ABSTRACT: 1. The action of beryllium on the following enzymes has been examined: alkaline phosphatase (Escherichia coli and kidney), acid phosphatase, phosphoprotein phosphatase, apyrase (potato), adenosine triphosphatase (liver nuclei, liver mitochondria, brain microsomes), glucose 6-phosphatase, polysaccharide phosphorylases a and b, phosphoglucomutase, hexokinase, phosphoglyceromutase, ribonuclease, A-esterase (rabbit serum), cholinesterase (horse serum), chymotrypsin. Alkaline phosphatase and phosphoglucomutase are inhibited by 1mum-beryllium sulphate whereas the other enzymes are largely unaffected by 1mm-beryllium sulphate. 2. Possible mechanisms for the inhibition of phosphoglucomutase and alkaline phosphatase are discussed.
Project description:1. The inhibition of phosphoglucomutase by beryllium has been examined. 2. Inhibition by beryllium does not occur unless a complex-forming agent such as cysteine or imidazole is present. It is therefore similar to activation by magnesium. 3. The inhibition is progressive and the rate follows first-order kinetics, which may be defined by a bimolecular rate constant. 4. In the presence of magnesium the rate of inhibition is less. By using a fixed time for inhibition competition between beryllium and magnesium may be demonstrated. After inhibition has taken place, the addition of magnesium does not reverse it.
Project description:1. Male rats were injected intravenously with amounts ranging from 0.08 to 111.0mumoles of [(7)Be]beryllium sulphate/kg. body wt. The distribution in the rat and the subcellular distribution of beryllium in the liver were determined. 2. Within the entire dose range a higher specific activity of beryllium was present in a mitochondrial fraction containing the lysosomes. Purification of this fraction confirmed that beryllium is taken up by lysosomes. 3. With doses approaching the LD(50), beryllium was also found in increasing amounts to be present in the liver cell nuclei. Beryllium also showed affinity towards isolated cell nuclei in vitro. Evidence is presented that they have one class of binding sites for beryllium. Mitochondria have less affinity for beryllium. 4. No evidence could be obtained of an affinity of beryllium for DNA or RNA by fractionation of nuclei and dialysis experiments. 5. The presence of beryllium in liver cell nuclei may be relevant to the effects of beryllium on nuclear structure and function.
Project description:1. The incorporation of thymidine into DNA of regenerating rat liver was measured at various times after partial hepatectomy. A single intravenous injection of 30mumol of beryllium/kg given immediately after the operation inhibited DNA synthesis 12, 16, 20, 24 and 28h later. 2. The activity of several enzymes critical to DNA synthesis (thymidine kinase, thymidylate kinase, thymidylate synthetase, deoxycytidylate deaminase and DNA polymerase) increased in control rats 20-24h after partial hepatectomy severalfold over the activity found in resting livers. After beryllium treatment this rise in activity was much less and it seemed as if beryllium would partially block the induction of DNA-synthesizing enzymes after partial hepatectomy. 3. Enzymes whose activities do not rise during liver regeneration were not affected by beryllium (aspartate transcarbamoylase, carbamoyl phosphate synthetase, uridine kinase and glucose 6-phosphatase). 4. No evidence was found in vitro that beryllium would specifically inhibit thymidine kinase or DNA polymerase. 5. The time-effect relationship between beryllium administration and thymidine kinase activity in vivo was examined. Measured 24h after partial hepatectomy, thymidine kinase activity was only affected if beryllium was given within the first 9-12h after partial hepatectomy. Beryllium given later, even in greatly increased doses, failed to have any effect on thymidine kinase. The possibility is discussed that beryllium inhibits enzyme induction at the transcriptional level.
