Search

Although many properties of polyatomic metal dusters have been rationalized by an electron shell model resembling that used for free atoms, it remained unclear how reliable this analogy is with respect to the angular momentum eigenstate character of the electronic wave functions. We studied free size-selected negatively charged clusters of sodium atoms ([Na.sub.n.sup.-]) of approximately spherical shape (n = 19, 40, 55, 58, 147) by angle-resolved photoelectron spectroscopy over a broad range of photon energies (1.5 to 5 electron volts). Highly anisotropic, state- and energy-dependent angular distributions emerged for all sizes. Welt-defined classes of energy dependence related to the approximate angular momenta of the bound-state orbitals indicate that the overall character of the valence electron wave functions is not appreciably influenced by the interaction with the ion background. The measured distributions nevertheless deviate strongly from the predictions of single-electron models, hinting at a distinct rote of correlated multielectron effects in the photoemission process.

Arterial pressure in most experimental and clinical hypertensions is exacerbated by salt. The effects of salt excess on right and left ventricular (RV and LV, respectively) functions and their respective coronary vasodilatory responses have been less explored. We therefore examined the effects of 8 wk of NaCl excess (8% in food) on arterial pressure, RV and LV functions (maximal rate of increase and decrease of ventricular pressure; dP/[dt.sub.max] and dP/[dt.sub.min]), coronary hemodynamics (microspheres), and collagen content (hydroxyproline assay and collagen volume fraction) in young adult normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR), aged 16 wk by the end of the study. Prolonged salt excess in WKY and SHR elevated pressure only modestly, but it markedly increased LV mass, especially in SHR. Moreover, salt excess significantly impaired RV and LV diastolic function in SHR but only LV diastolic function in WKY rats. However, salt loading affected neither RV nor LV contractile function in both strains. Interstitial and perivascular collagen deposition was increased, whereas coronary vasodilatory responses to dipyridamole diminished in both ventricles in the salt-loaded SHR but not in WKY rats. Therefore, accumulation of ventricular collagen as well as altered myocardial perfusion importantly contributed to the development of salt-related RV and LV dysfunctions in this model of naturally occurring hypertension. The unique effects of salt loading on both ventricles in SHR, but not WKY rats, strongly suggest that nonhemodynamic mechanisms in hypertensive disease participate pathophysiologically with salt-loading hypertension. These findings point to the conclusion that the concept of 'salt sensitivity' in hypertension is far more complex than simply its effects on arterial pressure or the LV. sodium excess: left and right ventricular function: spontaneously hypertensive rats; Wistar-Kyoto rats

