Ethylenediaminediacetic Acid Research Articles

A Novel tetrahydrocannabinol (THC) analog, 3,10,10-Trimethyl-1,2,3,4,4a,6,7,8,10,10a-decahydro-9-oxa-5-phenanthrenone (TDP), mitigates the decrease in cell viability in oxidatively-stressed osteosarcoma bone-like cell cultures, UMR 106-01 BSP (UMR cells)

Cannabinoids have been extensively studied in the field of cancer research. Tetrahydrocannabinol (THC) has shown promising results in influencing cellular proliferation and viability when used in association with other cannabinoids. However, not many studies have been done to explore the effect of THC analogs on osteosarcoma cells when used in concert with oxidative stressors like camptothecin (CPT). In this study, it was hypothesized that TDP would mitigate the oxidative effect of CPT on UMR cells. Briefly, synthesis of the novel THC analog, TDP, was attempted via a Knoevenagel condensation and a Diels-Alder reaction, using 1,3-cyclohexanediol dissolved in methanol and citronellal with ethylenediamine diacetic acid (EDDA) at a temperature of 60°C. UMR cells were routinely passaged, counted, plated in six-well culture plates at 480,000 cells/mL, then treated with 10-fold dilutions of TDP. The plates were incubated for 72 hours in a humidified incubator at 37 degrees Celsius with 5% carbon dioxide infusion. At the end of the experiment, the cells were routinely washed with HANKS buffered saline solution (HBSS), then counted using the Luna II Automated Cell Counter. In another experiment, designated cells were treated with different concentrations of CPT alone, while others were co-treated with different concentrations of TDP+CPT, following the protocol above. F test ANOVA was used to compare variances and all values in the results were expressed as means ± SD. The results from the attempted cannabinoid analog synthesis yielded an active novel THC analog, TDP. Serial dilutions treatment of the UMR cells with TDP alone showed its ability to decrease cell viability in a concentration-dependent manner. The treatment of the UMR cells with different concentrations of CPT alone resulted in a decrease in cell viability in a concentration-dependent manner. Co-treatment of the UMR cells with different concentrations of CPT+TDP showed that TDP was able to mitigate the effect of the oxidative stressor (CPT) on the UMR cell cultures. Moreover, the F Test ANOVA showed robust statistical significance (p values <0.05) regarding TDP’s ability to decrease the oxidative effect of CPT on UMR cells. Overall, the outcomes of this study suggest that active forms of THC analogs can be synthesized and tested in concert with oxidative stressors like CPT. This study opens the door to explore the mechanisms by which TDP exerts its effect on oxidatively-stressed cells and how it can possibly be used to prevent or mitigate the effect of oxidative stress on a variety of cells in culture. Moreover, the hopes of suggesting therapeutic uses of THC analogs, upon future mechanistic experimentations, is a goal. La Sierra University Title V Grant. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Synthesis of A Tetrahydrocannabinol (THC) Analog For Analyzing Cellular Proliferation in Concert With Epigallocatechin Gallate (EGCG) on A Bone‐like Cancer Cell Line (UMR 106‐01 BSP)

