SRXRF study of trace elements in hippocampus of pup rats after prenatal and postnatal exposure to low-level mercury

The damage in the pup rat brain with low-level mercury exposure, and the concentration variation of trace elements in the rat hippocampus was determined by synchrotron radiation X-ray fluorescence technique (SRXRF). Meanwhile, the levels and activities of glutathione (GSH), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA) in the hippocampus were also measured. The results showed that the low dose of inorganic mercury prenatal and postnatal exposure could lead to the significant increase of both copper and zinc contents and remarkable decrease of iron content in pup rat brain. Compared to the control group, the activities of antioxidant enzymes such as GSH-Px, SOD, the contents of GSH and MDA in the pup rat hippocampus of mercury-exposed group fell down obviously.     

ESR study of radiation resistance of some aza- and thiacrown ethers at 77 K

The objective of this study was to determine if a stable enriched tracer of Se-76 could be used to establish the delay time between a dietary intake of selenium and its appearance in various matrices. Selenium, an essential trace element, has been investigated at the Missouri University Research Reactor (MURR) for several years. Several matrices have been studied to determine selenium status in humans; these include fingernails, toenails, blood, hair, and urine. A cohort of five women and seven men was utilized for this study. Each subject ingested selenium supplements which were enriched in Se-76 (96.48%). Fingernails, toenails, whole blood, and blood sera were collected as biochemical indicators. Selenium concentrations and glutathione peroxidase activities were determined in blood sera and whole blood to monitor the effect of the selenium supplement in these matrices. Selenium concentrations were determined in fingernails and toenails prior to supplementation and for several months afterward to determine the delay time for the appearance of selenium. The effects of the selenium supplement on the selenium concentrations of the fingernails, toenails, whole blood, and blood sera and the effect of the supplement on glutathione peroxidase activity will be reported.     

Comparative Efficiencies of Trace Metal Extraction from Municipal Incinerator Ashes

Abstract

Five laboratory solvent extraction methods for the determination of leachable trace metals from municipal incinerator fly and bottom ashes are evaluated. The trace elements of interest were cadmium, chromium, copper, manganese and lead. Five different extractants, 0.1NHCl, 1.0 N ammonium acetate, methyl isobutyl ketone (MIBK), chloroform and hexane were used on each ash to determine comparative extraction efficiencies.

Extraction efficiencies of the five solvents were determined based on total metal concentration, and were found to rank in the following order: 0.1NHCl<1.0N ammonium acetate < MIBK < chloroform < hexane. No one solvent was optimal for obtaining environmentally available values for all five metals. The inorganic solvents, 0.1NHCl and 1.0N ammonium acetate, exhibited higher removal of trace metals from ash particles relative to the organic solvents. Manganese concentrations were removed more efficiently by 0.1NHCl, whereas 1.0 N ammonium acetate was more efficient for removing copper concentrations. Cadmium, Cr, and Pb could effectively be extracted by either of the two inorganic solvents. Concentrations of trace metals extracted from refuse ash appeared to be a function of the elemental boiling point and the species that exist on combustion. However, the classification of elements for refuse ash in this study strayed somewhat from the traditional geochemical classification scheme into which coal ash is placed.     

A semisynthetic glutathione peroxidase with high catalytic efficiency. Selenoglutathione transferase

Glutathione peroxidase (GPX) protects cells against oxidative damage by catalyzing the reduction of hydroperoxides by glutathione (GSH). GPX therefore has potential therapeutic value as an antioxidant, but its pharmacological development has been limited because GPX uses a selenocysteine as its catalytic group and it is difficult to generate selenium-containing proteins with traditional recombinant DNA technology. Here, we show that naturally occurring proteins can be modified to generate GPX activity. The rat theta-class glutathione transferase T2-2 (rGST T2-2) presents an ideal scaffold for the design of a novel GPX catalyst because it already binds GSH and contains a serine close to the substrate binding site, which can be chemically modified to bind selenium. The modified Se-rGST T2-2 efficiently catalyzes the reduction of hydrogen peroxide, and the GPX activity surpasses the activities of some natural GPXs.     