Endothelial nitric oxide synthase-deficient mice exhibit increased susceptibility to endotoxin-induced acute renal failure. Am J Physiol Renal Physiol 287: F1044-F1048, 2004; doi:10.1152/ajprenal.00136.2004.--Acute renal failure (ARF) in septic patients drastically increases the mortality to 50-80%. Nitric oxide (NO) has been shown to be increased in sepsis. Endothelial nitric oxide synthase (eNOS) is one of the major regulators of arterial blood pressure and regional blood flow; however, its in vivo role in septic ARF is still unclear. We hypothesized that eNOS affords a protective effect against the renal vasoconstriction during endotoxemia. Because there are no specific inhibitors for eNOS, the study was therefore undertaken in eNOS knockout mice. There was no significant difference in baseline glomerular filtration rate (GFR) between the wild-type mice and the eNOS knockout mice (140 [+ or -] 10 vs. 157 [+ or -] 18 [micro]l/min, n = 9, P = not significant). However, renal blood flow (RBF) was significantly decreased in eNOS knockout mice compared with the wild-type controls (0.62 [+ or -] 0.05 ml/min, n = 6 vs. 0.98 [+ or -] 0.13 ml/min, n = 8, P < 0.05). Mean arterial pressure (MAP) was significantly higher in eNOS knockout mice than the wild-type controls (109 [+ or -] 5 vs. 80 [+ or -] 1 mmHg, n = 10, P < 0.01). Thus renal vascular resistance (RVR) was much higher in eNOS knockout mice than in the wild-type mice (176 [+ or -] 2, n = 6 vs. 82 [+ or -] 1 mmHg*[ml.sup.-1]*[min.sup.-1], n = 8, P < 0.01). When 1.0 mg/kg LPS was injected, there was no change in MAP in either the wild-type (84 [+ or -] 3 mmHg, n = 10) or the eNOS knockout mice (105 [+ or -] 5 mmHg, n = 10). Although GFR (154 [+ or -] 22 [micro]l/min, n = 8) and RBF (1.19 [+ or -] 0.05 ml/min, n = 9) remained unchanged with the 1.0-mg/kg dose of LPS in the wild-type mice, GFR (83 [+ or -] 18 vs. 140 [+ or -] 10 [micro]l/min, n = 6, P < 0.01) and RBF (0.36 [+ or -] 0.04 vs. 0.62 [+ or -] 0.05 ml/min, n = 6, P < 0.01 ) decreased significantly in the eNOS knockout mice. Fractional excretion of sodium increased significantly in eNOS knockout mice during endotoxemia (3.61 [+ or -] 0.78, n = 7 vs. 0.95 [+ or -] 0.14, n = 6, P < 0.01), whereas it remained unchanged in the wild-type mice (0.59 [+ or -] 0.16, n = 9 vs. 0.42 [+ or -] 0.05, n = 6, P = not significant). In summary, eNOS knockout mice have increased RVR and are more susceptible to endotoxemic ARF than wild-type mice despite higher MAP. tractional excretion of sodium; vasoconstriction; renal vascular resistance

Edelman et al. have empirically shown that plasma water sodium concentration ([[[Na.sup.+]].sub.pw]) is equal to 1.11([Na.sub.e] + [K.sub.e])/TBW--25.6 (Edelman IS, Leibman J, O'Meara MP, Birkenfeld LW. J Clin Invest 37: 1236-1256, 1958). However, the physiological significance of the slope and y-intercept in this equation has not been previously considered. Our analysis demonstrates that there are several clinically relevant parameters determining the magnitude of the y-intercept that independently alter [[[Na.sup.+]].sub.pw]: 1) osmotically inactive exchangeable [Na.sup.+] and [K.sup.+]; 2) plasma water [K.sup.+] concentration; and 3) osmotically active non-[Na.sup.+] and non-[K.sup.+] osmoles. In addition, we demonstrate quantitatively the physiological significance of the slope in the Edelman equation and its role in modulating [[[Na.sup.+]].sub.pw]. The slope of 1.11 in this equation which Edelman et al. determined empirically can be theoretically predicted by considering the combined effect of the osmotic coefficient of Na+ salts at physiological concentrations and Gibbs-Donnan equilibrium. In addition, our results demonstrate that the slope has an independent quantitative impact on the magnitude of the y-intercept in the Edelman equation. From a physiological standpoint, the components of both the slope and the y-intercept need to be addressed when considering the factors that modulate [[[Na.sup.+]].sub.pw]. osmotic equilibrium; dysnatremia; osmotic coefficient; potassium