Cannabinoids have been extensively studied in the field of cancer research. Tetrahydrocannabinol (THC) has shown promising results in influencing cellular proliferation when in association with other cannabinoids. This traditional entourage effect solely focuses on the study of THC with other cannabinoids. However, not many studies have been done to explore the synergistic effect of THC analogs when used with non‐cannabinoid compounds. THC in its isolate form for experimentation is very strictly regulated. Therefore, this study was conducted in the pursuit of synthesizing and experimenting with analogs of THC to observe a potential entourage effect with epigallocatechin gallate (EGCG), a compound known for its efficacy to reduce proliferation at higher concentrations in UMR cells. It was hypothesized that active analogs of THC can be synthesized and used in concert with EGCG to potentiate decreased proliferation in the bone‐like cancer cell line UMR 106‐01 BSP (UMR cells). Briefly, a Knoevenagel condensation and a Diels‐Alder reaction using 1,3‐cyclohexanediol dissolved in methanol (MeOH) and citronellal with ethylenediamine diacetic acid (EDDA) at a temperature of 60℃ was used to synthesize a novel THC analog, 3,10,10‐Trimethyl‐1,2,3,4,4a,6,7,8,10,10a‐decahydro‐9‐oxa‐5‐phenanthrenone (TDP). UMR cells were routinely passaged, counted, plated in six‐well culture plates at 480,00 cells/mL, then treated with 10‐fold dilutions of TDP. The plates were incubated for 72 hours in a humidified incubator at 37 degrees Celsius with 5% carbon dioxide infusion. At the end of the experiment, the cells were routinely washed with HANKS buffered saline solution (HBSS), then routinely counted using the Luna Automated Cell Counter. In another experiment, designated cells were co‐treated with TDP+EGCG, following the protocol above. F test ANOVA was used to compare variances and all values in the results were expressed as means ± SD. The results from the attempted cannabinoid analog synthesis yielded a novel active THC analog, TDP. Serial dilutions treatment of the UMR cells with TDP alone showed its ability to decrease cell count in a concentration dependent manner. However, when coupled with higher concentrations of EGCG, the co‐treatment increased cell count rather than potentiating the effect of decreasing cellular proliferation. The F Test ANOVA showed robust statistical significance (p values <0.05) with regard to TDP’s effect of decreasing cell proliferation in UMR cells in a concentration‐dependent manner. Overall, the outcomes of this study suggest that active forms of THC analogs can be synthesized and tested in concert with other non‐cannabinoid compounds like EGCG. This study opens the door to explore the entourage effect of TDP with other non‐cannabinoid compounds that may provide another tool in the therapeutic treatment of bone cancer cells.

Fabrication of magnetic polymeric resin for the removal of toxic metals from aqueous medium: Kinetics and adsorption mechanisms

Discharge of heavy metals without proper treatment of the industrial wastewater and resulted damages to the aquatic ecosystems and human health. In the present study, a magnetic adsorbent containing carboxylic acid and amino functional groups was fabricated using ethylenediaminediacetic (EDDA) acid, glutaraldehyde and CuFe2O4 nanoparticles. The structure and composition of the fabricated nanocomposite (EG@ CuFe2O4) was analyzed by FTIR, TGA, XRD, BET, SEM, TEM, XPS etc, and employ for the removal of Hg(II) and Pb(II) from aqueous medium. The adsorption kinetics and adsorption isotherm model was used for further characterization of the adsorption process for the metal ions, and support the pseudo- second order kinetics and Langmuir model. The thermodynamic parameters (ΔGo < 0, ΔHo > 0) support, spontaneous and endothermic adsorption. All these results revealed that the as fabricated magnetic EG@ CuFe2O4 nanocomposite can be used as an eco-friendly, proficient and cheap adsorbent for the adsorption of heavy metals form aqueous solution.

Drug-release system of microchannel transport used in minimally invasive surgery for hemostasis.

BackgroundSucrose allyl ether (SAE) containing hemostatic drugs and a photoinitiator was established to treat mild postpartum hemorrhage or long-term continuous abnormal uterine bleeding in minimally invasive surgery (MIS) using a photopolymerization method.Methods and resultsReal-time infrared spectroscopy and rheological experiments showed that the SAE monomer with shear-thinning characteristics could polymerize rapidly into a transparent membrane. Cytotoxicity experiments in vitro showed that this system could elicit a long-term hemostatic effect. Tissue adhesion was also evaluated. The photo-stability of four delivered antifibrinolytic drugs (6-aminocaproic acid, ethylenediaminediacetic acid, tranexamic acid and p-(aminomethyl) benzoic acid) was tested by ultraviolet-photolysis experiments and illustrated by time-dependent density functional theory. Sustained-release experiments revealed that the formed film could be used as a drug carrier. Molecular docking and molecular dynamics were done to investigate the binding mechanism between hemostatic drugs as ligands and the human plasminogen kringle-1 (1HPK) as a target.ConclusionIt has been suggested that SAE with tranexamic acid could be a drug-release system of microchannel transport used in MIS. This system could tackle the dilemma of fluidity and adhesion in MIS. The photo-stable tranexamic acid was the most suitable drug according to its satisfactory binding energy, good photo-stability, and sustained release.

Pitfalls in Gallium-68 PSMA PET/CT Interpretation-A Pictorial Review.