模拟过氧化物酶催化性能的研究

过氧化物酶(POD)能催化H₂O₂氧化一系列氢供体(DH₂)转化成氧化型供体(D)。氢供体可以是邻联二茴香胺、4-氨基安替比林和苯酚及某些染料隐色体等。这类反应不仅可提供检测H₂O₂的灵敏方法,还可与产生H₂O₂的其它酶反应系统联用,测定葡萄糖、半乳糖、氨基酸、尿酸及胆醇等生物物质。     

Influence of heavy metals, especially lead, on lipid metabolism, serum alpha-tocopherol level, total antioxidant status, and erythrocyte redox status of copper smelter workers

An assessment of influence of the occupational exposure to heavy metals, especially lead, on serum lipids (including lipid peroxides), total antioxidant status, erythrocyte redox status, and serum alpha-tocopherol level was performed in a group of 141 healthy male copper smelter workers. The following parameters were measured: blood lead and cadmium levels, serum manganese, copper, zinc, calcium and magnesium levels, free erythrocyte protoporphyrins (FEP), total cholesterol, HDL₂-, HDL₃-cholesterol, triglycerides and lipid peroxides in serum, erythrocyte superoxide dismutase (SOD_E), catalase (Cat_E) and glutathion peroxidase (PxGSH_E) activities, erythrocyte reduced glutathione level (GSH_E), serum alpha-tocopherol level, and serum total antioxidant status (TAS). Mean Pb_B was within the norm range (328.2 ± 141.7 μg/L), but mean Mn_S concentration slightly exceeded 10 μg/L (11.04 ± 3.79 μg/L). Mean cholesterol and triglycerides concentrations were near the highest borderline values. We found a significantly negative correlation between lead levels and HDL₃-cholesterol (r = 0.253, P < 0.05). Erythocyte catalase activity and TAS were lowered. TAS showed significant negative correlation with Pb_B. A group of workers with Pb_B≥ 400 μg/L had significantly lower Cat_E, lower TAS, and lower HDL₃-cholesterol, compared to the workers with Pb < 400 μg/L. We have also found positive correlation between alpha-tocopherol and total cholesterol (r = 0.267, P < 0.05) and between alpha-tocopherol and LDL-cholesterol (r = 0.207, P < 0.05).     

Determination of Gold and Palladium in Manganese and Nickel Compounds by Atomic Absorption Spectrometry After Separation by Use of Amberlite XAD-7 Resin

Abstract

A method for preconcentration and determination of traces of Au and Pd from manganese, nickel and their compounds is described. The trace elements are preconcentrated at a small column filled with Amberlite XAD-7 resin. After their eluation the elements are determined by flame AAS. The relative standard deviations (N=10) were found to be lower than 5%; the detection limit (3s, N=20) for Au and Pd in metal samples is 0.07 μg/g.     

Trace metal detection in Šibenik Bay, Croatia: Cadmium, lead and copper with anodic stripping voltammetry and manganese via sonoelectrochemistry. A case study

The vertical profiles of the concentration of reactive Mn and total concentrations of Cd, Pb, and Cu ions in the water column of the ?ibenik Bay (Krka river estuary) were determined. The measured ranges of concentrations are: 60–1300 ng l^?1 for Mn, 5–13 ng l^?1 for Cd, 70–230 ng l^?1 for Pb, and 375–840 ng l^?1 for Cu. These values are comparable with the concentrations found in the unpolluted estuaries. The Krka river estuary is highly stratified, with the measured salinity gradient of 20% within a half meter of the freshwater-seawater interface (FSI). The main changes in the vertical profiles of the measured parameters occur in the FSI: the temperature increases for 1 °C and the pH decreases for 0.1 unit, whereas the metal concentrations show different behaviour. Generally, Mn, Pb, and Cd ions show the increase of concentrations in the FSI, while copper concentration profile indicates anthropogenic pollution in the brackish layer caused by agriculture activities and by the paint with copper basis used as an antifoulant biocide for the ships. UV-digested samples show an increase in manganese concentrations for at least 3.5 times comparing to non UV-digested. This suggests that in natural water manganese exists mainly in the form of inert complexes and as associated to particulate matter (about 70–80%). UV irradiation has no influence on the concentration of cadmium, while for lead an increase of 50% in the seawater layer is observed. The twofold increase of the copper concentration in the upper freshwater layer and at least the fourfold one in the seawater layer were measured in the UV-digested samples. These results show that copper is strongly bound to inert complexes, and that UV-digestion is necessary step in determination of the total metal concentrations in natural water samples. No significant increase of the metal concentrations in the deeper seawater layer was observed, indicating the absence of the processes of remobilization or dissolution of metals from the sediment. Presented results confirm that the new method for the determination of manganese by CSV on boron-doped diamond electrode with ultrasound enhanced accumulation can be successfully applied to natural waters.     