Okamoto, Maristela Mitiko, Doris Hissako Sumida, Carla Roberta Oliveira Carvalho, Alessandra Martins Vargas, Joel Claudio Heimann, Beatriz D'Agord Schaan, and Ubiratan Fabres Machado. Changes in dietary sodium consumption modulate GLUT4 gene expression and early steps of insulin signaling. Am J Physiol Regul Integr Comp Physiol 286: R779-R785, 2004. First published December 11, 2003; 10.1152/ajpregu.00396.2003.--Previous studies have shown that chronic salt overload increases insulin sensitivity, while chronic salt restriction decreases it. In the present study we investigated the influence of dietary sodium on 1) GLUT4 gene expression, by Northern and Western blotting analysis; 2) in vivo GLUT4 protein translocation, by measuring the GLUT4 protein in plasma membrane and microsome, before and after insulin injection; and 3) insulin signaling, by analyzing basal and insulin-stimulated tyrosine phosphorylation of insulin receptor (IR)-[beta], insulin receptor substrate (IRS)-1, and IRS-2. Wistar rats were fed normal-sodium (NS-0.5%), low-sodium (LS-0.06%), or high-sodium diets (HS-3.12%) for 9 wk and were killed under pentobarbital anesthesia. Compared with NS rats, HS rats increased (P < 0.05) the GLUT4 protein in adipose tissue and skeletal muscle, whereas GLUT4 mRNA was increased only in adipose tissue. GLUT4 expression was unchanged in LS rats compared with NS rats. The GLUT4 translocation in HS rats was higher (P < 0.05) both in basal and insulin-stimulated conditions. On the other hand. LS rats did not increase the GLUT4 translocation after insulin stimulus. Compared with NS rats, LS rats showed reduced (P < 0.01) basal and insulin-stimulated tyrosine phosphorylatinn of IRS-1 in skeletal muscle and IRS-2 in liver, whereas HS rats showed enhanced basal tyrosine phosphorylation of IRS-1 in skeletal muscle (P < 0.05) and of IRS-2 in liver. In summary, increased insulin sensitivity in HS rats is related to increased GLUT4 gene expression, enhanced insulin signaling, and GLUT4 translocation, whereas decreased insulin sensitivity of LS rats does not involve changes in GLUT4 gene expression but is related to impaired insulin signaling. low-sodium diet; high-sodium diet; insulin resistance; GLUT4 gene expression; insulin signaling

Reducing dietary sodium reduces blood pressure (BP), a major risk factor for cardiovascular disease, but few studies have specifically examined the effect on BP of altering dietary sodium in the context of a high potassium diet. This randomized, crossover study compared BP values in volunteer subjects self-selecting food intake and consuming low levels of sodium ([Na.sup.+]; 50 mmol/d) with those consuming high levels of sodium ([greater than or equal to] 120 mmol/d), in the context of a diet rich in potassium ([K.sup.+]). Sodium supplementation (NaSp) produced the difference in [Na.sup.+] intake. Subjects (n = 108; 64 women, 44 men; 16 on antihypertensive therapy) had a mean age of 47.0 [+ or -] 10.1 y. Subjects were given dietary advice to achieve a low sodium (LS) diet with high potassium intake (50 mmol [Na.sup.+]/d, >80 mmol [K.sup.+]/d) and were allocated to NaSp (120 mmol [Na.sup.+]/d) or placebo treatment for 4 wk before crossover. The LS diet decreased urinary [Na.sup.+] from baseline, 138.7 [+ or -] 5.3 mmol/d to 57.8 [+ or -] 3.8 mmol/d (P < 0.001). The NaSp treatment returned urinary [Na.sup.+] to baseline levels 142.4 [+ or -] 3.7 mmol/d. Urinary [K.sup.+] increased from baseline, 78.6 [+ or -] 2.3 to 86.6 [+ or -] 2.1 mmol/d with the LS diet and to 87.1 [+ or -] 2.1 mmol/d with NaSp treatment (P < 0.001). The LS diet reduced home systolic blood pressure (SBP) by 2.5 [+ or -] 0.8 mm Hg (P = 0.004), compared with the NaSp treatment. Hence, reducing [Na.sup.+] intake from 140 to 60 mmol/d significantly decreased home SBP in subjects dwelling in a community setting who consumed a self-selected [K.sup.+]-rich diet, and this dietary modification could assist in lowering blood pressure in the general population. KEY WORDS: * home blood pressure * sodium * potassium, diet * community

