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Enhanced phytoextraction: I. Effect of EDTA and citric acid on heavy metal mobility in a calcareous soil.

Phytoextraction, the use of plants to extract heavy metals from contaminated soils, could be an interesting alternative to conventional remediation technologies. However, calcareous soils with relatively high total metal contents are difficult to phytoremediate due to low soluble metal concentrations. Soil amendments such as ethylene diaminetetraacetate (EDTA) have been suggested to increase heavy metal bioavailability and uptake in aboveground plant parts. Strong persistence of EDTA and risks of leaching of potentially toxic metals and essential nutrients have led to research on easily biodegradable soil amendments such as citric acid. In our research, EDTA is regarded as a scientific benchmark with which degradable alternatives are compared for enhanced phytoextraction purposes. The effects of increasing doses of EDTA (0.1,1,10 mmol kg(-1) dry soil) and citric acid (0.01, 0.05, 0.25, 0.442, 0.5 mol kg(-1) dry soil) on bioavailable fractions of Cu, Zn, Cd, and Pb were assessed in one part of our study and results are presented in this article. The evolution of labile soil fractions of heavy metals over time was evaluated using water paste saturation extraction (approximately soluble fraction), extraction with 1 M NH4OAc at pH 7 (approximately exchangeable fraction), and extraction with 0.5 M NH4OAc + 05 M HOAc + 0.02 M EDTA at pH 4.65 (approximately potentially bioavailable fraction). Both citric acid and EDTA produced a rapid initial increase in labile heavy metal fractions. Metal mobilization remained constant in time for soils treated with EDTA, but a strong exponential decrease of labile metal fractions was noted for soils treated with citric acid. The half life of heavy metal mobilization by citric acid varied between 1.5 and 5.7 d. In the following article, the effect of heavy metal mobilization on uptake by Helianthus annuus will be presented.

Biodegradation, Environmental↗

Enhanced phytoextraction: II. Effect of EDTA and citric acid on heavy metal uptake by Helianthus annuus from a calcareous soil.

High biomass producing plant species, such as Helianthus annuus, have potential for removing large amounts of trace metals by harvesting the aboveground biomass if sufficient metal concentrations in their biomass can be achieved However, the low bioavailability of heavy metals in soils and the limited translocation of heavy metals to the shoots by most high biomass producing plant species limit the efficiency of the phytoextraction process. Amendment of a contaminated soil with ethylene diamine tetraacetic acid (EDTA) or citric acid increases soluble heavy metal concentrations, potentially rendering them more available for plant uptake. This article discusses the effects of EDTA and citric acid on the uptake of heavy metals and translocation to aboveground harvestable plant parts in Helianthus annuus. EDTA was included in the research for comparison purposes in our quest for less persistent alternatives, suitable for enhanced phytoextraction. Plants were grown in a calcareous soil moderately contaminated with Cu, Pb, Zn, and Cd and treated with increasing concentrations of EDTA (0.1, 1, 3, 5, 7, and 10 mmol kg(-1) soil) or citric acid (0.01, 0.05, 0.25, 0.442, and 0.5 mol kg(-1) soil). Heavy metal concentrations in harvested shoots increased with EDTA concentration but the actual amount of phytoextracted heavy metals decreased at high EDTA concentrations, due to severe growth depression. Helianthus annuus suffered heavy metal stress due to the significantly increased bioavailable metal fraction in the soil. The rapid mineralization of citric acid and the high buffering capacity of the soil made citric acid inefficient in increasing the phytoextracted amounts of heavy metals. Treatments that did not exceed the buffering capacity of the soil (< 0.442 mol kg(-1) soil) did not result in any significant increase in shoot heavy metal concentrations. Treatments with high concentrations resulted in a dissolution of the carbonates and compaction of the soil. These physicochemical changes caused growth depression of Helianthus annuus. EDTA and citric acid added before sowing of Helianthus annuus did not appear to be efficient amendments when phytoextraction of heavy metals from calcareous soils is considered.

Biodegradation, Environmental↗

Zonulae occludentes in junctional complex-enriched fractions from mouse liver: preliminary morphological and biochemical characterization.

