Lanthanum

The proposed method for ascorbic acid: AA (Vitamin C) determination is based on the oxidation of AA to dehydroascorbic acid with the CUPRAC reagent of total antioxidant capacity assay, i.e., Cu(II)-neocuproine (Nc), in ammonium acetate-containing medium at pH 7, where the absorbance of the formed bis(Nc)-copper(I) chelate is measured at 450 nm. The flavonoids (essentially flavones and flavonols) normally interfering with the CUPRAC procedure were separated with preliminary extraction as their La(III) chelates into ethylacetate (EtAc). The Cu(I)-Nc chelate responsible for color development was formed immediately with AA oxidation. Beer's law was obeyed between 8.0 × 10 −6 and 8.0 × 10 −5 M concentration range, with the equation of the linear calibration curve: A 450 nm = 1.60 × 10 4 C (mol dm −3 ) − 0.0596. The relative standard deviation (R.S.D.) in the analysis of N = 45 synthetic mixtures containing 1.25 × 10 −2 mM AA with flavonoids was 5.3%. The Cu(II)-Nc reagent is a lower redox-potential and therefore more selective oxidant than the Fe(III)-1,10-phenanthroline reagent conventionally used for the same assay. This feature makes the proposed method superior for real samples such as fruit juices containing weak reductants such as citrate, oxalate and tartarate that may otherwise produce positive errors in the Fe(III)-phen method when equilibrium is achieved. The developed method was applied to some commercial fruit juices and pharmaceutical preparations containing Vitamin C + bioflavonoids. The findings of the developed method for fruit juices and pharmaceuticals were statistically alike with those of HPLC. The proposed spectrophotometric method was practical, low-cost, rapid, and could reliably assay AA in the presence of flavonoids without enzymatic procedures open to interferences by enzyme inhibitors.

journal homepage: www.else vier.com/locate /wa tres w a t e r r e s e a r c h 4 7 ( 2 0 1 3 ) 5 9 3 0 e5 9 4 2 0043-1354/$ e see front matter ª 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.watres.2013.07.016 to predict concentrations of La 3þ ions and the potential for negative ecological impacts.

The determination of calcium in biologic fluids by atomic absorption spectrophotometry is interfered with by the presence of protein, cations, and those anions that form complexes with calcium. Such interference was overcome when lanthanum was included in a 1:50 dilution of serum or urine. Recovery of calcium added to calciumfree serum was 100%. The S.D. based on double-blind duplicates was 0.22 mg./lOO ml. Excellent statistical agreement was found between the test method and each of the 2 reference methods.

Background: Phosphate binders are commonly used in tablet form to help patients with hyperphosphatemia limit their absorption of dietary phosphate. These patients frequently have a heavy tablet burden so alternative formulations provide choice and may support adherence. Lanthanum carbonate (LC) is a phosphate binder currently available as a chewable tablet. This study was conducted to support an application for marketing authorization for the oral powder formulation within the European Union.

Caveolin-3, a muscle specific caveolin-related protein, is the principal structural protein of caveolar membranes. We have recently identified an autosomal dominant form of limb girdle muscular dystrophy (LGMD-1C) that is due to caveolin-3 deficiency and caveolin-3 gene mutations. Here, we studied by electron microscopy, including freeze-fracture and lanthanum staining, the distribution of caveolae and the organization of the T-tubule system in caveolin-3 deficient human muscle fibers. We found a severe impairment of caveolae formation at the muscle cell surface, demonstrating that caveolin-3 is essential for the formation and organization of caveolae in muscle fibers. In addition, we also detected a striking disorganization of the T-system openings at the subsarcolemmal level in LGMD-1C muscle fibers. These observations provide new perspectives in our understanding of the role of caveolin-3 in muscle and of the pathogenesis of muscle weakness in caveolin-3 deficient muscle.

A 'critical metal' is one that has important economic uses, but which also faces supply risks for geopolitical or environmental and sustainability reasons. The constrained nature of critical metals supply means proposed solutions to the problem commonly involve reducing demand and therefore reliance, via recycling, substitution and thrifting. However, most critical metals are presently only small markets and therefore such an approach ignores the potential of transformational market growth to reduce supply risk, by creating large, diverse, transparent markets with multiple sources of primary mine supply, akin to modern base metals markets. Research is therefore required into which critical metals have the greatest potential for such transformational market growth. This study therefore conducts an evaluation of 49 critical metals to determine which are nearest to the combined breakthroughs in discovery, supply and demand that may lead to transformational market growth. The study concludes that 13 markets from the 49 critical metals, being magnesium, silicon, barium, boron, lithium, cobalt, chromium, vanadium, gallium, strontium, cerium, lanthanum and scandium have the highest potential for transformational market growth and thus efforts to resolve supply risk in these markets may be better focussed on overcoming current market constraints and growing these markets, rather than lessening reliance by reducing demand.