The electroneutral sodium bicarbonate cotransporter 3 (NBC3) coimmunoprecipitates from renal lysates with the vacuolar [H.sup.+]-ATPase. In renal type A and B intercalated cells, NBC3 colocalizes with the vacuolar [H.sup.+]ATPase. The involvement of the COOH termini of NBC3 and the 56-kDa subunit of the proton pump in the interaction of these proteins was investigated. The intact and modified COOH termini of NBC3 and the 56-kDa subunit of the proton pump were synthesized, coupled to Sepharose beads, and used to pull down kidney membrane proteins. Both the 56-and the 70-kDa subunits of the proton pump, as well as a PDZ domain containing protein [Na.sup.+]/[H.sup.+] exchanger regulatory factor 1 (NHERF-1), were bound to the intact 18 amino acid NBC3 COOH terminus. A peptide truncated by five COOH-terminal amino acids did not bind these proteins. Replacement of the COOH-terminal leucine with glycine blocked binding of both the proton pump subunits but did not affect binding of NHERF-1. The 18 amino acid COOH terminus of the 56-kDa subunit of the proton pump bound NHERF-1 and NBC3, but the truncated and modified peptide did not. A complex of NBC3, the 56-kDa subunit of the proton pump, and NHERF-1 was identified in rat kidney. The data indicate that the COOH termini of NBC3 and the 56-kDa subunit of the vacuolar proton pump are PDZ-interacting motifs that are necessary for the interaction of these proteins. NHERF-1 is involved in the interaction of NBC3 and the vacuolar proton pump. sodium; bicarbonate; cotransporters; membrane; binding

Transport of alkali metals, particularly sodium and potassium, across cell membranes is an essential function performed by special proteins that enable cells to regulate inter- and extracellular ion concentrations with [...]

The crystal structure of the super conducting (ND3)xNaA2C60 (0.7

Io's sodium clouds result mostly from a combination of two atmospheric escape processes at Io. Neutralization of [Na.sup.+] and/or Na[X.sup.+] pickup ions produces the 'stream' and the 'jet' and results in a rectangular-shaped sodium nebula around Jupiter. Atmospheric sputtering of Na by plasma torus ions produces the 'banana cloud' near Io and a diamond-shaped sodium nebula. Charge exchange of thermal [Na.sup.+] with Na in Io's atmosphere does not appear to be a major atmospheric ejection process. The total ejection rate of sodium from Io varied from 3 x [10.sup.26] to 25 x [10.sup.26] atoms/s over seven years of observations. Our results provide further evidence that Io's atmospheric escape is driven from collisionally thick regions of the atmosphere rather than from the exosphere. Key Words: Io; atmospheric dynamics; satellite atmospheres; magnetospheres.

Experiments to define the critical curve for a series of silicate melts in equilibrium with a hydrous fluid were carried out in a hydrothermal diamond anvil cell. Silicate compositions studied were albite with several wt% excess [Na.sub.2]O, [B.sub.2][O.sub.3] and [F.sub.2][O.sub.-1]. Complete miscibility between melt and water was observed at lower pressure and temperature conditions compared to pure albite for all compositions. For albite + excess [Na.sub.2]O, the critical curve had been lowered by 143 and 247[degrees]C at 10 kbar for 5 and 10 wt% excess Na. For albite + 5 and 10 wt% F, the difference at 10 kbar was 147 and 246[degrees]C respectively, and for albite +5 and 10 wt% B differences of 168 and 262[degrees]C were found. These results are likely to be additive, with the presence of more than one of the components depressing the critical curve to even lower temperatures and pressures. The results suggest that in complex pegmatitic systems, complete miscibility between melt and fluid may be important in the final stages of crystallisation. The unusual properties of fluid phases under conditions close to the critical curve in a silicate melt-water system may be essential for the enrichment of trace elements in pegmatites as well as for the formation of typical pegmatite texture.

The sputtering and decomposition of the surface of Europa by fast ions and electrons lead to the production of an atomosphere containing sodium and potassium atoms. Here time-of-flight energy distributions are measured for Na and K sputtered from a vapor-deposited ice by 200-eV electrons. These data are then used in a Monte Carlo simulation for alkalis in Europa's atmosphere. Na/K ratios versus distance from Europa are calculated and compared to the recent observations in the range 6 to 18 Europan radii from the surface. Normalizing to the observations, the Na/K ratio for the loss rates is ~27 and the ratio for the average surface source rates is ~20. These ratios are very different from the Na/K ratio at Io and are larger than the Na/K ratio suggested for Europa's putative subsurface ocean, consistent with fractionation on freezing and upwelling of ocean material. Key Words: Europa; surface; satellite; atmosphere; composition.