Green Synthesized Silver Nanoparticles and Their Impact on the Antioxidant Response and Histology of Indian Major Carp <Emphasis Type="Italic">Labeo rohita</Emphasis>, with Combined Response Surface Methodology Analysis

Biosynthesis of silver nanoparticles has received considerable attention due to their cost-effective, eco-friendly and medicinal values. In this study, silver nanoparticles (Ag NPs) were synthesised using the aqueous leaf extracts of Piper nigrum. TEM images revealed that the particle is spherical with 20–50 nm in size. Furthermore, to evaluate the toxicity of synthesized Ag NPs, fish Labeo rohita were exposed to two different concentrations (2.5 µg/L as the treatment I and 5 µg/L as treatment II) for 35 days, and antioxidant parameters and histology of gill, liver and kidney were examined. A biphasic response in the activity of glutathione S-transferases (GST) was observed in gill and liver of fish. GST activity in the kidney of fish was significantly increased when compared to control group. Glutathione reductase (GR) activity in organs/tissue of fish were found to be increased while peroxidase (POD) activity was significantly decreased. Histopathological changes such as hyperplasia, proliferation of epithelial cells and fusion of lamellae were observed in both the concentrations. In liver, necrosis, nuclear degeneration and dilation of sinusoids were observed. Subsequently, the representative effects of POD activity were assessed based on the Box–Behnken Equation, 3-D contour plot and ANOVA analysis through response surface methodology analysis.     

On-site preconcentration and trace metal ions determination in the Okavango Delta water system, Botswana

Microcolumns containing 8-hydroxyquinoline azo-immobilized on controlled pore glass were incorporated in a field sampler for on-site collection, isolation and preconcentration of trace metal ions in waters of the Okavango Delta, Botswana. Sequestered trace metal ions were recovered by elution with 0.5 ml of 1.5 M nitric acid, and determined by graphite furnace atomic absorption spectrometry (GFAAS). This sampling and enrichment method minimizes sample contamination, and collection of large volumes of water samples for transporting, over long distances, to analytical laboratories is avoided.Data reported comprise one of the initial surveys on trace metal ion concentrations in waters of the Okavango Delta, Botswana. In waters with more efficient mixing, dissolved metal ion concentrations found were generally low with slightly elevated levels of manganese (7-19 μg l⁻¹), zinc (2.7-4.8 μg l⁻¹), nickel (0.2-2.5 μg l⁻¹) and copper (0.3-2.1 μg l⁻¹). For each trace metal ion, concentration levels seem to reflect zones of varying water conveyance, and show no obvious temporal and spatial variations apart from a slight increment from the inlet in the upper Delta to the outlets in the lower Delta.     