A macrocyclic hydrazone Schiff base was synthesized by reacting 1,4-dicarbonyl phenyl dihydrazide with 2,6-diformyl-4-methyl phenol and a series of metal complexes with this new Schiff base were synthesized by reaction with Co(II), Ni(II) and Cu(II) metal salts. The Schiff base and its complexes have been characterized by elemental analyses, IR, 1 H NMR, UV-vis, FAB mass, ESR spectra, fluorescence, thermal, magnetic and molar conductance data. The analytical data reveal that the Co(II), Ni(II) and Cu(II) complexes possess 2:1 metal-ligand ratios. All the complexes are non-electrolytes in DMF and DMSO due to their low molar conductance values. Infrared spectral data suggest that the hydrazone Schiff base behaves as a hexadentate ligand with NON NON donor sequence towards the metal ions. The ESR spectral data shows that the metal-ligand bond has considerable covalent character. The electrochemical behavior of the copper(II) complex was investigated by cyclic voltammetry. The Schiff base and its complexes have also been screened for their antibacterial (Escherichia coli, Staphylococcus aureus, Shigella dysentery, Micrococcus, Bacillus subtilis, Bacillus cereus and Pseudomonas aeruginosa) and antifungal activities (Aspergillus niger, Penicillium and Candida albicans) by MIC method. The brine shrimp bioassay was also carried out to study their in-vitro cytotoxic properties.

The role of the L-type calcium channel (Cav1.2) as a molecular switch that triggers secretion prior to Ca 2؉ transport has previously been demonstrated in bovine chromaffin cells and rat pancreatic beta cells. Here, we examined the effect of specific Cav1.2 allosteric modulators, BayK 8644 (BayK) and FPL64176 (FPL), on the kinetics of catecholamine release, as monitored by amperometry in single bovine chromaffin cells. We show that 2 M BayK or 0.5 M FPL accelerates the rate of catecholamine secretion to a similar extent in the presence either of the permeable Ca 2؉ and Ba 2؉ or the impermeable charge carrier La 3؉ . These results suggest that structural rearrangements generated through the binding of BayK or FPL, by altering the channel activity, could affect depolarization-evoked secretion prior to cation transport. FPL also accelerated the rate of secretion mediated by a Ca 2؉ -impermeable channel made by replacing the wild type ␣ 1 1.2 subunit was replaced with the mutant ␣ 1 1.2/ L775P. Furthermore, BayK and FPL modified the kinetic parameters of the fusion pore formation, which represent the initial contact between the vesicle lumen and the extracellular medium. A direct link between the channel activity and evoked secretion lends additional support to the view that the voltagegated Ca 2؉ channels act as a signaling molecular switch, triggering secretion upstream to ion transport into the cell. . 2 The abbreviations used are: VGCC, voltage-gated Ca 2ϩ channel; BayK 8644, 1,4-dihydro-2,6-dimethyl-5-nitro-4-[2(trifluoromethyl)phenyl]pyridine-3carboxylic acid methyl ester; FPL64176, (FPL) 2,5-dimethyl-4-[2-(phenylmethyl)benzoyl]-1H-pyrrole-3-carboxylic acid methyl ester; WT, wild type.

The strong increase in the consumption of rare earth elements (REE) in high-tech products and processes is accompanied by increasing amounts of REE released into the environment. Following the first report of Gd contamination of the hydrosphere in 1996, anthropogenic Gd originating from contrast agents has now been reported worldwide from river and estuarine waters, coastal seawater, groundwater and tap water. Recently, microcontamination with La, that is derived from a point source where catalysts for petroleum refining are produced, has been detected in the Rhine River in Germany and the Netherlands. Here we report the occurrence of yet another REE microcontamination of river water: in addition to anthropogenic Gd and La, the Rhine River now also shows significant amounts of anthropogenic Sm. The anthropogenic Sm, which enters the Rhine River north of Worms, Germany, with the same industrial wastewater that carries the anthropogenic La, can be traced through the Middle and Lower Rhine to the Netherlands. At Leverkusen, Germany, some 250 km downstream from the point source at Worms, anthropogenic Sm still contributes up to 87% of the total dissolved Sm concentration of the Rhine River. Results from ultrafiltration suggest that while the anthropogenic Gd is not particle-reactive and hence exclusively present in the truly dissolved REE pool (o10 kDa), the anthropogenic La and Sm are also present in the colloidal/nanoparticulate REE pool (between 10 kDa and 0.2 mm). Though difficult to quantify, our data suggest that the Rhine River may carry up to 5700 kg of anthropogenic La, up to 584 kg of anthropogenic Sm, and up to 730 kg of anthropogenic Gd per year toward the North Sea. There exist no regulatory limits for dissolved REE in natural waters, but total REE and Y (PREY) concentrations of up to 0.14 mg/kg in the plume downstream of and 52.2 mg/kg at the head of an effluent pipe at Rhine-km 447.3 at Worms get close to and well-above, respectively, the levels at which ecotoxicological effects have been documented. Because of the increasing use of REE and other formerly ‘‘exotic’’ trace elements in high-tech applications, these critical metals have now become emerging contaminants that should be monitored, and it appears that studies of their biogeochemical behavior in natural freshwaters might soon no longer be possible.