Volume diffusion rates of Ce, Sm, Dy, and Yb have been measured in a natural pyrope-rich garnet single crystal ([Py.sub.71][Alm.sub.16][Gr.sub.13]) at a pressure of 2.8 GPa and temperatures of 1,200-1,450 [degrees] C. Pieces of a single gem-quality pyrope megacryst were polished, coated with a thin layer of polycrystalline REE oxide, then annealed in a piston cylinder device for times between 2.6 and 90 h. Diffusion profiles in the annealed samples were measured by SIMS depth profiling. The dependence of diffusion rates on temperature can be described by the following Arrhenius equations (diffusion coefficients in [m.sup.2]/s): [log.sub.10][D.sub.Yb] = (-7.73 [+ or -] 0.97) - (343 [+ or -] 30 kJ [mol.sup.-1]/2.303RT) [log.sub.10][D.sub.Dy] = (-9.04 [+ or -] 0.97) - (302 [+ or -] 30 kJ [mol.sup.-1]/2.303RT) [log.sub.10][D.sub.Sm] = (-9.21 [+ or -] 0.97) - (300 [+ or -] 30 kJ [mol.sup.-1]/2.303RT) [log.sub.10][D.sub.Ce]! = (-9.74 [+ or -] 2.84) - (284 [+ or -] 91 kJ [mol.sup.-1]/2.303RT). There is no significant influence of ionic radius on diffusion rates; at each temperature the diffusion coefficients for Ce, Sm, Dy, and Yb are indistinguishable from each other within the measurement uncertainty. However, comparison with other diffusion data suggests that there is a strong influence of ionic charge on diffusion rates in garnet, with RE[E.sup.3+] diffusion rates more than two orders of magnitude slower than divalent cation diffusion rates. This implies that the Sm-Nd isotopic chronometer may close at significantly higher temperatures than thermometers based on divalent cation exchange, such as the garnet-biotite thermometer. REE diffusion rates in pyrope are similar to Yb and Dy diffusion rates in diopside at temperatures near the solidus of garnet lherzolite (~1,450 [degrees] C at 2.8 GPa), and are an order of magnitude faster than Nd, Ce, and La in high-Ca pyroxene at these conditions. At lower temperatures relevant to the lithospheric mantle and crust, REE diffusion rates in garnet are much faster than in high-Ca pyroxene, and closure temperatures for Nd isotopes in slowly-cooled garnets are ~200 [degrees] C lower than in high-Ca pyroxene.

Reclamation of sodic soils is imperative in many areas where deterioration of land and water resources is in progress. While the chemical mechanisms involved in the reclamation of sodic soils are well described and understood, the in situ physical processes undergoing during the salt leaching and cation substitution are normally not taken into consideration. Three sodic soils mixed with different amounts of gypsum were packed in columns and leached under saturated conditions for a period of time between 1 and 3 mo. Saturated hydraulic conductivity ([K.sub.sat]) was measured and a thin section was prepared for each of the columns. We used scanning electron microscopy (SEM) and image analysis to measure the size and shape of the aggregates and the pores, and correlated these with chemical and physical parameters. We divided the area by the perimeter (A/P) to quantify the size and A/[P.sup.2] to express geometry for both aggregates and pores. The size of the aggregates had a good correlation with the exchangeable Na percentage (ESP), bulk density, pore size, and [K.sub.sat]. There was no significant relationship between pore size and texture, indicating that transport models using particle-size distribution to infer porosity may not be successful in predicting water transport in soils under reclamation. The linear relationship between aggregate size and pore size indicates that the pore space is determined by the packing of the aggregates not the individual particles, this relationship may have implications not only for water transport but for modeling hydraulic properties in general.