In Vitro Effects of Isoorientin,Forsythoside B,and Verbascoside on Bovine Kidney Cortex Glutathione Reductase

Glutathione reductase (GR; E.C 1.6.4.2) catalyzes the reduction of oxidized glutathione to reduced glutathione by the nicotinamide adenine dinucleotide phosphate (NADPH) dependent mechanism. GR participates in the protection of the cell from the toxic effects of free radicals. In this study, we have investigated in vitro effects of isoorientin (C‐glycosyl flavonoid), verbascoside, and forsythoside B (phenylethanoids) on purified bovine kidney cortex GR. These compounds present in many plant species that have been used as medicinal plants and have an interesting spectrum of biological activity. We have demonstrated that these compounds inhibit bovine kidney cortex GR in a concentration‐dependent manner. Kinetic characterization of the inhibition is also done. Isoorientin is a noncompetitive inhibitor with respect to both glutathione disulfide (GSSG) (Ki_GSSG 0.023 ± 0.001 mM) and NADPH (Ki_NADPH 0.032 ± 0.001 mM). Forsythoside B acts as an uncompetitive inhibitor with respect to GSSG (Ki_GSSG 0.20 ± 0.014 mM) and NADPH (Ki_NADPH 0.267 ± 0.028 mM). Verbascoside acts as an uncompetitive inhibitor with respect to both GSSG (Ki_GSSG 0.242 ± 0.024 mM) and NADPH (Ki_NADPH 0.175 ± 0.016 mM). Inhibition of GR causes accumulation of reactive oxygen species and depletion of the glutathione pool. Inhibition of this enzyme may be significant in drug resistance.     

An investigation of the physicochemical properties of both glutathione peroxidase I and its complexes with polyelectrolytes as promising agents for the treatment of diseases of the central nervous system

A study of the kinetics of the thermal inactivation of glutathione peroxidase I was carried out. Glutathione peroxidase is an enzyme that plays a key role in the antioxidant protection system of the body. It was shown that oligomeric glutathione peroxidase I is inactivated by a monomolecular mechanism (37°C, pH 7.0, the enzyme concentrations 0.3 and 1 mg/mL). An effective method for stabilizing the enzyme by polyelectrolytes of different natures was proposed.     

Major and trace elements in sediments of the upper course of Lerma river

Summary The Lerma is one of the most important rivers of Mexico, where it drains highly populated and industrialized regions. The concentration of six major and trace elements: titanium, manganese, iron, zinc, copper and lead in the surface sediments of the upper course of Lerma river was investigated, in order to identify its distribution along the river and to recognize the principal sites of pollution. The surface sediment samples were collected at 8 sites distributed following the stream flow direction of the river. Major and trace elements concentrations were determined by energy dispersive X-ray spectrometry. The results show that the metal concentrations in the sediments decrease in the sequence: Fe > Ti > Mn > Zn > Cu > Pb. Concentration of Fe, Mn and Ti were significantly higher than the other metals in site 8,200 meters downstream the Alzate Dam. The high concentrations and spatial variations of Zn, Cu and Pb in the middle sites of the upper course of the Lerma River indicate that the river pollution is probably associated with urban and industrial discharges.     

Influence of heavy metals, especially lead, on lipid metabolism, serum alpha-tocopherol level, total antioxidant status, and erythrocyte redox status of copper smelter workers

An assessment of influence of the occupational exposure to heavy metals, especially lead, on serum lipids (including lipid peroxides), total antioxidant status, erythrocyte redox status, and serum alpha-tocopherol level was performed in a group of 141 healthy male copper smelter workers. The following parameters were measured: blood lead and cadmium levels, serum manganese, copper, zinc, calcium and magnesium levels, free erythrocyte protoporphyrins (FEP), total cholesterol, HDL₂-, HDL₃-cholesterol, triglycerides and lipid peroxides in serum, erythrocyte superoxide dismutase (SOD_E), catalase (Cat_E) and glutathion peroxidase (PxGSH_E) activities, erythrocyte reduced glutathione level (GSH_E), serum alpha-tocopherol level, and serum total antioxidant status (TAS). Mean Pb_B was within the norm range (328.2 ± 141.7 μg/L), but mean Mn_S concentration slightly exceeded 10 μg/L (11.04 ± 3.79 μg/L). Mean cholesterol and triglycerides concentrations were near the highest borderline values. We found a significantly negative correlation between lead levels and HDL₃-cholesterol (r = 0.253, P < 0.05). Erythocyte catalase activity and TAS were lowered. TAS showed significant negative correlation with Pb_B. A group of workers with Pb_B≥ 400 μg/L had significantly lower Cat_E, lower TAS, and lower HDL₃-cholesterol, compared to the workers with Pb < 400 μg/L. We have also found positive correlation between alpha-tocopherol and total cholesterol (r = 0.267, P < 0.05) and between alpha-tocopherol and LDL-cholesterol (r = 0.207, P < 0.05). Received: 28 July 1997 / Revised: 6 November 1997 / Accepted: 4 November 1997     