Low resistance junctions between axons of crayfish ganglia are studied by freeze-fracture and negative staining. In freeze-fracture, fracture planes that go through a junctional membrane expose two faces, both internal, called face A and face B. Face A belongs to the internal membrane leaflet and faces the gap. Face B belongs to the external membrane leaflet and faces the axoplasm. Face A displays pits, 60–100 Å in diameter, arranged in a hexagonal array with a unit cell of ∼200 Å. An ∼25 Å bump is frequently seen at the center of each pit. Some pits are occupied by a globule ∼125 Å in diameter, which displays a central depression ∼25 Å in size. Face B contains globules also arranged in a fairly regular hexagonal pattern. The center-to-center distance between adjacent globules is most frequently ∼200 Å; however, occasionally certain globules are seen separated by a distance as short as ∼125 Å. The top surface of the globules occasionally displays a starlike profile and seems ...

1 Several cations (Ba2+, Cd2+, Co2+, Cu2+, Mn2+, Ni2 + Zn2+ and La3+, all as chloride salts, 1-10001iM) were tested in the guinea-pig urinary bladder for their ability to: (i) modify contractile responses to electrical field stimulation (EFS), ATP, a,-methylene ATP (xP-meATP), carbachol (CCh), and KCl; (ii) affect ecto-ATPase activity. 2 Ba2+ (10-1000 iM) concentration-dependently potentiated contractile responses evoked by EFS (4-16 Hz), ATP (100 JM), a,,B-meATP (1 JM), CCh (0.5 JIM), and KCl (30 mM). Ni2+ at concentrations of 1-100 IM also potentiated contractility of the urinary bladder, but at concentrations tested its effect was not concentration-dependent. Cu2+ at a concentration of 10 JM and Cd2+ at a concentration of 1 JIM potentiated responses to all stimuli, except KC1. Ni2+ at a concentration of 1000 JIM and Cd2+ at a concentration of 100 JM inhibited contractions evoked by all stimuli, and at a concentration of 1000 JIM Cd2+ abolished any contractions. Responses to ATP and ap-meATP were selectively inhibited by Cu2+, Zn2+ or La3+, each at a concentration of 1 mM.

This study demonstrates the acute toxicity of lanthanum oxide nanoparticles (La 2 O 3 NP) on two sentinel aquatic species, fresh-water microalgae Chlorella sp. and the crustacean Daphnia magna. The morphology, size and charge of the nanoparticles were systematically studied. The algal growth inhibition assay confirmed absence of toxic effects of La 2 O 3 NP on Chlorella sp., even at higher concentration (1000 mg L À1 ) after 72 h exposure. Similarly, no significant toxic effects were observed on D. magna at concentrations of 250 mg L À1 or less, and considerable toxic effects were noted in higher concentrations (effective concentration [EC 50 ] 500 mg L À1 ; lethal dose [LD 50 ] 1000 mg L À1 ). In addition, attachment of La 2 O 3 NP on aquatic species was demonstrated using microscopy analysis. This study proved to be beneficial in understanding acute toxicity in order to provide environmental protection as part of risk assessment strategies.

Before the human cortex is able to process sensory information, young postmitotic neurons must maintain occasional bursts of action-potential firing to attract and keep synaptic contacts, to drive gene expression, and to transition to mature membrane properties. Before birth, human subplate (SP) neurons are spontaneously active, displaying bursts of electrical activity (plateau depolarizations with action potentials). Using whole-cell recordings in acute cortical slices, we investigated the source of this early activity. The spontaneous depolarizations in human SP neurons at midgestation (17-23 gestational weeks) were not completely eliminated by tetrodotoxin-a drug that blocks action potential firing and network activity-or by antagonists of glutamatergic, GABAergic, or glycinergic synaptic transmission. We then turned our focus away from standard chemical synapses to connexinbased gap junctions and hemichannels. PCR and immunohistochemical analysis identified the presence of connexins (Cx26/ Cx32/Cx36) in the human fetal cortex. However, the connexin-positive cells were not found in clusters but, rather, were dispersed in the SP zone. Also, gap junction-permeable dyes did not diffuse to neighboring cells, suggesting that SP neurons were not strongly coupled to other cells at this age. Application of the gap junction and hemichannel inhibitors octanol, flufenamic acid, and carbenoxolone significantly blocked spontaneous activity. The putative hemichannel antagonist lanthanum alone was a potent inhibitor of the spontaneous activity. Together, these data suggest that connexin hemichannels contribute to spontaneous depolarizations in the human fetal cortex during the second trimester of gestation.

