Studies on the effects of dietary beryllium at two different calcium concentrations in Achatina fulica (Pulmonata)

The mortality was highest in snails fed beryllium in the diet containing the sub-optimal concentration of calcium. There was no increase in weight over an 8 week period. Snails fed the diet containing the optimal concentration of calcium without added beryllium showed maximum weight increase but calcium alone may not be responsible for elevated growth rate. Dietary calcium enhancement appears to be responsible for the reduced concentration of zinc, magnesium, phosphate and beryllium in the tissues. Beryllium treatment did not affect the calcium concentration in the digestive gland tissue but increased zinc and magnesium in the shell. The results are discussed in relation to uptake studies and possible enzyme systems involved.     

Characteristics of beryllium bonds; a QTAIM study

The nature of beryllium bonds formed between BeX2 (X is H, F and Cl) and some Lewis bases have been investigated. The distribution of the Laplacian of electron density shows that there is a region of charge depletion around the Be atom, which, according to Laplacian complementary principal, can interact with a region of charge concentration of an atom in the base and form a beryllium bond. The molecular graphs of the investigated complexes indicate that beryllium in BeH2 and BeF2 can form “beryllium bonds” with O, N and P atoms but not with halogens. In addition, eight criteria based on QTAIM properties, including the values of electron density and its Laplacian at the BCP, penetration of beryllium and acceptor atom, charge, energy, volume and first atomic moment of beryllium atom, have been considered and compared with the corresponding ones in conventional hydrogen bonds. These bonds share many common features with very strong hydrogen bonds, however,some differences have also been observed.     

铍对口腔链球菌生长及粘附性能的影响

目的 研究铍离子(Be2+)对口腔链球菌的生长及粘附性能的影响,探讨口腔修复治疗后牙周损伤的微生物机制.方法 含有不同浓度Be2+(5、10、20和40 mg/L)的培养液厌氧培养口腔链球菌24h.检测不同浓 度Be2作用后细菌形态和菌落形成单位(CFU),以及口腔链球菌在唾液包被羟基磷灰石微粒表面的粘附抑制率.结果 铍离子作用后口腔链球菌长链缩短,菌体出现集结趋势.20 mg/L时,菌体表面出现“触角样”变化.随Be2+浓度增加,CFU值减小(P＜0.05),口腔链球菌生长抑制.各实验组口腔链球菌粘附抑制率高于阳性对照组(P＜0.05),但各Be2+浓度组之间粘附抑制率差异无统计学意义(P＞0.05).结论 铍离子抑制口腔链球菌的生长和在牙面的粘附,可能会导致修复体周围正常微生态环境失衡,引起牙周疾病.提示临床应尽量选用理化性能稳定的修复材料.     

Characterization of stable beryllium fluoride, aluminum fluoride, and vanadate containing myosin subfragment 1-nucleotide complexes.

Beryllium and aluminum fluorides are good phosphate analogues. These compounds, like orthovanadate, form stable complexes with myosin subfragment 1 (S1) in the presence of MgADP. The formation of the stable S1-nucleotide complexes is characterized by the loss of ATPase activity. For the complete loss of ATPase activity there was necessary a higher concentration of aluminum than of beryllium or vanadate. In the presence of MgATP the onset of the inhibition is delayed, which indicates that stable complexes cannot form when a specific site is occupied by the gamma-phosphate of ATP or by P(i) derived from the gamma-phosphate. The half-lives of the S1-MgADP-(BeF3-), S1-MgADP-(AlF4-), and S1-MgADP-Vi complexes at 0 degrees C are 7, 2, and 4 days, respectively. In the presence of actin the rate of decomposition of all of the complexes is significantly enhanced; however, the order of decomposition is reversed, the fastest rate being observed with beryllium and the slowest with aluminum. The formation of the S1-MgADP-(BeF3-) and S1-MgADP-(AlF4-) complexes is accompanied by an increase in tryptophan fluorescence similar to that observed upon addition of MgATP to S1. The fluorescence increase develops rather slowly, by suggesting that the rate-limiting step in the formation of the stable complex is an isomerization. The rate of the fluorescence change accompanying the formation of the Be complex is faster than that for the Al complex. Addition of vanadate to S1 causes a static quenching of the tryptophan fluorescence.(ABSTRACT TRUNCATED AT 250 WORDS)     

Relative toxicities of particulate and soluble forms of beryllium to a rat liver parenchymal cell line in culture and possible mechanisms of uptake.