A bile canaliculus-derived preparation containing junctional complexes has been obtained from mouse livers using subcellular fractionation techniques. The junctional complexes include structurally intact zonulae occludentes (ZOs). Extraction of this preparation with the anionic detergent sodium deoxycholate (DOC) left junctional ribbons, the detergent-insoluble zonular remnants of the junctional complexes. When visualized in negative stain electron microscopy, each of these ribbons contained a branching and anastomosing network of fibrils which appears similar to that of ZOs in freeze-fractured whole liver. Comparative measurements of freeze-fracture and negative stain fibril diameters and network densities support this relationship. SDS polyacrylamide gel analysis shows the DOC-insoluble junctional ribbons to be characterized by major polypeptides at 37,000 and at 48,000, with minor bands at 34,000, 41,000, 71,000, 86,000, 92,000, and 102,000. The ZO-containing membrane fractions have been isolated in the presence of EGTA in concentrations and under conditions shown by others to disrupt normal ZO morphology and physiology in whole living epithelia. The network of fibrils visualized in these fractions by negative staining is structurally resistant to treatment with DOC, but is either solubilized or disrupted by N-lauroylsarcosine.

Animals↗

The routine measurement of platelet volume: a comparison of light-scattering and aperture-impedance technologies.

The effect of dipotassium ethylenediaminetetra-acetic acid (EDTA) on platelet count and mean volume (MPV) was evaluated using two routine measurement systems, a Coulter S Plus (Phase 1) (S+) and a Technicon H6000 (H6000). In normal subjects (n = 29) MPV increased by 17% during 39 h storage in EDTA when measured by the S+. In contrast MPV decreased by 22% when measured by the H6000. MPV differences of up to 40% were observed between the two systems. Concomitant platelet counts, in both systems, changed by less than 4%. A mathematical model of the variation of MPV with storage time was constructed, enabling experimental results to be extrapolated, with accuracy, to time zero (MPV0). The H6000 average MPV0 was significantly larger than the S+ average MPV0. Using the anticoagulant sodium citrate and prostaglandin E1 (NaCitrate-PGE1) there were no significant changes in MPV measured by the S+ during 7 h storage, although a linear decrease in platelet count was observed. A decrease in H6000 MPV was observed whether the blood was stored in EDTA or NaCitrate-PGE1. Methodology, anti-coagulation and storage time all influence MPV. Until these determinants are standardised the clinical value of MPV cannot be assessed.

Blood Platelets↗

Electrical impedance and haematocrit of human blood with various anticoagulants.

The relationship between the electrical impedance parameters and the haematocrit of normal human blood has been determined at 37 degrees C in the haematocrit range of 20-60% for four types of anticoagulant: ACD, EDTA, sodium heparin and buffered sodium citrate. For plasma resistance Rp and interior resistance R(i), the measured data could be fitted by both the exponential expression and the Maxwell-Fricke expressions, Rp = a/(1-h) + b and R(i) = a/h + b, where a and b are constants and h is the haematocrit expressed as a decimal. The membrane capacitance Cm was found to be directly proportional to the haematocrit and could be normalized to 100% haematocrit by the Fricke formula, C100 = C(m)/(1-rho p/Rp), where rho p is the resistivity of plasma. Observed differences for Rp and C(m) among samples with various anticoagulants indicate that the type of anticoagulant influences the electrical properties of the red cells and the plasma.

Anticoagulants↗

Fe(III)-EDTA complex as iron fortification.

Fe(III)-EDTA as iron fortification presents several advantages over the other iron salts previously used including ferrous sulfate. This iron compound exchange completely with vegetable food iron in the lumen of the gut but with the characteristics that the absorption from both, extrinsic and intrinsic food iron, is higher than that expected from other iron salfs. The comparison between the iron absorption from Fe(III)-EDTA and ferrous sulfate as iron fortification indicates that the absorption form EDTA is about twice as high than that observed from ferrous sulfate. The data indicates that only 10 to 15 mg of iron as Fe(III)-EDTA as iron fortification would be necessary to prevent iron deficiency anemia in population relying their subsistence of vegetable food only and free of parastic infection producing blood loss.