Crustacean color change results from the differential translocation of chromatophore pigments, regulated by neurosecretory peptides like red pigment concentrating hormone (RPCH) that, in the red ovarian chromatophores of the freshwater shrimp Macrobrachium olfersi, triggers pigment aggregation via increased cytosolic cGMP and Ca 21 of both smooth endoplasmatic reticulum (SER) and extracellular origin. However, Ca 21 movements during RPCH signaling and the mechanisms that regulate intracellular [Ca 21 ] are enigmatic. We investigate Ca 21 transporters in the chromatophore plasma membrane and Ca 21 movements that occur during RPCH signal transduction. Inhibition of the plasma membrane Ca 21 -ATPase by La 31 and indirect inhibition of the Na 1 /Ca 21 exchanger by ouabain induce pigment aggregation, revealing a role for both in Ca 21 extrusion. Ca 21 channel blockade by La 31 or Cd 21 strongly inhibits slow-phase RPCH-triggered aggregation during which pigments disperse spontaneously. L-type Ca 21 channel blockade by gabapentin markedly reduces rapid-phase translocation velocity; N-or P/Q-type blockade by o-conotoxin MVIIC strongly inhibits RPCH-triggered aggregation and reduces velocity, effects revealing RPCH-signaled influx of extracellular Ca 21 . Plasma membrane depolarization, induced by increasing external K 1 from 5 to 50 mM, produces Ca 21 -dependent pigment aggregation, whereas removal of K 1 from the perfusate causes pigment hyperdispersion, disclosing a clear correlation between membrane depolarization and pigment aggregation; K 1 channel blockade by Ba 21 also partially inhibits RPCH action. We suggest that, during RPCH signal transduction, Ca 21 released from the SER, together with K 1 channel closure, causes chromatophore membrane depolarization, leading to the opening of predominantly N-and/or P/Q-type voltage-gated Ca 21 channels, and a Ca 21 /cGMP cascade, resulting in pigment aggregation.

The role of tight junctions in modulating responses from chorda tympani (taste) and lingual (general sensory) nerves are clarified in regard to their responses to salts. Chorda tympani (CT) responses elicited by organic sodium salts require greater Na + concentrations to elicit the same magnitude of response as NaC1. These data can be understood in terms of the organic anions (compared with C1-) producing larger liquid-junction potentials across tight junctions between taste cells which, in turn, reduces Na + influx into taste cells via amiloride-inhibitable channels. The anion contribution to the CT response to different Na + salts can be eliminated (or enhanced) by voltage clamping the tongue with negative (with respect to the serosal solution) potentials.

Cerium (III), lanthanum (III) and neodymium (III) complexes with 3,3'-benzylidenebis[4-hydroxycoumarin] were synthesized in view of their application as cytotoxic agents. The complexes were characterized by different physicochemical methods: elemental analysis, mass spectrometry, 1H NMR, 13C NMR and IR spectroscopy. The spectra of the complexes were interpreted on the basis of comparison with the spectrum of the free ligand. The vibrational analysis showed that in the complexes the ligand coordinated to the metal ion through both deprotonated hydroxyl groups; however, participation of the carbonyl groups in the coordination to the metal ion was also suggested. The evaluation of the cytotoxic activity of the novel lanthanide complexes on HL-60 myeloid cells revealed that they are potent cytotoxic agents. The cerium complex was found to exhibit superior activity in comparison to the lanthanum and neodymium coordination compounds, the latter being the least active. Our data give us reason to conclude that the newly synthesized lanthanide complexes should be submitted to further more detailed pharmacological and toxicological evaluation.