The novel Gallium-68 prostate-specific membrane antigen (PSMA)-bis [2-hydroxy-5-(carboxyethyl)benzyl] ethylenediamine-diacetic acid positron emission tomography (PET) tracer is increasingly used in the evaluation of prostate cancer, particularly in the detection of recurrent disease. However, PSMA is expressed in nonprostatic tissues, as well as in other pathologic conditions. Here we illustrate such interpretive pitfalls with relevant images that one may encounter while reporting PSMA PET/CT. This study aims to show variation in physiological distribution of PSMA activity and uptake in various benign and neoplastic disorders that may be misinterpreted as prostatic metastatic disease. These pitfalls are illustrated to enhance awareness, aiding a more accurate interpretation of the study. Retrospective database of all (68)Ga PSMA PET/CT was created and reviewed. In total, 1115 PSMA PET/CT studies performed between February 27, 2015, and May 31, 2017, were reviewed. Any unusual uptake of PSMA was documented, described, and followed up. All cases were then subdivided into the following 4 categories: physiological uptake, benign pathological uptake, nonprostatic neoplastic uptake, and miscellaneous uptake. A variety of nonprostatic tissues and lesions, including accessory salivary gland, celiac ganglion, gall bladder, Paget's bone disease, reactive lymph nodes, non–small cell lung cancer, renal cell cancer, and neuroendocrine tumor, were found to show PSMA uptake. PSMA uptake is not prostate-specific and can be taken up physiologically and pathologically in nonprostatic tissue. It is important for reporting physicians to recognize these findings and instigate appropriate investigations when required while avoiding unnecessary procedures in physiological variation.

Biological Evaluation of 99mTc-HYNIC-EDDA/tricine-(Ser)-D4 Peptide for Tumor Targeting.

D4 small peptide (Leu-Ala-Arg-Leu-Leu-Thr) was selected as an appropriate agent for specific targeting of epidermal growth factor receptor (EGFR). The aim of study was to investigate the 99mTc-labeled D4 peptide for non-small cell lung tumor targeting. HYNIC-(Ser)3-D4 peptide was labeled with 99mTc using mixture of tricine and ethylenediamine diacetic acid (EDDA) as co-ligands. The in vitro cellular uptake of radiolabeled peptide was evaluated by blocking test on human non-small cell lung cancer (A-549) cell line and its biodistribution was evaluated in A-549 xenografted nude mice. This conjugated peptide was labeled with 99mTc in high radiochemical purity and it was highly stable in buffer and serum. The un-blocked to blocked cellular radioactivity ratio was 4- fold that showed a specific binding of this radiolabeled peptide on A-549 cell. Animal biodistribution in A-549 xenografted nude mice showed rapid clearance from blood and other non-target organs. Tumor uptake values as %ID/g (percentage of injection dose per gram of tissue) were 2.47% and 1.30% at 1 and 4 h after injection. This study showed the 99mTc-EDDA/tricine-HYNIC-(Ser)3-D4 peptide had tumor targeting on the non-small cell lung tumor.

Comparison of macrocyclic and acyclic chelators for gallium-68 radiolabelling.