Research has been conducted on the crystal structure of the pore-forming part of the KcsA bacterial K (super)+ -selective channel. The possibility of a motiff for related voltage-gated channels has been examined.

Research has been conducted on Listeria monocytogenes. The isolation of the L. monocytogenes mutant have demonstrated that it is resistant to leucocin A.

Research has been conducted on the mammalian sodium/bile acid cotransporters (SBATs). Results indicate that sodium increases the reactivity with the thiol reagents and bile acids protect SBATs from inactivation.

Research has been conducted on the sodium-hydrogen exchanger regulatory factor (NHERF). The investigation of the ezrin binding for NHERF's function as a NHE3 regulator has been carried out.

Research has been conducted on the Na (super)+ -binding properties of factor X. The characterization of these properties is described.

Research has been conducted on the agent of cholera Vibrio cholerae. The identification of the nhaA gene in V. cholerae O1 wild-type epidemic strain has been carried out.

Research has been conducted on the N-terminal part of the Na (super)+/proline transporter of Escherichia coli. The transmembrane domain structural arrangement and functional dynamics have been investigated.

Research has been conducted on the oxaloacetate decarboxylase membrane-bound beta-subunit from Klebsiella pneumoniae. The decarboxylation of carboxybiotin coupled to Na (super)+ translocation is described.

Research has been conducted on the sodium, potassium and cesium salts. Results indicate that cesium and potassium locate between salicylaldimine ligands and sodium resides within the salicylaldimine oxygen planes.

Research has been conducted on the secretory Na (super)+ - K (super)+ - 2Cl (super)- cotransporter in rat parotid plasma membranes. The use of chemical cross-linker [3,3'-dithiobis-(sulfosuccinimidyl propionate)] is discussed.

Research has been conducted on the lipoprotein(a) [Lp(a)]. The effect of NaCl and 6-aminohexanoic acid on the Lp(a) structure has been investigated.

A new study investigates the characterization of the local cation environment and possible site preferences in mixed lithium-sodium chabazites, using solid-state NMR and neutron diffraction.

Research has been conducted on the factor Xa 225-loop to determine if it is a Na (super)+ -binding site. The expression of a factor Xa substitution mutant in mammalian cells is described.

Research has been conducted on the interactions of the voltage-dependent sodium channel with intracellular molecules. The modulation of the channel properties and localizations in neuronal cells is discussed.

Sodium mobility in SrS-based electroluminescent thin film stacks grown by atomic layer epitaxy was examined.

Research has been conducted on the generation of alpha-fluoromalonaldehyde sodium salt. The reaction of this salt with acid chlorides is described.

Brevetoxins, the toxic components of 'red tide' algae, all share one of two robust polycyclic ether backbone structures, but they are distinguished by differing side-chain substituents. Electrospray ionization mass spectrometry analyses of brevetoxins have shown that the polyether structure invariably has a very high affinity for sodium cations that results in the production of abundant (M + Na)(super +) ions even when sodium cations are only present as impurities. Because the ionic charge tends to remain localized on the sodium atom and because at least two bonds must be broken in order to produce polycyclic backbone fragmentation, it is extremely difficult to obtain abundant product ions (other than Na(super +)) from (M + Na)(super +) brevetoxin precursor ions in low-energy collision-induced dissociation (CID) MS/MS experiments. This report establishes that acid additives (oxalic acid, trifluoroacetic acid, and particularly hydrochloric acid) in aqueous methanol solutions can promote high yields of protonated brevetoxin molecules (MH(super +) ions) for Btx-1, -2, and -9 brevetoxins. Most importantly, unlike their (M + Na)(super +) counterparts, MH(super +) precursor ions offer readily detectable product ions in CID MS/MS experiments, even under low-energy collisions. This direct structural characterization approach has provided decomposition information from brevetoxins that was previously inaccessible, including the identification of diagnostic product ions for 'type A' brevetoxins (m/z 611) and 'type B' brevetoxins (m/z 779, 473, 179) and characteristic ions for Btx-1 (m/z 221, 139), Btx-2 (m/z 153), and Btx-9 (m/z 157, 85). Precursor ion scans and constant neutral loss scans are proposed to enable screening of individual type A or type B brevetoxins present in naturally occurring mixtures.