In this study, intracellular Ca 2 þ was measured as the Fura-2 ratio (R) of fluorescence excited at 340 and 380 nm (F 340 /F 380) in nonpressurized rat mesenteric small arterioles (+ (lumen diameter) 10-25 mm). The response to depolarization using 75 mM KCl was an increase in R from a baseline of 0.9670.01 ([Ca 2 þ ] i B74 nM) to 1.0470.01 (B128 nM) (n ¼ 80). 2 The response to 75 mM K þ was reversibly abolished in Ca 2 þ-free physiological saline solution, whereas phentolamine (10 mM) or tetrodotoxin (1 mM) had no effects. LaCl 3 (200 mM) inhibited 6179% of the response. 3 A [K þ ]-response curve indicated that the Ca 2 þ response was activated between 15 and 25 mM K þ. The data suggest that the Ca 2 þ response was caused by the activation of voltage-dependent Ca 2 þ channels. 4 Mibefradil use dependently inhibited the Ca 2 þ response to 75 mM K þ by 2972% (100 nM), 7377% (1 mM) or 8977% (10 mM). Pimozide (500 nM) use dependently inhibited the Ca 2 þ response by 8571%. 5 Nifedipine (1 mM) inhibited the Ca 2 þ response to 75 mM K þ by 41712%. The response was not inhibited by calciseptine (500 nM), o-agatoxin IVA (100 nM), o-conotoxin MVIIA (500 nM), or SNX-482 (100 nM). 6 Using reverse transcriptase-polymerase chain reaction, it was shown that neither Ca V 2.1a (P-type) nor Ca V 2.1b (Q-type) voltage-dependent Ca 2 þ channels were expressed in mesenteric arterioles, whereas the Ca V 3.1 (T-type) channel was expressed. Furthermore, no amplification products were detected when using specific primers for the b 1b , b 2 , or b 3 auxiliary subunits of high-voltage-activated Ca 2 þ channels. 7 The results suggest that the voltage-dependent Ca 2 þ channel activated by sustained depolarization in mesenteric arterioles does not classify as any of the high-voltage-activated channels (L-, P/Q-, Nor or R-type), but is likely to be a T-type channel. The possibility that the sustained Ca 2 þ influx observed was the result of a T-type window current is discussed.

The APS Journal Legacy Content is the corpus of 100 years of historical scientific research from the American Physiological Society research journals. This package goes back to the first issue of each of the APS journals including the American Journal of Physiology, first published in 1898. The full text scanned images of the printed pages are easily searchable. Downloads quickly in PDF format.

The study of ligand–receptor interactions using high-resolution NMR techniques, namely the saturation transfer difference (STD), is presented for the recognition process between La(III) complexes of 1,4,7,10-tetrakis(carboxymethyl)-1,4,7,10-tetraazacyclododecane monoamide and diethylenetriaminepentaacetic acid bisamide glycoconjugates and the galactose-specific lectin Ricinus communis agglutinin (RCA120). This new class of Gd(III)-based potential targeted MRI contrast agents (CAs), bearing one or two terminal sugar (galactosyl or lactosyl)

The rare earth elements (REEs) are increasingly being used as trace supplements in agriculture. This study measured the acute and chronic toxicity of one REE, lanthanum (La), to Daphnia carinata. The 48-h EC 50 of La to Daphnia was measured in three media of diering composition and hardness. Lanthanum was most toxic to Daphnia in soft tap water (TW) with an acute 48-h EC 50 of 43 lg/l compared with 1180 lg/l in ASTM hard water (ASTM). In the third daphnid growth medium (DW), based on diluted sea water, the acute 48-h EC 50 was 49 lg La/l, however, there was signi®cant precipitation of La in this media. The chronic toxicity of La to Daphnia was measured in the DW and ASTM media. Nominal exposure concentrations were 100, 200, 400, 600, 800, and 1000 lg La/l. Mortality was a more sensitive endpoint than growth or reproduction in both chronic experiments. Very little La was detected in either media after 24 h and the measured concentrations below were estimated by logarithmic mean of nominal and measured values. There was 100% mortality at concentrations P 80 lg La/l (400 lg/l nominal) by day six of the experiment using DW media, but no eect on survival growth or reproduction at lower concentrations. In the ASTM media, La caused signi®cant mortality to Daphnia at concentrations P 39 lg/l (200 lg/l nominal), however, at least one animal survived to the end of the study at each of the tested concentrations. There was no eect of La on growth of surviving daphnids at concentrations 57 lg/l (400 g/l), however, second brood clutch sizes were signi®cantly increased at 30, 39, and 57 lg/l (100, 200, 400 g/l nominal) compared with controls. Lanthanum also caused a delayed maturation in Daphnia. Ó

A biomass agricultural waste material, rice husk (RH) was used for preparation of activated carbon by chemical activation using phosphoric acid. The effect of various factors, e.g. time, pH, initial concentration and temperature of carbon on the adsorption capacity of lanthanum and erbium was quantitatively determined. It was found that the monolayer capacity is 175.4 mg g −1 for La(III) and 250 mg g −1 for Er(III). The calculated activation energy of La(III) adsorption on the activated carbon derived from rice husk was equal to 5.84 kJ/mol while it was 3.6 kJ/mol for Er(III), which confirm that the reaction is mainly particle-diffusion-controlled. The kinetics of sorption was described by a model of a pseudo-secondorder. External diffusion and intra-particular diffusion were examined. The experimental data show that the external diffusion and intra-particular diffusion are significant in the determination of the sorption rate. Therefore, the developed sorbent is considered as a better replacement technology for removal of La(III) and Er(III) ions from aqueous solution due to its low-cost and good efficiency, fast kinetics, as well as easy to handle and thus no or small amount of secondary sludge is obtained in this application.