Gallium-68 (68Ga) is a positron-emitting isotope used for clinical PET imaging of peptide receptor expression. 68Ga radiopharmaceuticals used in molecular PET imaging consist of disease-targeting biomolecules tethered to chelators that complex 68Ga3+. Ideally, the chelator will rapidly, quantitatively and stably coordinate 68Ga3+ at room temperature, near neutral pH and low chelator concentration, allowing for simple routine radiopharmaceutical formulation. Identification of chelators that fulfil these requirements will facilitate development of kit-based 68Ga radiopharmaceuticals. Herein the reaction of a range of widely used macrocyclic and acyclic chelators with 68Ga3+ is reported. Radiochemical yields have been measured under conditions of varying chelator concentrations, pH (3.5 and 6.5) and temperature (25 and 90 °C). These chelators are: 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA), 1,4,7-triazacyclononane macrocycles substituted with phosphonic (NOTP) and phosphinic (TRAP) groups at the amine, bis(2-hydroxybenzyl)ethylenediaminediacetic acid (HBED), a tris(hydroxypyridinone) containing three 1,6-dimethyl-3-hydroxypyridin-4-one groups (THP) and the hexadentate tris(hydroxamate) siderophore desferrioxamine-B (DFO). Competition studies have also been undertaken to assess relative complexation efficiencies of each chelator for 68Ga3+ under different pH and temperature conditions. Performing radiolabelling reactions at pH 6.5, 25 °C and 5-50 μM chelator concentration resulted in near quantitative radiochemical yields for all chelators, except DOTA. Radiochemical yields either decreased or were not substantially improved when the reactions were undertaken at lower pH or at higher temperature, except in the case of DOTA. THP and DFO were the most effective 68Ga3+ chelators at near-neutral pH and 25 °C, rapidly providing near-quantitative radiochemical yields at very low chelator concentrations. NOTP and HBED were only slightly less effective under these conditions. In competition studies with all other chelators, THP demonstrated highest reactivity for 68Ga3+ complexation under all conditions. These data point to THP possessing ideal properties for rapid, one-step kit-based syntheses of 68Ga-biomolecules for molecular PET imaging. LC-MS and 1H, 13C{1H} and 71Ga NMR studies of HBED complexes of Ga3+ showed that under the analytical conditions employed in this study, multiple HBED-bound Ga complexes exist. X-ray diffraction data indicated that crystals isolated from these solutions contained octahedral [Ga(HBED)(H2O)], with HBED coordinated in a pentadentate N2O3 mode, with only one phenolic group coordinated to Ga3+, and the remaining coordination site occupied by a water molecule.

Radiolabeled Rhein as Small-Molecule Necrosis Avid Agents for Imaging of Necrotic Myocardium.

A rapid and accurate identification of necrotic myocardium is of great importance for diagnosis, risk stratification, clinical decision-making, and prognosis evaluation of myocardial infarction. Here, we explored technetium-99m labeled rhein derivatives for rapid imaging of the necrotic myocardium. Three hydrazinonicotinic acid-linker-rhein (HYNIC-linker-rhein) derivatives were synthesized, and then, these synthetic compounds were labeled with technetium-99m using ethylenediaminediacetic acid (EDDA) and tricine as coligands [99mTc(EDDA)-HYNIC-linker-rhein]. The necrosis avidity of the three 99mTc-labeled rhein derivatives was tested in a mouse model of ethanol-induced muscular necrosis by gamma counting, histochemical staining, and autoradiography. A lead tracer for visualization of necrotic myocardium was assessed by single photon emission computed tomography/computed tomography (SPECT/CT) imaging in a rat model with reperfused myocardial infarction. The necrosis avidity mechanism of the tracer was explored by DNA binding studies in vitro and blocking experiments in vivo. Results showed that the uptake in necrotic muscles of the three 99mTc-compounds was higher than that in viable muscles (P < 0.001). Autoradiography and histochemical staining results were consistent with selective uptake of the radiotracer in the necrotic regions. Among the these tracers, 99mTc(EDDA)-HYNIC-ethylenediamine-rhein [99mTc(EDDA)-HYNIC-2C-rhein] displayed the best distribution profiles for imaging. The necrotic myocardium lesions were clearly visualized by SPECT/CT using 99mTc(EDDA)-HYNIC-2C-rhein at 1 h after injection. The necrotic-to-viable myocardium and necrotic myocardium-to-blood uptake ratios of 99mTc(EDDA)-HYNIC-2C-rhein were 4.79 and 3.02 at 1 h after injection. DNA binding studies suggested HYNIC-linker-rhein bound to DNA through intercalation. The uptake of 99mTc(EDDA)-HYNIC-2C-rhein in necrotic muscle was significantly blocked by excessive unlabeled rhein, with 77.61% decline at 1 h after coinjection. These findings suggested 99mTc(EDDA)-HYNIC-2C-rhein emerged as a "hot spot" imaging probe that has a potential for rapid imaging of necrotic myocardium. The necrosis avidity mechanism of 99mTc(EDDA)-HYNIC-linker-rhein may be due to its interaction with exposed DNA in necrotic tissues.

Introduction of an 8-aminooctanoic acid linker enhances uptake of 99mTc-labeled lactam bridge-cyclized α-MSH peptide in melanoma.

