Intracellular Ca2+ regulation by the leech giant glial cell.

PubMed

Nett, W; Deitmer, J W

1998-02-15

1. We have measured the intracellular Ca2+ concentration, [Ca2+]i, and the intracellular Na+ concentration, [Na+]i, with the fluorescent dyes fura-2 (for Ca2+) and SBFI (for Na+) in situ in giant glial cells of the central nervous system of the leech Hirudo medicinalis. 2. The basal [Ca2+]i was 79 +/- 35 nM (n = 27) in cells voltage clamped at -70 to -80 mV, and 75 +/- 29 nM (mean +/- S.D., n = 82) in unclamped cells at a mean membrane potential of -67 +/- 6 mV. 3. Removal of external Na+ evoked a small reversible [Ca2+]i increase of 29 +/- 21 nM (n = 27) in cells voltage clamped at -70 to -80 mV, and of 35 +/- 18 nM (n = 37) in unclamped cells. This [Ca2+]i increase, and the time constant of the subsequent [Ca2+]i recovery after Na+ re-addition, did not change significantly with the holding potential between -110 and -60 mV. 4. The basal [Na+]i was 5.6 +/- 1.3 mM (n = 18). Increasing [Na+]i by inhibiting the Na+-K+ pump with 100 microM ouabain had no effect on the [Ca2+]i rise upon removal of external Na+. 5. The time course of recovery from a [Ca2+]i load mediated by voltage-dependent Ca2+ influx during depolarization in high K+ was unaffected by the removal of external Na+. 6. Cyclopiazonic acid (10 muM), an inhibitor of the endoplasmic reticulum Ca2+-ATPase, caused a transient increase in [Ca2+]i of 28 +/- 11 nM (n = 5), and significantly slowed the recovery from imposed [Ca2+]i loads. 7. Iontophoretic injection of orthovanadate, an inhibitor of P-type ATPases including the plasma membrane Ca2+-ATPase, caused a persistent increase in the basal [Ca2+]i of 163 +/- 101 nM (n = 5) in standard saline, and of 427 +/- 338 nM in Na+-free saline (n = 5). Vanadate injection significantly slowed the recovery from [Ca2+]i loads. Removal of external Na+ during vanadate injection induced an additional, reversible [Ca2+]i increase of 254 +/- 64 nM (n = 3). 8. The results suggest that the low basal [Ca2+]i in these glial cells is predominantly maintained by a Ca2+-ATPase in the plasma membrane. This ATPase is also the main Ca2+ extruder after an intracellular Ca2+ load, while intracellular stores appear to contribute little to this recovery. A Na+-Ca2+ exchanger seems to play a minor role in the maintenance of basal [Ca2+]i in these cells, but becomes prominent when the plasma membrane Ca2+-ATPase is blocked.

Effect of Salinity and Alkalinity on Luciobarbus capito Gill Na+/K+-ATPase Enzyme Activity, Plasma Ion Concentration, and Osmotic Pressure

PubMed Central

2016-01-01

We evaluated the individual and combined effects of salinity and alkalinity on gill Na+/K+-ATPase enzyme activity, plasma ion concentration, and osmotic pressure in Luciobarbus capito. Increasing salinity concentrations (5, 8, 11, and 14 g/L) were associated with an initial increase and then decrease in L. capito gill Na+/K+-ATPase activity. Activity was affected by the difference between internal and external Na+ ion concentrations and osmotic pressure (P < 0.05). Both plasma ion (Na+, K+, and Cl−) concentration and osmotic pressure increased significantly (P < 0.05). An increase in alkalinity (15, 30, 45, and 60 mM) caused a significant increase in plasma K+ and urea nitrogen concentrations (P < 0.05) but had no effect on either plasma osmotic pressure or gill filament ATPase activity. In the two-factor experiment, the saline-alkaline interaction caused a significant increase in plasma ion (Na+, Cl−, and urea nitrogen) and osmotic pressure (P < 0.05). Variance analysis revealed that salinity, alkalinity, and their interaction significantly affected osmotic pressure, with salinity being most affected, followed by alkalinity, and their interaction. Gill filament ATPase activity increased at first and then decreased; peak values were observed in the orthogonal experiment group at a salinity of 8 g/L and alkalinity of 30 mM. PMID:27981049

Electric Field-Controlled Ion Transport In TiO2 Nanochannel.

PubMed

Li, Dan; Jing, Wenheng; Li, Shuaiqiang; Shen, Hao; Xing, Weihong

2015-06-03

On the basis of biological ion channels, we constructed TiO2 membranes with rigid channels of 2.3 nm to mimic biomembranes with flexible channels; an external electric field was employed to regulate ion transport in the confined channels at a high ionic strength in the absence of electrical double layer overlap. Results show that transport rates for both Na+ and Mg2+ were decreased irrespective of the direction of the electric field. Furthermore, a voltage-gated selective ion channel was formed, the Mg2+ channel closed at -2 V, and a reversed relative electric field gradient was at the same order of the concentration gradient, whereas the Na+ with smaller Stokes radius and lower valence was less sensitive to the electric field and thus preferentially occupied and passed the channel. Thus, when an external electric field is applied, membranes with larger nanochannels have promising applications in selective separation of mixture salts at a high concentration.

Osmotic and ionic regulation in shore crabs Carcinus maenas inhabiting a tidal estuary

NASA Astrophysics Data System (ADS)

Winkler, A.; Siebers, D.; Becker, W.

1988-03-01

Shore crabs Carcinus maenas were exposed to salinities fluctuating according to the natural tidal rhythm. To this end they were maintained in net cages positioned in the estuarine waters of the river Elbe. The cages were lifted every hour, and between 8 12 specimens were analyzed for hemolymph concentrations of Na, K, Ca, Mg, and osmolality. The results obtained were compared with the respective data measured in external brackish water. In addition, the specific activity of Na-K-ATPase in a posterior gill was determined. Hemolymph Na and Mg as well as branchial Na-K-ATPase were also determined in crabs collected in the North Sea and the Baltic. The results show that in C. maenas living in salinities fluctuating with the tides by approx. 15‰ S, Na, K and Ca were hyperregulated, and Mg was effectively hyporegulated. The concentrations of all hemolymph ions and the activity of the Na-K-ATPase were kept constant over the whole tidal cycle. In Baltic crabs, Na was effectively hyperregulated and gill Na-K-ATPase was significantly elevated by a factor of ca 2 when compared with North Sea crabs. It is suggested that long-term hyperregulation of Na in constant salinities results from an increased number of Na-K-ATPase molecules which may change by synthesis or degradation following salinity stress. Constant hemolymph levels of hyperregulated Na in crabs inhabiting fluctuating brackish water are accomplished by activation of existing Na-K-ATPase by low Na and inhibition by higher ambient concentrations.

Permeation of internal and external monovalent cations through the catfish cone photoreceptor cGMP-gated channel

PubMed Central

1995-01-01

The permeation of monovalent cations through the cGMP-gated channel of catfish cone outer segments was examined by measuring permeability and conductance ratios under biionic conditions. For monovalent cations presented on the cytoplasmic side of the channel, the permeability ratios with respect to extracellular Na followed the sequence NH4 > K > Li > Rb = Na > Cs while the conductance ratios at +50 mV followed the sequence Na approximately NH4 > K > Rb > Li = Cs. These patterns are broadly similar to the amphibian rod channel. The symmetry of the channel was tested by presenting the test ion on the extracellular side and using Na as the common reference ion on the cytoplasmic side. Under these biionic conditions, the permeability ratios with respect to Na at the intracellular side followed the sequence NH4 > Li > K > Na > Rb > Cs while the conductance ratios at +50 mV followed the sequence NH4 > K approximately Na > Rb > Li > Cs. Thus, the channel is asymmetric with respect to external and internal cations. Under symmetrical 120 mM ionic conditions, the single-channel conductance at +50 mV ranged from 58 pS in NH4 to 15 pS for Cs and was in the order NH4 > Na > K > Rb > Cs. Unexpectedly, the single-channel current-voltage relation showed sufficient outward rectification to account for the rectification observed in multichannel patches without invoking voltage dependence in gating. The concentration dependence of the reversal potential for K showed that chloride was impermeant. Anomalous mole fraction behavior was not observed, nor, over a limited concentration range, were multiple dissociation constants. An Eyring rate theory model with a single binding site was sufficient to explain these observations. PMID:8786344

PIXE analysis of cystic fibrosis sweat samples with an external proton beam

NASA Astrophysics Data System (ADS)

Sommer, F.; Massonnet, B.

1987-03-01

PIXE analysis with an external proton beam is used to study, in four control and five cystic fibrosis children, the elemental composition of sweat samples collected from different parts of the body during entire body hyperthermia. We observe no significant difference of sweat rates and of temperature variations between the two groups during sweat test. The statistical study of results obtained by PIXE analysis allows us to pick out amongst 8 elements studied, 6 elements (Na, Cl, Ca, Mn, Cu, Br) significatively different between the two groups of subjects. Using regression analysis, Na, Cl and Br concentrations could be used in a predictive equation of the state of health.

The ionic selectivity and calcium dependence of the light-sensitive pathway in toad rods.

PubMed Central

Hodgkin, A L; McNaughton, P A; Nunn, B J

1985-01-01

A new method is described for determining the effects of rapid changes in ionic concentration on the light-sensitive currents of rod outer segments. Replacing Na with another monovalent cation caused a rapid change in current followed by an exponential decline of time constant 0.5-2 s. From the magnitude of the initial rapid change in current we conclude that Li, Na, and K and Rb ions pass readily through the light-sensitive channel in the presence of 1 mM-Ca, whereas Cs crosses with difficulty and choline, tetramethylammonium and tetraethylammonium not at all. The effect of reducing Ca in the external medium indicates that the residual inward current recorded for a few seconds when Na is replaced by an impermeant ion is carried largely by Ca ions. With 1 microM-Ca in the external medium the relative ability of monovalent cations to carry light-sensitive current is Li:Na:K:Rb:Cs = 1.4:1:0.8:0.6:0.15. The same order applied in the physiological region but the values are less certain. Large transient inward currents are seen if external Ca is raised form 1 microM to 5 mM or more; these currents which are maximal in an isotonic Ca solution are presumably carried by Ca. The effect of monovalent cations on the number of open light-sensitive channels was tested by adding the cation to a solution containing 55 mM-Na. Na ions open light-sensitive channels with a delay, probably by promoting Na-Ca exchange; K and Rb close channels by inhibiting exchange; Li and Cs seem inert in the exchange mechanism. The rate at which inward current declines in low [Na]o or high [Ca]o is accelerated by weak background lights and slowed by 3-isobutyl-1-methylxanthine (IBMX), which inhibits the hydrolysis of cGMP. On returning to Ringer solution after a period in low [Na]o the current recovers with a delay of about 1 s which decreases as the Ca concentration of the low [Na]o medium is reduced. We conclude that intracellular Ca has a strong effect on the number of open light-sensitive channels. None the less, several observations are inconsistent with channel closure being dependent simply on combination with internal Ca. PMID:2580087

Electrolyte Concentration Effect of a Photoelectrochemical Cell Consisting of TiO 2 Nanotube Anode

DOE PAGES

Ren, Kai; Gan, Yong X.; Nikolaidis, Efstratios; ...

2013-01-01

The photoelectrochemical responses of a TiO 2 nanotube anode in ethylene glycol (EG), glycerol, ammonia, ethanol, urea, and Na 2 S electrolytes with different concentrations were investigated. The TiO 2 nanotube anode was highly efficient in photoelectrocatalysis in these solutions under UV light illumination. The photocurrent density is obviously affected by the concentration change. Na 2 S generated the highest photocurrent density at 0, 1, and 2 V bias voltages, but its concentration does not significantly affect the photocurrent density. Urea shows high open circuit voltage at proper concentration and low photocurrent at different concentrations. Externally applied bias voltage is alsomore » an important factor that changes the photoelectrochemical reaction process. In view of the open circuit voltage, EG, ammonia, and ethanol fuel cells show the trend that the open circuit voltage (OCV) increases with the increase of the concentration of the solutions. Glycerol has the highest OCV compared with others, and it deceases with the increase in the concentration because of the high viscosity. The OCV of the urea and Na 2 S solutions did not show obvious concentration effect.« less

Capacitive Neutralization Dialysis for Direct Energy Generation.

PubMed

Liu, Yue; Zhang, Yi; Ou-Yang, Wei; Bastos Sales, Bruno; Sun, Zhuo; Liu, Fei; Zhao, Ran

2017-08-15

Capacitive neutralization dialysis energy (CNDE) is proposed as a novel energy-harvesting technique that is able to utilize waste acid and alkaline solutions to produce electrical energy. CNDE is a modification based on neutralization dialysis. It was found that a higher NaCl concentration led to a higher open-circuit potential when the concentrations of acid and alkaline solutions were fixed. Upon closing of the circuit, the membrane potential was used as a driving force to move counter ions into the electrical double layers at the electrode-liquid interface, thereby creating an ionic current. Correspondingly, in the external circuit, electrons flow through an external resistor from one electrode to the other, thereby generating electrical energy directly. The influence of external resistances was studied to achieve greater energy extraction, with the maximum output of 110 mW/m 2 obtained by employing an external resistance of 5 Ω together with the AC-coated electrode.

The Photosynthesis, Na+/K+ Homeostasis and Osmotic Adjustment of Atriplex canescens in Response to Salinity

PubMed Central

Pan, Ya-Qing; Guo, Huan; Wang, Suo-Min; Zhao, Bingyu; Zhang, Jin-Lin; Ma, Qing; Yin, Hong-Ju; Bao, Ai-Ke

2016-01-01

Atriplex canescens (fourwing saltbush) is a C4 perennial fodder shrub with excellent resistance to salinity. However, the mechanisms underlying the salt tolerance in A. canescens are poorly understood. In this study, 5-weeks-old A. canescens seedlings were treated with various concentrations of external NaCl (0–400 mM). The results showed that the growth of A. canescens seedlings was significantly stimulated by moderate salinity (100 mM NaCl) and unaffected by high salinity (200 or 400 mM NaCl). Furthermore, A. canescens seedlings showed higher photosynthetic capacity under NaCl treatments (except for 100 mM NaCl treatment) with significant increases in net photosynthetic rate and water use efficiency. Under saline conditions, the A. canescens seedlings accumulated more Na+ in either plant tissues or salt bladders, and also retained relatively constant K+ in leaf tissues and bladders by enhancing the selective transport capacity for K+ over Na+ (ST value) from stem to leaf and from leaf to bladder. External NaCl treatments on A. canescens seedlings had no adverse impact on leaf relative water content, and this resulted from lower leaf osmotic potential under the salinity conditions. The contribution of Na+ to the leaf osmotic potential (Ψs) was sharply enhanced from 2% in control plants to 49% in plants subjected to 400 mM NaCl. However, the contribution of K+ to Ψs showed a significant decrease from 34% (control) to 9% under 400 mM NaCl. Interestingly, concentrations of betaine and free proline showed significant increase in the leaves of A. canescens seedlings, these compatible solutes presented up to 12% of contribution to Ψs under high salinity. These findings suggest that, under saline environments, A. canescens is able to enhance photosynthetic capacity, increase Na+ accumulation in tissues and salt bladders, maintain relative K+ homeostasis in leaves, and use inorganic ions and compatible solutes for osmotic adjustment which may contribute to the improvement of water status in plant. PMID:27379134

Growth and Photosynthetic Responses to Salinity of the Salt-marsh Shrub Atriplex portulacoides

PubMed Central

Redondo-Gómez, Susana; Mateos-Naranjo, Enrique; Davy, Anthony J.; Fernández-Muñoz, Francisco; Castellanos, Eloy M.; Luque, Teresa; Figueroa, M. Enrique

2007-01-01

Background and Aims Atriplex (Halimione) portulacoides is a halophytic, C3 shrub. It is virtually confined to coastal salt marshes, where it often dominates the vegetation. The aim of this study was to investigate its growth responses to salinity and the extent to which these could be explained by photosynthetic physiology. Methods The responses of young plants to salinity in the range 0–700 mol m−3 NaCl were investigated in a glasshouse experiment. The performance of plants was examined using classical growth analysis, measurements of gas exchange (infrared gas analysis), determination of chlorophyll fluorescence characteristics (modulated fluorimeter) and photosynthetic pigment concentrations; total ash, sodium, potassium and nitrogen concentrations, and relative water content were also determined. Key Results Plants accumulated Na+ approximately in proportion to external salinity. Salt stimulated growth up to an external concentration of 200 mol m−3 NaCl and some growth was maintained at higher salinities. The main determinant of growth response to salinity was unit leaf rate. This was itself reflected in rates of CO2 assimilation, which were not affected by 200 mol m−3 but were reduced at higher salinities. Reductions in net photosynthetic rate could be accounted for largely by lower stomatal conductance and intercellular CO2 concentration. Apart from possible effects of osmotic shock at the beginning of the experiment, salinity did not have any adverse effect on photosystem II (PSII). Neither the quantum efficiency of PSII (ΦPSII) nor the chlorophyll fluorescence ratio (Fv/Fm) were reduced by salinity, and lower mid-day values recovered by dawn. Mid-day Fv/Fm was in fact depressed more at low external sodium concentration, by the end of the experiment. Conclusions The growth responses of the hygro-halophyte A. portulacoides to salinity appear largely to depend on changes in its rate of photosynthetic gas exchange. Photosynthesis appears to be limited mainly through stomatal conductance and hence intercellular CO2 concentration, rather than by effects on PSII; moderate salinity might stimulate carboxylation capacity. This is in contrast to more extreme halophytes, for which an ability to maintain leaf area can partially offset declining rates of carbon assimilation at high salinity. PMID:17684026

Combined sodium ion sensitivity in agonist binding and internalization of vasopressin V1b receptors.

PubMed

Koshimizu, Taka-Aki; Kashiwazaki, Aki; Taniguchi, Junichi

2016-05-03

Reducing Na(+) in the extracellular environment may lead to two beneficial effects for increasing agonist binding to cell surface G-protein coupled receptors (GPCRs): reduction of Na(+)-mediated binding block and reduce of receptor internalization. However, such combined effects have not been explored. We used Chinese Hamster Ovary cells expressing vasopressin V1b receptors as a model to explore Na(+) sensitivity in agonist binding and receptor internalization. Under basal conditions, a large fraction of V1b receptors is located intracellularly, and a small fraction is in the plasma membrane. Decreases in external Na(+) increased cell surface [(3)H]AVP binding and decreased receptor internalization. Substitution of Na(+) by Cs(+) or NH4(+) inhibited agonist binding. To suppress receptor internalization, the concentration of NaCl, but not of CsCl, had to be less than 50 mM, due to the high sensitivity of the internalization machinery to Na(+) over Cs(+). Iso-osmotic supplementation of glucose or NH4Cl maintained internalization of the V1b receptor, even in a low-NaCl environment. Moreover, iodide ions, which acted as a counter anion, inhibited V1b agonist binding. In summary, we found external ionic conditions that could increase the presence of high-affinity state receptors at the cell surface with minimum internalization during agonist stimulations.

Combined sodium ion sensitivity in agonist binding and internalization of vasopressin V1b receptors

PubMed Central

Koshimizu, Taka-aki; Kashiwazaki, Aki; Taniguchi, Junichi

2016-01-01

Reducing Na+ in the extracellular environment may lead to two beneficial effects for increasing agonist binding to cell surface G-protein coupled receptors (GPCRs): reduction of Na+-mediated binding block and reduce of receptor internalization. However, such combined effects have not been explored. We used Chinese Hamster Ovary cells expressing vasopressin V1b receptors as a model to explore Na+ sensitivity in agonist binding and receptor internalization. Under basal conditions, a large fraction of V1b receptors is located intracellularly, and a small fraction is in the plasma membrane. Decreases in external Na+ increased cell surface [3H]AVP binding and decreased receptor internalization. Substitution of Na+ by Cs+ or NH4+ inhibited agonist binding. To suppress receptor internalization, the concentration of NaCl, but not of CsCl, had to be less than 50 mM, due to the high sensitivity of the internalization machinery to Na+ over Cs+. Iso-osmotic supplementation of glucose or NH4Cl maintained internalization of the V1b receptor, even in a low-NaCl environment. Moreover, iodide ions, which acted as a counter anion, inhibited V1b agonist binding. In summary, we found external ionic conditions that could increase the presence of high-affinity state receptors at the cell surface with minimum internalization during agonist stimulations. PMID:27138239

Electrogenic Na+/Ca2+ Exchange

PubMed Central

Danaceau, Jonathan P.; Lucero, Mary T.

2000-01-01

Olfactory receptor neurons (ORNs) from the squid, Lolliguncula brevis, respond to the odors l-glutamate or dopamine with increases in internal Ca2+ concentrations ([Ca2+]i). To directly asses the effects of increasing [Ca2+]i in perforated-patched squid ORNs, we applied 10 mM caffeine to release Ca2+ from internal stores. We observed an inward current response to caffeine. Monovalent cation replacement of Na+ from the external bath solution completely and selectively inhibited the caffeine-induced response, and ruled out the possibility of a Ca2+-dependent nonselective cation current. The strict dependence on internal Ca2+ and external Na+ indicated that the inward current was due to an electrogenic Na+/Ca2+ exchanger. Block of the caffeine-induced current by an inhibitor of Na+/Ca2+ exchange (50–100 μM 2′,4′-dichlorobenzamil) and reversibility of the exchanger current, further confirmed its presence. We tested whether Na+/Ca2+ exchange contributed to odor responses by applying the aquatic odor l-glutamate in the presence and absence of 2′,4′-dichlorobenzamil. We found that electrogenic Na+/Ca2+ exchange was responsible for ∼26% of the total current associated with glutamate-induced odor responses. Although Na+/Ca2+ exchangers are known to be present in ORNs from numerous species, this is the first work to demonstrate amplifying contributions of the exchanger current to odor transduction. PMID:10828249

Effects of anions and cations on the resting membrane potential of internally perfused barnacle muscle fibres

PubMed Central

Lakshminarayanaiah, N.; Rojas, E.

