Lead Binding Capacity Research Articles

Soluble dietary fiber from Prunus persica dregs alleviates gut microbiota dysfunction through lead excretion.

Lead (Pb) can pollute the environment and food through air, water and other means, resulting in human exposure to lead pollution, and there is no threshold level of lead toxicity, even small doses of lead will have a range of harmful effects in humans. This study demonstrates for the first time that dietary addition of soluble dietary fiber (SDF) from Prunus persica dregs reduces lead bioaccumulation in mice, and eliminates lead through feces. Compared with lead-exposed mice, SDF supplementation effectively prevented lead-induced changes in colon tissue, and increased expression of tight junction proteins (ZO-1 and occludin). We analyzed the effects of SDF on gut microbiota and metabolites by a combination of 16S rRNA high-throughput sequencing and untargeted metabolomics. The results showed that SDF altered lead-induced perturbations in the layout and structure of the gut microbiota, including increased Desulfovibrio and Alistipes abundance and decreased Bacteroidetes abundance. Meanwhile, we also provide evidence that SDF supplementation alters the levels of amino acids, bile acids, and lipids in the gut, and that these metabolites are closely associated with microbiota with good lead binding capacity. Therefore, we speculate that SDF has the potential to provide a protective effect against intestinal damage by promoting lead excretion.

Lead-binding biogenic polyelectrolyte multilayer coating for lead retention in perovskite solar cells.

Perovskite solar cells promise to deliver high efficiencies at low manufacturing costs. Yet on their way towards commercialization, they have to face the associated risk of potential lead leakage into the environment after damage to the cell's encapsulation. Here we present a new approach to generate a lead binding coating, based on a layer-by-layer deposition of biopolymers. A lead-adsorbing functionality was shown after subsequent crosslinking, demonstrating a high binding capacity. The lead binding capabilities could be further enhanced by increasing the thickness of the coatings, analyzed both in the supernatant and on the surface of the coated material. The thin-layered coating had a thickness of less than one micrometer, was stable even under low pH conditions and could successfully be transferred onto different substrates, ranging from silicon, gold and glass substrates to polymeric nonwoven materials with high surface areas, further increasing its lead binding capacity. This newly described coating was applied within perovskite solar cell stacks without impeding the overall efficiency but strongly reducing the amount of lead released after simulated rain tests on devices with damaged encapsulation. Accordingly, incorporation of lead-binding polyelectrolyte multilayers inside the encapsulation of perovskite solar cells shows great potential to limit the perovskite solar cells inherent risk of lead leakage in a sustainable manner.

Lead-binding capacity of calcium pectates with different molecular weight

Nowadays, heavy metal contamination of environment is considered as a serious threat to public health because of toxicity of these pollutants and the lack of effective materials with metal-binding properties. Some biopolymers such as pectins were proposed for removal of metal ions from industrial water disposals. Chemical structure of pectins is quite variable and substantially affects their metal binding properties. In this work, relationship between molecular weight and Pb(II)-binding capacity of calcium pectates was investigated in a batch sorption system. The results showed that all pectate samples are able to form complexes with Pb(II) ions. The effects of contact time, pH of the media and equilibrium metal concentration on metal-binding process were tested in experiments. The equilibrium time min required for uptake of Pb(II) by pectate compounds was found to be 60min. Langmuir and Freundlich models were applied for description of interactions between pectates and metal ions. Binding capacity of low molecular pectate was highest among all the samples tested. Langmuir model was figured out to be the best fit within the whole range of pH values. These results demonstrate that calcium pectate with low molecular weight is more promising agent for elimination of Pb(II) ions from contaminated wastewaters.