The purpose of this study was to examine the effects of amino acid, hydrocarbon, and polyethylene glycol (PEG) linkers on the melanoma targeting and imaging properties of (99m)Tc-labeled lactam bridge-cyclized HYNIC-linker-Nle-CycMSHhex (hydrazinonicotinamide-linker-Nle-c[Asp-His-DPhe-Arg-Trp-Lys]-CONH2) peptides. Four novel peptides (HYNIC-GGGNle-CycMSHhex, HYNIC-GSGNle-CycMSHhex, HYNIC-PEG2Nle-CycMSHhex, and HYNIC-AocNle-CycMSHhex) were designed and synthesized. The melanocortin-1 receptor binding affinities of the peptides were determined in B16/F1 melanoma cells. The biodistribution of (99m)Tc(ethylenediaminediacetic acid [EDDA])-HYNIC-GGGNle-CycMSHhex, (99m)Tc(EDDA)-HYNIC-GSGNle-CycMSHhex, (99m)Tc(EDDA)-HYNIC-PEG2Nle-CycMSHhex, and (99m)Tc(EDDA)-HYNIC-AocNle-CycMSHhex were determined in B16/F1 melanoma-bearing C57 mice at 2 h after injection to select a lead peptide for further evaluation. The melanoma targeting and imaging properties of (99m)Tc(EDDA)-HYNIC-AocNle-CycMSHhex were further examined because of its high melanoma uptake. The inhibitory concentrations of 50% (IC50) for HYNIC-GGGNle-CycMSHhex, HYNIC-GSGNle-CycMSHhex, HYNIC-PEG2Nle-CycMSHhex, and HYNIC-AocNle-CycMSHhex were 0.7 ± 0.1, 0.8 ± 0.09, 0.4 ± 0.08, and 0.3 ± 0.06 nM, respectively, in B16/F1 melanoma cells. Among these four (99m)Tc-labeled peptides, (99m)Tc(EDDA)-HYNIC-AocNle-CycMSHhex displayed the highest melanoma uptake (22.3 ± 1.72 percentage injected dose/g) at 2 h after injection. (99m)Tc(EDDA)-HYNIC-AocNle-CycMSHhex exhibited high tumor-to-normal-organ uptake ratios except for the kidneys. The tumor-to-kidney uptake ratios of (99m)Tc(EDDA)-HYNIC-AocNle-CycMSHhex were 3.29, 3.63, and 6.78 at 2, 4, and 24 h, respectively, after injection. The melanoma lesions were clearly visualized by SPECT/CT using (99m)Tc(EDDA)-HYNIC-AocNle-CycMSHhex as an imaging probe at 2 h after injection. High melanoma uptake and fast urinary clearance of (99m)Tc(EDDA)-HYNIC-AocNle-CycMSHhex highlighted its potential for metastatic melanoma detection in the future.

Structural Basis for Allosteric Coupling at the Membrane-Protein Interface in Gloeobacter violaceus Ligand-gated Ion Channel (GLIC)

Ligand binding at the extracellular domain of pentameric ligand-gated ion channels initiates a relay of conformational changes that culminates at the gate within the transmembrane domain. The interface between the two domains is a key structural entity that governs gating. Molecular events in signal transduction at the interface are poorly defined because of its intrinsically dynamic nature combined with functional modulation by membrane lipid and water vestibules. Here we used electron paramagnetic resonance spectroscopy to delineate protein motions underlying Gloeobacter violaceus ligand-gated ion channel gating in a membrane environment and report the interface conformation in the closed and the desensitized states. Extensive intrasubunit interactions were observed in the closed state that are weakened upon desensitization and replaced by newer intersubunit contacts. Gating involves major rearrangements of the interfacial loops, accompanied by reorganization of the protein-lipid-water interface. These structural changes may serve as targets for modulation of gating by lipids, alcohols, and amphipathic drug molecules.