1973-01-01

1. Single barnacle muscle fibres from Megabalanus psittacus (Darwin) were internally perfused with a number of K salt solutions (200 mM) which were made isotonic to the barnacle saline with sucrose. 2. 200 mM-K acetate solution, in general, was found to be more effective than other solutions of K salts in generating and maintaining stable resting membrane potential of -56·0 ± 0·7 mV (all potentials are referred to the external solutions as ground). The various K salts, on the basis of the magnitude of the resting potential they generated in the muscle fibres, followed the sequence, acetate > isethionate > aspartate > glutamate > fluoride > monohydrogen phosphate > succinate > citrate > sulphate > oxalate > iodobenzoate > ferrocyanide > chlorate > nitrate > chloride > thiocyanate > iodide > bromide > cyanide. 3. The resting potential in muscle fibres perfused with solutions of acetate, aspartate and glutamate increased linearly with the logarithm of the K concentration (slope = 30·4 mV for K acetate and 27·4 for K aspartate and glutamate) when the ionic strength of the solutions was progressively increased from 50 to 650 mM. On the other hand, similar increase of ionic strength beyond 200 mM of solutions of K isethionate, fluoride, monohydrogen phosphate, succinate and citrate depolarized the muscle fibres. 4. Perfusion of acetate solutions of other alkali metal ions gave low values for the resting potential and followed the sequence K > Na > Rb > Li > Cs. Also NH4 and Tris ions gave low values for the resting potential which underwent oscillations associated with the twitching of the fibre and occasionally became positive in value (action potential). 5. Addition of tetraethyl ammonium chloride (TEA-Cl), 20-100 mM, to K acetate solutions (200 mM) depolarized the fibre membrane and the consequent reduction of resting potential varied linearly with the logarithm of TEA concentration. 6. Replacement of chloride ion by acetate or isethionate in the external solution did not change significantly the resting potential although the values were consistently lower by about 2 mV. 7. Complete elimination of K in the external solution and reduction of its ionic strength using sucrose depolarized the muscle fibres by about 27 mV when Na was changed from 475 to 1 mM. Under these conditions, external solutions completely in acetate form gave resting potentials which were more positive than those observed in completely chloride solutions by 6-8 mV. 8. Replacement of Na by Li, Tris, choline, tetramethyl or tetraethyl ammonium ion in the external solution made the values of the resting potential more positive (depolarization). Similarly increasing the concentration of K (or Cs or Rb in place of K) by correspondingly decreasing the concentration of Na in the outside solution depolarized the fibres and the resting potential became zero at a concentration of 280 mM (or 308 or 1500 mM for Rb or Cs, respectively) on extrapolation. PMID:4754874

Sodium-dependent nitrate transport at the plasma membrane of leaf cells of the marine higher plant Zostera marina L.

PubMed

García-Sánchez, M J; Jaime, M P; Ramos, A; Sanders, D; Fernández, J A

2000-03-01

NO(3)(-) is present at micromolar concentrations in seawater and must be absorbed by marine plants against a steep electrochemical potential difference across the plasma membrane. We studied NO(3)(-) transport in the marine angiosperm Zostera marina L. to address the question of how NO(3)(-) uptake is energized. Electrophysiological studies demonstrated that micromolar concentrations of NO(3)(-) induced depolarizations of the plasma membrane of leaf cells. Depolarizations showed saturation kinetics (K(m) = 2.31 +/- 0.78 microM NO(3)(-)) and were enhanced in alkaline conditions. The addition of NO(3)(-) did not affect the membrane potential in the absence of Na(+), but depolarizations were restored when Na(+) was resupplied. NO(3)(-)-induced depolarizations at increasing Na(+) concentrations showed saturation kinetics (K(m) = 0.72 +/- 0.18 mM Na(+)). Monensin, an ionophore that dissipates the Na(+) electrochemical potential, inhibited NO(3)(-)-evoked depolarizations by 85%, and NO(3)(-) uptake (measured by depletion from the external medium) was stimulated by Na(+) ions and by light. Our results strongly suggest that NO(3)(-) uptake in Z. marina is mediated by a high-affinity Na(+)-symport system, which is described here (for the first time to our knowledge) in an angiosperm. Coupling the uptake of NO(3)(-) to that of Na(+) enables the steep inwardly-directed electrochemical potential for Na(+) to drive net accumulation of NO(3)(-) within leaf cells.

Cevimeline-induced monophasic salivation from the mouse submandibular gland: decreased Na+ content in saliva results from specific and early activation of Na+/H+ exchange.

PubMed

Kondo, Yusuke; Nakamoto, Tetsuji; Mukaibo, Taro; Kidokoro, Manami; Masaki, Chihiro; Hosokawa, Ryuji

2011-04-01

Cevimeline and pilocarpine are muscarinic agonists used clinically to treat dry mouth. In this study, we explored fluid secretion from mouse submandibular glands to determine the mechanism of cevimeline, pilocarpine, and an experimentally used agent carbachol. Cevimeline evoked almost the same amount of secretion at concentrations from 30 μM to 1 mM. Pilocarpine also induced secretion at a concentration as low as 1 μM and was the most powerful secretagogue at 10 μM. Secretion was induced by carbachol at 0.1 μM, with maximum secretion at 1.0 μM. Cevimeline induced monophasic secretion at all concentrations tested, whereas higher concentrations of pilocarpine and carbachol induced secretion with variable kinetics, i.e., an initial transient high flow rate, followed by decreased secretion after 2 to 3 min. In the presence of an epithelial Na(+) channel blocker, amiloride, neither carbachol nor pilocarpine affected the Na(+) level of secreted saliva; however, it significantly increased the Na(+) content of cevimeline-induced saliva. The intracellular Ca(2+) response of acinar cells was almost identical among all three agents, although recovery after drug removal was slower for cevimeline and pilocarpine. A profound decrease in intracellular pH was observed during pilocarpine and carbachol treatment, whereas intracellular acidification induced by cevimeline was only seen in the presence of a Na(+)/H(+) exchange inhibitor. When external HCO(3)(-) was removed, cevimeline-induced saliva significantly decreased. These findings suggest that cevimeline specifically activates Na(+)/H(+) exchange and may promote Na(+) reabsorption by stabilizing epithelial sodium channel activity.

Physiological evidence for a sodium-dependent high-affinity phosphate and nitrate transport at the plasma membrane of leaf and root cells of Zostera marina L.

PubMed

Rubio, L; Linares-Rueda, A; García-Sánchez, M J; Fernández, J A

2005-02-01

Zostera marina L. is an angiosperm that grows in a medium in which inorganic phosphate (P(i)) and nitrate (NO(3)(-)) are present in micromolar concentrations and must be absorbed against a steep electrochemical potential gradient. The operation of a Na(+)-dependent NO(3)(-) transport was previously demonstrated in leaf cells of this plant, suggesting that other Na(+)-coupled systems could mediate the uptake of anions. To address this question, P(i) transport was studied in leaves and roots of Z. marina, as well as NO(3)(-) uptake in roots. Electrophysiological studies demonstrated that micromolar concentrations of P(i) induced depolarizations of the plasma membrane of root cells. However, this effect was not observed in leaf cells. P(i)-induced depolarizations showed Michaelis-Menten kinetics (K(m)=1.5+/-0.6 microM P(i); D(max)=7.8+/-0.8 mV), and were not observed in the absence of Na(+). However, depolarizations were restored when Na(+) was resupplied. NO(3)(-) additions also evoked depolarizations of the plasma membrane of root cells only in the presence of Na(+). Both NO(3)(-)- and P(i)-induced depolarizations were accompanied by an increase in cytoplasmic Na(+) activity, detected by Na(+)-sensitive microelectrodes. P(i) net uptake (measured in depletion experiments) was stimulated by Na(+). These results strongly suggest that P(i) uptake in roots of Z. marina is mediated by a high-affinity Na(+)-dependent transport system. Both NO(3)(-) and P(i) transport systems exploit the steep inwardly directed electrochemical potential gradient for Na(+), considering the low cytoplasmic Na(+) activity (10.7+/-3.3 mM Na(+)) and the high external Na(+) concentration (500 mM Na(+)).

Sodium and Potassium Fluxes and Compartmentation in Roots of Atriplex and Oat 1

PubMed Central

Mills, David; Robinson, Kenneth; Hodges, Thomas K.

1985-01-01

K+ and Na+ fluxes and ion content have been studied in roots of Atriplex nummularia Lindl. and Avena sativa L. cv Goodfield grown in 3 millimolar K+ with or without 3 or 50 millimolar NaCl. Compartmental analysis was carried out with entire root systems under steady-state conditions. Increasing ambient Na+ concentrations from 0 to 50 millimolar altered K+, in Atriplex, as follows: slightly decreased the cytoplasmic content (Qc), the vacuolar content (Qv), and the plasma membrane influx and efflux. Xylem transport for K+ decreased by 63% in Atriplex. For oat roots, similar increases in Na+ altered K+ parameters as follows: plasma membrane influx and efflux decreased by about 80%. Qc decreased by 65%, and xylem transport decreased by 91%. No change, however, was observed in Qv for K+. Increasing ambient Na+ resulted in higher (3 to 5-fold) Na+ fluxes across the plasma membrane and in Qc of both species. In Atriplex, Na+ fluxes across the tonoplast and Qv increased as external Na+ was increased. In oat, however, no significant change was observed in Na+ flux across the tonoplast or in Qv as external Na+ was increased. In oat roots, Na+ reduced K+ uptake markedly; in Atriplex, this was not as pronounced. However, even at high Na+ levels, the influx transport system at the plasma membrane of both species preferred K+ over Na+. Based upon the Ussing-Teorell equation, it was concluded that active inward transport of K+ occurred across the plasma membrane, and passive movement of K+ occurred across the tonoplast in both species. Na+, in oat roots, was actively pumped out of the cytoplasm to the exterior, whereas, in Atriplex, Na+ was passively distributed between the free space, cytoplasm, and vacuole. PMID:16664273

Sodium and potassium fluxes and compartmentation in roots of atriplex and oat.

PubMed

Mills, D; Robinson, K; Hodges, T K

1985-07-01

K(+) and Na(+) fluxes and ion content have been studied in roots of Atriplex nummularia Lindl. and Avena sativa L. cv Goodfield grown in 3 millimolar K(+) with or without 3 or 50 millimolar NaCl. Compartmental analysis was carried out with entire root systems under steady-state conditions.Increasing ambient Na(+) concentrations from 0 to 50 millimolar altered K(+), in Atriplex, as follows: slightly decreased the cytoplasmic content (Q(c)), the vacuolar content (Q(v)), and the plasma membrane influx and efflux. Xylem transport for K(+) decreased by 63% in Atriplex. For oat roots, similar increases in Na(+) altered K(+) parameters as follows: plasma membrane influx and efflux decreased by about 80%. Q(c) decreased by 65%, and xylem transport decreased by 91%. No change, however, was observed in Q(v) for K(+). Increasing ambient Na(+) resulted in higher (3 to 5-fold) Na(+) fluxes across the plasma membrane and in Q(c) of both species. In Atriplex, Na(+) fluxes across the tonoplast and Q(v) increased as external Na(+) was increased. In oat, however, no significant change was observed in Na(+) flux across the tonoplast or in Q(v) as external Na(+) was increased. In oat roots, Na(+) reduced K(+) uptake markedly; in Atriplex, this was not as pronounced. However, even at high Na(+) levels, the influx transport system at the plasma membrane of both species preferred K(+) over Na(+).Based upon the Ussing-Teorell equation, it was concluded that active inward transport of K(+) occurred across the plasma membrane, and passive movement of K(+) occurred across the tonoplast in both species. Na(+), in oat roots, was actively pumped out of the cytoplasm to the exterior, whereas, in Atriplex, Na(+) was passively distributed between the free space, cytoplasm, and vacuole.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harrington, Timothy D.; Babauta, Jerome T.; Davenport, Emily K.

We investigated ion transport limitations on 3D graphite felt electrodes by growing Geobacter sulfurreducens biofilms with advection to eliminate external mass transfer limitations. We characterized ion transport limitations by: (i) showing that serially increasing NaCl concentration up to 200mM increased current linearly up to a total of þ273% vs. 0mM NaCl under advective conditions; (ii) growing the biofilm with a starting concentration of 200mM NaCl, which led to a maximum current increase of 400% vs. current generation without NaCl, and (iii) showing that un-colonized surface area remained even after steadystate current was reached. After accounting for iR effects, we confirmedmore » that the excess surface area existed despite a non-zero overpotential. The fact that the biofilm was constrained from colonizing and producing further current under these conditions confirmed the biofilms under study here were ion transport-limited. Our work demonstrates that the use of high surface area electrodes may not increase current density when the system design allows ion transport limitations to become dominant.« less

Modeling the effects of sodium chloride, acetic acid, and intracellular pH on survival of Escherichia coli O157:H7.

PubMed

Hosein, Althea M; Breidt, Frederick; Smith, Charles E

2011-02-01

Microbiological safety has been a critical issue for acid and acidified foods since it became clear that acid-tolerant pathogens such as Escherichia coli O157:H7 can survive (even though they are unable to grow) in a pH range of 3 to 4, which is typical for these classes of food products. The primary antimicrobial compounds in these products are acetic acid and NaCl, which can alter the intracellular physiology of E. coli O157:H7, leading to cell death. For combinations of acetic acid and NaCl at pH 3.2 (a pH value typical for non-heat-processed acidified vegetables), survival curves were described by using a Weibull model. The data revealed a protective effect of NaCl concentration on cell survival for selected acetic acid concentrations. The intracellular pH of an E. coli O157:H7 strain exposed to acetic acid concentrations of up to 40 mM and NaCl concentrations between 2 and 4% was determined. A reduction in the intracellular pH was observed for increasing acetic acid concentrations with an external pH of 3.2. Comparing intracellular pH with Weibull model predictions showed that decreases in intracellular pH were significantly correlated with the corresponding times required to achieve a 5-log reduction in the number of bacteria.

Salt-induction of betaine aldehyde dehydrogenase mRNA, protein, and enzymatic activity in sugar beet. [Beta vulgaris L

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCue, K.F.; Hanson, A.D.

1991-05-01

In Chenopodiaceae such as sugar beet (Beta vulgaris L.), glycine betaine (betaine) accumulates in response to drought or salinity stress and functions in the cytoplasm as a compatible osmolyte. The last enzyme in the biosynthetic pathway, betaine aldehyde dehydrogenase (BADH), increases as much as 4-fold in response to rising salinity in the external medium. This increase is accompanied by an increase in both protein and mRNA levels. The steady state increases in BADH were examined at a series of NaCl concentrations from 100 to 500 mM NaCl. BADH protein levels were examined by native PAGE, and by western blot analysismore » using antibodies raised against BADH purified from spinach. mRNA levels were examined by northern plot analysis of total RNA isolated from the leaves and hybridized with a sugar beet BADH cDNA clone. The time course for BADH mRNA induction was determined in a salt shock experiment utilizing 400 mM NaCl added to the external growth medium. Disappearance of BADH was examined in a salt relief experiment using plants step-wise salinized to 500 mM NaCl and then returned to 0 mM NaCl.« less

Origin and voltage dependence of asparagine-induced depolarization in intestinal cells of Xenopus embryo.

PubMed Central

Bergman, C; Bergman, J

1985-01-01

The kinetics and voltage dependence of asparagine (Asn)-induced depolarization in endoderm cells from Xenopus laevis embryos were analysed using current-clamp techniques. The depolarization is assumed to reflect the activation of an amino acid membrane carrier; it is accompanied by a slight increase in membrane resistance and cannot be explained by only the electrogenic character of the Asn carrier. It is proposed that the Asn depolarization arises, at least in part, from the decrease of the permeability ratio PK/PNa indirectly associated with the Na-coupled amino acid uptake. At room temperature (20-23 degrees C) the Asn response develops according to a single exponential function whose time constant is correlated with the final level of depolarization. Both amplitude and rise time of the depolarization are sensitive to variations of membrane potential and changes in Asn or Na external concentrations. Lowering the temperature decreases the amplitude of the Asn depolarization and increases its rise time with a Q10 factor of two; the kinetics remain of the Michaelis-Menten type, with a marked decrease in delta Emax and no change in Km. When the holding potential is altered by depolarizing and hyperpolarizing currents, the Asn response varies according to a bell-shaped characteristic presenting an optimum near the normal resting level. Membrane depolarizations induced by Na/K-pump inhibitors or high external K concentrations reduce the size of the Asn response; repolarizing the cell by current injection does not reverse the inhibitory effect of external K ions. Hyperpolarizing the membrane with a K-free Ringer solution increases the amplitude of the Asn response. In all these cases a decrease in delta Emax accounts for the apparent voltage sensitivity of the carrier mechanism. When induced by alterations of [K]o, an additional change in Km is observed, suggesting a K/Na-competitive inhibition of the Asn carrier. The results are discussed in terms of the amino acid carrier and passive membrane properties. It is suggested that the outward K-electrochemical gradient contributes an additional source of energy to the Na-dependent Asn uptake. PMID:4057089

Mechanism of potassium ion uptake by the Na+/K+-ATPase

PubMed Central

Castillo, Juan P.; Rui, Huan; Basilio, Daniel; Das, Avisek; Roux, Benoît; Latorre, Ramon; Bezanilla, Francisco; Holmgren, Miguel

2015-01-01

The Na+/K+-ATPase restores sodium (Na+) and potassium (K+) electrochemical gradients dissipated by action potentials and ion-coupled transport processes. As ions are transported, they become transiently trapped between intracellular and extracellular gates. Once the external gate opens, three Na+ ions are released, followed by the binding and occlusion of two K+ ions. While the mechanisms of Na+ release have been well characterized by the study of transient Na+ currents, smaller and faster transient currents mediated by external K+ have been more difficult to study. Here we show that external K+ ions travelling to their binding sites sense only a small fraction of the electric field as they rapidly and simultaneously become occluded. Consistent with these results, molecular dynamics simulations of a pump model show a wide water-filled access channel connecting the binding site to the external solution. These results suggest a mechanism of K+ gating different from that of Na+ occlusion. PMID:26205423

Inward current activated by carbachol in rat intestinal smooth muscle cells.

PubMed Central

Ito, S; Ohta, T; Nakazato, Y

1993-01-01

1. Carbachol (0.1 mM or 10 microM)-evoked inward currents were studied with standard and perforated whole-cell patch clamp techniques in smooth muscle cells isolated from rat small intestine. The intracellular free Ca2+ concentration was monitored simultaneously with the fura-2 method. 2. With a K(+)-containing pipette solution, carbachol produced an inward current at -60 mV and a large outward current at -20 mV. 3. When NaCl was substituted for KCl in the external and pipette solutions, carbachol elicited inward currents at holding potentials more inside-negative than 0 mV. The reversal potential of the carbachol-induced current altered when external chloride (-0.9 mV) was replaced by iodide (-21.2 mV), thiocyanate (-27.0 mV) and glutamate (18.2 mV). The carbachol-induced current at -60 mV was slightly decreased by the replacement of external NaCl with Tris-Cl. 4. The carbachol-induced inward current at -60 mV was accompanied by an increase in the intracellular concentration of free Ca2+. Both responses to carbachol were observed 2 min after exposure of the cells to a Ca(2+)-free solution containing 2 mM EGTA. 5. Intracellular application of heparin inhibited the inward current and Ca2+ transient responses to carbachol but not those to caffeine (10 mM). An inward current and Ca2+ transient were elicited after the patch membrane was ruptured at -60 mV, using a patch pipette containing inositol 1,4,5-trisphosphate (InsP3). 6. It is concluded that the carbachol-induced inward current is due to increases in membrane Cl- and Na+ conductances. Ca2+ released from InsP3-sensitive stores may play a role in increasing both conductances. PMID:7508506

Effect of Azotobacter vinelandii and compatible solutes on germination wheat seeds and root concentrations of sodium and potassium under salt stress.

PubMed

Silini, A; Silini-Chérif, H; Ghoul, M

2012-02-01

The effect of plant growth-promoting Rhizobacteria (PGPR) and exogenous application of compatible solutes on seed germination and root concentrations of sodium and potassium of two wheat varieties (Triticum durum L.) were evaluated under saline stress. In this experiment, Azotobacter vinelandii strain DSM85, glycine betaine and proline were used. Inoculated seeds for each variety were placed on Whatman paper in 9 cm Petri dishes containing 15 mL of distilled water or NaCl solutions at various concentrations (control, 100, 200, 300 mM) supplemented with or without glycine betaine (GB) or proline at 5 mM. The results indicated that addition of proline (5 mM) stimulated the production of indol acetic acid and the growth of A. vinelandii at 200 and 300 mM NaCl, respectively. The germination rate index and the germination final percentage decreased significantly (p < 0.05) with increasing salinity level. The germination was significantly diminished at 300 mM with significant variation among varieties and Waha variety had higher germination percentage than Bousselam variety. Inoculation of seeds by A. vinelandii and exogenous application of proline had significantly positive effect on the germination at this concentration of NaCl. The rate of accumulation of Na+ in roots was important at 100 mM and increased at 200 mM. The concentration of K+ decreased when salinity increased. The effect of inoculation or inoculation with proline decreased the accumulation of Na' and reduced the loss of K+ under salt stress. From the present study we can conclude that the use of A. vinelandii strain DSM85 and external application of low concentrations of proline on seeds might be considered as a strategy for the protection of plants under saline stress.

Down-regulation of voltage-dependent sodium channels initiated by sodium influx in developing neurons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dargent, B.; Couraud, F.

