear to be cumulative if enough time has elapsed between exposures.

Aerosols↗
PubMed2001

Sensitive and selective ion chromatographic method for the determination of trace beryllium in water samples.

A selective and sensitive ion chromatographic method has been developed for the determination of beryllium in a number of water samples at low-microg/l concentrations. The separation was performed on a 250x4.0 mm I.D. iminodiacetic acid functionalised silica gel column. Chromatographed Be(II) was detected using visible detection at 590 nm following post-column reaction with chrome azurol S (CAS). The optimum separation and derivatisation conditions were studied in detail. The optimum eluent conditions were found to be 0.4 M KNO3, adjusted to pH 2.5 using HNO3, with optimum post-column detection being achieved using a solution containing 0.26 mM CAS, 2% Triton X-100, 50 mM 2-(N-morpholino)ethanesulfonic acid, pH 6.0. Under the above conditions, the concentration detection limit for Be(II) was found to be 3 microg/l in a standard solution and 4 microg/l in a typical tap water sample, using a 250 microl injection. The method was linear over the investigated range of 10 microg/l to 10 mg/l and highly reproducible. The method was successfully applied to a number of water samples of varying matrix complexity, including simulated seawater, and also to a natural freshwater certified reference material NIST 1640.

Beryllium↗
PubMed2001

Inhibition of normal human lung fibroblast growth by beryllium.

Inhalation of particulate beryllium (Be) and its compounds causes chronic Be disease (CBD) in a relatively small subset ( approximately 1-6%) of exposed individuals. Hallmarks of this pulmonary disease include increases in several cell types, including lung fibroblasts, that contribute to the fibrotic component of the disorder. In this regard, enhancements in cell proliferation appear to play a fundamental role in CBD development and progression. Paradoxically, however, some existing evidence suggests that Be actually has antiproliferative effects. In order to gain further information about the effects of Be on cell growth, we: (1) assessed cell proliferation and cell cycle effects of low concentrations of Be in normal human diploid fibroblasts, and (2) investigated the molecular pathway(s) by which the cell cycle disturbing effects of Be may be mediated. Treatment of human lung and skin fibroblasts with Be added in the soluble form of BeSO(4) (0.1-100 microM) caused inhibitions of their growth in culture in a concentration-dependent manner. Such growth inhibition was found to persist, even after cells were further cultured in Be(2+)-free medium. Flow cytometric analyses of cellular DNA labeled with the DNA-binding fluorochrome DAPI revealed that Be causes a G(0)-G(1)/pre-S phase arrest. Western blot analyses indicated that the Be-induced G(0)-G(1)/pre-S phase arrest involves elevations in TP53 (p53) and the cyclin-dependent kinase inhibitor CDKN1A (p21(Waf-1,Cip1)). That Be at low concentrations inhibits the growth of normal human fibroblasts suggests the possibility of the existence of abnormal cell cycle inhibitory responses to Be in individuals who are sensitive to the metal and ultimately develop CBD.

Beryllium↗
PubMed1999

Fallout beryllium-7 as a tracer in soil erosion investigations.

Recent developments in the use of the environmental radionuclides 137Cs and 210Pb for documenting medium-term soil erosion rates must be seen as an important advance. However, measurements of these radionuclides provide estimates of medium-term (i.e. ca. 45 or 100 years) soil redistribution rates and there is a need to explore the potential for using complementary radionuclides, to estimate erosion rates associated with individual events or short periods. Beryllium-7 (7Be, t0.5 = 53 days) has the potential to fulfil these requirements. This contribution presents some preliminary results from an investigation undertaken in a field near Crediton, UK, which successfully demonstrates the potential for using 7Be as a tracer in soil erosion investigations.

Beryllium↗
PubMed1995

Differential scanning calorimetric study of the complexes of myosin subfragment 1 with nucleoside diphosphates and vanadate or beryllium fluoride.

It has been recently shown by differential scanning calorimetry (DSC) that the formation of stable complexes of myosin subfragment 1 (S1) with Mg-ADP and orthovanadate (Vi) or beryllium fluoride (BeFx) causes a global conformational change in the S1 molecule which is reflected in a pronounced increase of S1 thermal stability and in a significant change of S1 domain structure [Shriver, J. W., & Kamath U. (1990) Biochemistry 29, 2556-2564; Levitsky, D. I., Shnyrov, V. L., Khvorov, N. V., Bukatina, A. E., Vedenkina, N. S., Permyakov, E. A., Nikolaeva, O. P., & Poglazov, B. F. (1992) Eur. J. Biochem. 209, 829-835; Bobkov, A. A., Khvorov, N. V., Golitsina, N. L., & Levitsky, D. I. (1993) FEBS Lett. 332, 64-66]. In this work, which continues the previous investigations, we report on a DSC study of the complexes of S1 with various nucleoside diphosphates (NDP). In the absence of Vi or BeFx the various Mg(2+)-NDP and Mg(2+)-PPi had a similar effect on the S1 conformation. All of them had practically no influence on the temperature of the thermal transition but increased its sharpness. However, in the presence of Vi or BeFx the effects of Mg(2+)-NDP complexes were quite different from each other and strongly depended on the base structure of NDP; their effectiveness in inducing conformational changes in S1 and the stability of these complexes decreased in the following order: ADP > CDP >> UDP >> IDP > GDP.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Diphosphate↗
PubMed1993

Characterization of the inhibition of rabbit muscle adenylate kinase by fluoride and beryllium ions.