The relative toxicities of particulate beryllium phosphate, soluble beryllium sulphate and a beryllium sulphosalicylate complex to a rat liver parencymal derived cell line have been examined in culture. Due to the propensity of beryllium salts to form beryllium phosphate in solution the incubation medium used was free of inorganic phosphate. Cell death measured by the loss of cellular lactate dehydrogenase into the medium can be produced within 76 h from beryllium phosphate and beryllium sulphosalicylate or 48 h from beryllium sulphate provided the cells have, irrespective of the form of added beryllium, taken up a minimum of 2--5 nmol Be/10(6) cells. Whilst beryllium phosphate was readily taken up as a particle, beryllium complexed with excess sulphosalicylate was not so markedly accumulated by the cells except possibly by formation of small amounts of beryllium phosphate in the medium as a result of inorganic phosphate lost from the cells. The extent of beryllium uptake from beryllium sulphate quantitatively most resembled that observed for beryllium phosphate but was largely independent of beryllium phosphate formation in the medium and not accompanied by the uptake of the SO42- anion. However, the accumulation of beryllium derived from beryllium sulphate did appear to be associated with the production of a sedimentable from believed most probably to be colloidal beryllium hydroxide. The uptake of all forms of beryllium was temperature sensitive and metabolic inhibitor studies and treatment of the cells with trypsin or neuraminidase supported the view that the distinct behaviour of beryllium derived from beryllium sulphate may be related to the enhanced toxicity of this form both under the conditions used and when administered to experimental animals.     

Potential binding modes of beryllium with the class II major histocompatibility complex HLA-DP: a combined theoretical and structural database study

In an effort to understand the molecular basis of chronic beryllium disease (CBD), a study of the chemical relationship between beryllium, antigen, and the major histocompatibility complex II, HLA-DP, was undertaken. A homology model of the HLA-DP protein was developed. An analysis of the sequences of HLA-DPB1 and HLA-DPA1 alleles most common among CBD patients revealed several carboxylate rich regions in the peptide-binding cleft. These regions contain many hard Lewis base sites that may provide bonding opportunities for beryllium, a hard Lewis acid. Quantum chemistry calculations and structural database results support the presence of beryllium clusters, bridged by carboxylate, hydroxo, and/or oxo ligands, in the HLA-DP binding cleft. These results strongly suggest that beryllium clusters are an integral part of the antigen, and may even act solely as antigen. This work provides an initial model for thinking about beryllium interactions with proteins relevant to CBD and other metal-induced diseases.     

Effects of inhibitors on luminal opening of Ca2+ binding sites in an E2P-like complex of sarcoplasmic reticulum Ca22+-ATPase with Be22+-fluoride

We document here the intrinsic fluorescence and 45Ca2+ binding properties of putative "E2P-related" complexes of Ca2+-free ATPase with fluoride, formed in the presence of magnesium, aluminum, or beryllium. Intrinsic fluorescence measurements suggest that in the absence of inhibitors, the ATPase complex with beryllium fluoride (but not those with magnesium or aluminum fluoride) does constitute an appropriate analog of the "ADP-insensitive" phosphorylated form of Ca2+-ATPase, the so-called "E2P" state. 45Ca2+ binding measurements, performed in the presence of 100 mm KCl, 5 mm Mg2+, and 20% Me2SO at pH 8, demonstrate that this ATPase complex with beryllium fluoride (but again not those with magnesium or aluminum fluoride) has its Ca2+ binding sites accessible for rapid, low affinity (submillimolar) binding of Ca2+ from the luminal side of SR. In addition, we specifically demonstrate that in this E2P-like form of ATPase, the presence of thapsigargin, 2,5-di-tert-butyl-1,4-dihydroxybenzene, or cyclopiazonic acid prevents 45Ca2+ binding (i.e. presumably prevents opening of the 45Ca2+ binding sites on the SR luminal side). Since crystals of E2P-related forms of ATPase have up to now been described in the presence of thapsigargin only, these results suggest that crystallizing an inhibitor-free E2P-like form of ATPase (like its complex with beryllium fluoride) would be highly desirable, to unambiguously confirm previous predictions about the exit pathway from the ATPase transmembrane Ca2+ binding sites to the SR luminal medium.     