Synthesis, characterization, and antioxidant activity of some ebselen analogues

Simple synthetic routes for several analogues of the anti-inflammatory organoselenium drug, ebselen, are described. The compounds are characterized by (1)H, (13)C, and (77)Se NMR spectroscopy and mass spectral techniques and, in some cases, by single-crystal X-ray diffraction studies. The glutathione peroxidase (GPx)-like antioxidant activity has been studied by using H(2)O(2), tBuOOH, and Cum-OOH as substrates, and thiophenol (PhSH, 4-Me-C(6)H(4)SH) and glutathione (GSH) as cosubstrates. Density functional theory (DFT) calculations have been performed on these systems to understand the effects of various substituents on the (77)Se NMR chemical shifts; these results have been compared with the experimental data. The experimental and theoretical results suggest that the presence of a phenyl substituent on the nitrogen atom is important for the antioxidant activity of ebselen. While ebselen and its analogues are poor catalysts in aromatic thiol assays, these compounds exhibit high GPx activity when GSH is used as the cosubstrate. The poor catalytic activity of ebselen analogues in the presence of aromatic thiols such as PhSH and 4-Me-C(6)H(4)SH can be ascribed to the undesired thiol exchange reaction that takes place at the selenium center due to SeO nonbonding interactions. To understand the effects of different peroxides on the catalytic activities, we have determined the initial rates at various concentrations of GSH and peroxides. These data suggest that the nature of peroxide has little effect on the catalytic efficiencies, although the initial reaction rates observed with hydrogen peroxide were found to be higher than that with tBuOOH and Cum-OOH. In contrast to the effect of peroxides, the nature of thiols appears to have a dramatic effect on the catalytic activity of ebselen and its related derivatives.     

Cyclodextrin-derived chalcogenides as glutathione peroxidase mimics and their protection of mitochondria against oxidative damage

A series of novel glutathione peroxidase (GPx) mimics based on organochalcogen cyclodextrin (CD) dimer were synthesized. Their GPx-like antioxidant activities were studied using hydrogen peroxide H₂O₂, tert-butylhydroperoxide (BHP), and cumene hydroperoxide (CHP) as substrates and glutathione as thiol co-substrate. The results showed that 6A,6B-ditelluronic acid-A,6B′-tellurium bridged γ-cyclodextrin (6-diTe-γ-CD) had the highest peroxidase activity, which was ~670-fold higher than ebselen, a well-known GPx mimic. Reduction of lipophilic CHP often proceeded much faster than reduction of the more hydrophilic H₂O₂ or BHP, which cannot bind into the hydrophobic interior of the CD. The biological activities were also evaluated for their capacity to protect mitochondria against ferrous sulfate/ascorbate-induced oxidative damage. 6-diTe-γ-CD was the best inhibitor which significantly suppressed ferrous sulfate/ascorbate-induced cytotoxicity as determined by swelling of mitochondria, lipid peroxidation and cytochrome c oxidase activity. Our data suggests that 6-diTe-γ-CD has potential pharmaceutical application in the treatment of ROS-mediated diseases.     