Prevention of gastrointestinal lead poisoning using recombinant Lactococcus lactis expressing human metallothionein-I fusion protein

Low-level lead poisoning is an insidious disease that affects millions of children worldwide, leading to biochemical and neurological dysfunctions. Blocking lead uptake via the gastrointestinal tract is an important prevention strategy. With this in mind, we constructed the recombinant Lactococcus lactis strain pGSMT/MG1363, which constitutively expressed the fusion protein glutathione S-transferase (GST)–small molecule ubiquitin-like modifier protein (SUMO)–metallothionein-I (GST-SUMO-MT). The thermodynamic data indicated that the average number of lead bound to a GST-SUMO-MT molecule was 3.655 and this binding reaction was a spontaneous, exothermic and entropy-increasing process. The total lead-binding capacity of pGSMT/MG1363 was 4.11 ± 0.15 mg/g dry mass. Oral administration of pGSMT/MG1363 (1 × 1010 Colony-Forming Units) to pubertal male rats that were also treated with 5 mg/kg of lead acetate daily significantly inhibited the increase of blood lead levels, the impairment of hepatic function and the decrease of testosterone concentration in the serum, which were all impaired in rats treated by lead acetate alone. Moreover, the administration of pGSMT/MG1363 for 6 weeks did not affect the serum concentration of calcium, magnesium, potassium or sodium ions. This study provides a convenient and economical biomaterial for preventing lead poisoning via the digestive tract.

Lactobacillus plantarum CCFM8661 Alleviates Lead Toxicity in Mice

Lead causes a broad range of adverse effects in humans and animals. The objective was to evaluate the potency of lactobacilli to bind lead in vitro and the protective effects of a selected Lactobacillus plantarum CCFM8661 against lead-induced toxicity in mice. Nine strains of bacteria were used to investigate their binding abilities of lead in vitro, and L. plantarum CCFM8661 was selected for animal experiments because of its excellent lead binding capacity. Both living and dead L. plantarum CCFM8661 were used to treat 90 male Kunming mice during or after the exposure to 1g/L lead acetate in drinking water. The results showed oral administration of both living and dead L. plantarum CCFM8661 offered a significant protective effect against lead toxicity by recovering blood δ-aminolevulinic acid dehydratase activity, decreasing the lead levels in blood and tissues, and preventing alterations in the levels of glutathione, glutathione peroxidase, malondialdehyde, superoxide dismutase, and reactive oxygen species caused by lead exposure. Moreover, L. plantarum CCFM8661 was more effective when administered consistently during the entire lead exposure, not after the exposure. Our results suggest that L. plantarum CCFM8661 has the potency to provide a dietary strategy against lead toxicity.

Water-soluble organo-building blocks of aminoclay as a soil-flushing agent for heavy metal contaminated soil

We demonstrated that water-soluble aminopropyl magnesium functionalized phyllosilicate could be used as a soil-flushing agent for heavy metal contaminated soils. Soil flushing has been an attractive means to remediate heavy metal contamination because it is less disruptive to the soil environment after the treatment was performed. However, development of efficient and non-toxic soil-flushing agents is still required. We have synthesized aminoclays with three different central metal ions such as magnesium, aluminum, and ferric ions and investigated applicability of aminoclays as soil flushing agents. Among them, magnesium (Mg)-centered aminoclay showed the smallest size distribution and superior water solubility, up to 100 mg/mL. Mg aminoclay exhibited cadmium and lead binding capacity of 26.50 and 91.31 mg/g of Mg clay, respectively, at near neutral pH, but it showed negligible binding affinity to metals in acidic conditions. For soil flushing with Mg clay at neutral pH showed cadmium and lead were efficiently extracted from soils by Mg clay, suggesting strong binding ability of Mg clay with cadmium and lead. As the organic matter and clay compositions increased in the soil, the removal efficiency by Mg clay decreased and the operation time increased.

Lead-Binding Proteins: A Review

Lead-binding proteins are a series of low molecular weight proteins, analogous to metallothionein, which segregate lead in a nontoxic form in several organs (kidney, brain, lung, liver, erythrocyte). Whether the lead-binding proteins in every organ are identical or different remains to be determined. In the erythrocyte, delta-aminolevulinic acid dehydratase (ALAD) isoforms have commanded the greatest attention as proteins and enzymes that are both inhibitable and inducible by lead. ALAD-2, although it binds lead to a greater degree than ALAD-1, appears to bind lead in a less toxic form. What may be of greater significance is that a low molecular weight lead-binding protein, approximately 10 kDa, appears in the erythrocyte once blood lead exceeds 39 μg/dL and eventually surpasses the lead-binding capacity of ALAD. In brain and kidney of environmentally exposed humans and animals, a cytoplasmic lead-binding protein has been identified as thymosin β4, a 5 kDa protein. In kidney, but not brain, another lead-binding protein has been identified as acyl-CoA binding protein, a 9 kDa protein. Each of these proteins, when coincubated with liver ALAD and titrated with lead, diminishes the inhibition of ALAD by lead, verifying their ability to segregate lead in a nontoxic form.