1990-08-01

To address the issue of whether regulatory feedback exists between the electrical activity of a neuron and ion-channel density, the authors investigated the effect of Na{sup +}-channel activators (scorpion {alpha} toxin, batrachotoxin, and veratridine) on the density of Na{sup +} channels in fetal rat brain neurons in vitro. A partial but rapid (t{sub 1/2}, 15 min) disappearance of surface Na{sup +} channels was observed as measured by a decrease in the specific binding of ({sup 3}H)saxitoxin and {sup 125}I-labeled scorpion {beta} toxin and a decrease in specific {sup 22}Na{sup +} uptake. Moreover, the increase in the number of Na{sup +}more » channels that normally occurs during neuronal maturation in vitro was inhibited by chronic channel activator treatment. The induced disappearance of Na{sup +} channels was abolished by tetrodotoxin, was found to be dependent on the external Na{sup +} concentration, and was prevented when either choline (a nonpermeant ion) or Li{sup +} (a permeant ion) was substituted for Na{sup +}. Amphotericin B, a Na{sup +} ionophore, and monensin were able to mimick the effect of Na{sup +}-channel activators, while a KCl depolarization failed to do this. This feedback regulation seems to be a neuronal property since Na{sup +}-channel density in cultured astrocytes was not affected by channel activator treatment or by amphotericin B. The present evidence suggests that an increase in intracellular Na{sup +} concentration, whether elicited by Na{sup +}-channel activators or mediated by a Na{sup +} ionophore, can induce a decrease in surface Na{sup +} channels and therefore is involved in down-regulation of Na{sup +}-channel density in fetal rat brain neurons in vitro.« less

External K+ dependence of strong inward rectifier K+ channel conductance is caused not by K+ but by competitive pore blockade by external Na.

PubMed

Ishihara, Keiko

2018-06-15

Strong inward rectifier K + (sKir) channels determine the membrane potentials of many types of excitable and nonexcitable cells, most notably the resting potentials of cardiac myocytes. They show little outward current during membrane depolarization (i.e., strong inward rectification) because of the channel blockade by cytoplasmic polyamines, which depends on the deviation of the membrane potential from the K + equilibrium potential ( V - E K ) when the extracellular K + concentration ([K + ] out ) is changed. Because their open - channel conductance is apparently proportional to the "square root" of [K + ] out , increases/decreases in [K + ] out enhance/diminish outward currents through sKir channels at membrane potentials near their reversal potential, which also affects, for example, the repolarization and action-potential duration of cardiac myocytes. Despite its importance, however, the mechanism underlying the [K + ] out dependence of the open sKir channel conductance has remained elusive. By studying Kir2.1, the canonical member of the sKir channel family, we first show that the outward currents of Kir2.1 are observed under the external K + -free condition when its inward rectification is reduced and that the complete inhibition of the currents at 0 [K + ] out results solely from pore blockade caused by the polyamines. Moreover, the noted square-root proportionality of the open sKir channel conductance to [K + ] out is mediated by the pore blockade by the external Na + , which is competitive with the external K + Our results show that external K + itself does not activate or facilitate K + permeation through the open sKir channel to mediate the apparent external K + dependence of its open channel conductance. The paradoxical increase/decrease in outward sKir channel currents during alternations in [K + ] out , which is physiologically relevant, is caused by competition from impermeant extracellular Na . © 2018 Ishihara.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Conte, F.P.; Droukas, P.C.; Ewing, R.D.

The development of brine shrimp embryos, A. salina, incubated in media of increasing salinity is delayed as evidenced by decreased emergence and lengthening of the time for excystment. Prehydration of cysts at low temperature (3/sup 0/C) for four to ten hours in distilled water eliminates asynchrony of the population in regard to emergency and hatching times. Internal concentration glycerol, which controls the rate of hydration of the cyst stage, is markedly affected by external salinity. Water balance in the cyst stage is maintained via the trehalose-glycerol mechanism which generates a simple passive diffusional gradient across the chitinous shell allowing watermore » to pass. Non-gaseous solutes, such as sodium and glycerol, do not pass through the chitin-membrane barrier. Rupturing the shell by emergence initiates the onset of the prenaupliar stage; it is accompanied by the appearance of large amounts of free glycerol in the external media, decreasing levels of internal glycerol, increased concentrations of internal sodium and the first detectable levels of the cationic transport enzyme, Na + K-ATPase. Continual loss of free glycerol through the cellular and hatching membranes causes the excysting embryo to convert from a trehalose-glycerol mechanism to a sodium-mediated transport system in order to maintain larval water balance. Ontogeny of the sodium regulating mechanism requires formation of Na + K-ATPase. The production of new Na + K-ATPase, as evidenced by incorporation of /sup 14/C-amino acids into polypeptide subunits and density-gradient centrifugation of radioactive membrane vesicles rich in Na + K-ATPase, may play an important role and, if so, it appears to be initiated between E-1 and E-2 stages.« less

Interaction of external alkali metal ions with the Na-K pump of human erythrocytes: a comparison of their effects on activation of the pump and on the rate of ouabain binding

PubMed Central

1978-01-01

The effects of external alkali metal ions on the rate of ouabain binding and on the rate of the Na-K pump were examined in human red blood cells. In Na-containing solutions, K, Cs, and Li decreased the rate of ouabain binding. For K and Cs, the kinetics of this effect were similar to those for their activation of the pump. In Na-free (choline- substituted) solutions the rate of ouabain binding was decreased by K whereas it was promoted by Cs and Li. External Na increased the rate of ouabain binding whether or not external K was present, and the kinetics of this effect were not the same as those for inhibition of the pump by Na. These findings are interpreted to mean that not only do the cations affect ouabain binding at the external loading sites on the pump from which ions are translocated inward, but that there are additional sites on the external aspect of the pump at which cations can promote ouabain binding, and that these sites can be occupied by Li, Na, and Cs. It is postulated that these latter sites are those from which Na is discharged after outward translocation by the pump. PMID:702113

Nitrate transport in the cyanobacterium Anacystis nidulans R2. Kinetic and energetic aspects.

PubMed Central

Rodríguez, R; Lara, C; Guerrero, M G

1992-01-01

Nitrate transport has been studied in the cyanobacterium Anacystis nidulans R2 by monitoring intracellular nitrate accumulation in intact cells of the mutant strain FM6, which lacks nitrate reductase activity and is therefore unable to reduce the transported nitrate. Kinetic analysis of nitrate transport as a function of external nitrate concentration revealed apparent substrate inhibition, with a peak velocity at 20-25 microM-nitrate. A Ks (NO3-) of 1 microM was calculated. Nitrate transport exhibited a stringent requirement for Na+. Neither Li+ nor K+ could substitute for Na+. Monensin depressed nitrate transport in a concentration-dependent manner, inhibition being more than 60% at 2 microM, indicating that the Na(+)-dependence of active nitrate transport relies on the maintenance of a Na+ electrochemical gradient. The operation of an Na+/NO3- symport system is suggested. Nitrite behaved as an effective competitive inhibitor of nitrate transport, with a Ki (NO2-) of 3 microM. The time course of nitrite inhibition of nitrate transport was consistent with competitive inhibition by mixed alternative substrates. Nitrate and nitrite might be transported by the same carrier. PMID:1554347

Excess surface area in bioelectrochemical systems causes ion transport limitations.

PubMed

Harrington, Timothy D; Babauta, Jerome T; Davenport, Emily K; Renslow, Ryan S; Beyenal, Haluk

2015-05-01

We investigated ion transport limitations on 3D graphite felt electrodes by growing Geobacter sulfurreducens biofilms with advection to eliminate external mass transfer limitations. We characterized ion transport limitations by: (i) showing that serially increasing NaCl concentration up to 200 mM increased current linearly up to a total of +273% vs. 0 mM NaCl under advective conditions; (ii) growing the biofilm with a starting concentration of 200 mM NaCl, which led to a maximum current increase of 400% vs. current generation without NaCl, and (iii) showing that un-colonized surface area remained even after steady-state current was reached. After accounting for iR effects, we confirmed that the excess surface area existed despite a non-zero overpotential. The fact that the biofilm was constrained from colonizing and producing further current under these conditions confirmed the biofilms under study here were ion transport-limited. Our work demonstrates that the use of high surface area electrodes may not increase current density when the system design allows ion transport limitations to become dominant. © 2014 Wiley Periodicals, Inc.

Physiological Response of Lactobacillus plantarum to Salt and Nonelectrolyte Stress

PubMed Central

Glaasker, Erwin; Tjan, Frans S. B.; Ter Steeg, Pieter F.; Konings, Wil N.; Poolman, Bert

1998-01-01

In this report, we compared the effects on the growth of Lactobacillus plantarum of raising the medium molarity by high concentrations of KCl or NaCl and iso-osmotic concentrations of nonionic compounds. Analysis of cellular extracts for organic constituents by nuclear magnetic resonance spectroscopy showed that salt-stressed cells do not contain detectable amounts of organic osmolytes, whereas sugar-stressed cells contain sugar (and some sugar-derived) compounds. The cytoplasmic concentrations of lactose and sucrose in growing cells are always similar to the concentrations in the medium. By using the activity of the glycine betaine transport system as a measure of hyperosmotic conditions, we show that, in contrast to KCl and NaCl, high concentrations of sugars (lactose or sucrose) impose only a transient osmotic stress because external and internal sugars equilibrate after some time. Analysis of lactose (and sucrose) uptake also indicates that the corresponding transport systems are neither significantly induced nor activated directly by hyperosmotic conditions. The systems operate by facilitated diffusion and have very high apparent affinity constants for transport (>50 mM for lactose), which explains why low sugar concentrations do not protect against hyperosmotic conditions. We conclude that the more severe growth inhibition by salt stress than by equiosmolal concentrations of sugars reflects the inability of the cells to accumulate K+ (or Na+) to levels high enough to restore turgor as well as deleterious effects of the electrolytes intracellularly. PMID:9721316

Properties of whole cell currents in isolated olfactory neurons from the chilean toad Caudiverbera caudiverbera.

PubMed

Delgado, R; Labarca, P

1993-06-01

Isolated olfactory neurons from the chilean toad Caudiverbera caudiverbera were found to possess a same set of currents. Outward currents, made of a delayed rectifier and a Ca(2+)-dependent component, were blocked by replacing K+ by Cs+ in the patch pipette, in the presence of millimolar concentrations of tetraethylammonium and 4-aminopyridine in the external solution. Inward currents were made of a transient and a maintained component. The transient was abolished in the absence of external Na+ and was blocked by tetrodotoxin, with an apparent dissociation constant (KDapp) of 25.4 +/- 0.3 nM. The maintained inward currents were suppressed on removing external Ca2+, could be carried also by Ba2+, and were selectively blocked by Cd2+ (KDapp = 3.2 +/- 1.3 microM). A variety of agents found to block the maintained Ca2+ inward currents, including Co2+ and Ni2+, at millimolar concentrations, and nifedipine, verapamil, amiloride, and the amiloride analogue benzamil, at micromolar concentrations, were also effective in either modifying the gating of, or in blocking, the transient inward currents.

The Bacterial Flagellar Type III Export Gate Complex Is a Dual Fuel Engine That Can Use Both H+ and Na+ for Flagellar Protein Export

PubMed Central

Minamino, Tohru; Morimoto, Yusuke V.; Hara, Noritaka; Aldridge, Phillip D.; Namba, Keiichi

2016-01-01

The bacterial flagellar type III export apparatus utilizes ATP and proton motive force (PMF) to transport flagellar proteins to the distal end of the growing flagellar structure for self-assembly. The transmembrane export gate complex is a H+–protein antiporter, of which activity is greatly augmented by an associated cytoplasmic ATPase complex. Here, we report that the export gate complex can use sodium motive force (SMF) in addition to PMF across the cytoplasmic membrane to drive protein export. Protein export was considerably reduced in the absence of the ATPase complex and a pH gradient across the membrane, but Na+ increased it dramatically. Phenamil, a blocker of Na+ translocation, inhibited protein export. Overexpression of FlhA increased the intracellular Na+ concentration in the presence of 100 mM NaCl but not in its absence, suggesting that FlhA acts as a Na+ channel. In wild-type cells, however, neither Na+ nor phenamil affected protein export, indicating that the Na+ channel activity of FlhA is suppressed by the ATPase complex. We propose that the export gate by itself is a dual fuel engine that uses both PMF and SMF for protein export and that the ATPase complex switches this dual fuel engine into a PMF-driven export machinery to become much more robust against environmental changes in external pH and Na+ concentration. PMID:26943926

The Bacterial Flagellar Type III Export Gate Complex Is a Dual Fuel Engine That Can Use Both H+ and Na+ for Flagellar Protein Export.

PubMed

Minamino, Tohru; Morimoto, Yusuke V; Hara, Noritaka; Aldridge, Phillip D; Namba, Keiichi

2016-03-01

The bacterial flagellar type III export apparatus utilizes ATP and proton motive force (PMF) to transport flagellar proteins to the distal end of the growing flagellar structure for self-assembly. The transmembrane export gate complex is a H+-protein antiporter, of which activity is greatly augmented by an associated cytoplasmic ATPase complex. Here, we report that the export gate complex can use sodium motive force (SMF) in addition to PMF across the cytoplasmic membrane to drive protein export. Protein export was considerably reduced in the absence of the ATPase complex and a pH gradient across the membrane, but Na+ increased it dramatically. Phenamil, a blocker of Na+ translocation, inhibited protein export. Overexpression of FlhA increased the intracellular Na+ concentration in the presence of 100 mM NaCl but not in its absence, suggesting that FlhA acts as a Na+ channel. In wild-type cells, however, neither Na+ nor phenamil affected protein export, indicating that the Na+ channel activity of FlhA is suppressed by the ATPase complex. We propose that the export gate by itself is a dual fuel engine that uses both PMF and SMF for protein export and that the ATPase complex switches this dual fuel engine into a PMF-driven export machinery to become much more robust against environmental changes in external pH and Na+ concentration.

Renal hypertension prevents run training modification of cardiomyocyte diastolic Ca2+ regulation in male rats.

PubMed

Palmer, B M; Lynch, J M; Snyder, S M; Moore, R L

2001-06-01

The combined effects of endurance run training and renal hypertension on cytosolic Ca2+ concentration ([Ca2+]c) dynamics and Na+-dependent Ca2+ regulation in rat left ventricular cardiomyocytes were examined. Male Fischer 344 rats underwent stenosis of the left renal artery [hypertensive (Ht), n = 18] or a sham operation [normotensive (Nt), n = 20]. One-half of the rats from each group were treadmill trained for >16 wk. Cardiomyocyte fura 2 fluorescence ratio transients were recorded for 7 min during electrical pacing at 0.5 Hz, 2 mM extracellular Ca2+ concentration, and 29 degrees C. The rate of [Ca2+]c decline was not changed by run training in the Nt group but was reduced in the Ht group. At 7 min, cardiomyocytes were exposed to 10 mM caffeine in the absence of Na+ and Ca2+, which triggered sarcoplasmic reticular Ca2+ release and suppressed Ca2+ efflux via Na+/Ca2+ exchanger. External Na+ was then added, and Na+-dependent Ca2+ efflux rate was recorded. Treadmill training significantly enhanced Na+-dependent Ca2+ efflux rate under these conditions in the Nt group but not in the Ht group. These data provide evidence that renal hypertension prevents the normal run training-induced modifications in diastolic [Ca2+]c regulation mechanisms, including Na+/Ca2+ exchanger.

Fundamental properties of local anesthetics: half-maximal blocking concentrations for tonic block of Na+ and K+ channels in peripheral nerve.

PubMed

Bräu, M E; Vogel, W; Hempelmann, G

1998-10-01

Local anesthetics suppress excitability by interfering with ion channel function. Ensheathment of peripheral nerve fibers, however, impedes diffusion of drugs to the ion channels and may influence the evaluation of local anesthetic potencies. Investigating ion channels in excised membrane patches avoids these diffusion barriers. We investigated the effect of local anesthetics with voltage-dependent Na+ and K+ channels in enzymatically dissociated sciatic nerve fibers of Xenopus laevis using the patch clamp method. The outside-out configuration was chosen to apply drugs to the external face of the membrane. Local anesthetics reversibly blocked the transient Na+ inward current, as well as the steady-state K+ outward current. Half-maximal tonic inhibiting concentrations (IC50), as obtained from concentration-effect curves for Na+ current block were: tetracaine 0.7 microM, etidocaine 18 microM, bupivacaine 27 microM, procaine 60 microM, mepivacaine 149 microM, and lidocaine 204 microM. The values for voltage-dependent K+ current block were: bupivacaine 92 microM, etidocaine 176 microM, tetracaine 946 microM, lidocaine 1118 microM, mepivacaine 2305 microM, and procaine 6302 microM. Correlation of potencies with octanol:buffer partition coefficients (logP0) revealed that ester-bound local anesthetics were more potent in blocking Na+ channels than amide drugs. Within these groups, lipophilicity governed local anesthetic potency. We conclude that local anesthetic action on peripheral nerve ion channels is mediated via lipophilic drug-channel interactions. Half-maximal blocking concentrations of commonly used local anesthetics for Na+ and K+ channel block were determined on small membrane patches of peripheral nerve fibers. Because drugs can directly diffuse to the ion channel in this model, these data result from direct interactions of the drugs with ion channels.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Katz, D.M.; Kimelberg, H.K.

Primary astrocyte cultures prepared from the cerebral cortices of neonatal rats showed significant accumulation of serotonin (5-hydroxytryptamine; (/sup 3/H)-5-HT). At concentrations in the range of 0.01 to 0.7 microM (/sup 3/H)-5-HT, this uptake was 50 to 85% Na+ dependent and gave a Km of 0.40 +/- 0.11 microM (/sup 3/H)-5-HT and a Vmax of 6.42 +/- 0.85 (+/- SEM) pmol of (/sup 3/H)-5-HT/mg of protein/4 min for the Na+-dependent component. In the absence of Na+ the uptake was nonsaturable. Omission of the monoamine oxidase inhibitor pargyline markedly reduced the Na+-dependent component of (/sup 3/H)-5-HT uptake but had a negligible effectmore » on the Na+-independent component. This suggest significant oxidative deamination of serotonin after it has been taken up by the high affinity system, followed by release of its metabolite. The authors estimated that this system enabled the cells to concentrate (/sup 3/H)-5-HT up to 44-fold at an external (/sup 3/H)-5-HT concentration of 10(-7) M. Inhibition of (/sup 3/H)-5-HT uptake by a number of clinically effective antidepressants was also consistent with a specific high affinity uptake mechanism for 5-HT, the order of effectiveness of inhibition being chlorimipramine greater than fluoxetine greater than imipramine = amitriptyline greater than desmethylimipramine greater than iprindole greater than mianserin. Uptake of (/sup 3/H)-5-HT was dependent on the presence of Cl- as well as Na+ in the medium, and the effect of omission of both ions was nonadditive. Varying the concentration of K+ in the media from 1 to 50 mM had a limited effect on (/sup 3/H)-5-HT uptake.« less

The secretion of alkali metal ions by the perfused cat pancreas as influenced by the composition and osmolality of the external environment and by inhibitors of metabolism and Na+, K+-ATPase activity

PubMed Central

Case, R. M.; Scratcherd, T.

1974-01-01

1. The secretion of sodium, potassium and lithium has been studied in the isolated cat pancreas, perfused with bicarbonate buffered saline solutions of varying composition and osmolality, and stimulated maximally with secretin. 2. Under isosmolal conditions, when perfusate sodium chloride was replaced by sucrose, sodium secretion and potassium secretion were directly related to perfusate sodium concentration, [Na]p. 3. When osmolality was varied by increasing or decreasing perfusate sodium chloride concentration, the secretion of sodium and of potassium were maximal at [Na]p of about 120 and 80 mM respectively. 4. At a given [Na]p, sodium secretion was greater under hypo-osmolal conditions than under isosmolal conditions. 5. When potassium concentration was varied over the range 0-130 mM under isosmolal conditions, by adjusting perfusate NaCl concentration, the secretion of potassium and of sodium were maximal at [K]p of about 50 and 10 mM respectively. Water flux was maximal at a [K]p of 10-15 mM. The concentration of potassium in the secretion was almost identical with that in the perfusate over the whole concentration range. 6. Replacement of perfusate sodium by lithium reduced the volume of secretion, though a small secretion was maintained even in the complete absence of sodium. The concentration of lithium in the secretion was generally slightly greater than that in the perfusate. 7. Omission of potassium from the perfusate reduced secretion by about 65%. Rubidium was a complete substitute for potassium; caesium was not. 8. Energy for secretion is derived largely from oxidative phosphorylation. Secretion was reduced by more than 90% under anaerobic conditions and in the presence of dinitrophenol or cyanide. Removal of glucose from the perfusate reduced secretion by more than 50% within 30 min; lactate was a complete substitute for glucose. 9. Ouabain, ethacrinic acid and frusimide, known inhibitors of Na+, K+-ATPase activity, all inhibited pancreatic electrolyte secretion. 10. The observations are interpreted with reference to the nature of active transport processes involved in pancreatic electrolyte secretion. PMID:4281836

Relative contributions of the fraction of unfrozen water and of salt concentration to the survival of slowly frozen human erythrocytes.