Properties, composition, and structure of stearic acid-stearate monolayers on alkaline earth solutions

Interactions between alkaline earth ions and the carboxylate ligand in a stearic acid surface film have been investigated by IR spectrophotometry and surface chemical procedures. The frequency and shape of the carboxylate absorption band and the effect of hydration and pH on band characteristics suggest that beryllium, magnesium, and calcium ions form calcium-type complexes with the stearate ligand while strontium and barium ions form both calcium-type complexes and more ionic barium-type complexes, which have lower carboxylate band maxima. Since IR band frequencies in anhydrous calcium-type complexes are directly proportional to the charge/(crystal radius) ratio, it is apparent that covalency decreases in the order: Be > Mg > Ca > Sr > Ba. The decreasing order of stability constants estimated from spectrophotometric titration data, Be > Ca > Mg > Sr > Ba, demonstrates that calcium behaves anomalously. This anomalous behavior is also apparent in the high solid-to-liquid phase transition temperature and small surface area of the calcium-carboxylate film compared to films composed of complexes with the other ions. A geometric factor related to the ionic radius and the radius of the carboxylate binding site formed by a calcium stearate lattice is proposed to explain the unique properties of calcium-carboxylate surface films. Although the beryllium complex has the highest carboxylate band frequency and stability constant, it gives an atypical "expanded" surface film. A hydrogen bonded lattice formed with a soluble beryllium monohydrate is suggested as an explanation for this film property.     

Analysis of time-dependent recovery from beryllium toxicity following chelation therapy and antioxidant supplementation

Efforts have been made to minimize the toxic effect caused by beryllium. Adult cyclic rats of Sprague Dawley strain were administered a bolus dose of 50mg/kg beryllium nitrate intramuscularly. The chelation therapy with glutathione (GSH), dimercapto propane sulfonic acid (DMPS)+ selenium (Se) and D-Penicillamine (DPA) + Se was given for 3 days followed by a rest of 1,3 and 7 days respectively. The results revealed a significant fall in the blood sugar level, serum alkaline phosphatase activity, serum proteins. A significant rise in the transaminases i.e. aspartate aminotranferase and alanine aminotranferase pattern is indicative of leakage of enzymes from liver resulting in alterations in the cell permeability. A rise in the hepatic lipid peroxidation activity is a direct indication of oxidative damage resulting in free radical generation. Results of the distribution studies by atomic absorption spectrophotometry reveal an increased concentration of beryllium in liver and kidney followed by lung and uterus. The relative ability of 3 chelating agents to act as antagonists for acute beryllium poisoning have been examined in liver, kidney, lungs and uterus. The appreciable change in the beryllium concentration in various organs is duration-dependent during the entire period being highly significant after 7 days rest. From the biochemical assays, and distribution studies it can be assumed that DPA+Se was the most effective therapeutic agent followed by DMPS+Se and GSH. Thus it can be concluded that DPA+Se is a better therapeutic agent as compared to DMPS+Se and GSH.     

Nitric acid dissolution of large mixed cellulose ester filters for beryllium determination

Defense program use of beryllium has resulted in the need for a wide variety of sampling methods to assess the potential for airborne beryllium particulates. One technique employed in field sampling uses large (8 × 10 in.) mixed cellulose ester (MCE) filters in high volume air samplers. Standard methods for the acid digestion and analysis of the large MCE filters cannot be utilized as the increase in filter mass leads to an uncontrolled exothermic reaction (open flames). As this compromises data quality and presents a significant safety hazard, we propose here an alternative method for digesting these large filters to ensure a solution compatible with ICP-AES (inductively coupled plasma-atomic emission spectroscopy) analysis. The method is a modification of well accepted hot plate digestion methods, which avoids the use of the most hazardous acids such as perchloric or hydrofluoric. While only beryllium was investigated, it is likely that other metals on filters could be digested by this method. Filter media were spiked with a variety of beryllium sources to test the digestion, including beryllium solution spikes, beryllium metal, beryllium oxide and beryllium in soil. Recovery of beryllium metal (103%), beryllium in soil (96%) and beryllium solution spikes (93%) were excellent.     

Effect of a beryllium complex on growth of Pseudomonas fluorescens (types R and S). II. Competition with magnesium]

A study of the inhibitory action of beryllium on the growth of Pseudomonas fluorescens reveals that the observed effect can be partly explained by competition between beryllium and magnesium in various processes which are indispensable to cellular metabolism. In addition, an "adaptation" phenomenon is observed which appears to be based on the selection of cells which are more highly resistant towards the inhibitor.     