Ethylenediaminediacetic acid bis(carbido amide chitosan): Synthesis and evaluation as solid carrier to fabricate nanoemulsion

We have optimized the synthesis of spray dried ethylenediaminediacetic acid bis(carbido amide chitosan) (ED-chitosan) microparticles employing 32 full factorial design. The ED-chitosan microparticles were characterized using FTIR-ATR, DSC analysis, oil adsorbing capacity, oil desorbing capacity, surface free energy and dynamic advancing contact angle. The ED-chitosan microparticles were found to have enhanced dispersive component of surface free energy as compared to Aerosil 200. However, they showed lower polar component. This was associated with similar oil adsorbing capacity but higher desorbing capacity. The SEM analysis supported ability of ED-chitosan microparticles to completely spread lipophillic drug over its surface. The reconstituted nanoemulsion generated from ED-chitosan was stable (neutral zeta potential), spherical shaped and 110nm size (TEM analysis). Further, these nanoemulsions when prepared with primaquine were successfully enhanced in vitro dissolution and its ex vivo performance. Thus, the study showed new possibilities of industrial acceptance of ED-chitosan microparticles as a solid carrier for the fabrication of nanoemulsion.

In vitro evaluation of 99mTc-EDDA/tricine-HYNIC-Q-Litorin in gastrin-releasing peptide receptor positive tumor cell lines

Bombesin and its derivatives exhibit a high affinity for gastrin-releasing peptide receptor (GRPr), which is over-expressed in a variety of human cancers (prostate, pancreatic, lung, etc.). The aim of this study was to investigate the in vitro potential of the hydrazinonicotinamide (HYNIC)-Q-Litorin. 99mTc labeling was performed by using different co-ligands: tricine and ethylenediamine diacetic acid (EDDA). The radiochemical stability of radiolabeled peptide conjugates was checked at room temperature and in cysteine solution up to 24 h. The in vitro cell uptake of 99mTc-EDDA-HYNIC-Q-Litorin and 99mTc-tricine-HYNIC-Q-Litorin were evaluated on pancreatic tumor and control cell lines. Optimum specific activity and incubation time were determined for all the cell lines. The results showed that the cell uptake of the radiolabeled peptide conjugates in tumor cell lines were higher than in the control cell line. The findings of this study indicated the need for further development of in vivo study as a radiopharmaceutical for pancreatic tumor imaging.

The DNA binding site specificity and antiproliferative property of ternary Pt(ii) and Zn(ii) complexes of phenanthroline and N,N′-ethylenediaminediacetic acid

The binding site specificity of the ternary complexes, [M(II)(phen)(edda)] (M(II) = Pt(2+) and Zn(2+); phen = 1,10-phenanthroline; edda = N,N'-ethylenediaminediacetic acid), for the self-complementary oligonucleotides (ODNs), ds(C(1)G(2)C(3)G(4)A(5)A(6)T(7)T(8)C(9)G(10)C(11)G(12))(2) (ODN1) and ds(C(1)G(2)C(3)G(4)T(5)A(6)T(7)A(8)C(9)G(10)C(11)G(12))(2) (ODN2), was studied by NMR measurements. The results indicated that [Pt(ii)(phen)(edda)] was partially intercalated between C(3)/G(10) and G(4)/C(9) base pairs of ODN1 and ODN2 in the major grooves, whereas [Zn(II)(phen)(edda)] was bound specifically to the TATA region of ODN2 in the minor groove and to the terminal G(2)/C(11) base pair of ODN1 in the major groove. The preference for the TATA sequence over the AATT sequence in the binding of [Zn(phen)(edda)] was attributed to the wider minor groove width of the TATA sequence. The bindings of the complexes to ct-DNA were also studied by UV, CD, and fluorescence spectroscopy. Additionally, the antiproliferative property of [Pt(II)(phen)(edda)] towards MCF7 breast cancer cells and normal MCF10-A cells was compared with that of [Zn(II)(phen)(edda)].