PubMed Central

Mazur, P; Rall, W F; Rigopoulos, N

1981-01-01

As suspensions of cells freeze, the electrolytes and other solutes in the external solution concentrate progressively, and the cells undergo osmotic dehydration if cooling is slow. The progressive concentration of solute comes about as increasing amounts of pure ice precipitate out of solution and cause the liquid-filled channels in which the cells are sequestered to dwindle in size. The consensus has been that slow freezing injury is related to the composition of the solution in these channels and not to the amount of residual liquid. The purpose of the research reported here was to test this assumption on human erythrocytes. Ordinarily, solute concentration and the amount of liquid in the unfrozen channels are inversely coupled. To vary them independently, one must vary the initial solute concentration. Two solutes were used here: NaCl and the permeating protective additive glycerol. To vary the total initial solute concentration while holding the mass ratio of glycerol to NaCl constant, we had to allow the NaCl tonicity to depart from isotonic. Specifically, human red cells were suspended in solutions with weight ratios of glycerol to NaCl of either 5.42 or 11.26, where the concentrations of NaCl were 0.6, 0.75, 1.0, 2.0, 3.0, or 4.0 times isotonic. Samples were then frozen to various subzero temperatures, which were chosen to produce various molalities of NaCl (0.24-3.30) while holding the fraction of unfrozen water constant, or conversely to produce various unfrozen fractions (0.03-0.5) while holding the molality of salt constant. (Not all combinations of these values were possible). The following general findings emerged: (a) few cells survived the freezing of greater than 90% of the extracellular water regardless of the salt concentration in the residual unfrozen portion. (b) When the fraction of frozen water was less than 75% the majority of the cells survived even when the salt concentration in the unfrozen portion exceeded 2 molal. (c) Salt concentration affected survival significantly only when the frozen fraction lay between 75 and 90%. To find a major effect on survival of the fraction of water that remains unfrozen was unexpected. It may require major modifications in how cryobiologists view solution-effect injury and its prevention. PMID:7326328

Ca/Na selectivity coefficients from the Poisson-Boltzmann theory

NASA Astrophysics Data System (ADS)

Hedström, Magnus; Karnland, Ola

As a model for ion equilibrium in montmorillonite, the Poisson-Boltzmann (PB) equation was solved for two parallel charged surfaces in contact with an external NaCl/CaCl 2 mixed solution. The ion concentration profiles in the montmorillonite interlayer were obtained from the PB equation and integration of those gave the occupancy of Na + and Ca 2+ in the clay. That information together with the composition of the external electrolyte were then used for the calculation of the Gaines-Thomas selectivity coefficient K GT. The predictions from the model were compared to experimental data from batch as well as compacted conditions, and the agreement was generally good. With a surface layer-charge density of one unit charge per 145 Å 2, which is close to the value for Wyoming-type montmorillonite, the calculated selectivity coefficients were found to vary from about 4 in batch to 8 in compacted montmorillonite with dry density ∼1700 kg/m 3. From the point of view of assessing the evolution, with regard to sodium-calcium ion exchange, of the bentonite buffer in a repository for spent nuclear fuel, these results justify the use of data obtained in batch experiments.

Treatment of synthetic arsenate wastewater with iron-air fuel cell electrocoagulation to supply drinking water and electricity in remote areas.

PubMed

Kim, Jung Hwan; Maitlo, Hubdar Ali; Park, Joo Yang

2017-05-15

Electrocoagulation with an iron-air fuel cell is an innovative arsenate removal system that can operate without an external electricity supply. Thus, this technology is advantageous for treating wastewater in remote regions where it is difficult to supply electricity. In this study, the possibility of real applications of this system for arsenate treatment with electricity production was verified through electrolyte effect investigations using a small-scale fuel cell and performance testing of a liter-scale fuel cell stack. The electrolyte species studied were NaCl, Na 2 SO 4 , and NaHCO 3 . NaCl was overall the most effective electrolyte for arsenate treatment, although Na 2 SO 4 produced the greatest electrical current and power density. In addition, although the current density and power density were proportional to the concentrations of NaCl and Na 2 SO 4 , the use of concentrations above 20 mM of NaCl and Na 2 SO 4 inhibited arsenate treatment due to competition effects between anions and arsenate in adsorption onto the iron hydroxide. The dominant iron hydroxide produced at the iron anode was found to be lepidocrocite by means of Raman spectroscopy. A liter-scale four-stack iron-air fuel cell with 10 mM NaCl electrolyte was found to be able to treat about 300 L of 1 ppm arsenate solution to below 10 ppb during 1 day, based on its 60-min treatment capacity, as well as produce the maximum power density of 250 mW/m 2 . Copyright © 2017 Elsevier Ltd. All rights reserved.

Salt adaptation in Bufo bufo

PubMed Central

Ferreira, H. G.; Jesus, C. H.

1973-01-01

1. The capacity of adaptation of toads (Bufo bufo) to environments of high salinity was studied and the relative importance of skin, kidney and urinary bladder in controlling the balance of water and salt was assessed. 2. Toads were kept in NaCl solutions of 20, 50, 110, 150 and 220 mM and studied in their fourth week of adaptation. A group of animals considered as `control' was kept in wet soil with free access to water. Plasma, ureter urine, and bladder and colon contents were analysed for sodium, potassium, chloride and osmolality, and total body sodium and water were determined. Absorption of water and 22Na through the skin, and water flow and sodium excretion through the ureter, of intact animals was studied. Hydrosmotic water transport through the isolated urinary bladder of `control' and adapted animals was determined. The effects of pitressin and aldosterone on the water and sodium balance are described. 3. The survival rates of toads kept in saline concentrations up to 150 mM were identical to that of `control' animals, but half of the animals kept in 220 mM died within 4 weeks. 4. There is a linear correlation between the sodium concentrations and osmolality of plasma and of the external media. 5. The sodium concentration in colon contents rose with rising external concentrations, up to values higher than the values in plasma. 6. Sodium concentrations and osmolalities of ureter and bladder urine increased in adapted animals, the values for bladder urine becoming much higher than those for ureter urine in animals adapted to 110, 150 and 220 mM. 7. Total body water, as a percentage of total weight was kept within very narrow limits, although the total body sodium increased with adaptation. 8. Absorption of water through the skin for the same osmotic gradients was smaller in adapted than in `control' animals. 9. The ureteral output of water of toads adapted to 110 and 150 mM-NaCl was larger than the water absorption through the skin. 10. Skin absorption of sodium was lower in animals adapted to concentrated saline solutions than in `control' animals. 11. Sodium output by the ureter was identical to skin absorption in `control' animals adapted to 20, 50 and 110 mM-NaCl but was higher in animals adapted to 150 mM-NaCl. 12. Aldosterone increased the absorption of sodium in `control' and adapted toads, but at all dose levels absorption by control was greater than by adapted animals. 13. The stimulation of water absorption by vasopressin in vivo or in isolated bladders was not modified in animals adapted to high salinities. PMID:4633911

Physiological basis of a steady endogenous current in rat lumbrical muscle

PubMed Central

1984-01-01

In an attempt to determine the mechanism by which rat skeletal muscle endplates generate a steady outward current, we measured the effects of several drugs (furosemide, bumetanide, 9-anthracene carboxylic acid [9- AC]) and changes in external ion concentration (Na+, K+, Cl-, Ba++) on resting membrane potential (Vm) and on the steady outward current. Each of the following treatments caused a 10-15-mV hyperpolarization of the membrane: replacement of extracellular Cl- with isethionate, addition of furosemide or bumetanide, and addition of 9-AC. These results suggest that Cl- is actively accumulated by the muscle fibers and that the equilibrium potential of Cl- is more positive than the membrane potential. Removal of external Na+ also caused a large hyperpolarization and is consistent with evidence in other tissues that active Cl- accumulation requires external Na+. The same treatments greatly reduced or abolished the steady outward current, with a time course that paralleled the changes in Vm. These results cannot be explained by a model in which the steady outward current is assumed to arise as a result of a nonuniform distribution of Na+ conductance, but they are consistent with models in which the steady current is produced by a nonuniform distribution of GCl or GK. Other treatments (Na+-free and K+-free solutions, and 50 microM BaCl2) caused a temporary reversal of the steady current. Parallel measurements of Vm suggested that in none of these cases did the electrochemical driving force for K+ change sign, which makes it unlikely that the steady current arises as a result of a nonuniform distribution of GK. All of the results, however, are consistent with a model in which the steady outward current arises as a result of a nonuniform distribution of Cl- conductance, with GCl lower near the endplate than in extrajunctional regions. PMID:6325581

Graphene/blue-phosphorus heterostructure as potential anode materials for sodium-ion batteries

NASA Astrophysics Data System (ADS)

Fan, Kaimin; Tang, Ting; Wu, Shiyun; Zhang, Zhiyuan

2018-01-01

The first-principles calculations based on density functional theory (DFT) have been implemented to investigate the graphene/blue-phosphorus (G/BP) heterostructure as potential anode material for SIBs. The adsorption and diffusion behaviors of sodium (Na) in G/BP heterostructure and the effect of external electric field on Na adsorption have been investigated. The results indicate that G/BP heterostructure with Na adsorption is metallic due to Na incorporation, which is of benefit for electronic conductivity as anode material. The results show that the design of G/BP heterostructure is an efficient scheme to enhance the Na adsorption in G/BP without affecting the high mobility of Na in the G/BP heterostructure surface. The present work demonstrates that the external electric field can effectively modulate the adsorption of Na, and the adsorption behavior of Na is more sensitive to the external electric field when E > 0.10 V Å-1 in G/BP heterostructure. The Mulliken population analysis and DOS calculations have been performed to explore the charge transfer and the interaction between Na and G/BP.

On the origin of a sustained increase in cytosolic Ca2+ concentration after a toxic glutamate treatment of the nerve cell culture.

PubMed

Khodorov, B; Pinelis, V; Golovina, V; Fajuk, D; Andreeva, N; Uvarova, T; Khaspekov, L; Victorov, I

1993-06-21

A sustained increase of cytosolic Ca2+ concentration, [Ca2+]i, (Ca2+ plateau) was induced by a 15-min treatment with 50 microM glutamate of cultured cerebellar granule cells and hippocampal neurons in a Mg(2+)-free solution. Plateau proved to be insensitive to inhibition of Na+o/Ca2+i exchange caused by removal external Na+ in the post-glutamate period. A approximately 10(5)-fold reduction of [Ca2+]o (from 1.5 mM to 20 nM) in the post-glutamate period caused in most cells only a slow and small decrease in [Ca2+]i, although the same low-Ca2+ trial before glutamate treatment caused in hippocampal cells very quick blockade of spontaneous [Ca2+]i oscillation and a decrease in the basal [Ca2+]i. The results suggest that the Ca2+ plateau is due to a suppression of the Ca2+ extrusion from the cell (in particular via Na+/Ca2+ exchange) rather than from a persistent increase in Ca2+ permeability of neuronal membrane.

Electrical conductivity of H2O-NaCl fluids to 10 kbar

NASA Astrophysics Data System (ADS)

Sinmyo, R.; Keppler, H.

2016-12-01

Magnetotelluric studies often reveal zones of elevated electrical conductivity in the mantle wedge above subducting slabs, in the deep crust below fold belts, or below active volcanoes. Since both aqueous fluids and hydrous silivate melts may be highly conductive, they may both account for these observations. Distinguishing between these two posssibilities, however, is difficult. One reason for this problem is that while there are very good conductivity data for silicate melts, such data do not exist for aqueous fluids under the relevant conditions of pressure, temperature and solute concentration. Most crustal and mantle fluids likely contain some NaCl, which greatly enhances conductivity due to its partial dissociation into Na+ and Cl-. We therefore studied the electrical conductivity of 0.01, 0.1 and 1 m NaCl solutions in water to 10 kbar and 600 °C. The measurements were carried out in externally-heated diamond cells containing two gaskets separated by an insulating ring of diamond, following a method described by Ni et al. (2014). The two gaskets were used as electrodes and full impedance spectra were measured from 30 Hz to 10 MHz using a Solartron 1260 impedance analyzer. Electrical conductivity was generally found to increase with pressure temperature, and fluid density. The conductivity increase observed upon variation of NaCl concentration from 0.1m to 1m was smaller than from 0.01m to 0.1m, which reflects the reduced degree of dissociation at high NaCl concentration. In general, the data show that already a very small fraction of NaCl-bearing aqueous fluid is sufficient to enhance bulk conductivities to values that would be expected for a high degree of partial melting. Accordingly, aqueous fluids may be distinguished from hydrous melts by comparing magnetotelluric and seismic data. H2O-NaCl fluids may enhance electrical conductivities with little disturbance of vp or vp/vs ratios.

Physical-Chemical Basis of the Protection of Slowly Frozen Human Erythrocytes by Glycerol

PubMed Central

Rall, W. F.; Mazur, Peter; Souzu, Hiroshi

1978-01-01

One theory of freezing damage suggests that slowly cooled cells are killed by being exposed to increasing concentrations of electrolytes as the suspending medium freezes. A corollary to this view is that protective additives such as glycerol protect cells by acting colligatively to reduce the electrolyte concentration at any subzero temperature. Recently published phase-diagram data for the ternary system glycerol-NaCl-water by M. L. Shepard et al. (Cryobiology, 13:9-23, 1976), in combination with the data on human red cell survival vs. subzero temperature presented here and in the companion study of Souzu and Mazur (Biophys. J., 23:89-100), permit a precise test of this theory. Appropriate liquidus phase-diagram information for the solutions used in the red cell freezing experiments was obtained by interpolation of the liquidus data of Shepard and his co-workers. The results of phase-diagram analysis of red cell survival indicate that the correlation between the temperature that yields 50% hemolysis (LT50) and the electrolyte concentration attained at that temperature in various concentrations of glycerol is poor. With increasing concentrations of glycerol, the cells were killed at progressively lower concentrations of NaCl. For example, the LT50 for cells frozen in the absence of glycerol corresponds to a NaCl concentration of 12 weight percent (2.4 molal), while for cells frozen in 1.75 M glycerol in buffered saline the LT50 corresponds to 3.0 weight percent NaCl (1.3 molal). The data, in combination with other findings, lead to two conclusions: (a) The protection from glycerol is due to its colligative ability to reduce the concentration of sodium chloride in the external medium, but (b) the protection is less than that expected from colligative effects; apparently glycerol itself can also be a source of damage, probably because it renders the red cells susceptible to osmotic shock during thawing. PMID:667300

Membrane potentials in pinched-off presynaptic nerve ternimals monitored with a fluorescent probe: evidence that synaptosomes have potassium diffusion potentials.

PubMed Central

Blaustein, M P; Goldring, J M

1975-01-01

1. Some physiological properties of tissue fractions from rat brain homogenates have been examined. Of the three fractions studied (presynaptic nerve terminals, mitochondria and fragmented membranes), only the nerve terminals (synaptosomes) have the ability to accumulate 42K from physiological salt solutions. 2. The ability to accumulate and retain K is lost if synaptosomes are exposed to very hypotonic solutions. The K uptake and total K content is reduced by ouabain and by inhibitors of glycolysis and oxidative phosphorylation. 3. These results suggest that synaptosomes in physiological saline accumulate K against a concentration gradient, and may have K diffusion potentials across their surface membranes. The voltage-sensitive fluorescent probe, 3,3'-dipentyl 2,2'-oxacarbocyanine (CC5), was used to test this possibility. 4. In the squid axon, the fluorescent emission of CC5 is directly proportional to membrane potential; depolarization causes an increase in fluorescence. 5. The fluorescence of synaptosomes ('synaptosome fluorescence') treated with CC5 is increased when [K]o is increased or [K]o is reduced; replacement of external Na by Li or choline has little effect on the synaptosome fluorescence. In quantitative terms, synaptosome fluorescence is proportional to log ([K]o plus 0-05[Na]o). Rb is about as effective as K in enhancing synaptosome fluorescence; Cs is about 1/4 as effective. The effect of increased [K]o is reversible. 6. The fluorescence data provide corroborative evidence that there is normally a large K gradient ([K]o smaller than [I]i) across the synaptosome surface membrane. The data suggest the [K]i may be in excess of 100 mM. 7. Replacement of Cl- by methylsulphate did not significantly affect the relationship between synaptosome fluorescence and [K]o, nor did removal of external Ca. 8. The fluorescence of CC5-treated mitochondria, membrane fragmnets, or lysed synaptosomes is unaffected by changes in the K concentration of the medium. 9. Veratridine and gramicidin D, both of which enhance Na permeability (PNa) in some intact tissues, increase synaptosome fluorescence when added to the standard medium. The increment is greatly reduced or abolished when external Na is replaced by choline. 10. If synaptosomes are first Na-loaded (by pre-treatment with cyanide + iodoacetate), and then placed in a choline medium, addition of gramicidin D significantly decreases fluorescence. This effect could be explained if, with [Na]o smaller than [Na]i, the increase in PNa causes the synaptosomes to hyperpolarize. 11. The veratridine-induced increase in synaptosome fluorescence was prevented by 3 times 10- minus 7M tetrodotoxin, which also blocks the depolarizing effect of veratridine in intact neurones. 12. The main conclusion is that synaptosomes may retain resting membrane potentials and the ability to increase Na permeability. PMID:49421

Potassium Fluxes in Desheathed Frog Sciatic Nerve

PubMed Central

Hurlbut, William P.

1963-01-01

Desheathed frog (R. pipiens) sciatic nerves were soaked in Na-deficient solutions, and measurements were made of their Na and K contents and of the movements of K42. When a nerve is in Ringer's solution, the Na fluxes are equal to the K fluxes, and about 75 per cent of the K influx is due to active transport. The Na content and the Na efflux are linearly related to the Na concentration of the bathing solution, while the K content and the K fluxes are not so related. When a nerve is in a solution in which 75 per cent of the NaCl has been replaced by choline chloride or sucrose, the active K influx exceeds the active Na efflux, and the K content is maintained. When a nerve is soaked in a solution that contains Li, the K42 uptake is inhibited, and the nerve loses K and gains Li. When a Li-loaded nerve recovers in a Li-free solution, K is taken up in exchange for Li. This uptake of K requires Na in the external solution. It is concluded that the active transports of K and of Na may be due to different processes, that an accumulation of K occurs only in exchange for an intracellular cation, which need not be Na, and that Na plays a specific, but unknown, role in K transport. PMID:14043000

Dehydroepiandrosterone sulfate (DHEAS) suppresses P2X purinoceptor-coupled responses in PC12 cells.

PubMed

Liu, P S; Hsieh, H L; Lin, C M

2001-09-01

Some steroids rapidly alter neuronal excitability through interaction with neurotransmitter-gated ion channels in addition to their well-known genomic effects via intracellular steroid receptors. Such effects were found in GABA receptor, nicotinic receptors, yet not investigated in P2X purinoceptors. In this study, the effects of dehydroepiandrosterone sulfate on the P2 purinoceptor was investigated. Results show that dehydroepiandrosterone sulfate acutely inhibits P2X purinoceptor functions in PC12 cells. Dehydroepiandrosterone sulfate suppressed ATP-induced cytosolic free calcium concentration ([Ca(2+)](i)) rise, cytosolic free sodium concentration ([Na(+)](i)) rise, and dopamine secretion in the presence of external calcium, but had no effect on ATP-induced [Ca(2+)](i) rise in the absence of external calcium or on UTP-induced [Ca(2+)](i) rise in the absence or presence of external calcium. Our data show that dehydroepiandrosterone sulfate exerted its effect on P2X, but not on the P2Y purinoceptors found in PC12 cells. Estradiol and estrone have similar effects on P2X purinoceptor, but dehydroepiandrosterone and progesterone do not.

Nitrogen removal and electricity production at a double-chamber microbial fuel cell with cathode nitrite denitrification.

PubMed

Yu, Yangyang; Zhao, Jianqiang; Wang, Sha; Zhao, Huimin; Ding, Xiaoqian; Gao, Kun

2017-12-01

Double-chamber microbial fuel cell was applied to investigate the performance of the electricity production and nitrite denitrification through feeding nitrite into the cathode. Factors influencing denitrification performance and power production, such as external resistance, influent nitrite concentration and Nitrite Oxygen Bacteria inhibitors, were studied. The results show that when the concentration of nitrite nitrogen and external resistance were 100 mg L -1 and 10 Ω, respectively, the nitrite denitrification reached the best state. The NaN 3 can inhibit nitrite oxidation effectively; meanwhile, the nitrite denitrification with N 2 O as the final products was largely improved. The [Formula: see text] was reduced to [Formula: see text], causing the cathode denitrification coulombic efficiency to exceed 100%. In chemoautotrophic bio-nitrification, microorganisms may utilize H 2 O to oxidize nitrite under anaerobic conditions. Proteobacteria might play a major role in the process of denitrification in MFC.

Interaction of External K, Na, and Cardioactive Steroids with the Na-K Pump of the Human Red Blood Cell

PubMed Central

Sachs, John R.

1974-01-01

The interaction of extracellular Na (Nao), K (Ko), and strophanthidin with the Na-K pump of the human red blood cell has been investigated. Inhibition by submaximal concentrations of strophanthidin rapidly reaches a level which does not increase further over a relatively long period of time. Under these circumstances, it is possible to apply a steady-state kinetic analysis to the interaction of Nao, Ko, and strophanthidin with the pump. In Na-free solutions, strophanthidin increases the apparent K1/2 of the pump for Ko, but does not change the form of the relation between the reciprocal of the active K influx (i M K P–1) and the reciprocal of [Ko] ([Ko]–1); the relation both in the presence and absence of strophanthidin is adequately described by a straight line. In solutions containing Na, strophanthidin changes the form of the curve describing the relation between i M K P–1 vs. [Ko]–1; the curve becomes more parabolic in solutions containing strophanthidin. The rate of ouabain binding to K-free cells has also been measured; in the absence of K, the rate of binding is unaffected by Nao. The data are considered in terms of a simple kinetic model. The findings can be explained if it is supposed that at low external K the form of the pump combined with one Nao is more likely to combine with strophanthidin than is the uncombined form of the pump. The uncombined form of the pump is more likely to combine with K even at very low Ko than with strophanthidin. PMID:4812632

Protection against salt toxicity in Azolla pinnata-Anabaena azollae symbiotic association by using combined-N sources.