Role of chelating agents and antioxidants in beryllium induced toxicity

The present study was conducted to evaluate the therapeutic effectiveness of chelating agents [glutathione, 2,3 dimercapto propane sulfonic acid (DMPS) and D-penicillamine (DPA)] in combination with antioxidant (sodium selenite) in beryllium induced toxicity in female rats. A bolus dose of 50mg/kg-beryllium nitrate was administered singly followed by chelation therapy with GSH, DMPS + Se and DPA + Se at various durations of 1,3 and 7 days respectively. Results revealed a significant fall in the glycogen content, whereas, a marginal fall in the protein was also observed. The enzymatic activity of alkaline phosphatase and adenosine triphosphatase was depleted; on the contrary, there was a significant rise in the acid phosphatase and glucose-6-phosphatase pattern. A rise in the hepatic lipid peroxidation activity is a direct indication of oxidative damage resulting in free radical generation. The distribution of the metal by atomic absorption spectrophotometry revealed an increased concentration of beryllium in liver and kidney, followed by lung and uterus. The relative ability of three chelating agents to act as antagonists, for acute beryllium poisoning, have been examined in liver, kidney, lungs and uterus. The appreciable change in the beryllium concentration in various organs is duration dependent during the entire period being highly significant at 7 days regimen. Biochemical and distribution studies reveal that DPA + Se was the most effective therapeutic agent followed by DMPS + Se and GSH.     

Beryllium binding at neutral pH: the importance of the Be-O-Be motif

Beryllium speciation at physiological conditions is critical to understanding chronic beryllium disease (CBD). The MHC-class II receptor alleles that have been linked to CBD have more than six carboxylates in a short 20 amino acid segment of the binding pocket and it has been suggested that beryllium may bind within the MHC-class II receptor via the carboxylates. Previous reports also show that citric acid binds beryllium significantly stronger than similar carboxylate ligands such as tartaric acid and is one of the few ligands that can compete with hydrolysis to solubilize beryllium across the entire pH range at molar concentrations. We have characterized the binding of Be to citric acid and shown using a combination of NMR, mass spectrometry and ligand competition studies that Be2L and Be4L2 species dominate. A Be-O-Be linkage with the bridging oxygen coming from the aliphatic alcohol is critical to the stability of the complex. We show through competition experiments that the most stable Be-O-Be arrangement has one Be in a five-member ring and the other Be in a six-member ring. The unusual deprotonation of an aliphatic alcohol (pK(a) = 18) at neutral pH has significant ramifications on the potential interactions of Be with biological ligands such as carbohydrates and Ser and Thr residues.     

Uptake, distribution and binding of beryllium to organelles of the rat liver cell

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.     

Beryllium uptake and related biological effects studied in THP-1 differentiated macrophages

Investigation of cellular uptake of metal compounds is important in understanding metal-related toxicity and diseases. Inhalation of beryllium aerosols can cause chronic beryllium disease, a progressive, granulomatous fibrosis of the lung. Studies in laboratory animals and cultured animal cells indicate that alveolar macrophages take up beryllium compounds and participate in a hypersensitivity immune response to a beryllium-containing antigen. In the present work, human monocyte cell line THP-1 was induced with phorbol myristate acetate to differentiate into a macrophage. This cell with characteristics of human alveolar macrophages was employed to study cellular beryllium uptake and related biological effects. Morphological changes, phagocytosis of fluorescent latex beads, and cell surface CD14 expression were used to verify the successful differentiation of THP-1 monocytes into macrophages. An improved mass spectrometry method for quantitative analysis of intracellular beryllium as opposed to the traditional radioisotopic approach was developed using ICP-MS. The influence of the solubility of beryllium compounds, exposure duration, and beryllium concentration on the incorporation of beryllium was studied. Our data indicated that the uptake of particulate BeO was much more significant than that of soluble BeSO(4), suggesting the major cellular uptake pathway is phagocytosis. Nevertheless, subsequent DAPI nuclear staining and PARP cleavage study indicated that beryllium uptake had a negligible effect on the apoptosis of THP-1 macrophages compared to the unstimulated macrophage control. Meanwhile, no substantial variation of tumour necrosis factor-alpha production was observed for THP-1 macrophages upon beryllium exposure. These data imply alveolar macrophages could have some level of tolerance to beryllium and this may explain why most Be-exposed individuals remain healthy throughout life.     