Project description:1. High-voltage paper-electrophoresis methods have been used for the separation of (32)P-labelled phosphoesters. 2. Evidence is presented which indicates that (32)P-labelled phosphopeptides, obtained after acid hydrolysis of phosphoglyceromutase incubated with impure 2,3-di[(32)P]phosphoglycerate, are derived from phosphoglucomutase contamination. 3. The hydrolysis of 2,3-di[(32)P]phosphoglycerate by phosphoglyceromutase has been studied. After an apparent instantaneous hydrolysis of 1 mole of coenzyme/mole of enzyme the reaction proceeds at a very low rate. 4. This hydrolysis seems to be due to the destruction of an enzyme-coenzyme complex. The proportions of the decomposition products of the complex vary according to further handling (pH of ionophoresis). 5. The inorganic [(32)P]phosphate produced by the hydrolysis of the complex and the inorganic [(32)P]phosphate produced by the slow phosphatase activity can be differentiated by the ability of the former to be incorporated into non-radioactive substrate before enzyme denaturation. 6. The effect of enzyme concentration on the stoicheiometry of the slow phosphatase hydrolysis of the diphosphoglycerate is described and this suggests that it may occur via two independent reactions, one of them being the decomposition of the enzyme-coenzyme complex on standing.
Project description:We aimed at investigating mortality among beryllium-exposed workers, according to solubility of beryllium and beryllium compounds. We conducted an historical cohort study of 16,115 workers employed during 1925-2008 in 15 facilities, including eight entailing exposure to insoluble beryllium and seven entailing exposure to soluble/mixed beryllium compounds, who were followed up for mortality until 2011. Data were analyzed using indirect standardization and Cox regression modeling. Lung cancer standardized mortality ratio (SMR, national reference rates) was 1.02 (95% confidence interval [CI]: 0.94-1.10) in the whole cohort, 0.88 (95% CI: 0.75-1.03) in the insoluble beryllium subcohort, and 1.09 (95% CI: 0.99-1.09) in the soluble/mixed beryllium subcohort. For lung cancer, there was an association with period of hire in soluble/mixed beryllium plants but not in insoluble plants, and, conversely, employment in soluble/mixed plants was associated with increased mortality only among workers hired before 1955. There was no trend with duration of employment. Mortality from chronic beryllium disease increased, in particular, among workers hired before 1955 in soluble/mixed beryllium facilities. There was no increase in lung cancer mortality in the entire cohort and lung cancer mortality was not increased among beryllium workers hired in 1955 or later in soluble/mixed beryllium facilities, or at any time among those employed in insoluble beryllium facilities.
Project description:A beryllium(II)-ion-selective poly(ethylenedioxythiophene) (PEDOT) solid contact electrode comprising 9,10-dinitrobenzo-9-crown-3-ether was successfully developed. The all-solid-state contact electrode, with an oxygen-containing cation-sensing membrane combined with an electropolymerized PEDOT layer, exhibited the best response characteristics. The performance of the constructed electrode was evaluated and optimized using potentiometry, conductance measurements, constant-current chronopotentiometry, and electrochemical impedance spectroscopy (EIS). Under optimized conditions, which were found for an ion-selective membrane (ISM) composition of 3% ionophore, 30% polyvinylchloride (PVC), 64% o-nitro phenyl octyl ether (o-NPOE), and 3% sodium tetraphenylborate (NaTPB), the fabricated electrode exhibited a good performance over a wide concentration range (10-2.5-10-7.0 M) and a wide pH range of 2.0-9.0, with a Nernstian slope of 29.5 mV/D for the beryllium (II) ion and a detection limit as low as 10-7.0 M. The developed electrode shows good selectivity for the beryllium(II) ion over alkali, alkaline earth, transition, and heavy metal ions.