Comparative equilibrium studies of sorption of Pb(II) ions by sodium and calcium alginate

The absorption of Pb(II) ions from aqueous solution by different alginate compounds was studied in a batch sorption system. Water soluble sodium alginate and insoluble calcium alginate beads were investigated. The lead-binding capacity of both alginate compounds was highest within the pH range 6-8. The binding capacities and rates of Pb(II) ions by alginate compounds were evaluated. The Langmuir, Freundlich, and Bruneaur, Emmet and Teller (BET) sorption models were applied to describe the isotherms and isotherm constants. Sorption isothermal data could be well interpreted by the Langmuir model. The results obtained through the study suggest that alginate compounds are favorable sorbents. The largest amount of Pb(II) ions were bound by sodium alginate although the difference between two compounds was slight. Therefore, alginate substances may be considered as an alternative for sorption and removal of Pb(II) ions from wastewaters.

Equilibrium studies of sorption of lead(II) ions by different pectin compounds

The adsorption of Pb(II) ions from aqueous solution by different pectin compounds was studied in a batch sorption system. Water-soluble low- and high-esterified pectins and insoluble calcium pectate beads were investigated. The lead-binding capacity of all pectin compounds was highest within the pH range from 7 to 8. The binding capacities and rates of Pb(II) ions by pectin compounds were evaluated. The Langmuir, Freundlich and BET sorption models were applied to describe the isotherms and isotherm constants. Sorption isothermal data could be well interpreted by the Langmuir model. These results obtained through the study suggest that pectin compounds are favorable sorbers. The largest amount of Pb(II) ions were bound by pectin with the low degree of esterfication. Therefore, pectin substances may be considered as perspective for sorption and removal of Pb(II) ions from wastewaters.

Lead Absorption and Excretion in Rats Given Insoluble Salts of Pectin and Alginate

Exposure to environmental lead remains a widespread problem in most industrialized countries. Usage of modern agents purposed for elimination of heavy metals as well as for therapy and prevention of chronic poisoning does frequently result in toxic signs. Dietary nonstarch polysaccharides were suggested to be effective when used for this purpose. The present study was conducted to estimate metal binding capacity and effects of calcium salts of pectate and alginate on lead absorption, distribution, and removal with feces. Under in vitro conditions calcium alginate showed the highest lead-binding capacity in comparison with other agents studied. Metal binding capacity of calcium pectate was slightly lower. In rats simultaneous administration of lead acetate and suspensions containing calcium alginate or calcium pectate prevented metal absorption and significantly reduced lead accumulation in inner organs and femur. In experiments estimating lead removal from inner organs and femur in rats preliminary exposed to the heavy metal, calcium alginate and calcium pectate were the most effective agents studied in comparison with others, as indicated by reduced lead concentration in organs and femur as well as increased metal content in feces of laboratory animals. The results suggest that calcium pectate and calcium alginate may be considered perspective dietary compounds purposed for prevention and treatment of chronic lead poisoning.

Fish Uptake of Inorganic and Mucus Complexes of Lead

Carassius auratus were exposed to lead in synthetic water. Mucus secreted from the fish was measured and characterized for its lead binding capacity. The increase in mucus concentration in the water depended on secretion and degradation rates and the former was speeded up by lead. The complexation between mucus and lead can be described based on a single-site interaction model. Lead speciation in the system with or without mucus was calculated using chemical equilibrium modeling. The dominant species of lead was PbCO30. Other major species included Pb(OH)+, Pb(OH)20, Pb(CO3)22−, Pb–mucus, and Pb2+, among which free lead and lead hydroxo complexes were available to fish uptake.