Remobilization of 60Co, 85Sr, 137Cs, 152Eu, and 241Am from a Contaminated Soil Column by Groundwater and Organic Ligands

The desorption rate of 60Co, 85Sr, 137Cs, 152Eu, and 241Am from soil collected from Inshas disposal site in Egypt was investigated to understand the desorption and mobility of these radionuclides in the environment. Effect of a synthetic groundwater (GW) and the GW amended to 2 × 10−5M of ethylenediaminetetraacetic acid (EDTA) or ethylenediaminediacetic acid (EDDA), GW+ETDA and GW+EDDA, respectively, was studied in flow-through experiments. These experiments were designed to compare the influence of EDTA relative to one of its degradation products that can exist in natural water, EDDA. First-order desorption and two-site first-order desorption equations were used to describe the time-dependent desorption data. The desorption rate for 85Sr and 137Cs was high in the first 50 h followed by a slow release suggesting that two different mechanisms involved. The trace metal removal was not completely reversible for all radionuclides tracers except for 85Sr. The quantity of 85Sr, 137Cs, 152Eu, and 241Am desorbed from soil follows the order GW+EDTA > GW+EDDA > GW, while 60Co gives unexpected trends where the effect of EDDA is twice as high as that of EDTA. This behavior was discussed based on the aqueous species distribution of 60Co in both aqueous solutions.

Preparation of a New Polystyrene Supported-Ethylenediaminediacetic Acid Resin and its Sorption Behavior toward Divalent Metal Ions

A new polystyrene-supported ethylenediaminediacetic acid resin has been synthesized through a reaction between the amination of the commercially available 4-chloromethyl polystyrene polymer with ethylenediamine and the subsequent carboxymethylation with monobromoacetic acid, using ethylenediamine as spacer. The chelation behavior of this resin toward the divalent metal ions Cu2+, Ni2+, Zn2+, and Pb2+ in aqueous solutions was investigated. Batch equilibration experiments were carried out as a function of contact time, pH, amount of metal-ion, and polymer mass. The amount of metal-ion uptake of the polymer was determined by using atomic absorption spectrometry (AAS). Results of the investigation revealed that the resin exhibited higher capacities and a more pronounced adsorption toward Cu2+ and that the metal-ion uptake follows the order: Cu2+ > Zn2+ > Ni2+ > Pb2+. The adsorption and binding capacity of the resin toward the various metal ions investigated are discussed.

Phase-Separation and Domain-Formation in Cholesterol-Sphingomyelin Mixture: Pulse-EPR Oxygen Probing

Membranes made of Chol/ESM (cholesterol/egg sphingomyelin) mixtures were investigated using saturation-recovery electron paramagnetic resonance spin-labeling methods, in which bimolecular collisions of relaxation agents (oxygen or nickel ethylenediamine diacetic acid) with spin labels are measured. Liquid-disordered (ld) and liquid-ordered (lo) phases, and cholesterol bilayer domains (CBDs) were discriminated and characterized by profiles of the oxygen transport parameter (OTP). In the ld phase, coexisting with the lo phase, the OTP profile is bell-shaped and lies above that in the pure ESM membrane. Changes in the OTP profile across the lo phase are complex. When the lo phase coexists with the ld phase, the OTP profile is similar to that across the pure ESM membrane but with a steeper bell shape. With an increase in cholesterol concentration (up to the cholesterol-solubility threshold), the profile becomes rectangular, with low OTP values from the membrane surface to the depth of C9, and high values in the membrane center. This approximately threefold increase in the OTP occurs at the depth at which the rigid ring structure of cholesterol is immersed. Further addition of cholesterol and the formation of the CBD does not affect the OTP profile across the lo phase. OTP values in the CBD are significantly lower than in the lo phase.

Speciation of cobalt, nickel and zinc-ethylenediaminediacetate complexes with N-heterocycle ligand – Synthesis, spectroscopic and structural studies

Cobalt, nickel and zinc N-heterocycle chelated ethylenediaminediacetates [Co(edda)(phen)]·(NH 4Cl)·1/3H 2O ( 1), [Ni(edda)(phen)]·3H 2O ( 2), [Co(edda)(bpy)]·(NH 4Cl)·2H 2O ( 3), [Ni(edda)(bpy)]·4H 2O ( 4), [Zn(edda)(bpy)]·4H 2O ( 5) (H 2edda = ethylenediaminediacetic acid, phen = 1,10-phenanthroline, bpy = 2,2′-bipyridine) were isolated in pure forms and characterized spectroscopically. The X-ray structural analyses reveal that neutral mononuclear complexes contain both edda and phen/bpy ligands. Divalent metal ions are octahedrally bound by a bidentate phen or bpy ligand, and a tetradentately edda through carboxyl and amine groups. The co-existences of phen/bpy and edda in the complexes show no decomposition between phen/bpy and edda ligands. This is supported by the trace of 13C NMR spectra with less-bound zinc complex. Further comparisons of the bond distances between Co 2+/Ni 2+/Zn 2+ ions with edda indicate that cobalt and nickel interact much stronger than those of zinc complexes.