Absorption↗

Use of alkaline phosphatase to correct the underestimation of fosphenytoin concentration in serum measured by phenytoin immunoassays.

The pharmacologic activity of fosphenytoin, a new phosphate ester pro-drug of phenytoin, is due to in vivo conversion to phenytoin. Fosphenytoin concentrations cannot be accurately estimated by phenytoin immunoassays (fluorescence polarization and chemiluminescence) owing to the nonlinear relation between fosphenytoin concentration and the observed cross-reactivity. The problem of slow conversion of fosphenytoin to phenytoin in serum in vitro can be circumvented by rapidly converting fosphenytoin to phenytoin in vitro by alkaline phosphatase. Drug-free serum, heparin, EDTA, or citrated plasma were supplemented with 2 concentrations of fosphenytoin. Then to 1-mL aliquots of specimen, no enzyme (control), 10 microL, or 25 microL of enzyme solution was added. The specimens were incubated, and phenytoin concentrations were measured by fluorescence polarization and chemiluminescent assays. In the absence of enzyme, we observed little conversion of fosphenytoin to phenytoin, but in the presence of only 10 microL of enzyme, the conversion of fosphenytoin to phenytoin was complete in 5 minutes. We also observed complete conversion of fosphenytoin to phenytoin by alkaline phosphatase in heparin, EDTA, and citrated plasma. If clinically indicated, the phenytoin concentration can be measured before and after addition of enzyme to roughly estimate the rate of conversion.

Alkaline Phosphatase↗

Restoration of hemoglobin function in stored EDTA blood. Application in identification of hemoglobin variants with abnormal oxygen affinity.

The incubation of stored blood in a mixture of inosine, pyruvate, glucose, and phosphate restores the O2 affinity of hemoglobin to physiologic levels, as measured by the configuration of the dissociation curve and the P50. This regeneration of normal hemoglobin function not only is consistent for samples anticoagulated with EDTA and stored eight days at 4 C but also is demonstrable for at least 19 days of 4 C storage of EDTA-anticoagulated whole blood. This regeneration procedure is simple to perform and makes it possible to measure reliably O2 affinity in blood samples transmitted by mail.

Blood Preservation↗

The role of anticoagulation in the measurement of platelet volumes.

The effect of anticoagulation on platelet size stability was studied using blood collected in seven different anticoagulants and stored at room temperature for up to eight hours. The mean platelet volume (MPV) value was most stable in blood collected in 15% ACD and ACD/Na2EDTA. In blood collected in Na2EDTA, K3EDTA, or 11.9% ACD, there was an increase in MPV in the first two hours, after which the MPVs remained stable up to eight hours. Sodium citrate and heparin proved unreliable for the measurement of platelet volume. Platelet counts were stable (less than 5% variation) in all anticoagulants except heparin, which had 16% variation for the eight hours of study. Simultaneously, RBC counts and mean corpuscular volume (MCV) measurements were stable in all seven anticoagulants, with sodium citrate producing the most variation. A negative correlation was observed between MCV and pH of the anticoagulated blood. WBC counts showed less than 3% variation in all anticoagulants except sodium citrate and heparin. Separate experiments demonstrated that electrolyte composition, pH, tonicity, and method of calcium chelation all influenced the stability of the MPV. Of the anticoagulants studied, ACD/Na2 EDTA appeared to provide the best conditions of anticoagulation for both routine clinical and research laboratory measurement of the MPV. It inhibited platelet activation but left the platelets in their normal discoid shape. Platelets could be removed from the anticoagulant and studied in functional assays for up to eight hours after blood drawing. Both platelet counts and MPVs remained stable in blood collected in ACD/Na2 EDTA anticoagulant for up to eight hours at room temperature. In 52 volunteers studied, an inverse correlation (r = -0.72, P less than 0.001) was observed between platelet count and MPV, suggesting that the circulating platelet mass may be a more important indicator of platelet homeostasis than either the platelet count or the mean platelet volume alone.