PubMed

Mishra, A K; Singh, Satya S

2006-09-01

Protection from salt stress was observed in the terms of yield (fresh and dry weight, chlorophyll and protein) and nitrogenase activity. Azollapinnata appeared highly sensitive to 40 mM external NaCl stress. Fronds of Azolla unable to grow beyond a concentration of 30 mM NaCl and accordingly death was recorded at 40 mM NaCl on the 6th day of incubation. Yield was inhibited by various levels of NaCl (0, 10, 20 and 30 mM). Addition of combined-N to the growth medium protected the association partially from salt toxicity. Among the N-sources (NO3-, NH4+ and urea) tried, urea mitigated the salt-induced toxicity most efficiently. Reduction in nitrogenase activity was observed when intact Azolla was grown in nutrient medium either supplemented with different levels of NaCl or combined nitrogen. Only NO3- (5 mM) protected the enzymatic activity from salt toxicity while other concentrations of ammonium, nitrate and urea slowed down the salt-induced inhibition of enzyme activity in Azolla-Anabaena association. These results suggested that an optimum protection from salt stress could be obtained by using a combination of combined nitrogen sources. The reason for this protection might be due to the availability of combined nitrogen to the association, nitrogen is only available through the biological nitrogen fixation which is the most sensitive to salt stress.

Two Distinct Families of Protein Kinases Are Required for Plant Growth under High External Mg2+ Concentrations in Arabidopsis1

PubMed Central

Mogami, Junro; Fujita, Yasunari; Yoshida, Takuya; Tsukiori, Yoshifumi; Nakagami, Hirofumi; Nomura, Yuko; Fujiwara, Toru; Nishida, Sho; Yanagisawa, Shuichi; Ishida, Tetsuya; Takahashi, Fuminori; Morimoto, Kyoko; Kidokoro, Satoshi; Mizoi, Junya; Shinozaki, Kazuo

2015-01-01

Protein phosphorylation events play key roles in maintaining cellular ion homeostasis in higher plants, and the regulatory roles of these events in Na+ and K+ transport have been studied extensively. However, the regulatory mechanisms governing Mg2+ transport and homeostasis in higher plants remain poorly understood, despite the vital roles of Mg2+ in cellular function. A member of subclass III sucrose nonfermenting-1-related protein kinase2 (SnRK2), SRK2D/SnRK2.2, functions as a key positive regulator of abscisic acid (ABA)-mediated signaling in response to water deficit stresses in Arabidopsis (Arabidopsis thaliana). Here, we used immunoprecipitation coupled with liquid chromatography-tandem mass spectrometry analyses to identify Calcineurin B-like-interacting protein kinase26 (CIPK26) as a novel protein that physically interacts with SRK2D. In addition to CIPK26, three additional CIPKs (CIPK3, CIPK9, and CIPK23) can physically interact with SRK2D in planta. The srk2d/e/i triple mutant lacking all three members of subclass III SnRK2 and the cipk26/3/9/23 quadruple mutant lacking CIPK26, CIPK3, CIPK9, and CIPK23 showed reduced shoot growth under high external Mg2+ concentrations. Similarly, several ABA biosynthesis-deficient mutants, including aba2-1, were susceptible to high external Mg2+ concentrations. Taken together, our findings provided genetic evidence that SRK2D/E/I and CIPK26/3/9/23 are required for plant growth under high external Mg2+ concentrations in Arabidopsis. Furthermore, we showed that ABA, a key molecule in water deficit stress signaling, also serves as a signaling molecule in plant growth under high external Mg2+ concentrations. These results suggested that SRK2D/E/I- and CIPK26/3/9/23-mediated phosphorylation signaling pathways maintain cellular Mg2+ homeostasis. PMID:25614064

Selectivity of externally facing ion-binding sites in the Na/K pump to alkali metals and organic cations

PubMed Central

Ratheal, Ian M.; Virgin, Gail K.; Yu, Haibo; Roux, Benoît; Gatto, Craig; Artigas, Pablo

2010-01-01

The Na/K pump is a P-type ATPase that exchanges three intracellular Na+ ions for two extracellular K+ ions through the plasmalemma of nearly all animal cells. The mechanisms involved in cation selection by the pump's ion-binding sites (site I and site II bind either Na+ or K+; site III binds only Na+) are poorly understood. We studied cation selectivity by outward-facing sites (high K+ affinity) of Na/K pumps expressed in Xenopus oocytes, under voltage clamp. Guanidinium+, methylguanidinium+, and aminoguanidinium+ produced two phenomena possibly reflecting actions at site III: (i) voltage-dependent inhibition (VDI) of outwardly directed pump current at saturating K+, and (ii) induction of pump-mediated, guanidinium-derivative–carried inward current at negative potentials without Na+ and K+. In contrast, formamidinium+ and acetamidinium+ induced K+-like outward currents. Measurement of ouabain-sensitive ATPase activity and radiolabeled cation uptake confirmed that these cations are external K+ congeners. Molecular dynamics simulations indicate that bound organic cations induce minor distortion of the binding sites. Among tested metals, only Li+ induced Na+-like VDI, whereas all metals tested except Na+ induced K+-like outward currents. Pump-mediated K+-like organic cation transport challenges the concept of rigid structural models in which ion specificity at site I and site II arises from a precise and unique arrangement of coordinating ligands. Furthermore, actions by guanidinium+ derivatives suggest that Na+ binds to site III in a hydrated form and that the inward current observed without external Na+ and K+ represents cation transport when normal occlusion at sites I and II is impaired. These results provide insights on external ion selectivity at the three binding sites. PMID:20937860

Unidirectional Flux Balance of Monovalent Ions in Cells with Na/Na and Li/Na Exchange: Experimental and Computational Studies on Lymphoid U937 Cells

PubMed Central

Vereninov, Igor A.; Yurinskaya, Valentina E.; Model, Michael A.; Vereninov, Alexey A.

2016-01-01

Monovalent ion traffic across the cell membrane occurs via various pathways. Evaluation of individual fluxes in whole cell is hampered by their strong interdependence. This difficulty can be overcome by computational analysis of the whole cell flux balance. However, the previous computational studies disregarded ion movement of the self-exchange type. We have taken this exchange into account. The developed software allows determination of unidirectional fluxes of all monovalent ions via the major pathways both under the balanced state and during transient processes. We show how the problem of finding the rate coefficients can be solved by measurement of monovalent ion concentrations and some of the fluxes. Interdependence of fluxes due to the mandatory conditions of electroneutrality and osmotic balance and due to specific effects can be discriminated, enabling one to identify specific changes in ion transfer machinery under varied conditions. To test the effectiveness of the developed approach we made use of the fact that Li/Na exchange is known to be an analogue of the coupled Na/Na exchange. Thus, we compared the predicted and experimental data obtained on U937 cells under varied Li+ concentrations and following inhibition of the sodium pump with ouabain. We found that the coupled Na/Na exchange in U937 cells comprises a significant portion of the entire Na+ turnover. The data showed that the loading of the sodium pump by Li/Na exchange involved in the secondary active Li+ transport at 1–10 mM external Li+ is small. This result may be extrapolated to similar Li+ and Na+ flux relationships in erythrocytes and other cells in patients treated with Li+ in therapeutic doses. The developed computational approach is applicable for studying various cells and can be useful in education for demonstrating the effects of individual transporters and channels on ion gradients, cell water content and membrane potential. PMID:27159324

Intracellular pH Regulation in Cultured Astrocytes from Rat Hippocampus

PubMed Central

Bevensee, Mark O.; Apkon, Michael; Boron, Walter F.

1997-01-01

In the preceding paper (Bevensee, M.O., R.A. Weed, and W.F. Boron. 1997. J. Gen. Physiol. 110: 453–465.), we showed that a Na+-driven influx of HCO3 − causes the increase in intracellular pH (pHi) observed when astrocytes cultured from rat hippocampus are exposed to 5% CO2/17 mM HCO3 −. In the present study, we used the pH-sensitive fluorescent indicator 2′,7′-biscarboxyethyl-5,6-carboxyfluorescein (BCECF) and the perforated patch-clamp technique to determine whether this transporter is a Na+-driven Cl-HCO3 exchanger, an electrogenic Na/HCO3 cotransporter, or an electroneutral Na/HCO3 cotransporter. To determine if the transporter is a Na+-driven Cl-HCO3 exchanger, we depleted the cells of intracellular Cl− by incubating them in a Cl−-free solution for an average of ∼11 min. We verified the depletion with the Cl−-sensitive dye N-(6-methoxyquinolyl)acetoethyl ester (MQAE). In Cl−-depleted cells, the pHi still increases after one or more exposures to CO2/HCO3 −. Furthermore, the pHi decrease elicited by external Na+ removal does not require external Cl−. Therefore, the transporter cannot be a Na+-driven Cl-HCO3 exchanger. To determine if the transporter is an electrogenic Na/ HCO3 cotransporter, we measured pHi and plasma membrane voltage (Vm) while removing external Na+, in the presence/absence of CO2/HCO3 − and in the presence/absence of 400 μM 4,4′-diisothiocyanatostilbene-2,2′-disulphonic acid (DIDS). The CO2/HCO3 − solutions contained 20% CO2 and 68 mM HCO3 −, pH 7.3, to maximize the HCO3 − flux. In pHi experiments, removing external Na+ in the presence of CO2/HCO3 − elicited an equivalent HCO3 − efflux of 281 μM s−1. The HCO3 − influx elicited by returning external Na+ was inhibited 63% by DIDS, so that the predicted DIDS-sensitive Vm change was 3.3 mV. Indeed, we found that removing external Na+ elicited a DIDS-sensitive depolarization that was 2.6 mV larger in the presence than in the absence of CO2/ HCO3 −. Thus, the Na/HCO3 cotransporter is electrogenic. Because a cotransporter with a Na+:HCO3 − stoichiometry of 1:3 or higher would predict a net HCO3 − efflux, rather than the required influx, we conclude that rat hippocampal astrocytes have an electrogenic Na/HCO3 cotransporter with a stoichiometry of 1:2. PMID:9379176

Regulation of K+ Transport in Tomato Roots by the TSS1 Locus. Implications in Salt Tolerance1

PubMed Central

Rubio, Lourdes; Rosado, Abel; Linares-Rueda, Adolfo; Borsani, Omar; García-Sánchez, María J.; Valpuesta, Victoriano; Fernández, José A.; Botella, Miguel A.

2004-01-01

The tss1 tomato (Lycopersicon esculentum) mutant exhibited reduced growth in low K+ and hypersensitivity to Na+ and Li+. Increased Ca2+ in the culture medium suppressed the Na+ hypersensitivity and the growth defect on low K+ medium of tss1 seedlings. Interestingly, removing NH4+ from the growth medium suppressed all growth defects of tss1, suggesting a defective NH4+-insensitive component of K+ transport. We performed electrophysiological studies to understand the contribution of the NH4+-sensitive and -insensitive components of K+ transport in wild-type and tss1 roots. Although at 1 mm Ca2+ we found no differences in affinity for K+ uptake between wild type and tss1 in the absence of NH4+, the maximum depolarization value was about one-half in tss1, suggesting that a set of K+ transporters is inactive in the mutant. However, these transporters became active by raising the external Ca2+ concentration. In the presence of NH4+, a reduced affinity for K+ was observed in both types of seedlings, but tss1 at 1 mm Ca2+ exhibited a 2-fold higher Km than wild type did. This defect was again corrected by raising the external concentration of Ca2+. Therefore, membrane potential measurements in root cells indicated that tss1 is affected in both NH4+-sensitive and -insensitive components of K+ transport at low Ca2+ concentrations and that this defective transport is rescued by increasing the concentration of Ca2+. Our results suggest that the TSS1 gene product is part of a crucial pathway mediating the beneficial effects of Ca2+ involved in K+ nutrition and salt tolerance. PMID:14684839

Cisplatin combined with hyperthermia kills HepG2 cells in intraoperative blood salvage but preserves the function of erythrocytes.

PubMed

Yang, Jin-ting; Tang, Li-hui; Liu, Yun-qing; Wang, Yin; Wang, Lie-ju; Zhang, Feng-jiang; Yan, Min

2015-05-01

The safe use of intraoperative blood salvage (IBS) in cancer surgery remains controversial. Here, we investigated the killing effect of cisplatin combined with hyperthermia on human hepatocarcinoma (HepG2) cells and erythrocytes from IBS in vitro. HepG2 cells were mixed with concentrated erythrocytes and pretreated with cisplatin (50, 100, and 200 μg/ml) alone at 37 °C for 60 min and cisplatin (25, 50, 100, and 200 μg/ml) combined with hyperthermia at 42 °C for 60 min. After pretreatment, the cell viability, colony formation and DNA metabolism in HepG2 and the Na(+)-K(+)-ATPase activity, 2,3-diphosphoglycerate (2,3-DPG) concentration, free hemoglobin (Hb) level, osmotic fragility, membrane phosphatidylserine externalization, and blood gas variables in erythrocytes were determined. Pretreatment with cisplatin (50, 100, and 200 μg/ml) combined with hyperthermia (42 °C) for 60 min significantly decreased HepG2 cell viability, and completely inhibited colony formation and DNA metabolism when the HepG2 cell concentration was 5×10(4) ml(-1) in the erythrocyte (P<0.01). Erythrocytic Na(+)-K(+)-ATPase activity, 2,3-DPG level, phosphatidylserine externalization, and extra-erythrocytic free Hb were significantly altered by hyperthermia plus high concentrations of cisplatin (100 and 200 μg/ml) (P<0.05), but not by hyperthermia plus 50 μg/ml cisplatin (P>0.05). In conclusion, pretreatment with cisplatin (50 μg/ml) combined with hyperthermia (42 °C) for 60 min effectively eliminated HepG2 cells from IBS but did not significantly affect erythrocytes in vitro.

Chloride currents activated by caffeine in rat intestinal smooth muscle cells.

PubMed Central

Ohta, T; Ito, S; Nakazato, Y

1993-01-01

1. Current responses to caffeine in single smooth muscle cells isolated from rat intestine were studied with the whole-cell patch clamp technique. Intracellular calcium concentration, [Ca2+]i, was simultaneously monitored with fura-2 (0.1 mM) introduced into the cell through a patch pipette. 2. With a potassium-containing pipette solution, caffeine (10 mM) produced an outward current at a holding potential of 0 mV and an inward current at -60 mV, both of which were accompanied by parallel increases in [Ca2+]i. The outward current response disappeared after the removal of K+ from pipette solutions, indicating that caffeine activates a Ca(2+)-activated K+ conductance. 3. When NaCl was present in both pipette and external solutions as the major constituent, caffeine evoked an inward current at -60 mV simultaneously with a rise in [Ca2+]i. The reversal potential (Er) of this current was about 0 mV. 4. Substitution of Tris+ or choline+ for external Na+ did not alter the Er. When external Cl- was replaced by thiocyanate-, iodide- or glutamate-, the Er changed to respectively -55, -38 and +35 mV. 5. The current response to caffeine decreased with increasing concentration of EGTA in the pipette solution. The caffeine-induced current and the intracellular Ca2+ transient was still observed for a few minutes after exposure of the cells to Ca(2+)-free external solution containing 2 mM EGTA. Caffeine failed to produce an inward current and Ca2+ transient after treatment with extracellular ryanodine. 6. It is concluded that caffeine caused an increase in membrane Cl- conductance and in K+ conductance resulting from a rise in [Ca2+]i derived from ryanodine-sensitive intracellular Ca2+ stores in isolated smooth muscle cells of the rat intestine. PMID:8229831

Measurement of the terrestrial and anthropogenic radionuclide concentrations in Bafra Kizilirmak delta (bird sanctuary) in Turkey.

PubMed

Mutuk, Halil; Gümüs, Hasan; Turhan, Seref

2014-01-01

In this study, the activity concentrations of terrestrial and anthropogenic radionuclides in the soil samples collected from Bafra Kızılırmak Delta were measured by using gamma spectrometry with an NaI(Tl) detector. The average values of activity concentrations of (238)U, (232)Th and (40)K were found to be 37.2±2.8, 33.7±3.1 and 413.0±59.8 Bq kg(-1), respectively. (137)Cs was also measured in some samples. It has a mean value of 13.8±1.0 Bq kg(-1). From the activity concentrations, the absorbed gamma dose rates in outdoor and the corresponding annual effective dose rates and external hazard index (Hex) were estimated.

Aspects of Salt Tolerance in a NaCl-Selected Stable Cell Line of Citrus sinensis.

PubMed

Ben-Hayyim, G; Kochba, J

1983-07-01

A NaCl-tolerant cell line which was selected from ovular callus of ;Shamouti' orange (Citrus sinensis L. Osbeck) proved to be a true cell line variant. This conclusion is based on the following observations. (a) Cells which have been removed from the selection pressure for at least four passages retain the same NaCl tolerance as do cells which are kept constantly on 0.2 molar NaCl. (b) Na(+) and Cl(-) uptake are considerably lower in salt-tolerant cells (R-10) than in salt-sensitive cells (L-5) at a given external NaCl concentration. (c) Growth of salt-tolerant cells is markedly suppressed upon replacement of NaCl by KCl, whereas the growth of salt-sensitive cells is only slightly affected. Accumulation of K(+) and Cl(-) accompanies the inhibition of growth. Experiments carried out with sodium and potassium sulfate suggest that the toxic effect is due to the accumulated Cl(-). (d) Removal of Ca(2+) from the growth medium severely inhibits the growth of salt-tolerant cells in the presence of NaCl, while it has a minor effect on growth of salt-sensitive cells in the presence of NaCl. (e) Electron micrographs show that the salt-tolerant cells have very big vacuoles when exposed to salt, while the size of the vacuoles of the salt-sensitive cells does not change.

Aspects of Salt Tolerance in a NaCl-Selected Stable Cell Line of Citrus sinensis1

PubMed Central

Ben-Hayyim, Gozal; Kochba, Joshua

1983-01-01

A NaCl-tolerant cell line which was selected from ovular callus of `Shamouti' orange (Citrus sinensis L. Osbeck) proved to be a true cell line variant. This conclusion is based on the following observations. (a) Cells which have been removed from the selection pressure for at least four passages retain the same NaCl tolerance as do cells which are kept constantly on 0.2 molar NaCl. (b) Na+ and Cl− uptake are considerably lower in salt-tolerant cells (R-10) than in salt-sensitive cells (L-5) at a given external NaCl concentration. (c) Growth of salt-tolerant cells is markedly suppressed upon replacement of NaCl by KCl, whereas the growth of salt-sensitive cells is only slightly affected. Accumulation of K+ and Cl− accompanies the inhibition of growth. Experiments carried out with sodium and potassium sulfate suggest that the toxic effect is due to the accumulated Cl−. (d) Removal of Ca2+ from the growth medium severely inhibits the growth of salt-tolerant cells in the presence of NaCl, while it has a minor effect on growth of salt-sensitive cells in the presence of NaCl. (e) Electron micrographs show that the salt-tolerant cells have very big vacuoles when exposed to salt, while the size of the vacuoles of the salt-sensitive cells does not change. Images Fig. 3 PMID:16663067

Sodium uptake in different life stages of crustaceans: the water flea Daphnia magna Strauss.

PubMed

Bianchini, Adalto; Wood, Chris M

2008-02-01

The concentration-dependent kinetics and main mechanisms of whole-body Na+ uptake were assessed in neonate and adult water flea Daphnia magna Strauss acclimated to moderately hard water (0.6 mmol l(-1) NaCl, 1.0 mmol l(-1) CaCO3 and 0.15 mmol l(-1) MgSO4.7H2O; pH 8.2). Whole-body Na+ uptake is independent of the presence of Cl(-) in the external medium and kinetic parameters are dependent on the life stage. Adults have a lower maximum capacity of Na+ transport on a mass-specific basis but a higher affinity for Na+ when compared to neonates. Based on pharmacological analyses, mechanisms involved in whole-body Na+ uptake differ according to the life stage considered. In neonates, a proton pump-coupled Na+ channel appears to play an important role in the whole-body Na+ uptake at the apical membrane. However, they do not appear to contribute to whole-body Na+ uptake in adults, where only the Na+ channel seems to be present, associated with the Na+/H+ exchanger. In both cases, carbonic anhydrase contributes by providing H+ for the transporters. At the basolateral membrane of the salt-transporting epithelia of neonates, Na+ is pumped from the cells to the extracellular fluid by a Na+, K+-ATPase and a Na+/Cl(-) exchanger whereas K+ and Cl(-) move through specific channels. In adults, a Na+/K+/2Cl(-) cotransporter replaces the Na+/Cl(-) exchanger. Differential sensitivity of neonates and adults to iono- and osmoregulatory toxicants, such as metals, are discussed with respect to differences in whole-body Na+ uptake kinetics, as well as in the mechanisms of Na+ transport involved in the whole-body Na+ uptake in the two life stages.

Regulation of potassium transport in human lens epithelial cells.

PubMed

Lauf, Peter K; Warwar, Ronald; Brown, Thomas L; Adragna, Norma C

2006-01-01

The major K influx pathways and their response to thiol modification by N-ethylmaleimide (NEM) and protein kinase and phosphatase inhibitors were characterized in human lens epithelial B3 (HLE-B3) cells with Rb as K congener. Ouabain (0.1 mM) and bumetanide (5 microM) discriminated between the Na/K pump ( approximately 35% of total Rb influx) and Na-K-2Cl cotransport (NKCC) ( approximately 50%). Cl-replacement with nitrate or sulfamate revealed <10% residual [ouabain+bumetanide]-insensitive K-Cl cotransport (KCC). At 0.3-0.5 mM, NEM stimulated the Na/K pump by 2-fold independent of external Na, KCC between 2 and 4-fold, and abolished approximately 90% of NKCC. Calyculin-A, a serine/threonine protein phosphatase-1 inhibitor, did not affect NKCC but inhibited KCC, whereas 10 microM staurosporine, a serine/threonine kinase inhibitor, abolished NKCC, and stimulated KCC only when followed by NEM treatment. The tyrosine-kinase inhibitor genistein, at concentrations >100 microM, activated the Na/K pump and abolished NKCC but did not affect KCC. The data suggest at least partial inverse regulation of KCC and NKCC in HLE-B3 cells by signaling cascades involving serine, threonine and tyrosine phosphorylation/dephosphorylation equilibria.