Abbreviations used in this paper: fMLP, N-formyl L-methionine L-Histologically, analysis of liver biopsy specimens from leucine peptide; HRP, horseradish peroxidase; TJ, tight junction; patients with IBD can show inflammation of portal areas, TNBS, trinitrobenzene sulfonic acid.

We examined ion channels derived from a chloroform extract of isolated, dehydrated rat liver mitochondria. The extraction method was previously used to isolate a channel-forming complex containing poly-3-hydroxybutyrate and calcium polyphosphate from Escherichia coli. This complex is also present in eukaryotic membranes, and is located primarily in mitochondria. Reconstituted channels showed multiple subconductance levels and were voltage-dependent, showing an increased probability of higher conductance states at voltages near zero. In symmetric 150 mM KCl, the maximal conductance of the channel ranged from 350 pS to 750 pS. For voltages .660 mV, conductance fluctuated in the range of ;50-;200 pS. In the presence of a 1:3 gradient of KCl, at pH ¼ 7.4, selectivity periodically switched between different states ranging from weakly anion-selective (V rev ; ÿ15 mV) to ideally cation-selective (V rev ; 129 mV), without a significant change in its conductance. Overall, the diverse, but highly reproducible, channel activity most closely resembled the behavior of the permeability transition pore channel seen in patch-clamp experiments on native mitoplasts. We suggest that the isolated complex may represent the ion-conducting module from the permeability transition pore.

ILs based on the bis(trifluoromethylsulfonyl)imide anion ((CF3SO2)2N-, noted TFSI-) have recently gained a growing of interest because of their hydrophobic character, their superior chemical and thermal stability, their low viscosity, low melting point, high conductivity and high radiolytic stability. All of these criteria are very important for electrodeposition of actinides and lanthanides, known to be very electropositive elements. These TFSI - based ILs have then been selected to study the electrodeposition of neodymium and lanthanum. The work has been focused on the Nd(TFSI)3 and La(TFSI)3 salts, which are very water sensitive. Moreover, the redox properties of both ILs and metallic salts depend on the water content. All experiments have then been carried out in an argon – filled dry box (H2O < 10 ppm ; O2 < 1 ppm).

Optimal phosphate control in dialysis patients is extremely challenging. A growing awareness of the deleterious effect of mineral metabolism imbalances together with the lack of a satisfactory explanation for the exaggerated mortality rate in patients undergoing renal replacement therapy has led to a renewed effort to refine our approach to hyperphosphatemia. However, despite the remarkable improvements in dialysis techniques, phosphate control has not substantially improved. Achieving normo-phosphatemia presents a multitude of practical and scientific challenges related to the optimal target level, cardiovascular health, and drug toxicities. It is the aim of the present review to summarize briefly the controversies associated with currently available phosphate binders, a cornerstone in the current management of hyperphosphatemia.

Rare earth elements (REEs) enriched fertilizers have been commonly used in China since the 1980s, thus inducing a growing concern about their environmental impact in agriculture. In this work, the effect of some light REEs nitrate mixture and La 3+ nitrate on seed germination, seedling growth and antioxidant metabolism in Triticum durum was investigated with the aim of clarifying the potential benefits or damages of REEs on plants. Seed pre-soaking for 8 h with La 3+ and REEs nitrate inhibited seed germination at low concentrations (0.01 mM and 0.1 mM), while pre-soaking for 2 and 4 h already inhibited seed germination when higher concentrations (1 mM and 10 mM) of La 3+ and REEs nitrate were used. La 3+ and REEs nitrate treatment also affected seedling growth. Root growth was enhanced and inhibited at low and high concentrations, respectively. Shoot growth was inhibited by La 3+ and REEs nitrate at all tested concentrations after 12 d of treatments. Enzymatic and non enzymatic antioxidants were differently affected by La 3+ and REEs nitrate and their behaviour changed also depending on the plant organ. In roots La 3+ and REEs nitrate treatments induced an increase in ascorbate (ASC) and glutathione (GSH) contents. In shoots only La 3+ nitrate induced an increase in the ASC content whereas GSH decreased following both La 3+ and REEs nitrate treatments. An increase in ASC peroxidase activity was observed in shoots and roots, while catalase did not change in roots and slightly decreased in shoots. The possible role of the increase in some antioxidants as indicators of stress caused by lanthanide treatments is discussed.