Frontal analysis continuous capillary electrophoresis (FACCE) was carried out for a series of random copolymers of an ionic monomer, sodium 2-(acrylamido)-2methylpropanesulfonate (AMPS), and a nonionic monomer, acrylamide (AAM). The electropherograms appeared in order of anionic content and were generally sigmoidal, in contrast to that of hyaluronic acid (HA), which was abrupt and discontinuous. This difference could be related to the compositional heterogeneity of the copolymers, completely absent in the biopolymer. Through the range of copolymer composition (10-100% AMPS) the relationship between average mobility and nominal AMPS content could be described by a calibration curve, making it possible to deduce the compositional distribution of copolymer samples.

The feasibility of quantifying sodium and potassium in single human eryfthrocytes was demonstrated by spectrochemical analysis of emissions from plasmas produced by 193-nm laser ablation of blood cells confined in a sheath flow. In one scheme, single blood cells that happened to be in the ablation volume were sampled. In another scheme, individual blood cells were first sighted and then synchronously ablated downstream. Plasma emission spectra of single ablated cells were captured, and the ratios of the analyte line intensity to the root-mean-square fluctuation of the continuum background were measured to be about 18 for sodium and 30 for potassium.

Research has been conducted on the Na-buserite preparation by means of the double-aging method. Stabilization of Na-buserite is discussed.

Research has been conducted on the CuCl (sub)2 . 2H (sub)2 O. The reaction of this compound with disodium terephthalate in aqueous solutions is analyzed.

Research was conducted to examine the role of Arg residues conserved in the Na+/proline transporter of Escherichia coli. Arg40 located at the cytoplasmic end of transmembrane domain II and Arg117 in cytoplasmic loop 4 of PutP were subjected to amino acid substitution analysis. Results demonstrate that Arg117 plays a critical role at a stage prior to complete functional insertion of PutP into the membrane by stabilizing a folding intermediate.

Research has been conducted on the Rhodobacter sphaeroides. Investigation on its ability to function in place of the pomA and pomB genes of Vibrio alginolyticus is discussed.

A sensitive method for the determination of ultratrace organotin species in seawater is described. The merits and demerits of derivatization methods using Grignard reagent or sodium tetracethylborate (NaBEt(sub 4) were evaluated in terms of derivatigation efficiency, applicability to the programmed temperature vaporization (PTV) method, and procedural blanks. The sensitivity of the gas chromatography/inductively coupled plasma mass spectrometry (GC/ICPMS) was improved by more than 100-fold by operating the shield torch at normal plasma conditions, compared with that obtained without using it. The absolute detection limit as tin reached subfemtogram (fg) levels. Furthermore, the detection limit in terms of relative concentration was improved 100-fold by using the PTV method, which enabled the injection of a large sample volume of as much as 100 mu L without loss of analyte. When the organotin species in seawater were extracted into hexane with a preconcentration factor of 1000 after ethylation with NaBEt(sub 4) and 100 mu L aliquot of the extract was injected into the GC, the instrumental detection limit in relative concentration reached 0.01 pg/L in original seawater. Sources of contamination of organotin species during the sample preparation were examined, and a purification method of NaBEt(sub 4) was developed. Finally, the method was successfully applied to open ocean seawater samples containing organotin species at the level of 1-100 pg/L.

Research has been conducted on the amine solvates preparation and characterization. The use of IR and NMR spectroscopy is described.

Research is presented investigating the use of a density functional method and cluster models to study the interaction between aluminium atoms with sodium cation and six-rings of a zeolite framework.