The study and application of biomimic peroxidase ferric 2-hydroxy-1-naphthaldehyde thiosemicarbazone (Fe(III)-HNT)

Ferric 2-hydroxy-1-naphthaldehyde thiosemicarbazone (Fe(III)-HNT) has been synthesized and used to mimic the active group of horseradish peroxidase (HRP). The catalytic characteristics of this mimic-enzyme catalyst in the oxidation reaction of ascorbic acid with hydrogen peroxide has been studied. The experimental results showed that this peroxidase model compound has similar catalytic activity that of HRP. The catalytic activity of Fe(III)-HNT has been compared with those of HRP and common mimic-enzymes, metalloporphyrins (e.g. metal tetrakis(sulphophenyl)porphyrin (Me-TPPS(4))). Though the catalytic activity of Fe(III)-HNT is 75% of that of HRP, it can be used as a new kind of mimic-enzyme catalyst in determination of trace H(2)O(2). By coupling this mimetic catalytic reaction with the catalytic reaction of glucose oxidase, glucose can be determined indirectly. Under experimental conditions the linear relationship between DeltaA(265) and glucose concentration was in the range of 2.0-40.0 mug ml(-1), The correlation coefficient (r) was 0.9996. The R.S.D. (P=0.05, n=6) was 0.24%. The detection limit was determined to be 0.238 mug ml(-1). It was applied successfully to the determination of glucose in normal human and diabetic urine. The values of determination by the proposed method were compared with those of a routine method (enzymic glucose determination) applied in an hospital clinical laboratory. The agreement was very good.     

Organic complexation and total dissolved trace metal analysis in estuarine waters: comparison of solvent-extraction graphite furnace atomic absorption spectrometric and chelating resin flow injection inductively coupled plasma-mass spectrometric analysis

The measured concentrations of cadmium, cobalt, copper, nickel, lead, zinc, and manganese in acidified (pH<2) estuarine water samples analyzed for total dissolved trace metal concentrations using on-line chelating resin column partitioning with inductively coupled plasma-mass spectrometry (CRCP-ICP-MS) were compared to those analyzed by graphite furnace atomic absorption spectrometry (GFAAS) after liquid-liquid extraction using a combination of 1-pyrrolidinedithiocarbamate/diethyldithiocarbamate (PDC/DDC). Although there was good agreement between the two sets of analyses for cadmium, lead, manganese, and zinc concentrations, those of cobalt, copper, and nickel determined by CRCP-ICP-MS were found to be 10-20% lower than those determined by solvent-extraction GFAAS. The different yields were positively correlated (R>0.961, simple linear regression) to the dissolved organic carbon (DOC) concentration of the samples. Good agreement between the two methods for cobalt and copper was achieved after ultraviolet (UV) digestion of the acidified samples. Samples collected from the South Bay of the San Francisco Estuary with high DOC showed the greatest difference for cobalt, copper, and nickel which is tentatively attributed to complexation with humic material for copper and cobalt and strong synthetic chelating agents such as ethylenediaminetetraacetic acid (EDTA) for nickel. This is consistent with previous studies on copper, nickel and cobalt complexation in this region. We recommend UV digestion of acidified estuarine samples prior to multi-element analysis by chelating resin flow injection ICP-MS methods.     

Heavy Metal Concentrations in Water,Sediment and Fish from Izmit Bay,Turkey

Abstract

Mercury, cadmium and lead levels in water, sediment and fish samples from Izmit Bay, Turkey have been determined. Sampling and analysis methods are described. Variations of heavy metal concentrations from different sampling stations are discussed. Results indicate that the levels of mercury and cadmium were highest in the vicinity of a chlor-alkali plant while the highest concentration of lead was near a metallic pipe factory. The amounts of heavy metals found in the shoreline sediment samples were similar to those found in fish species from the bay.     

长期低浓度铅暴露对人体微量元素的影响

测定了１５名长时间从事低剂量铅接触的女工血铅、铜、锌、铁、锰及铜锌超氧化物歧化酶活性、脂质过氧化产物二级降解物丙二醛含量,并以同年龄组同地区非铅暴露人群作对照。结果显示：暴露组的血铅、铜、ＭＤＡ含量高于对照组;而血锌Ｃｕ－Ｚｎ－ＳＯＤ活性低于对照组;血Ｍｎ、Ｆｅ两组无明显差异。