cis,trans-Abscisic acid (ABA) plays an important role in plant growth and development, regulation of seed maturation, germination, and adaptation to environmental stresses. Knowledge of ABA mechanisms of action and the interactions of components required for ABA signal transduction is far from complete. Using transient gene expression in rice protoplasts, we observed additive and inhibitory effects between maize VP1 (Viviparous-1, a transcriptional activator) and a dominant-negative mutant protein phosphatase, ABI1-1 (ABA-insensitive-1-1), from Arabidopsis. Lanthanide ions were shown to be specific agonists of ABA-inducible gene expression and to interact synergistically with ABA and overexpressed VP1. Both VP1 and lanthanum activities could be antagonized by coexpression of ABI1-1, which demonstrates the specific ABA dependence of these effectors on ABA-regulated gene expression. We obtained pharmacological evidence that phospholipase D (PLD) functions in ABA-inducible gene expression in rice. Antagonism of ABA, VP1, and lanthanum synergy by 1-butanol, a specific inhibitor of PLD, was similar to the inhibition by coexpression of ABI1-1. These results demonstrate that ABA, VP1, lanthanum, PLD, and ABI1 are all involved in ABA-regulated gene expression and are consistent with an integrated model whereby La 3؉ acts upstream of PLD.

"Electrospinning process was utilized to fabricate lanthanum doped bismuth ultrafine
nanofibers. PVA was used as precursor polymer solution with bismuth acetate/lanthanum acetate,
followed by calcination at 800oC. The produced nanofibers and calcined crystal structures were
characterized by using scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques.
The results indicated that samples after calcination should be sintered more than one to obtain pure
crystalline phase.
"

Due to increasing use of lanthanides/actinides in nuclear and civil applications, understanding the impact of these metal ions on human health and environment is a growing concern. Hemoglobin (Hb), which occurs in all the kingdom of living organism, is the most abundant protein in human blood. In present study, effect of lanthanides and actinides [thorium: Th(IV), uranium: U(VI), lanthanum: La(III), cerium: Ce(III) and (IV)] on the structure and function of Hb has been investigated. Results showed that these metal ions, except Ce(IV) interacted with carbonyl and amide groups of Hb, which resulted in the loss of its alpha-helix conformation. However, beyond 75μM, these ions affected heme moiety. Metal-heme interaction was found to affect oxygen-binding of Hb, which seems to be governed by their closeness with the charge-to-ionic-radius ratio of iron(III). Consistently, Ce(IV) being closest to iron(III), exhibited a greater effect on heme. Binding constant and binding stoichiometry of...

The role of tight junctions in modulating responses from chorda tympani (taste) and lingual (general sensory) nerves are clarified in regard to their responses to salts. Chorda tympani (CT) responses elicited by organic sodium salts require greater Na + concentrations to elicit the same magnitude of response as NaC1. These data can be understood in terms of the organic anions (compared with C1-) producing larger liquid-junction potentials across tight junctions between taste cells which, in turn, reduces Na + influx into taste cells via amiloride-inhibitable channels. The anion contribution to the CT response to different Na + salts can be eliminated (or enhanced) by voltage clamping the tongue with negative (with respect to the serosal solution) potentials. Whole nerve recordings from the lingual branch of the trigeminal nerve elicited by NaC1 (and other salts) were reversibly inhibited by the tight junction blocker, LaCI3. These data suggest that small hydrophilic molecules elicit responses from trigeminal fibers by diffusing across tight junctions between epithelial cells and altering the composition of the extracellular space.

We investigated implications of nanostructure formation on structural and magnetotransport properties of La 0 7 Sr 0 3 MnO 3 compound. The polycrystalline nanomaterials of variable grain sizes were synthesized by using sol-gel method. The structural parameters obtained by Rietveld refinement of the X-ray diffraction data indicated that the samples possess perovskite structure with orthorhombic Pnma symmetry. The X-ray Photoemission Spectra showed chemical shift in the lowest particle size sample due to oxygen deficiency. The average particle size observed through transmission electron microscopy varied from 22 nm to 34 nm. The particle size induced metal-insulator transition and substantial increase in electrical resistivity observed in these nanomaterials are in contrast with the bulk material phase diagram. We also observed temperature and magnetic field dependent colossal magnetoresistance. The low-field magnetoresistance is substantially enhanced in nanomaterials samples, making it more promising for device applications. A divergence in field cooled and zero field cooled magnetization indicated possibility of magnetic spin-glass behavior.