Structure of Apolipoprotein A-I N Terminus on Nascent High Density Lipoproteins

Apolipoprotein A-I (apoA-I) is the major protein component of high density lipoproteins (HDL) and a critical element of cholesterol metabolism. To better elucidate the role of the apoA-I structure-function in cholesterol metabolism, the conformation of the apoA-I N terminus (residues 6-98) on nascent HDL was examined by electron paramagnetic resonance (EPR) spectroscopic analysis. A series of 93 apoA-I variants bearing single nitroxide spin label at positions 6-98 was reconstituted onto 9.6-nm HDL particles (rHDL). These particles were subjected to EPR spectral analysis, measuring regional flexibility and side chain solvent accessibility. Secondary structure was elucidated from side-chain mobility and molecular accessibility, wherein two major α-helical domains were localized to residues 6-34 and 50-98. We identified an unstructured segment (residues 35-39) and a β-strand (residues 40-49) between the two helices. Residues 14, 19, 34, 37, 41, and 58 were examined by EPR on 7.8, 8.4, and 9.6 nm rHDL to assess the effect of particle size on the N-terminal structure. Residues 14, 19, and 58 showed no significant rHDL size-dependent spectral or accessibility differences, whereas residues 34, 37, and 41 displayed moderate spectral changes along with substantial rHDL size-dependent differences in molecular accessibility. We have elucidated the secondary structure of the N-terminal domain of apoA-I on 9.6 nm rHDL (residues 6-98) and identified residues in this region that are affected by particle size. We conclude that the inter-helical segment (residues 35-49) plays a role in the adaptation of apoA-I to the particle size of HDL.

Mobility of radionuclides in soil/groundwater system: Comparing the influence of EDTA and four of its degradation products

The adsorption behavior of 241Am, 60Co, 137Cs and 85Sr in the presence and absence of chelating ligands (ethylenediaminetetraacetic acid, ethylenediaminediacetic acid, hydroxyethyliminodiacetic acid, iminodiaceiticacid and methyliminodiacetic acid) was investigated. Sorption affinity in the absence of chelating ligands followed: Am(III) > Co(II) > Cs(I) > Sr(II). The presence of chelating ligands generally had little effect on sorption of 85Sr and 137Cs with K d values 110 and 690 mL g −1, respectively. But at 0.02 M of ethylenediaminetetraacetic or hydroxyethyliminodiacetic, the K d decreased to 5 or 63 mL g −1, respectively, where thermochemical modeling indicated almost all 85Sr is complexed with these ligands. The K d values for 241Am and 60Co generally decreased with increasing chelating agent concentrations. In notable cases, the K d values for Am increased at specific concentrations of 10 −3 M for IDA, MIDA and 10 −4 M for EDDA. This is proposed to be due to formation of a ternary surface complex.

Ferric iron complexes of dopamine and 5,6-dihydroxyindole with nta, edda, and edta as ancillary ligands

Coordination of the neurotransmitter dopamine (DA) and the metal-binding component of neuromelanin 5,6-dihydroxyindole (DHI) with ferric iron has been studied in aqueous solution in the presence of ancillary ligands containing amine nitrogen and carboxylate oxygen donor sites. With nitrilotriacetic acid (nta) and ethylenediamine diacetic acid (edda) coligands, coordination of the catecholate ligands DA and DHI is observed to be complete at physiological pH. The resulting complexes of DA have the characteristic two-component electronic spectrum observed characteristically for L 4Fe(Cat) complexes. The spectrum obtained with DHI consists of a single broad absorption in the visible region. Both DA and DHI are able to coordinate with Fe 3+ in the presence of edta, displacing carboxylate oxygen donors at pH values just above physiological pH. These results demonstrate the strong affinity of DA and DHI for Fe 3+, pointing to in vivo complex formation in neuronal mixtures at physiological pH.