Adult↗

Pasteurella multocida: plasma lysozyme in bacteremic and lipopolysaccharide-exposed turkeys.

Plasma lysozyme was measured in turkeys with experimental fowl cholera produced by either of two serotypes of Pasteurella multocida. Lysozyme was not detected in preexposure plasma, whereas plasma sampled when turkeys were terminally bacteremic contained 7.0-7.5 microgram of lysozyme/ml. Plasma lysozyme was measured in turkeys inoculated intravenously with P. multocida lipopolysaccharide (LPS). Turkeys inoculated with 10 microgram of LPS produced plasma lysozyme detectable for 2 hr after inoculation; those inoculated with 500 microgram of LPS produced plasma lysozyme detectable for at least 6 hr after inoculation. Egg-white lysozyme, equivalent in concentration to the plasma lysozyme detected in bacteremic turkeys, was active upon young cultures of P. multocida and increased the degree of lysis of P. multocida cells treated with deoxycholate. Lysozyme, ethylenediaminetetraacetate, and deoxycholate in combination produced the highest degree of lysis of P. multocida cells.

Animals↗

Effect of myosin DTNB light chain on the actin-myosin interaction in the presence of ATP.

The influence of the DTNB light chain of myosin on its enzymatic activities was examined by studying the superprecipitation of actomyosin and the actin-activated ATPase of heavy meromyosin (HMM) [EC 3.6.1.3]. Although the Ca2+-, Mg2+-, and EDTA-ATPase activities of control and DTNB myosin were practically the same, the superprecipitation of actomyosin prepared from actin and DTNB myosin occurred more slowly than that of control myosin. The apparent binding constant obtained from double-reciprocal plots of actin-activated ATPase of DTNB HMM was lower than that of control HMM. Recombination of DTNB myosin and HMM with DTNB light chains restored the original properties of myosin and HMM. The removal of DTNB light chain from myosin had no effect on the formation of the rigor complex between actin and myosin. These results suggest that the DTNB light chain participates in the interaction of myosin with actin in the presence of ATP.

Actins↗

The effect of the EAAEAE insert on the property of human metallothionein-3.

MT3 shows apparently different properties and function from MT1 even though they have 70% sequence homology. Possibly the two inserts, Thr5 and a negatively charged hexapeptide at position-55 in MT3, play important roles. A series of MT3 variants around the EAAEAE hexapeptide have been prepared by site-directed mutagenesis and their properties and reactivity towards pH, EDTA and DTNB have been studied. Our detailed studies revealed that the EAAEAE insert is essential to the property of MT3. It is the hexapeptide insert, to some extent, making the MT3 alpha-domain looser and lower stability of the metal-thiolate cluster, which could be accessed more easily.

Dithionitrobenzoic Acid↗

Effect of transition metals (Mn, Cu, Fe) and deoxycholic acid (DA) on the conversion of PrPC to PrPres.

The PMCA (protein misfolding cyclic amplification) technique has been shown to drive the amplification of misfolded prion protein by PrP(Sc) seeds during several cycles of incubation-sonication. Here, we report that cyclic amplification of normal hamster brain homogenates treated with a number of transition metals (manganese [Mn], copper [Cu], and iron [Fe]) leads to conversion of PrP(C) into protease-resistant PrP(res). The efficiency of PrP(res) formation and the glycoforms induced by Mn were different from those obtained by Cu and Fe. Previous results have shown higher Mn and lower Cu levels in the affinity-purified PrP(Sc) from the brain of prion diseases compared with normal hamster brain homogenates. We focused on Mn because we observed higher levels of Mn in whole brain, mitochondria, and scrapie-associated fibril-enriched fractions from the brains of animals with prion disease. In the presence of minute quantities of Mn-induced PrP(res) template with a large amount of PrP(C), PrP(res) amplification is observed. A metal chelater, EDTA reverses the effect of Mn on PrP(res) amplification, suggesting that Mn may play a role in the formation of PrP(res). It has been proposed that metal-catalyzed oxidation of PrP leads to the oxidation of amino acids and extensive aggregation of oxidized PrP. Carboxyl acids such as deoxycholic acid (DA) are oxidized molecules produced by 3' oxidation pathway. In in vitro studies, the potent effect of Mn on PrP(res) amplification is augmented by DA in a dose-dependent manner. On the basis of the evidence of the elevated Mn levels in scrapie-associated fibril (SAF)-enriched preparations from the brains of animals with prion disease, Mn-loaded PrP and oxidized molecules such as carboxyl acids may contribute to the formation of the scrapie isoform of PrP in prion diseases.