Project description:Metal-induced hypersensitivity is driven by T-cell sensitization to metal ions. Although numerous metals are associated with the development of diffuse parenchymal lung disease, beryllium-induced hypersensitivity is the best-studied to date. This review focuses on the interaction between innate and adaptive immunity that leads to the development of chronic beryllium disease. After beryllium exposure, activation of the innate immune system occurs through the engagement of pattern-recognition receptors. This activation leads to cell death, release of alarmins, and activation and migration of dendritic cells to lung-draining lymph nodes. These events culminate in the development of an adaptive immune response that is characterized by beryllium-specific, T-helper type 1-polarized, CD4+ T-cells and granuloma formation in the lung. The unique ability of beryllium to bind to human leukocyte antigen-DP molecules that express a glutamic acid at position 69 of the β-chain alters the charge and conformation of the human leukocyte antigen-DP-peptide complex. These changes induce post-translational modifications that are recognized as non-self. In essence, the ability of beryllium to create neoantigens underlies the genesis of chronic beryllium disease, and demonstrates the similarity between beryllium-induced hypersensitivity and autoimmunity.
Project description:Chronic beryllium disease (CBD) is a granulomatous lung disorder caused by a hypersensitivity to beryllium and characterized by the accumulation of beryllium-specific CD4(+) T cells in the lung. Genetic susceptibility to beryllium-induced disease is strongly associated with HLA-DP alleles possessing a glutamic acid at the 69th position of the ?-chain (?Glu69). The structure of HLA-DP2, the most prevalent ?Glu69-containing molecule, revealed a unique solvent-exposed acidic pocket that includes ?Glu69 and represents the putative beryllium-binding site. The delineation of mimotopes and endogenous self-peptides that complete the ??TCR ligand for beryllium-specific CD4(+) T cells suggests a unique role of these peptides in metal ion coordination and the generation of altered self-peptides, blurring the distinction between hypersensitivity and autoimmunity.
Project description:Beryllium salts (here, beryllium sulphate) can produce a cytostatic effect in some cell types. The basis for this effect may include increased expression of proliferation inhibitors, reduced expression of proliferation promoters, or both. This study sought to determine the role of p53, the tumour-suppressing transcription factor, in mediating beryllium-induced cytostasis.Human A172 glioma cells express wild-type TP53 gene. Activity of p53 was experimentally manipulated using siRNA and related approaches. Key elements of the beryllium-response were compared in normal and p53-knockdown A172 cells using RT-PCR and Western blotting.In A172 cells, 10 ?m BeSO4 caused 300% increase in CDKN1A (cyclin-dependent kinase inhibitor p21) mRNA and 90% reduction of CCNE2 (cyclin E2) mRNA. The increased p21 mRNA and reduced cyclin E2 mRNA were each dependent on presence of functional p53. For p21, increased mRNA led to commensurately increased protein levels. In contrast, reduction in cyclin E2 mRNA levels did not lead to corresponding reductions in cyclin E2 protein. The proteasomal inhibitor MG-132 caused p53 protein to increase, but it had no effect on cyclin E2 protein levels. Cycloheximide time course studies indicated that the cyclin E2 protein half-life was more than 12 hours in these cells.Beryllium elicited p53-dependent changes in mRNA levels of key determinants of cell proliferation such as p21 and cyclin E2. However, cyclin E2 protein appeared to be aberrantly regulated in this cell type, as its turnover was unexpectedly slow.
Project description:Aldehydes play a key role in the human metabolism. Therefore, it is essential to know their reactivity with beryllium compounds in order to assess its effects in the body. The reactivity of simple aldehydes towards beryllium halides (F, Cl, Br, I) was studied through solution and solid-state techniques and revealed distinctively different reactivities of the beryllium halides, with BeF2 being the least and BeI2 the most reactive. Rearrangement and aldol condensation reactions were observed and monitored by in situ NMR spectroscopy. Crystal structures of various compounds obtained by Be2+ -catalyzed cyclization, rearrangement, and aldol addition reactions or ligation of beryllium halides have been determined, including unprecedented one-dimensional BeCl2 chains and the first structurally characterized example of an 1-iodo-alkoxide. Long-term studies showed that only aldehydes without a β-H can form stable beryllium complexes, whereas other aldehydes are oligo- and polymerized or decomposed by beryllium halides.