Fixation of lead in contaminated soils by co‐agglomeration with metal binding agents*

Abstract Adsorption of lead from an aqueous solution by both agricultural peat moss and soil has been measured. The results may be described by a Langmuir isotherm model. Adsorption isotherms fitted the “H”; type described in the Giles classification. Saturation adsorption was reached at equilibrium lead concentrations > 3000 mg/L for peat, compared with ∼ 250 mg/L for soil. Calculation of the isotherm parameters showed the maximum lead adsorption to be 150 mg lead/g of peat. This compared with only 12.64 mg/g of lead for soil alone. Several tests were carried out to evaluate the lead binding capacity of peat in a spiked soil sample. Results from leaching tests (Environmental Protection Agency, EPA, Toxicity Characteristic Leaching Procedure, TCLP, at pH 2.9) on soil‐peat mixtures confirmed the excellent metal binding capacity of peat in the samples tested. The amount of lead leached from a soil sample, spiked with 1840 mg/kg of water‐soluble lead, decreased with increasing amounts of peat loading. Total fixation was achieved at a peat loading of 20%. In addition to peat, several other agents were tested for their suitability as fixing agents in heavy‐metal contaminated soils. These included: gypsum, lime, autoshredder residue, fly ash, and a sample of oil sands fines. Liquid phase agglomeration was used to coagglomerate these materials with soil as a means to fix lead in artificially contaminated samples. The agglomeration process is advantageous in that it allows concurrent fixation of heavy metals and solvent extraction of organic contaminants. In terms of material handling and equipment, a combined process will be more economical than conventional methods requiring separate extraction and leaching steps.

Smooth endoplasmic reticulum and other agranular reticulum in frog retinal photoreceptors.

Frog retinal photoreceptors are favourable material for studying a number of unresolved issues concerning the interconnections, three-dimensional organization and functions of intracellular membrane systems in neurons. At least two distinct regions of smooth endoplasmic reticulum (SER) are present in these cells. One region, the subellipsoid SER, is located in rod cells at the base of the mitochondria-rich ellipsoid region, and is comprised of arrays of stacked tubules which exhibit frequent continuities with the rough endoplasmic reticulum (RER). The subellipsoid SER is also present throughout the ellipsoid region and at the apex of the inner segment. The second region of SER, the axonal SER, is comprised of agranular sacs and tubules present in the axons of rod cells, the perinuclear and Golgi regions of rod and cone cells and the synaptic terminals of rod and cone cells. There sacs and tubules exhibit continuities with cisternae of RER and with the nuclear envelope. Serial section analyses indicate that this SER can extend as a continuous networking along the entire length of the rod axons and throughout synaptic terminals. The axonal SER is distinct from the subellipsoid SER not only in location and morphology but also in its ability to bind divalent lead ions, a property it shares with synaptic vesicles, with agranular sacs at one face to the Golgi apparatus and with sacs extending from the Golgi apparatus toward the axons hillock. These latter sacs may serve in transport from the Golgi region to the axon. The axons SER in the axon, terminals, and the perinuculear and Golgi regions appear to be a source of synaptic vesicles as evidenced by this lead binding capacity and by the observation of vesicles, with the size (50-75 nm) and appearance of synaptic vesicles, budding from SER in direct continuity, with RER. The endoplasmic reticulum (ER) in synaptic terminals of frog photoreceptors is not continuous with endocytic structures found in the same region, such as blunt-ended tubules or anastomosing networks of tubules. Nor does the ER acquire exogenous horseradish peroxidase. These observations suggest that the ER does not play a direct role in membrane recycling in photoreceptors.

鉛吸収の血清蛋白分屑に及ぼす影響に関する研究 : 鉛作業者について

The decrease of albumin and globulin ratio (A/G) measured by the salting-out method and the increase of γ-globulin level by the Kunkel Method in lead workers' sera were already reported by some authors in the past. The decrease of A/G ratio was observed also in the experimental lead poisoning of animals by other authors. For the purpose of making a comparative study on symptoms and the protein fraction changes due to lead absorption, an electrophoretic study on the sera of lead workers in a storage battery factory was undertaken by means of the Tiselius apparatus. Further, by the Zone electrophoresis, it was tried to determine the fraction, to which lead was supposed to be bound. The results were as follows: 1. The lead workers with slight anemia by lead absorption showed a higher level of γ-globulin percentage of serum protein than those without any symptom of anemia as well as healthy controls. 2. Lead in the serum was mainly found in the fraction which corresponds to that of albumin and there seemed to be no relation between the cause of γ-globulin percentage increase and the lead-binding capacity of protein fraction of the serum.