Ab initio molecular orbital methods at different levels of theory were used to calculate the structures and sodium affinities of polyelectrolytes containing zeolitic fragments. The sodium affinity was found to decrease due to the substitution of an OCH3 group by an OSiH3 group in the zeolitic fragments and increase due to substitution of boron atoms for aluminum atoms. In two of the systems, the addition of a sodium cation resulted in a decrease in the Al-O-C and Al-O-Si bond angles.

The linear isotherm regularity (LIR), a thermodynamic equation of state, was used to predict the metal-non-metal transition that occur when density decreases. Results revealed several changes in liquid structure while the transition is occurring, indicating a deviation from the linearity predicted by the LIR. An appropriate equation of state was then derived and used to predict a transition for liquids CS, Rb, Na and Hg. The predictions were found to agree well with experimental results. The transition was also observed to be neither first order nor second order.

The side arm effects on cyclen-alkali metal cation binding are investigated by preparing various armed cyclens in which ester, amide, nitrile and pyridine moieties are appended as cation-ligating side arms to a 12-membered ring. Ester, amide and pyridine-armed 12-membered cyclens are found to easily accomodate a Na+ ion in a 3D manner and highly discriminate the cation from Li+ and K+ ions. It was also observed that these cyclens are more efficient and selective in binding Na+ ion than common Na+ ion-selective ligands.

Research was conducted to identify the effect produced by anoxia on Na+-K+ pump activity and to determine how trout erythrocytes maintain energy equilibrium. Microcalorimetric measurements of the heat production of cell suspensions quantified the changes in metabolic activity that were linked to normoxia-to-anoxia transitions. Results demonstrate that the cells maintained their ATP contents stable and were viable for hours in the absence of oxygen although the metabolic activity was reduced during anoxia to one-third of the normoxic value.

The function of acidic amino acid residues in cation recognition and selectivity by the Na+/dicarboxylate cotransporter NaDC-1 was studied by site-directed mutagenesis and expression in Xenopus oocytes. Four of the residues tested, Asp-52, Glu-74, Glu-101 and Glu-332, were observed to be unessential for transport activity. However, substitutions of Asp-373 and Glu-475, conserved residues found in transmembrane domains M8 and M9, respectively, modified transport kinetics.

The effects of cortisol treatment on renal cortical Na+-K+-ATPase were studied in relation to proximal tubule salt transport. The results showed that physiologically relevant maturation of Na+-K+-ATPase with physiological doses of glucocorticoids in 132 day fetal sheep could be induced. Increased protein abundance was pointed to as a possible source of increased activity but the remainder appeared to have resulted from posttranscriptional and posttranslational influences.

A study was conducted to analyze the influence of sodium on the electrical and structural characteristics of CuInSe2. Defect computations were carried out by placing the point defect at a center of an artificially large unit cell supporting N molecules. Results indicated that that sodium will replace copper to form a more stable NaInSe2 if available in stoichiometric quantities. In small quantities, sodium will form defects on copper site and In site.

A study was conducted to analyze whether dopamine transporter activity could be minimized by a treatment that induces the drive underlying the motivated behavior of sodium appetite in rats. The animals were treated with diuretic furosemide before euthanasia. Results indicated that a direct action of also is one possible mechanism by which sodium depletion promotes a reduction in dopamine transporter activity in the nucleus accumbens.

The electrochemical promotion of propene combustion was investigated in a sodium Beta'-alumina-supported platinum film catalyst. Sodium was found to enhance the chemisorption of oxygen and inhibit the adsorption of propene. Results also indicated that catalyst poisoning is due to the thick layers consisting of sodium carbonate and that the promotion and poisoning behavior is fully reversible as a function of catalyst potential.

Cluster model calculations at the Hartree-Fock/6-31G(d) level were carried out to study the local coordination environments of Li+ and Na+ ions in single- and mixed-alkali silicate glasses. Results indicated that the average coordination number of alkali cations increases from Li to Na and each alkali cation is located in individual sites in the single- and mixed-alkali clusters. There is also significant site mismatch during the hopping of the alkali cations.