Whether activation of the calcium receptor (CaR) modulates secretory events was investigated by real-time fluorescence and confocal microscopy using fura 2 and FM1-43 fluorescent dye. Two paradigms were used : human parathyroid cells, which are stimulated by a step from a high to a low extracellular calcium concentration ([Ca# + ] ext ), and rMTC6-23 cells, a rat medullary thyroid carcinoma cell line whose secretion is stimulated by an increase in [Ca# + ] ext . Parathyroid cells were dispersed from parathyroid adenomas removed from 18 patients with primary hyperparathyroidism. In both cell types, incubation with FM1-43 (2 µM) resulted in staining of the plasma membranes, which was rapidly increased following changes in [Ca# + ] ext known to stimulate secretion. A high [Ca# + ] ext and lanthanum (La$ + ) decreased the membrane-associated FM1-43 fluorescence. Prolonged incubation (5-30 min) in the presence of FM1-43 resulted in accumulation of the dye in the cytoplasm, its granular distribution suggesting targeting of the secretory compartment. These data suggest that FM1-43 fluorescence is determined by :

Al-resistant (alr) mutants of Arabidopsis thaliana were isolated and characterized to gain a better understanding of the genetic and physiological mechanisms of Al resistance. alr mutants were identified on the basis of enhanced root growth in the presence of levels of Al that strongly inhibited root growth in wild-type seedlings. Genetic analysis of the alr mutants showed that Al resistance was semidominant, and chromosome mapping of the mutants with microsatellite and random amplified polymorphic DNA markers indicated that the mutants mapped to two sites in the Arabidopsis genome: one locus on chromosome 1 (alr-108, alr-128, alr-131, and alr-139) and another on chromosome 4 (alr-104). Al accumulation in roots of mutant seedlings was studied by staining with the fluorescent Al-indicator dye morin and quantified via inductively coupled argon plasma mass spectrometry. It was found that the alr mutants accumulated lower levels of Al in the root tips compared with wild type. The possibility that the mutants released Alchelating organic acids was examined. The mutants that mapped together on chromosome 1 released greater amounts of citrate or malate (as well as pyruvate) compared with wild type, suggesting that Al exclusion from roots of these alr mutants results from enhanced organic acid exudation. Roots of alr-104, on the other hand, did not exhibit increased release of malate or citrate, but did alkalinize the rhizosphere to a greater extent than wild-type roots. A detailed examination of Al resistance in this mutant is described in an accompanying paper J. Degenhardt, P.B. Larsen, S.H. Howell, L.V. Kochian [1998] Plant Physiol 117: 19-27). ; fax 1-607-255-2459. Abbreviations: EMS, ethyl methylsulfonate; ICP-MS, inductively coupled argon plasma MS; RAPD, random amplified polymorphic DNA.

Salicylaldehyde 2-phenylquinoline-4-carboylhydrazone (H 2 L), and its novel copper(II), cobalt(II), and nickel(II) complexes MHL Á Cl Á nH 2 O [M=Cu n = 3 (1), M=Co n = 2 (2), M=Ni n = 3.5 (3)] have been synthesized and characterized by elemental analysis, molar conductivity, spectroscopic, and thermal analysis. The interaction of these complexes with calf thymus DNA was investigated by UV absorption spectroscopy, fluorescence spectroscopy, cyclic voltammetry, and viscosity measurements. The results suggest that these complexes bind to DNA via an intercalation binding mode and their affinity to DNA follows the order of 3 [ 1[ 2.

The objective of these studies was to define the roles of calcium and sodium in uterine smooth muscle excitation. The double sucrose-gap technique was used for current-clamp and voltage-clamp experiments. It was shown that neither sodium nor calcium alone is capable of supporting excitation in estrogen-dominated uterine smooth muscle. Calcium dependence was explained in part by increased membrane "leakage" current in calcium-free solution and calcium control of the voltage dependence of the early transient conductance. High concentrations of TTX did not affect the magnitude of the peak transient current while La++, Mn++, and Co + + greatly reduced or abolished it and decreased the steady-state current. From these and other data it was concluded that the regenerative mechanism in uterine smooth muscle has the functional characteristics of a single transient conductance channel whose activation requires the presence of both sodium and calcium. Insensitivity to TTX indicates that the molecular structure of the channel is unlike that in certain sodium-dependent systems, while the effects of LaI, Mn + + , Co++, and Ca + + reveal a similar dependence of conductances on extracellular polyvalent cations.

Quantum mechanical optical potential methods for calculating inclusive isotope and element production cross sections from the fragmenting of heavy nuclei by intermediate-and high-energy protons and heavy ions are presented based upon a modi®ed abrasion±ablation-FSI (frictional spectator interaction) collision model. The abrasion stage is treated as a quantum mechanical knockout process that leaves the residual prefragment in an excited state. Prefragment excitation energies are estimated using a combined liquid drop and FSI method. In ablation the prefragment deexcites by particle and photon emission to produce the ®nal fragment. Contributions from electromagnetic dissociation to single nucleon removal cross sections are incorporated using a Weiszacker±Williams theory that includes electric dipole and electric quadrupole interactions. Estimates of elemental and isotopic production cross sections are in good agreement with published cross section measurements for a variety of projectile-target-beam energy combinations. Ó 0168-583X/99/$ ± see front matter Ó 1999 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 8 -5 8 3 X ( 9 8 ) 0 0 9 5 7 -4