Statistical differentiation of bananas according to their mineral composition.

PubMed

Forster, Markus Paul; Rodríguez Rodríguez, Elena; Martín, Jacinto Darias; Díaz Romero, Carlos

2002-10-09

The concentrations of Na, K, Ca, Mg, Fe, Cu, Zn, and Mn were determined in banana cultivars Gran enana and Pequeña enana cultivated in Tenerife and in cv. Gran enana bananas from Ecuador. The mineral concentrations in the bananas from Tenerife and from Ecuador were clearly different. The cultivar did not influence the mineral concentrations except in the case of Fe. Variations according to cultivation method (greenhouse and outdoors) and farming style (conventional and organic) in the mineral concentrations in the bananas from Tenerife were observed. The mineral concentrations in the internal part of the banana were higher than those in the middle and external parts. Representation of double log correlations K-Mg and Zn-Mn tended to separate the banana samples according to origin. Applying factor and cluster analysis, the bananas from Ecuador were well separated from the bananas produced in Tenerife, and therefore, these are useful tools for differentiating the origin of bananas.

Dehydration process in NaCl solutions under various external electric fields

NASA Astrophysics Data System (ADS)

Kadota, Kazunori; Shimosaka, Atsuko; Shirakawa, Yoshiyuki; Hidaka, Jusuke

2007-06-01

Ionic motions at solid-liquid interface in supersaturated NaCl solutions have been investigated by molecular dynamics (MD) simulation for understanding crystal growth processes. The density profile in the vicinity of the interfaces between NaCl(100) and the supersaturated NaCl solution was calculated. Diffusion coefficients of water molecules in the solution were estimated as a function of distance from the crystal interface. It turned out that the structure and dynamics of the solution in the interfaces was different from those of bulk solution owing to electric fields depending on the surface charge. Therefore, the electric field was applied to the supersaturated solutions and dehydration phenomenon occurring in the process of the crystal growth was discussed. As the electric field increased, it was observed that the Na+ keeping strongly hydration structure broke out by the electric force. In supersaturated concentration, the solution structure is significantly different from that of dilution and has a complicated structure with hydration ions and clusters of NaCl. If the electric fields were applied to the solutions, the breakout of hydration structure was not affected with increasing the supersaturated ratio. This reason is that the cluster structures are destroyed by the electric force. The situation depends on the electric field or crystal surface structure.

The external pore loop interacts with S6 and S3-S4 linker in domain 4 to assume an essential role in gating control and anticonvulsant action in the Na+ channel

PubMed Central

Yang, Ya-Chin; Hsieh, Jui-Yi

2009-01-01

Carbamazepine, phenytoin, and lamotrigine are widely prescribed anticonvulsants in neurological clinics. These drugs bind to the same receptor site, probably with the diphenyl motif in their structure, to inhibit the Na+ channel. However, the location of the drug receptor remains controversial. In this study, we demonstrate close proximity and potential interaction between an external aromatic residue (W1716 in the external pore loop) and an internal aromatic residue (F1764 in the pore-lining part of the sixth transmembrane segment, S6) of domain 4 (D4), both being closely related to anticonvulsant and/or local anesthetic binding to the Na+ channel. Double-mutant cycle analysis reveals significant cooperativity between the two phenyl residues for anticonvulsant binding. Concomitant F1764C mutation evidently decreases the susceptibility of W1716C to external Cd2+ and membrane-impermeable methanethiosulfonate reagents. Also, the W1716E/F1764R and G1715E/F1764R double mutations significantly alter the selectivity for Na+ over K+ and markedly shift the activation curve, respectively. W1716 and F1764 therefore very likely form a link connecting the outer and inner compartments of the Na+ channel pore (in addition to the selectivity filter). Anticonvulsants and local anesthetics may well traverse this “S6 recess” without trespassing on the selectivity filter. Furthermore, we found that Y1618K, a point mutation in the S3-4 linker (the extracellular extension of D4S4), significantly alters the consequences of carbamazepine binding to the Na+ channel. The effect of Y1618K mutation, however, is abolished by concomitant point mutations in the vicinity of Y1618, but not by those in the internally located inactivation machinery, supporting a direct local rather than a long-range allosteric action. Moreover, Y1618 could interact with D4 pore residues W1716 and L1719 to have a profound effect on both channel gating and anticonvulsant action. We conclude that there are direct interactions among the external S3-4 linker, the external pore loop, and the internal S6 segment in D4, making the external pore loop a pivotal point critically coordinating ion permeation, gating, and anticonvulsant binding in the Na+ channel. PMID:19635852

The external pore loop interacts with S6 and S3-S4 linker in domain 4 to assume an essential role in gating control and anticonvulsant action in the Na(+) channel.

PubMed

Yang, Ya-Chin; Hsieh, Jui-Yi; Kuo, Chung-Chin

2009-08-01

Carbamazepine, phenytoin, and lamotrigine are widely prescribed anticonvulsants in neurological clinics. These drugs bind to the same receptor site, probably with the diphenyl motif in their structure, to inhibit the Na(+) channel. However, the location of the drug receptor remains controversial. In this study, we demonstrate close proximity and potential interaction between an external aromatic residue (W1716 in the external pore loop) and an internal aromatic residue (F1764 in the pore-lining part of the sixth transmembrane segment, S6) of domain 4 (D4), both being closely related to anticonvulsant and/or local anesthetic binding to the Na(+) channel. Double-mutant cycle analysis reveals significant cooperativity between the two phenyl residues for anticonvulsant binding. Concomitant F1764C mutation evidently decreases the susceptibility of W1716C to external Cd(2+) and membrane-impermeable methanethiosulfonate reagents. Also, the W1716E/F1764R and G1715E/F1764R double mutations significantly alter the selectivity for Na(+) over K(+) and markedly shift the activation curve, respectively. W1716 and F1764 therefore very likely form a link connecting the outer and inner compartments of the Na(+) channel pore (in addition to the selectivity filter). Anticonvulsants and local anesthetics may well traverse this "S6 recess" without trespassing on the selectivity filter. Furthermore, we found that Y1618K, a point mutation in the S3-4 linker (the extracellular extension of D4S4), significantly alters the consequences of carbamazepine binding to the Na(+) channel. The effect of Y1618K mutation, however, is abolished by concomitant point mutations in the vicinity of Y1618, but not by those in the internally located inactivation machinery, supporting a direct local rather than a long-range allosteric action. Moreover, Y1618 could interact with D4 pore residues W1716 and L1719 to have a profound effect on both channel gating and anticonvulsant action. We conclude that there are direct interactions among the external S3-4 linker, the external pore loop, and the internal S6 segment in D4, making the external pore loop a pivotal point critically coordinating ion permeation, gating, and anticonvulsant binding in the Na(+) channel.

Long-living nanobubbles of dissolved gas in aqueous solutions of salts and erythrocyte suspensions.

PubMed

Bunkin, Nikolai F; Ninham, Barry W; Ignatiev, Pavel S; Kozlov, Valery A; Shkirin, Alexey V; Starosvetskij, Artem V

2011-03-01

Results of experiments combining laser modulation interference microscopy and Mueller matrix scatterometry show that macroscopic scatterers of light are present in liquids free of external solid impurities. Experimental data on distilled water and aqueous NaCl solutions of various concentrations as well as physiological saline solution are reported. The experimental data can be interpreted by using a model of micron-scale clusters composed of polydisperse air nanobubbles having effective radii of 70-100 nm. Their concentration increases with the growth of ionic content. We hypothesize that under certain conditions those clusters of nanobubbles can affect the erythrocyte structure. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Adsorption and desorption of carbaryl on hexadecyl trimethyl ammonium bromide modified zeolite NaY using RGB portable photometer

NASA Astrophysics Data System (ADS)

Patdhanagul, Nopbhasinthu; Chanpaka, Saiphon; Intharaksa, Orapan; Sirival, Rujikarn; Thanomsith, Kannikar; Wongkwanklom, Sarayuth

2018-04-01

The carbaryl adsorption-desorption isotherms of zeolite NaY and hexadecyl trimethyl ammonium bromide (HTAB) modified zeolite NaY were investigated. Zeolite NaY was synthesized and modified by HTAB in the concentration range 0.1 - 10.0 mM. The adsorption isotherms indicated that zeolite modified with HTAB could significantly enhance the carbaryl adsorption capacity. Zeolite NaY modified with 5.0 mM HTAB gave great carbaryl adsorption because of hydrophilic surface. The 5.0 mM HTAB could adsorb up to 145.75 ppm g-1 of carbaryl which was equivalent to a 36.7% increase. The Surface area characterization showed the remaining of pore volume and pore size diameter and external surface area whereas the BET surface area and micropore surface area of modified zeolite slightly decreased. The XRD results indicate that modification of zeolite NaY with HTAB does not change the crystallinity of the starting zeolite. The elemental analysis indicated that the Si/Al ratio of synthesized zeolite NaY was close to 2.43. Desorption of carbaryl was tested by organic solvents such as methanol, ethanol, tetrahydrofuran, hexane and Deionized water. The results demonstrated that the percentage desorption of methanol is the highest. Carbaryl was quantitatively desorbed with percentage desorption of 82-100 %. It indicated sorption mechanism of carbaryl on the modified sorbent which was principally driven by hydrophobic forces.

Optical study of active ion transport in lipid vesicles containing reconstituted Na,K-ATPase.

PubMed

Apell, H J; Marcus, M M; Anner, B M; Oetliker, H; Läuger, P

1985-01-01

A fluorescence method is described for the measurement of ATP-driven ion fluxes in lipid vesicles containing purified Na,K-ATPase. The membrane voltage of enzyme containing vesicles was measured by using a voltage-sensitive indocyanine dye. By addition of valinomycin the vesicle membrane is made selectively permeable to K+ so that the membrane voltage approaches the Nernst potential for K+. With constant external K+ concentration, the time course of internal K+ concentration can be continuously measured as change of the fluorescence signal after activation of the pump. The optical method has a higher time resolution than tracer-flux experiments and allows an accurate determination of initial flux rates. From the temperature dependence of active K+ transport its activation energy was determined to be 115 kJ/mol. ATP-stimulated electrogenic pumping can be measured as fast fluorescence change when the membrane conductance is low (i.e., at low or zero valinomycin concentration). In accordance with expectation, the amplitude of the fast signal change increases with decreasing passive ion permeability of the vesicle membrane. The resolution of the charge movement is so high that a few pump turnovers can be easily detected.

Strophanthidin-sensitive sodium fluxes in metabolically poisoned frog skeletal muscle

PubMed Central

1976-01-01

Strophanthidin-sensitive and insensitive unidirectional fluxes of Na were measured in fog sartorius muscles whose internal Na levels were elevated by overnight storage in the cold. ATP levels were lowered, and ADP levels raised, by metabolic poisoning with either 2,4- dinitrofluorobenzene or iodoacetamide. Strophanthidin-sensitive Na efflux and influx both increased after poisoning, while strophanthidin- insensitives fluxes did not. The increase in efflux did not require the presence of external K but was greatly attenuated when Li replaced Na as the major external cation. Membrane potential was not markedly altered by 2,4-dinitrofluorobenzene. These observations indicate that the sodium pump of frog skeletal muscle resembles that of squid giant axon and human erythrocyte in its ability to catalyze Na-Na exchange to an extent determined by intracellular ATP/ADP levels. PMID:1086888

Acid pretreatment and enzymatic saccharification of brown seaweed for polyhydroxybutyrate (PHB) production using Cupriavidus necator.

PubMed

Azizi, Nahid; Najafpour, Ghasem; Younesi, Habibollah

2017-08-01

The brown seaweed Sargassum sp. was used as a feedstock to produce polyhydroxybutyarte (PHB) using Cupriavidus necator PTCC 1615. In order to release monomeric sugars, dilute acid hydrolysis of Sargassum sp. biomass was followed by enzymatic saccharification. In addition, the effect of different nitrogen sources was evaluated for PHB production. The fermentation of hydrolysate with the ammonium sulfate as selected nitrogen source resulted PHB yield of 0.54±0.01g/g reducing sugar. Then, NaCl was used as external stress factor which was added to the media. Addition of 8g/L NaCl had a positive impact on high PHB yield of 0.74±0.01g/g reducing sugar. Increasing trend of NaCl concentration to 16g/L was found to inhibit the production of PHB. Based on obtained results using 20g/L of reducing sugar, at desired condition the highest cell dry weight and PHB concentrations were 5.36±0.22 and 3.93±0.24g/L, respectively. The findings of this study reveal that Sargassum sp. is a promising feedstock for biopolymer production. The characteristics of produced PHB were analyzed by FTIR, differential scanning calorimetry and 1 H NMR. Copyright © 2017 Elsevier B.V. All rights reserved.

Optimization of cyanide extraction from wastewater using emulsion liquid membrane system by response surface methodology.

PubMed

Xue, Juan Qin; Liu, Ni Na; Li, Guo Ping; Dang, Long Tao

To solve the disposal problem of cyanide wastewater, removal of cyanide from wastewater using a water-in-oil emulsion type of emulsion liquid membrane (ELM) was studied in this work. Specifically, the effects of surfactant Span-80, carrier trioctylamine (TOA), stripping agent NaOH solution and the emulsion-to-external-phase-volume ratio on removal of cyanide were investigated. Removal of total cyanide was determined using the silver nitrate titration method. Regression analysis and optimization of the conditions were conducted using the Design-Expert software and response surface methodology (RSM). The actual cyanide removals and the removals predicted using RSM analysis were in close agreement, and the optimal conditions were determined to be as follows: the volume fraction of Span-80, 4% (v/v); the volume fraction of TOA, 4% (v/v); the concentration of NaOH, 1% (w/v); and the emulsion-to-external-phase volume ratio, 1:7. Under the optimum conditions, the removal of total cyanide was 95.07%, and the RSM predicted removal was 94.90%, with a small exception. The treatment of cyanide wastewater using an ELM is an effective technique for application in industry.

Selective inhibition of K(+)-stimulation of Na,K-ATPase by bretylium.

PubMed Central

Tiku, P. E.; Nowell, P. T.

1991-01-01

1. The effects of bretylium were investigated on purified Na,K-ATPase from guinea-pig heart and on the Na/K pump in trout erythrocytes, with a view to further identifying the mechanism(s) associated with its antiarrhythmic effects. 2. Na,K-ATPase activity of the thiocyanate-dispersed enzyme was determined by the measurement of inorganic phosphate produced by ATP hydrolysis. 3. When the concentrations of each of the Na,K-ATPase activating components were varied in turn, bretylium (1-5 mmol l-1) exhibited competitive-type effects against K+ with a Ki of 1.4 mmol l-1 and noncompetitive-type effects against Na+, Mg2+ and ATP. 4. In K+ influx studies in trout erythrocytes with 86Rb+ used as the marker, the inhibition of total influx observed with bretylium (5 and 10 mmol l-1) was attributable to the bretylium cation selectively inhibiting the Na/K pump-mediated influx with the associated tosylate anion inhibiting Na/K cotransport. 5. The observed inhibition kinetics indicated that the bretylium cation (2-15 mmol l-1) competitively inhibited K+ stimulation of the Na/K pump at 6 and 1.25 mmol l-1 external K+ with a mean K1 of 2.3 mmol l-1. 6. The effects demonstrated on the functioning Na/K pump in erythrocytes confirmed the Na,K-ATPase findings, with bretylium selectively inhibiting K+ stimulation of the pump mechanism in both cases. 7. It is suggested that Na,K-ATPase inhibition may contribute to the antiarrhythmic and positive inotropic effects of bretylium with the cardiac accumulation of bretylium also possibly being a further important factor. PMID:1667290

Sulfur-oxidizing autotrophic and mixotrophic denitrification processes for drinking water treatment: elimination of excess sulfate production and alkalinity requirement.

PubMed

Sahinkaya, Erkan; Dursun, Nesrin

2012-09-01

This study evaluated the elimination of alkalinity need and excess sulfate generation of sulfur-based autotrophic denitrification process by stimulating simultaneous autotrophic and heterotrophic (mixotrophic) denitrification process in a column bioreactor by methanol supplementation. Also, denitrification performances of sulfur-based autotrophic and mixotrophic processes were compared. In autotrophic process, acidity produced by denitrifying sulfur-oxidizing bacteria was neutralized by the external NaHCO(3) supplementation. After stimulating mixotrophic denitrification process, the alkalinity need of the autotrophic process was satisfied by the alkalinity produced by heterotrophic denitrifiers. Decreasing and lastly eliminating the external alkalinity supplementation did not adversely affect the process performance. Complete denitrification of 75 mg L(-1) NO(3)-N under mixotrophic conditions at 4 h hydraulic retention time was achieved without external alkalinity supplementation and with effluent sulfate concentration lower than the drinking water guideline value of 250 mg L(-1). The denitrification rate of mixotrophic process (0.45 g NO(3)-N L(-1) d(-1)) was higher than that of autotrophic one (0.3 g NO(3)-N L(-1) d(-1)). Batch studies showed that the sulfur-based autotrophic nitrate reduction rate increased with increasing initial nitrate concentration and transient accumulation of nitrite was observed. Copyright © 2012 Elsevier Ltd. All rights reserved.

Noninvasive Evaluation of Heavy Metal Uptake and Storage in Micoralgae Using a Fluorescence Resonance Energy Transfer-Based Heavy Metal Biosensor1[C][W][OPEN

PubMed Central

Rajamani, Sathish; Torres, Moacir; Falcao, Vanessa; Ewalt Gray, Jaime; Coury, Daniel A.; Colepicolo, Pio; Sayre, Richard

2014-01-01

We have developed a fluorescence resonance energy transfer (FRET)-based heavy metal biosensor for the quantification of bioavailable free heavy metals in the cytoplasm of the microalga Chlamydomonas reinhardtii. The biosensor is composed of an end-to-end fusion of cyan fluorescent protein (CFP), chicken metallothionein II (MT-II), and yellow fluorescent protein (YFP). In vitro measurements of YFP/CFP fluorescence emission ratios indicated that the addition of metals to the purified biosensor enhanced FRET between CFP and YFP, consistent with heavy metal-induced folding of MT-II. A maximum YFP/CFP FRET ratio of 2.8 was observed in the presence of saturating concentrations of heavy metals. The sensitivity of the biosensor was greatest for Hg2+ followed by Cd2+ ≈ Pb2+ > Zn2+ > Cu2+. The heavy metal biosensor was unresponsive to metals that do not bind to MT-II (Na+ and Mg2+). When expressed in C. reinhardtii, we observed a differential metal-dependent response to saturating external concentrations (1.6 mm) of heavy metals (Pb2+ > Cd2+) that was unlike that observed for the isolated biosensor (in vitro). Significantly, analysis of metal uptake kinetics indicated that equilibration of the cytoplasm with externally applied heavy metals occurred within seconds. Our results also indicated that algae have substantial buffering capacity for free heavy metals in their cytosol, even at high external metal concentrations. PMID:24368336

Noninvasive evaluation of heavy metal uptake and storage in micoralgae using a fluorescence resonance energy transfer-based heavy metal biosensor.

PubMed

Rajamani, Sathish; Torres, Moacir; Falcao, Vanessa; Ewalt Gray, Jaime; Coury, Daniel A; Colepicolo, Pio; Sayre, Richard

2014-02-01

We have developed a fluorescence resonance energy transfer (FRET)-based heavy metal biosensor for the quantification of bioavailable free heavy metals in the cytoplasm of the microalga Chlamydomonas reinhardtii. The biosensor is composed of an end-to-end fusion of cyan fluorescent protein (CFP), chicken metallothionein II (MT-II), and yellow fluorescent protein (YFP). In vitro measurements of YFP/CFP fluorescence emission ratios indicated that the addition of metals to the purified biosensor enhanced FRET between CFP and YFP, consistent with heavy metal-induced folding of MT-II. A maximum YFP/CFP FRET ratio of 2.8 was observed in the presence of saturating concentrations of heavy metals. The sensitivity of the biosensor was greatest for Hg2+ followed by Cd2+≈Pb2+>Zn2+>Cu2+. The heavy metal biosensor was unresponsive to metals that do not bind to MT-II (Na+ and Mg2+). When expressed in C. reinhardtii, we observed a differential metal-dependent response to saturating external concentrations (1.6 mm) of heavy metals (Pb2+>Cd2+) that was unlike that observed for the isolated biosensor (in vitro). Significantly, analysis of metal uptake kinetics indicated that equilibration of the cytoplasm with externally applied heavy metals occurred within seconds. Our results also indicated that algae have substantial buffering capacity for free heavy metals in their cytosol, even at high external metal concentrations.

In vitro Studies of the Gain and Exchange of Calcium in Frog Skeletal Muscle

PubMed Central

Cosmos, Ethel; Harris, Eric J.