Animals↗

Sulfite supported lipid peroxidation in propofol emulsions.

BACKGROUND: Sodium metabisulfite is added to a commercial propofol emulsion as an antimicrobial agent. The sulfite ion (SO3(-2)) is capable of undergoing a number of reactions, including autooxidation and the promotion of lipid peroxidation. This study evaluated sulfite reactivity in propofol emulsions by determining thiobarbituric acid reacting substances (TBARS), sulfite depletion, and emulsion pH in emulsions containing sulfite or EDTA. METHODS: Commercial EDTA and sulfite propofol emulsions were compared, and 10% soybean oil emulsion containing various additives were evaluated for TBARS, sulfite, and pH. TBARS were analyzed with a modified thiobarbituric acid method. Sulfite was analyzed by the reaction of sulfite with 5,5'-dithiobis(2-nitrobenzoic acid). pH was measured by glass electrode methodology. RESULTS: Thiobarbituric acid reacting substances were detectable in commercial sulfite propofol emulsions in concentrations ranging from 0.02 to 0.22 microg/ml based on malondialdehyde. No TBARS were detected in EDTA propofol emulsions. Incubation (37 degrees C, up to 6 h) of sulfite propofol emulsions in air resulted in further increases in TBARS (35-160%). No increases occurred in incubated EDTA propofol emulsions. Metabisulfite (0.25 mg/ml) alone added to 10% soybean oil resulted in large increases in TBARS that were inhibited in part by propofol (10 mg/ml) and completely by ascorbic acid (0.05 mg/ml). Soybean oil emulsion pH declined rapidly on the addition of metabisulfite (0.25 mg/ml). The addition of propofol (10 mg/ml) partially inhibited the decline in pH and ascorbic acid (0.05 mg/ml) completely inhibited it. CONCLUSION: These results show that sulfite supports the peroxidation of lipids in soybean oil emulsions and propofol functions to partially inhibit these processes.

Ascorbic Acid↗

Measurement of platelet volume using a variety of different anticoagulant and antiplatelet mixtures.

Mean platelet volume (MPV), a measure of platelet size, has previously been noted to change in a time dependent manner in ethylene-diaminetetraacetic acid (EDTA) and citrate anticoagulants. We measured MPV in healthy volunteers using several different anticoagulants and at different temperatures. In ten volunteers MPV was measured (Sysmex NE 8000 autoanalyser) serially over a 29 h period in 15 different anticoagulant/antiplatelet combinations kept at room temperature and on ice-water mixture. We evaluated the following mixtures: K3EDTA, K3EDTA/prostaglandin E1 (PGE1), K3EDTA/PGE1/theophylline, Na2EDTA, Na2EDTA/PGE1, citrate 1:9, citrate 1:4, citrate 1:9/PGE1/theophylline, citrate 1:4/PGE1/theophylline, citrate 1:9/PGE1, citrate 1:9/dextrose, citrate 1:4/dextrose, acid-citrate-dextrose (ACD) 15%, ACD 11.9%, ACD 11.9%/Na2EDTA. In a second experiment we evaluated MPV, at room temperature only, in a further 20 volunteers in K3EDTA, citrate 1:9, ACD 11.9%/Na2EDTA, ACD 11.9% (total = 30) and citrate-phosphate-dextrose-adenine (CPDA; total = 20). Over the 29 h period there was a significant positive trend of increasing MPV in K3EDTA, CPDA and ACD 11.9%/Na2EDTA and a negative trend in citrate 1:9. ACD 11.9% showed no significant change in MPV with time at room temperature. This methodology should enable the wider application of MPV measurement for routine clinical and research studies.

Adult↗