In the presence of NaF, BeCl2, ADP, and Mg2+, rabbit muscle adenylate kinase was strongly inhibited. Molecules responsible for the inhibition were identified after subjecting the inhibited enzyme to filtration-centrifugation through small Sephadex G-50 columns. Full inhibition was correlated with the entrapment of 2 mol of ADP, 1 mol of beryllium, and 1 mol of magnesium per mole of enzyme; when an excess of AMP was present together with ADP, only 1 mol of bound ADP was detected in the desalted inhibited enzyme, due to the release of a loosely bound AMP. The fluorometal species identified in the ADP-fluoroberyllate entrapped complex were BeF+, BeF2, and BeF3-. When inhibited adenylate kinase was diluted in a medium deprived of the inhibitory species, the enzyme activity was progressively recovered, and a k(off) value of 0.23 min-1 for the release of the inhibitor complex was calculated. The possibility that the inhibitory nucleotide-fluoroberyllate complex behaves as a transition-state analog is discussed.

Adenosine Diphosphate↗
PubMed1993

Kinetic and equilibrium analysis of the interactions of actomyosin subfragment-1.ADP with beryllium fluoride.

The hypothesis that the stable ternary complex formed between myosin subfragment-1, MgADP and beryllium fluoride (BeF3-), denoted S-1 not equal to .ADP.BeF3-, is an analog of the intermediate state S-1**.ADP.P(i) has been tested in this work by examining the interactions of S-1 not equal to .ADP.BeF3- with actin. Equilibrium binding measurements revealed that actin bound weakly to the S-1 not equal to .ADP.BeF3- complex (Ka = 10(4) M-1) in the presence of 40 mM KCl. The stability of this complex was strongly salt-dependent. The association constant of BeF3- to the acto-S-1.ADP complex (KBe approximately 10(3) M-1) was 100-fold weaker than its binding to the S-1.ADP complex. While inhibiting the S-1 ATPase strongly, BeF3- had no effect on the Vmax value (10 +/- 1.0 s-1) of the actin-activated ATPase of S-1. The rates of BeF3- binding and dissociation from the acto-S-1.ADP.BeF3- complex were determined by stopped-flow measurements. The hyperbolic dependence of the rates of BeF3- binding to acto-S-1.ADP (kobs) on BeF3- concentrations suggested that the acto-S-1.ADP.BeF3- complex was formed in at least two steps: binding followed by isomerization. The binding constant was 1.2 x 10(3) M-1, and the maximum kobs was 2.5 s-1. The dissociation of BeF3- from the acto-S-1.ADP.BeF3- complex was monitored via decrease in the fluorescence of 1-N6-ethenoadenosine diphosphate (epsilon ADP). The fluorescence decrease fitted two exponential terms.(ABSTRACT TRUNCATED AT 250 WORDS)

Actins↗
PubMed1997

Inhibition of P-glycoprotein ATPase activity by beryllium fluoride.

ATPase activity of P-glycoprotein (multidrug-resistance protein) was found to be potently inhibited by beryllium fluoride (BeFx) in combination with MgATP, MgADP, or corresponding Mg-8-azido-nucleotides. Inhibition was due to trapping of nucleoside diphosphate at catalytic sites. Full inhibition was achieved on trapping of 1 mol of nucleotide per mol of Pgp. Reactivation was slow (t(1/2) = 32 min at 37 degrees C), and release of trapped nucleotide correlated with recovery of ATPase. Trapping of 8-azido-ADP followed by UV irradiation yielded permanent inactivation and specific labeling of Pgp in plasma membranes. Both N- and C-terminal nucleotide binding sites were labeled. These findings give strong confirmation of the concepts that in intact Pgp both nucleotide sites are active in MgATP hydrolysis, and that they interact strongly. The characteristics of inhibition by BeFx were similar in general to those seen with vanadate. However, PPi gave strong protection against BeFx inhibition, and in this respect, inhibition by BeFx was clearly different from vanadate inhibition.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1999

Klebsiella pneumoniae nitrogenase: formation and stability of putative beryllium fluoride-ADP transition state complexes.