Effect of inactive impurities on the burning of ICF targets

The efficiency of thermonuclear burning of the spherical deuterium-tritium (DT) plasma of inertial confinement fusion (ICF) targets in the presence of low-Z impurities (such as lithium, carbon, or beryllium) with arbitrary concentrations is investigated. The effect of impurities produced due to the mixing of the thermonuclear fuel with the material of the structural elements of the target during its compression on the process of target burning is studied, and the possibility of using solid noncryogenic thermonuclear fuels in ICF targets is analyzed. Analytical dependences of the ignition energy and target thermonuclear gain on the impurity concentration are obtained. The models are constructed for homogeneous and inhomogeneous plasmas for the case in which the burning is initiated in the central heated region of the target and then propagates into the surrounding relatively cold fuel. Two possible configurations of an inhomogeneous plasma, namely, an isobaric configuration formed in the case of spark ignition of the target and an isochoric configuration formed in the case of fast ignition, are considered. The results of numerical simulations of the burning of the DT plasma of ICF targets in a wide range of impurity concentrations are presented. The simulations were performed using the TEPA one-dimensional code, in which the thermonuclear burning kinetics is calculated by the Monte Carlo method. It is shown that the strongest negative effect related to the presence of impurities is an increase in the energy of target ignition. It is substantiated that the most promising solid noncryogenic fuel is DT hydride of beryllium (BeDT). The requirements to the plasma parameters at which BeDT can be used as a fuel in noncryogenic ICF targets are determined. Variants of using noncryogenic targets with a solid thermonuclear fuel are proposed.     

Effect of iron-beryllium antagonism on the growth ofPseudomonas fluorescens type S

Studies of the growth ofPseudomonas fluorescens type S in acidified peptone nutrient broth supplemented with potassium dioxalatoberyllate show that the inhibitory action of beryllium on the lag phase can be strongly counteracted by an increase in the iron content of the medium. In terms of relative concentrations, Fe³⁺ is up to 250 times more effective than Mg²⁺ as an antagonist of beryllium under the conditions employed. Conversely, evidence of the effect of beryllium on iron-dependent constituents of the cell is provided by the fact that cultures ofPseudomonas fluorescens adapted to relatively high concentrations of beryllium show a marked decrease in cytoohromec content.     

Immunogenetic factors in beryllium sensitization and chronic beryllium disease

Exposure to beryllium in the workplace can cause beryllium sensitization and chronic beryllium disease. Sensitization to beryllium can be detected in the laboratory using the beryllium lymphocyte proliferation test. It was shown that anti-HLA antibodies could block the beryllium-specific response in the beryllium lymphocyte proliferation test, thereby implicating HLA genes in chronic beryllium disease. A supratypic genetic marker, HLA-DPB1*E69, was found to be strongly associated with immunologic sensitization to beryllium and chronic beryllium disease in beryllium workers. However, there are 40 HLA-DPB1 gene variants that have E69 but that also have other DNA sequence variations. The purpose of the study was to evaluate the evidence for potential differential susceptibility that may be associated with the physical characteristics of HLA protein molecules for which different HLA-DPB1*E69 variants code; that is, do some HLA-DPB1*E69 variants convey higher risk of beryllium sensitization and chronic beryllium disease than others. To do this, two approaches were pursued: first, detailed analysis of the findings from the published literature was performed, and second, computational chemistry was used to seek clues concerning the physical properties of the HLA protein molecules for which these alleles code. Among the 40 HLA-DPB1 gene variants that code for E69, molecular epidemiological studies have suggested a risk hierarchy, where some variants appear to convey low to moderate risk of chronic beryllium disease (e.g., HLA-DPB1*0201, approximately 3-fold increased risk), some convey an intermediate risk (e.g., HLA-DPB1*1901, approximately 5-fold) and others convey high risk (e.g., HLA-DPB1*1701, >10-fold). Molecular modeling has been used to further investigate a potential mechanistic basis for these observations. We found a strong correlation between the hierarchical order of risk of chronic beryllium disease associated with specific alleles and the predicted surface electrostatic potential and charge of the corresponding isotypes. Therefore, when alleles were grouped by the relative negative charge on the molecules for which they code, the data suggest that those alleles associated with the most negatively charged proteins carry the greatest risk of beryllium sensitization and disease.     

Characterization of the aluminum and beryllium fluoride species bound to F-actin and microtubules at the site of the gamma-phosphate of the nucleotide

Aluminum fluoride and beryllium fluoride complexes have previously been shown to bind tightly to F-ADP-actin and GDP-microtubules in competition with Pi and to mimic the XDP-Pi transient state of the polymerization. The structure of the bound complexes is investigated here in further detail. Using a fluoride ion-specific electrode, the number of fluoride atoms per aluminum or beryllium atom in the bound complex could be determined. The results indicate that AIF-4 and either BeF2(OH)-.H2O or BeF3-.H2O are the tightly bound species in both F-actin and microtubules. The dependences of the binding on pF and pH are consistent with this conclusion. The possible geometries of aluminum and beryllium fluorides in the gamma-phosphate subsite of the nucleotide are discussed in correlation with the catalytic mechanism of nucleotide hydrolysis.