1961-01-01

(1) The Ca++, Na+, and K+ contents of frog sartorius muscles were found analytically after exposure to various media including some containing labeled Ca++. (2) During storage in media with 100 to 120 mM Na+ and 1 mM Ca++ both Na+ and Ca++ are gained while K+ is lost; there is a high correlation between Na+ and Ca++ gains. (3) When Ca++ gain occurs from a solution containing labeled Ca++ there is also some exchange of the original Ca++ with the labeled Ca++. The amount exchanged is considerably less (e.g. 50 per cent) than the total amount of labeled Ca++ taken up by the tissue. (4) When the external Na+ concentration is reduced to 30 mM the amount of labeled Ca++ taken up is increased. Part of the increase is attributable to a greater net gain and part to a greater degree of exchange. (5) It is pointed out that muscles which have been loaded in vitro with labeled Ca++ will not provide a valid measure of the exchangeability of the normal Ca++ content present at the time of dissection. (6) Comparison is made between results obtained using Sr89 and Ca45 as labels for the Ca++. Little, if any, difference is perceptible. PMID:13695749

Control of synthesis and release of radioactive acetylcholine in brain slices from the rat. Effects of neurotropic drugs

PubMed Central

Grewaal, D. S.; Quastel, J. H.

1973-01-01

1. Studies of the synthesis and release of radioactive acetylcholine in rat brain-cortex slices incubated in Locke–bicarbonate–[U-14C]glucose media, containing paraoxon as cholinesterase inhibitor, revealed the following phenomena: (a) dependence of K+-or protoveratrine-stimulated acetylcholine synthesis and release on the presence of Na+ and Ca2+ in the incubation medium, (b) enhanced release of radioactive acetylcholine by substances that promote depolarization at the nerve cell membrane (e.g. high K+, ouabain, protoveratrine, sodium l-glutamate, high concentration of acetylcholine), (c) failure of acetylcholine synthesis to keep pace with acetylcholine release under certain conditions (e.g. the presence of ouabain or lack of Na+). 2. Stimulation by K+ of radioactive acetylcholine synthesis was directly proportional to the external concentration of Na+, but some synthesis and release of radioactive acetylcholine occurred in the absence of Na+ as well as in the absence of Ca2+. 3. The Na+ dependence of K+-stimulated acetylcholine synthesis was partly due to suppression of choline transport, as addition of small concentrations of choline partly neutralized the effect of Na+ lack, and partly due to the suppression of the activity of the Na+ pump. 4. Protoveratrine caused a greatly increased release of radioactive acetylcholine without stimulating total radioactive acetylcholine synthesis. Protoveratrine was ineffective in the absence of Ca2+ from the incubation medium. It completely blocked K+ stimulation of acetylcholine synthesis and release. 5. Tetrodotoxin abolished the effects of protoveratrine on acetylcholine release. It had blocking effects (partial or complete) on the action of high K+, sodium l-glutamate and lack of Ca2+ on acetylcholine synthesis and release. 6. Unlabelled exogenous acetylcholine did not diminish the content of labelled tissue acetylcholine, derived from labelled glucose, suggesting that no exchange with vesicular acetylcholine took place. In the presence of 4mm-KCl it caused some increase in the release of labelled acetylcholine. 7. The barbiturates (Amytal, pentothal), whilst having no significant effects on labelled acetylcholine synthesis in unstimulated brain except at high concentration (1mm), diminished or abolished (at 0.25 or 0.5mm) the enhanced release of acetylcholine, due to high K+ or lack of Ca2+. The fall in tissue content of acetylcholine, due to lack of Ca2+, was diminished or abolished by pentothal (0.25 or 0.5mm) or Amytal (0.25mm). PMID:4722896

Binding of benzocaine in batrachotoxin-modified Na+ channels. State- dependent interactions

PubMed Central

1994-01-01

Hille (1977. Journal of General Physiology. 69:497-515) first proposed a modulated receptor hypothesis (MRH) to explain the action of benzocaine in voltage-gated Na+ channels. Using the MRH as a framework, we examined benzocaine binding in batrachotoxin (BTX)-modified Na+ channels under voltage-clamp conditions using either step or ramp command signals. We found that benzocaine binding is strongly voltage dependent. At -70 mV, the concentration of benzocaine that inhibits 50% of BTX-modified Na+ currents in GH3 cells (IC50) is 0.2 mM, whereas at +50 mV, the IC50 is 1.3 mM. Dose-response curves indicate that only one molecule of benzocaine is required to bind with one BTX-modified Na+ channel at -70 mV, whereas approximately two molecules are needed at +50 mV. Upon treatment with the inactivation modifier chloramine-T, the binding affinity of benzocaine is reduced significantly at -70 mV, probably as a result of the removal of the inactivated state of BTX- modified Na+ channels. The same treatment, however, enhances the binding affinity of cocaine near this voltage. External Na+ ions appear to have little effect on benzocaine binding, although they do affect cocaine binding. We conclude that two mechanisms underlie the action of local anesthetics in BTX-modified Na+ channels. Unlike open-channel blockers such as cocaine and bupivacaine, neutral benzocaine binds preferentially with BTX-modified Na+ channels in a closed state. Furthermore, benzocaine can be modified chemically so that it behaves like an open-channel blocker. This compound also elicits a use- dependent block in unmodified Na+ channels after repetitive depolarizations, whereas benzocaine does not. The implications of these findings for the MRH theory will be discussed. PMID:8195785

Intracellular Requirements for Passive Proton Transport through the Na+,K+-ATPase.

PubMed

Stanley, Kevin S; Meyer, Dylan J; Gatto, Craig; Artigas, Pablo

2016-12-06

The Na + ,K + -ATPase (NKA or Na/K pump) hydrolyzes one ATP to exchange three intracellular Na+ (Na + i ) for two extracellular K+ (K + o ) across the plasma membrane by cycling through a set of reversible transitions between phosphorylated and dephosphorylated conformations, alternately opening ion-binding sites externally (E2) or internally (E1). With subsaturating [Na + ] o and [K + ] o , the phosphorylated E2P conformation passively imports protons generating an inward current (I H ), which may be exacerbated in NKA-subunit mutations associated with human disease. To elucidate the mechanisms of I H , we studied the effects of intracellular ligands (transported ions, nucleotides, and beryllium fluoride) on I H and, for comparison, on transient currents measured at normal Na + o (Q Na ). Utilizing inside-out patches from Xenopus oocytes heterologously expressing NKA, we observed that 1) in the presence of Na + i , I H and Q Na were both activated by ATP, but not ADP; 2) the [Na + ] i dependence of I H in saturating ATP showed K 0.5,Na  = 1.8 ± 0.2 mM and the [ATP] dependence at saturating [Na + ] i yielded K 0.5,ATP  = 48 ± 11 μM (in comparison, Na + i -dependent Q Na yields K 0.5,Na  = 0.8 ± 0.2 mM and K 0.5,ATP  = 0.43 ± 0.03 μM; 3) ATP activated I H in the presence of K + i (∼15% of the I H observed in Na + i ) only when Mg 2+ i was also present; and 4) beryllium fluoride induced maximal I H  even in the absence of nucleotide. These data indicate that I H occurs when NKA is in an externally open E2P state with nucleotide bound, a conformation that can be reached through forward Na/K pump phosphorylation of E1, with Na + i and ATP, or by backward binding of K + i to E1, which drives the pump to the occluded E2(2K), where free P i (at the micromolar levels found in millimolar ATP solutions) promotes external release of occluded K + by backdoor NKA phosphorylation. Maximal I H through beryllium-fluorinated NKA indicates that this complex mimics ATP-bound E2P states. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Sodium-bicarbonate cotransport in retinal Müller (glial) cells of the salamander.

PubMed

Newman, E A

1991-12-01

An electrogenic Na+/HCO3- cotransport system was studied in freshly dissociated Müller cells of the salamander retina. Cotransporter currents were recorded from isolated cells using the whole-cell, voltage-clamp technique following the block of K+ conductance with external Ba2+ and internal Cs+. At constant pHo, an outward current was evoked when extracellular HCO3- concentration was raised by pressure ejecting a HCO3(-)-buffered solution onto the surface of cells bathed in nominally HCO3(-)-free solution. The HCO3(-)-evoked outward current was reduced to 4.4% of control by 0.5 mM DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulfonate), to 28.8% of control by 2 mM DNDS (4,4'-dinitrostilbene-2,2'-disulfonate), and to 28.4% of control by 2 mM harmaline. Substitution of choline for Na+ in bath and ejection solutions reduced the response to 1.3% of control. Bicarbonate-evoked currents of normal magnitude were recorded when methane sulfonate was substituted for Cl- in bath, ejection, and intracellular solutions. Similarly, an outward current was evoked when extracellular Na+ concentration was raised in the presence of HCO3-. The Na(+)-evoked response was reduced to 16.2% of control by 2 mM DNDS and was abolished by removal of HCO3- from bath and ejection solutions. Taken together, these results (block by stilbenes and harmaline, HCO3- and Na+ dependence, Cl- independence) indicate that salamander Müller cells possess an electrogenic Na+/HCO3- cotransport system. Na+/HCO3- cotransporter sites were localized primarily at the endfoot region of Müller cells. Ejection of HCO3- onto the endfoot evoked outward currents 10 times larger than currents evoked by ejections onto the opposite (distal) end of the cell. The reversal potential of the cotransporter was determined by DNDS block of cotransport current. In the absence of a transmembrane HCO3- gradient, the reversal potential varied systematically as a function of the transmembrane Na+ gradient. The reversal potential was -0.1 mV for a [Na+]o:[Na+]i ratio of 1:1 and -25.2 mV for a Na+ gradient ratio of 7.4:1. Based on these values, the estimated stoichiometry of the cotransporter was 2.80 +/- 0.13:1 (HCO3-:Na+). Possible functions of the glial cell Na+/HCO3- cotransporter, including the regulation of CO2 in the retina and the regulation of cerebral blood flow, are discussed.

A Salt-Inducible Mn-Catalase (KatB) Protects Cyanobacterium from Oxidative Stress.

PubMed

Chakravarty, Dhiman; Banerjee, Manisha; Bihani, Subhash C; Ballal, Anand

2016-02-01

Catalases, enzymes that detoxify H2O2, are widely distributed in all phyla, including cyanobacteria. Unlike the heme-containing catalases, the physiological roles of Mn-catalases remain inadequately characterized. In the cyanobacterium Anabaena, pretreatment of cells with NaCl resulted in unusually enhanced tolerance to oxidative stress. On exposure to H2O2, the NaCl-treated Anabaena showed reduced formation of reactive oxygen species, peroxides, and oxidized proteins than the control cells (i.e. not treated with NaCl) exposed to H2O2. This protective effect correlated well with the substantial increase in production of KatB, a Mn-catalase. Addition of NaCl did not safeguard the katB mutant from H2O2, suggesting that KatB was indeed responsible for detoxifying the externally added H2O2. Moreover, Anabaena deficient in KatB was susceptible to oxidative effects of salinity stress. The katB gene was strongly induced in response to osmotic stress or desiccation. Promoter-gfp analysis showed katB to be expressed only in the vegetative cells but not in heterocysts. Biochemically, KatB was an efficient, robust catalase that remained active in the presence of high concentrations of NaCl. Our findings unravel the role of Mn-catalase in acclimatization to salt/oxidative stress and demonstrate that the oxidative stress resistance of an organism can be enhanced by a simple compound such as NaCl. © 2016 American Society of Plant Biologists. All Rights Reserved.

Effect of NaNO3 concentration on anodic electrochemical behavior on the Sb surface in NaOH solution

NASA Astrophysics Data System (ADS)

He, Yun-long; Xu, Rui-dong; He, Shi-wei; Chen, Han-sen; Li, Kuo; Zhu, Yun; Shen, Qing-feng

2018-03-01

The effect of NaNO3 concentration on the anodic electrochemical behavior of antimony in 4 M NaOH solution was investigated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) analyses. The mechanism of NO 3 - concentration effect on the anodic electrochemical behavior of antimony was proposed, and its availability was confirmed by experimental results. The effect of NaNO3 on the anodic behavior of antimony in NaOH solution can be interpreted as a stepwise formation of different antimony compounds with different NaNO3 concentrations. Metallic antimony is apt to be oxidized into Sb2O3 within the NaNO3 concentration range of 0-0.48 M. NaSbO3 can be found on the antimony surface when the NaNO3 concentration increases gradually. Insoluable NaSbO3 inhibits the anodic oxidation of antimony due to its shielding effect on the mass transport of the reactants and products. Surface morphology and composition were analyzed by X-ray photoelectron spectroscopy (XPS), scanning electronic microscopy (SEM), and electron dispersion spectroscopy (EDS) analyses. Results indicate that the anodic oxidation layer is composed of Sb2O3, NaSbO3, and Sb. The atomic proportion of antimony in the form of NaSbO3 increases with increasing NaNO3 concentration due to the powerful oxidizing property of NaNO3.

Pre-Steady-State Kinetics of Ba-Ca Exchange Reveals a Second Electrogenic Step Involved in Ca2+ Translocation by the Na-Ca Exchanger

PubMed Central

Haase, Andreas; Hartung, Klaus

2009-01-01

Kinetic properties of the Na-Ca exchanger (guinea pig NCX1) expressed in Xenopus oocytes were investigated with excised membrane patches in the inside-out configuration and photolytic Ca2+ concentration jumps with either 5 mM extracellular Sr2+ or Ba2+. After a Ca2+ concentration jump on the cytoplasmic side, the exchanger performed Sr-Ca or Ba-Ca exchange. In the Sr-Ca mode, currents are transient and decay in a monoexponential manner similar to that of currents in the Ca-Ca exchange mode described before. Currents recorded in the Ba-Ca mode are also transient, but the decay is biphasic. In the Sr-Ca mode the amount of charge translocated increases at negative potentials in agreement with experiments performed in the Ca-Ca mode. In the Ba-Ca mode the total amount of charge translocated after a Ca2+ concentration jump is ∼4 to 5 times that in Ca-Ca or Sr-Ca mode. In the Ba-Ca mode the voltage dependence of charge translocation depends on the Ca2+ concentration on the cytosolic side before the Ca2+ concentration jump. At low initial Ca2+ levels (∼0.5 μM), charge translocation is voltage independent. At a higher initial concentration (1 μM Ca2+), the amount of charge translocated increases at positive potentials. Biphasic relaxation of the current was also observed in the Ca-Ca mode if the external Ca2+ concentration was reduced to ≤0.5 mM. The results reported here and in previous publications can be described by using a 6-state model with two voltage-dependent conformational transitions. PMID:19486679

Loss of EGF binding and cation transport response during differentiation of mouse neuroblastoma cells.

PubMed

Mummery, C L; van der Saag, P T; de Laat, S W

1983-01-01

Mouse neuroblastoma cells (clone N1E-115) differentiate in culture upon withdrawal of serum growth factors and acquire the characteristics of neurons. We have shown tht exponentially growing N1E-115 cells possess functional epidermal growth factor (EGF) receptors but that the capacity for binding EGF and for stimulation of DNA synthesis is lost as the cells differentiate. Furthermore, in exponentially growing cells, EGF induces a rapid increase in amiloride-sensitive Na+ influx, followed by stimulation of the (Na+-K+)ATPase, indicating that activation of the Na+/H+ exchange mechanism in N1E-115 cells [1] may be induced by EGF. The ionic response is also lost during differentiation, but we have shown that the stimulation of both Na+ and K+ influx is directly proportional to the number of occupied receptors in all cells whether exponentially growing or differentiating, thus only indirectly dependent on the external EGF concentration. The linearity of the relationships indicates that there is no rate-limiting step between EGF binding and the ionic response. Our data would suggest that as neuroblastoma cells differentiate and acquire neuronal properties, their ability to respond to mitogens, both biologically and in the activation of cation transport processes, progressively decreases owing to the loss of the appropriate receptors.

Estimation of external dose by car-borne survey in Kerala, India.

PubMed

Hosoda, Masahiro; Tokonami, Shinji; Omori, Yasutaka; Sahoo, Sarata Kumar; Akiba, Suminori; Sorimachi, Atsuyuki; Ishikawa, Tetsuo; Nair, Raghu Ram; Jayalekshmi, Padmavathy Amma; Sebastian, Paul; Iwaoka, Kazuki; Akata, Naofumi; Kudo, Hiromi

2015-01-01

A car-borne survey was carried out in Kerala, India to estimate external dose. Measurements were made with a 3-in × 3-in NaI(Tl) scintillation spectrometer from September 23 to 27, 2013. The routes were selected from 12 Panchayats in Karunagappally Taluk which were classified into high level, mid-level and low level high background radiation (HBR) areas. A heterogeneous distribution of air kerma rates was seen in the dose rate distribution map. The maximum air kerma rate, 2.1 μGy/h, was observed on a beach sand surface. 232Th activity concentration for the beach sand was higher than that for soil and grass surfaces, and the range of activity concentration was estimated to be 0.7-2.3 kBq/kg. The contribution of 232Th to air kerma rate was over 70% at the measurement points with values larger than 0.34 μGy/h. The maximum value of the annual effective dose in Karunagappally Taluk was observed around coastal areas, and it was estimated to be 13 mSv/y. More than 30% of all the annual effective doses obtained in this survey exceeded 1 mSv/y.

Evaluating cleansing effects on trace elements and stable isotope values in feathers of oiled birds.

PubMed

Valladares, Sonia; Moreno, Roćio; Jover, Lluis; Sanpera, Carola

2010-01-01

Feathers of seabirds are widely used as a nondestructive tissue for pollution monitoring of trace elements, as well as convenient samples for trophic ecology studies by means of stable isotope analysis (SIA). Nevertheless, feathers can be occasionally impregnated with oil from deliberate ship discharges and from massive oil spill accidents. The feather structure makes them effective traps for particles and are subject to external contamination. It is unknown to what extent the oil adhered to feathers can change trace element concentrations or stable isotope signatures. This study has two primary objectives: (1) to assess if there are differences between trace element concentrations and stable isotope signatures of oiled and clean feathers, and (2) to determine if the cleansing of oiled feathers using commonly applied techniques such as sodium hydroxide (NaOH) washes in combination with an organic solvent (hexane) is more effective than using NaOH alone. In order to do this, we analysed trace elements (Se, Hg, Pb, Cu and Zn) and stable isotopes (delta(13)C and delta(15)N) of individual feathers of yellow-legged gulls (Larus michahellis) which were affected by the 2002 Prestige oil spill in Galicia (NW Spain). Two sets of feathers were analysed, one group were oil-free (Control group) and the other had oil adhered to its surface (Oiled group). We expected to find differences between control and oiled feathers when cleaning exclusively with NaOH and no differences when using hexane. Our results did not show significant differences between Control and Oiled groups as a consequence of the cleansing method used. Unexpectedly, the additional cleansing with hexane resulted in decreasing selenium concentrations and increasing zinc and delta(15)N values in all groups of feathers.

A fluorescence method for determination of glucose transport by intestinal BBMV of common carp.

PubMed

Yang, Li-Ping; Yan, Xiao; Zheng, Wen-Jia; Hu, Jun-Yi; Zhang, Yu-Ru; Qin, Chao-Bin; Meng, Xiao-Lin; Lu, Rong-Hua; Chen, Fang; Xie, Di-Zhi; Nie, Guo-Xing

2017-11-15

Epithelial brush-border membrane vesicles (BBMVs) were isolated from the intestine of common carp and studied systematically by enzyme activity, transmission electron microscopy and immunoblotting. The uptake time course and the substrate concentration effect were assessed, and then, the ability of phlorizin and cytochalasin B to inhibit uptake was analyzed. The results show that sucrase, alkaline phosphatase and Na + -K + -ATPase activities in these vesicles were enriched 7.94-, 6.74- and 0.42-fold, respectively, indicating a relatively pure preparation of apical membrane with little basolateral contamination. The vesicular structure was in complete closure, as confirmed by electron microscopy. The presence of SGLT1 on the BBMVs was confirmed by Western blot analysis. In the time course experiment, the glucose uptake by BBMVs in Na + medium displayed an initial accumulation (overshoot) at 5 min followed by a rapid return to equilibrium values at 60 min. Over the 2-NBDG concentration range selected, the external 2-NBDG concentration in NaSCN medium graphed as a curved line. Phlorizin and cytochalasin B had an obvious inhibitory effect on 2-NBDG transport in carp BBMVs, and the detected fluorescence intensity decreased. The inhibition rate in the 1000 μM group was the strongest at 64.18% and 63.61% of phlorizin and cytochalasin B, respectively, indicating the presence of carriers other than SGLT1. This study is the first to demonstrate that 2-NBDG can be used as a convenient and sensitive probe to detect glucose uptake in fish BBMVs. This technology will provide a convenient method to discover new effects and factors in glucose metabolism. Copyright © 2017. Published by Elsevier Inc.

Osmoadaptation and osmoregulation in archaea.

PubMed

Roberts, M F

2000-09-01

The response of archaea to changes in external NaCl is reviewed and compared to what is known about osmoadaptation and osmoregulation in bacteria and eukaryotes. Cells placed in altered external NaCl exhibit short term and long term responses. The earliest events are likely to be water movement through aquaporin-like channels (efflux if external NaCl has been increased, influx into the cell if the external NaCl has been decreased) and ion movement (e.g., K+ moving in the direction opposite to water flow) through channels sensitive to osmotic pressure. Accumulation of organic solutes, either by uptake from the medium or de novo synthesis, is triggered after these initial changes. Archaea have some unique organic solutes (osmolytes) that are not used by other organisms. These as well as other more common solutes have a role in stabilizing macromolecules from denaturation. Many osmolytes are distinguished by their stability in the cell and their lack of strong interactions with cellular components. A cell may respond by accumulating one or more temporary osmolytes, then over time readjust the intracellular solute distribution to what is optimal for cell growth under the new conditions. Coupled with the movement and accumulation of solutes is the induction of stress proteins (e.g., chaperonins) and, in some cases, transcriptional regulation of key enzymes. The response to NaCl stress of Methanococcus thermolithotrophicus is presented as an example of how one particular archaeon responds and adapts to altered osmotic pressure. Clearly, the detailed response of other archaea to osmotic stress will be needed in order to identify features (aside from some of the organic osmolytes) unique to the organisms in this kingdom.