Incubation of the MoFe protein (Kp1) and Fe protein (Kp2), the component proteins of Klebsiella pneumoniae nitrogenase, with BeF(3)(-) and MgADP resulted in a progressive inhibition of nitrogenase activity. We have shown that at high Kp2 to Kp1 molar ratios this inhibition is due to the formation of an inactive complex with a stoichiometry corresponding to Kp1.{Kp2.(MgADP.BeFx)2}2. At lower Kp2:Kp1 ratios, an equilibrium between this 2:1 complex, the partially active 1:1 Kp1.Kp2.(MgADP. BeFx)2 complex, and active nitrogenase components was demonstrated. The inhibition was reversible since incubation of the 1:1 complex in the absence of MgADP and beryllium resulted in complete restoration of activity over 30 h. Under pseudo-first-order conditions with regard to nitrogenase components and MgADP, the kinetics of the rate of inhibition with increasing concentrations of BeF(3)(-) showed a square dependence on [BeF(3)(-)], consistent with the binding of two Be atoms by Kp2 in the complex. Analytical fplc gel filtration profiles of Kp1.Kp2 incubation mixtures at equilibrium resolved the 2:1 complex and the 1:1 complex from free Kp1. Deconvolution of the equilibrium profiles gave concentrations of the components allowing constants for their formation of 2.1 x 10(6) and 5.6 x 10(5) M(-1) to be calculated for the 1:1 and 2:1 complexes, respectively. When the active site concentration of the different species was taken into account, values for the two constants were the same, indicating the two binding sites for Kp2 are the same for Kp1 with one or both sites unoccupied. The value for K(1) we obtain from this study is comparable with the value derived from pre-steady-state studies of nitrogenase. Analysis of the elution profile obtained on gel filtration of a 1:1 ratio incubation mixture containing 20 microM nitrogenase components showed 97% of the Kp2 present initially to be complexed. These data provide the first unequivocal demonstration that Fe protein preparations which may contain up to 50% of a species of Fe protein defective in electron transfer is nevertheless fully competent in complex formation with MoFe protein.

Adenosine Diphosphate↗
PubMed2001

Beryllium-7 as a tracer of short-term sediment deposition and resuspension in the Fox River, Wisconsin.

Short-term (approximately monthly) sediment deposition and resuspension rates of surficial bed sediments in two PCB-laden impoundments on the Fox River, WI, were determined in the summer and fall of 1998 using 7Be, a naturally occurring radioisotope produced in the atmosphere. Decay-corrected activities and inventories of 7Be were measured in bed sediment and in suspended particles. Beryllium-7 activities generally decreased with depth in the top 5-10 cm of sediments and ranged from undetectable to approximately 0.9 pCi cm(-3). Inventories of 7Be, calculated from the sum of activities from all depths, ranged from 0.87 to 3.74 pCi cm(-2), and the values covaried between sites likely reflecting a common atmospheric input signal. Activities of 7Be did not correlate directly with rainfall. Partitioning the 7Be flux into "new" and "residual" components indicated that net deposition was occurring most of the time during the summer. Net erosion, however, was observed at the upstream site from the final collection in the fall. This erosion event was estimated to have removed 0.10 g (cm of sediment)(-2), corresponding to approximately 0.5 cm of sediment depth, and approximately 6-10 kg of polychlorinated biphenyls (PCBs) over the whole deposit. Short-term accumulation rates were up to approximately 130 times higher than the long-term rates calculated from 137Cs profiles, suggesting an extremely dynamic sediment transport environment, even within an impounded river system.

Beryllium↗
PubMed2004

Beryllium(II) binding to ATP and ADP: potentiometric determination of the thermodynamic constants and implications for in vivo toxicity.

Highly toxic beryllium(II) is divalent metal ion with a high charge density, making it a potential target for binding to bio-molecules rich in O donor groups. In aqueous solution Be2+ binds to ATP and ADP to form 1:1 Be2+:ATP and Be2+:ADP complexes in relatively acidic media. At neutral pH the complex formed undergoes hydrolysis. Be2+ binding to ATP and ADP is much stronger than Ca2+ and Mg2+ binding. The high affinity of Be2+ toward ATP and ADP binding suggests a mechanism relevant to understanding the in vivo chemical toxicity of this metal.

Adenosine Diphosphate↗
PubMed2006

A review of workplace aerosol sampling procedures and their relevance to the assessment of beryllium exposures.

Standardized conventions governing the fractions of airborne particles that can penetrate the human head airways, the thoracic airways and the alveolar spaces have been internationally (although not universally) adopted. Several agencies involved in setting limit values for occupational exposure concentrations have taken these conventions into account when considering the appropriate standard for specific chemicals, in order to ensure the standards are biologically relevant. A convention is selected based on the characteristic health effects, and forms the basis of measurement against the limiting concentration value. In order to assess exposure for comparison to this metric or any other purposes, it is necessary to choose a sampler whose performance matches the convention, and protocols have been developed and used to test sampler performance. Several aerosol sampling devices are available, nominally at least, for each of the conventions. Some considerations important to the sampling of airborne particles containing beryllium with regard to the sampling conventions, the test protocols and sampler performance are discussed.

Aerosols↗