Osmoadaptation and osmoregulation in archaea: update 2004.

PubMed

Roberts, Mary F

2004-09-01

The response of archaea to changes in external NaCl is reviewed and compared to what is known about osmoadaptation and osmoregulation in bacteria and eukaryotes. Cells placed in altered external NaCl exhibit short term and long term responses. The earliest events are likely to be water movement through aquaporin-like channels (efflux if external NaCl has been increased, influx into the cell if the external NaCl has been decreased) and ion movement (e.g., K+ moving in the direction opposite to water flow) through channels sensitive to osmotic pressure. A brief discussion of recent structures of homologues of these membrane proteins is presented. Accumulation of organic solutes, either by uptake from the medium or de novo synthesis, is triggered after these initial changes. Archaea have some unique organic solutes (osmolytes) that are not used by other organisms. These as well as other more common solutes have a role in stabilizing macromolecules from denaturation. Many osmolytes are distinguished by their stability in the cell and their lack of strong interactions with cellular components. A cell may respond by accumulating one or more temporary osmolytes, then over time readjust the intracellular solute distribution to what is optimal for cell growth under the new conditions. Coupled with the movement and accumulation of solutes is the induction of stress proteins (e.g., chaperonins) and, in some cases, transcriptional regulation of key enzymes. The response to NaCl stress of Methanococcus thermolithotrophicus is presented as an example of how one particular archaeon responds and adapts to altered osmotic pressure. The detailed response of many other archaea to osmotic stress will be needed in order to identify features (aside from some of the organic osmolytes) unique to the organisms in this kingdom.

40 CFR Table 29 to Subpart G of... - Seal Related Factors for External Floating Roof Vessels

Code of Federal Regulations, 2012 CFR

2012-07-01

...: Primary seal only 1.2 1.5 1.3 1.5 With shoe-mounted secondary seal 0.8 1.2 1.4 1.2 With rim-mounted... shield 0.8 0.9 NA NA With rim-mounted secondary seal 0.7 0.4 NA NA Vapor mounted resilient seal: Primary... Synthetic Organic Chemical Manufacturing Industry for Process Vents, Storage Vessels, Transfer Operations...

40 CFR Table 29 to Subpart G of... - Seal Related Factors for External Floating Roof Vessels

Code of Federal Regulations, 2014 CFR

2014-07-01

...: Primary seal only 1.2 1.5 1.3 1.5 With shoe-mounted secondary seal 0.8 1.2 1.4 1.2 With rim-mounted... shield 0.8 0.9 NA NA With rim-mounted secondary seal 0.7 0.4 NA NA Vapor mounted resilient seal: Primary... Synthetic Organic Chemical Manufacturing Industry for Process Vents, Storage Vessels, Transfer Operations...

40 CFR Table 29 to Subpart G of... - Seal Related Factors for External Floating Roof Vessels

Code of Federal Regulations, 2013 CFR

2013-07-01

...: Primary seal only 1.2 1.5 1.3 1.5 With shoe-mounted secondary seal 0.8 1.2 1.4 1.2 With rim-mounted... shield 0.8 0.9 NA NA With rim-mounted secondary seal 0.7 0.4 NA NA Vapor mounted resilient seal: Primary... Synthetic Organic Chemical Manufacturing Industry for Process Vents, Storage Vessels, Transfer Operations...

Concentrated Electrolyte for the Sodium-Oxygen Battery: Solvation Structure and Improved Cycle Life.

PubMed

He, Mingfu; Lau, Kah Chun; Ren, Xiaodi; Xiao, Neng; McCulloch, William D; Curtiss, Larry A; Wu, Yiying

2016-12-05

Alkali metal-oxygen batteries are of great interests for energy storage because of their unparalleled theoretical energy densities. Particularly attractive is the emerging Na-O 2 battery because of the formation of superoxide as the discharge product. Dimethyl sulfoxide (DMSO) is a promising solvent for this battery but its instability towards Na makes it impractical in the Na-O 2 battery. Herein we report the enhanced stability of Na in DMSO solutions containing concentrated sodium trifluoromethanesulfonimide (NaTFSI) salts (>3 mol kg -1 ). Raman spectra of NaTFSI/DMSO electrolytes and ab initio molecular dynamics simulation reveal the Na + solvation number in DMSO and the formation of Na(DMSO) 3 (TFSI)-like solvation structure. The majority of DMSO molecules solvating Na + in concentrated solutions reduces the available free DMSO molecules that can react with Na and renders the TFSI anion decomposition, which protects Na from reacting with the electrolyte. Using these concentrated electrolytes, Na-O 2 batteries can be cycled forming sodium superoxide (NaO 2 ) as the sole discharge product with improved long cycle life, highlighting the beneficial role of concentrated electrolytes for Na-based batteries. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Concentrated Electrolyte for the Sodium-Oxygen Battery: Solvation Structure and Improved Cycle Life

DOE PAGES

He, Mingfu; Lau, Kah Chun; Ren, Xiaodi; ...

2016-11-03

Alkali metal-oxygen batteries are of great interests for energy storage because of their unparalleled theoretical energy densities. Particularly attractive is the emerging Na-O 2 battery because of the formation of superoxide as the discharge product. Dimethyl sulfoxide (DMSO) is a promising solvent for this battery but its instability towards Na makes it impractical in the Na-O 2 battery. Here in this paper, we report the enhanced stability of Na in DMSO solutions containing concentrated sodium trifluoromethanesulfonimide (NaTFSI) salts (>3molkg -1). Raman spectra of NaTFSI/DMSO electrolytes and abinitio molecular dynamics simulation reveal the Na + solvation number in DMSO and themore » formation of Na(DMSO) 3(TFSI)-like solvation structure. The majority of DMSO molecules solvating Na + in concentrated solutions reduces the available free DMSO molecules that can react with Na and renders the TFSI anion decomposition, which protects Na from reacting with the electrolyte. Using these concentrated electrolytes, Na-O 2 batteries can be cycled forming sodium superoxide (NaO 2) as the sole discharge product with improved long cycle life, highlighting the beneficial role of concentrated electrolytes for Na-based batteries.« less

Exploring the Structure of the Voltage-gated Na+ Channel by an Engineered Drug Access Pathway to the Receptor Site for Local Anesthetics*

PubMed Central

Lukacs, Peter; Gawali, Vaibhavkumar S.; Cervenka, Rene; Ke, Song; Koenig, Xaver; Rubi, Lena; Zarrabi, Touran; Hilber, Karlheinz; Stary-Weinzinger, Anna; Todt, Hannes

2014-01-01

Despite the availability of several crystal structures of bacterial voltage-gated Na+ channels, the structure of eukaryotic Na+ channels is still undefined. We used predictions from available homology models and crystal structures to modulate an external access pathway for the membrane-impermeant local anesthetic derivative QX-222 into the internal vestibule of the mammalian rNaV1.4 channel. Potassium channel-based homology models predict amino acid Ile-1575 in domain IV segment 6 to be in close proximity to Lys-1237 of the domain III pore-loop selectivity filter. The mutation K1237E has been shown previously to increase the diameter of the selectivity filter. We found that an access pathway for external QX-222 created by mutations of Ile-1575 was abolished by the additional mutation K1237E, supporting the notion of a close spatial relationship between sites 1237 and 1575. Crystal structures of bacterial voltage-gated Na+ channels predict that the side chain of rNaV1.4 Trp-1531 of the domain IV pore-loop projects into the space between domain IV segment 6 and domain III pore-loop and, therefore, should obstruct the putative external access pathway. Indeed, mutations W1531A and W1531G allowed for exceptionally rapid access of QX-222. In addition, W1531G created a second non-selective ion-conducting pore, bypassing the outer vestibule but probably merging into the internal vestibule, allowing for control by the activation gate. These data suggest a strong structural similarity between bacterial and eukaryotic voltage-gated Na+ channels. PMID:24947510

Intracellular acidification-induced alkali metal cation/H+ exchange in human neutrophils

PubMed Central

1987-01-01

Pretreatment of isolated human neutrophils (resting pHi congruent to 7.25 at pHo 7.40) with 30 mM NH4Cl for 30 min leads to an intracellular acidification (pHi congruen to 6.60) when the NH4Cl prepulse is removed. Thereafter, in 140 mM Na+ medium, pHi recovers exponentially with time (initial rate, approximately 0.12 pH/min) to reach the normal resting pHi by approximately 20 min, a process that is accomplished mainly, if not exclusively, though an exchange of internal H+ for external Na+. This Na+/H+ countertransport is stimulated by external Na+ (Km congruent to 21 mM) and by external Li+ (Km congruent to 14 mM), though the maximal transport rate for Na+ is about twice that for Li+. Both Na+ and Li+ compete as substrates for the same translocation sites on the exchange carrier. Other alkali metal cations, such as K+, Rb+, or Cs+, do not promote pHi recovery, owing to an apparent lack of affinity for the carrier. The exchange system is unaffected by ouabain or furosemide, but can be competitively inhibited by the diuretic amiloride (Ki congruent to 8 microM). The influx of Na+ or Li+ is accompanied by an equivalent counter-reflux of H+, indicating a 1:1 stoichiometry for the exchange reaction, a finding consistent with the lack of voltage sensitivity (i.e., electroneutrality) of pHi recovery. These studies indicate that the predominant mechanism in human neutrophils for pHi regulation after intracellular acidification is an amiloride-sensitive alkali metal cation/H+ exchange that shares a number of important features with similar recovery processes in a variety of other mammalian cell types. PMID:3694176

Intracellular and Extracellular pH and Ca Are Bound to Control Mitosis in the Early Sea Urchin Embryo via ERK and MPF Activities

PubMed Central

Ciapa, Brigitte; Philippe, Laetitia

2013-01-01

Studies aiming to predict the impact on marine life of ocean acidification and of altered salinity have shown altered development in various species including sea urchins. We have analyzed how external Na, Ca, pH and bicarbonate control the first mitotic divisions of sea urchin embryos. Intracellular free Ca (Cai) and pH (pHi) and the activities of the MAP kinase ERK and of MPF regulate mitosis in various types of cells including oocytes and early embryos. We found that intracellular acidification of fertilized eggs by Na-acetate induces a huge activation of ERK at time of mitosis. This also stops the cell cycle and leads to cell death, which can be bypassed by treatment with the MEK inhibitor U0126. Similar intracellular acidification induced in external medium containing low sodium or 5-(N-Methyl-N-isobutyl) amiloride, an inhibitor of the Na+/H+ exchanger, also stops the cell cycle and leads to cell death. In that case, an increase in Cai and in the phosphorylation of tyr-cdc2 occurs during mitosis, modifications that depend on external Ca. Our results indicate that the levels of pHi and Cai determine accurate levels of Ptyr-Cdc2 and P-ERK capable of ensuring progression through the first mitotic cycles. These intracellular parameters rely on external Ca, Na and bicarbonate, alterations of which during climate changes could act synergistically to perturb the early marine life. PMID:23785474

Intracellular and extracellular pH and Ca are bound to control mitosis in the early sea urchin embryo via ERK and MPF activities.

PubMed

Ciapa, Brigitte; Philippe, Laetitia

2013-01-01

Studies aiming to predict the impact on marine life of ocean acidification and of altered salinity have shown altered development in various species including sea urchins. We have analyzed how external Na, Ca, pH and bicarbonate control the first mitotic divisions of sea urchin embryos. Intracellular free Ca (Cai) and pH (pHi) and the activities of the MAP kinase ERK and of MPF regulate mitosis in various types of cells including oocytes and early embryos. We found that intracellular acidification of fertilized eggs by Na-acetate induces a huge activation of ERK at time of mitosis. This also stops the cell cycle and leads to cell death, which can be bypassed by treatment with the MEK inhibitor U0126. Similar intracellular acidification induced in external medium containing low sodium or 5-(N-Methyl-N-isobutyl) amiloride, an inhibitor of the Na(+)/H(+) exchanger, also stops the cell cycle and leads to cell death. In that case, an increase in Cai and in the phosphorylation of tyr-cdc2 occurs during mitosis, modifications that depend on external Ca. Our results indicate that the levels of pHi and Cai determine accurate levels of Ptyr-Cdc2 and P-ERK capable of ensuring progression through the first mitotic cycles. These intracellular parameters rely on external Ca, Na and bicarbonate, alterations of which during climate changes could act synergistically to perturb the early marine life.

Nucleus-acoustic Solitons in Self-gravitating Magnetized Quantum Plasmas

NASA Astrophysics Data System (ADS)

Saaduzzaman, Dewan Mohammad; Amina, Moriom; Mamun, Abdullah Al

2018-03-01

The basic properties of the nucleus-acoustic (NA) solitary waves (SWs) are investigated in a super-dense self-gravitating magnetized quantum plasma (SDSGMQP) system in the presence of an external magnetic field, whose constituents are the non-degenerate light as well as heavy nuclei, and non-/ultra-relativistically degenerate electrons. The Korteweg-de Vries (KdV) equation has been derived by employing the reductive perturbation method. The NA SWs are formed with negative (positive) electrostatic (self-gravitational) potential. It is also observed that the effects of non-/ultra-relativistically degenerate electron pressure and the obliqueness of the external magnetic field significantly change the basic properties (e.g., amplitude, width, and speed) of NA SWs. The implications of the findings of our present investigation in explaining the physics behind the formation of the NA SWs in astrophysical compact objects like neutron stars are briefly discussed.

High concentrations of Na+ and Cl- ions in soil solution have simultaneous detrimental effects on growth of faba bean under salinity stress.

PubMed

Tavakkoli, Ehsan; Rengasamy, Pichu; McDonald, Glenn K

2010-10-01

Despite the fact that most plants accumulate both sodium (Na(+)) and chloride (Cl(-)) ions to high concentration in their shoot tissues when grown in saline soils, most research on salt tolerance in annual plants has focused on the toxic effects of Na(+) accumulation. There have also been some recent concerns about the ability of hydroponic systems to predict the responses of plants to salinity in soil. To address these two issues, an experiment was conducted to compare the responses to Na(+) and to Cl(-) separately in comparison with the response to NaCl in a soil-based system using two varieties of faba bean (Vicia faba), that differed in salinity tolerance. The variety Nura is a salt-sensitive variety that accumulates Na(+) and Cl(-) to high concentrations while the line 1487/7 is salt tolerant which accumulates lower concentrations of Na(+) and Cl(-). Soils were prepared which were treated with Na(+) or Cl(-) by using a combination of different Na(+) salts and Cl(-) salts, respectively, or with NaCl. While this method produced Na(+)-dominant and Cl(-)-dominant soils, it unavoidably led to changes in the availability of other anions and cations, but tissue analysis of the plants did not indicate any nutritional deficiencies or toxicities other than those targeted by the salt treatments. The growth, water use, ionic composition, photosynthesis, and chlorophyll fluorescence were measured. Both high Na(+) and high Cl(-) reduced growth of faba bean but plants were more sensitive to Cl(-) than to Na(+). The reductions in growth and photosynthesis were greater under NaCl stress and the effect was mainly additive. An important difference to previous hydroponic studies was that increasing the concentrations of NaCl in the soil increased the concentration of Cl(-) more than the concentration of Na(+). The data showed that salinity caused by high concentrations of NaCl can reduce growth by the accumulation of high concentrations of both Na(+) and Cl(-) simultaneously, but the effects of the two ions may differ. High Cl(-) concentration reduces the photosynthetic capacity and quantum yield due to chlorophyll degradation which may result from a structural impact of high Cl(-) concentration on PSII. High Na(+) interferes with K(+) and Ca(2+) nutrition and disturbs efficient stomatal regulation which results in a depression of photosynthesis and growth. These results suggest that the importance of Cl(-) toxicity as a cause of reductions in growth and yield under salinity stress may have been underestimated.

Functional comparison of the reverse mode of Na+/Ca2+ exchangers NCX1.1 and NCX1.5 expressed in CHO cells.

PubMed

Long, Yan; Wang, Wei-ping; Yuan, Hui; Ma, Shi-ping; Feng, Nan; Wang, Ling; Wang, Xiao-liang

2013-05-01

To investigate the reverse mode function of Na(+)/Ca(2+) exchangers NCX1.1 and NCX1.5 expressed in CHO cells as well as their modulations by PKC and PKA. CHO-K1 cells were transfected with pcDNA3.1 (+) plasmid carrying cDNA of rat cardiac NCX1.1 and brain NCX1.5. The expression of NCX1.1 and NCX1.5 was examined using Western blot analysis. The intracellular Ca(2+) level ([Ca(2+)]i) was measured using Ca(2+) imaging. Whole-cell NCX currents were recorded using patch-clamp technique. Reverse mode NCX activity was elicited by perfusion with Na(+)-free medium. Ca(2+) paradox was induced by Ca(2+)-free EBSS medium, followed by Ca(2+)-containing solution (1.8 or 3.8 mmol/L CaCl2). The protein levels of NCX1.1 and NCX1.5 expressed in CHO cells had no significant difference. The reverse modes of NCX1.1 and NCX1.5 in CHO cells exhibited a transient increase of [Ca(2+)]i, which was followed by a Ca(2+) level plateau at higher external Ca(2+) concentrations. In contrast, the wild type CHO cells showed a steady increase of [Ca(2+)]i at higher external Ca(2+) concentrations. The PKC activator PMA (0.3-10 μmol/L) and PKA activator 8-Br-cAMP (10-100 μmol/L) significantly enhanced the reverse mode activity of NCX1.1 and NCX1.5 in CHO cells. NCX1.1 was 2.4-fold more sensitive to PKC activation than NCX1.5, whereas the sensitivity of the two NCX isoforms to PKA activation had no difference. Both PKC- and PKA-enhanced NCX reverse mode activities in CHO cells were suppressed by NCX inhibitor KB-R7943 (30 μmol/L). Both NCX1.1 and NCX1.5 are functional in regulating and maintaining stable [Ca(2+)]i in CHO cells and differentially regulated by PKA and PKC. The two NCX isoforms might be useful drug targets for heart and brain protection.

Trans-proximal tubular steady-state concentration differences studied by micro-puncture and tissue content of sodium and chloride at varying intraluminal sodium concentrations in vitro in rat kidney cortex slices: evidence for a multisite sodium transport system.

PubMed Central

Györy, A Z; Roby, H

1977-01-01

1. With the aid of micropuncture techniques, proximal tubular transepithelial concentration differences for Na (deltaC Na) and chloride (deltaC Cl) were measured in kidney cortex slices at bathing fluid Na concentrations from 10 to 400 m-mole. kg-1. Tissue content of water, Na and K was also measured in such slices. Under steady-state conditions of zero net flux of NaCl and water, deltaC Na represents the sum of active Na transport, factored by the tubular permeability coefficient added to a component of flux due to electrical forces. 2. The relation between bathing fluid Na concentraton and deltaC Na appeared sigmoid in form suggesting an allosteric mechanism for the transport step. 3. Transtubular potential difference, calculated from transepithelial Cl distribution ratios, did not appear constant at the various bathing fluid Na concentrations. Correcting for the effect of these potential differences on the value of each deltaC Na did not convert the sigmoid transport curve to a hyperbolic one, confirming the suggested allosteric nature of the active Na transport step. 4. Intracellular Na content varied linearly with bathing fluid Na concentrations implying free entry of this cation into the cell. This also suggests that the sigmoid transport curve is related to the properties of the active Na transport pump. PMID:856986

Potassium uptake supporting plant growth in the absence of AKT1 channel activity: Inhibition by ammonium and stimulation by sodium

NASA Technical Reports Server (NTRS)

Spalding, E. P.; Hirsch, R. E.; Lewis, D. R.; Qi, Z.; Sussman, M. R.; Lewis, B. D.

1999-01-01

A transferred-DNA insertion mutant of Arabidopsis that lacks AKT1 inward-rectifying K+ channel activity in root cells was obtained previously by a reverse-genetic strategy, enabling a dissection of the K+-uptake apparatus of the root into AKT1 and non-AKT1 components. Membrane potential measurements in root cells demonstrated that the AKT1 component of the wild-type K+ permeability was between 55 and 63% when external [K+] was between 10 and 1,000 microM, and NH4+ was absent. NH4+ specifically inhibited the non-AKT1 component, apparently by competing for K+ binding sites on the transporter(s). This inhibition by NH4+ had significant consequences for akt1 plants: K+ permeability, 86Rb+ fluxes into roots, seed germination, and seedling growth rate of the mutant were each similarly inhibited by NH4+. Wild-type plants were much more resistant to NH4+. Thus, AKT1 channels conduct the K+ influx necessary for the growth of Arabidopsis embryos and seedlings in conditions that block the non-AKT1 mechanism. In contrast to the effects of NH4+, Na+ and H+ significantly stimulated the non-AKT1 portion of the K+ permeability. Stimulation of akt1 growth rate by Na+, a predicted consequence of the previous result, was observed when external [K+] was 10 microM. Collectively, these results indicate that the AKT1 channel is an important component of the K+ uptake apparatus supporting growth, even in the "high-affinity" range of K+ concentrations. In the absence of AKT1 channel activity, an NH4+-sensitive, Na+/H+-stimulated mechanism can suffice.

Role of monovalent cations in fluid secretion from the exocrine rabbit pancreas.

PubMed

Kuijpers, G A; Van Nooy, I G; De Pont, J J

1989-08-21

The role of Na+ in fluid secretion by the isolated rabbit pancreas was investigated. The fluid secretion rate is reduced upon replacement of Na+ in the bathing medium by Li+, K+ or choline. The inhibition depends on the nature of the substituting cation, and is largest with choline. Upon replacement, the substituent cation appears in the secreted fluid, and the Na+ concentration in the secreted fluid is decreased in a mirror-like fashion. When Na+ is replaced by Li+ or choline, the secretory Na+ concentration is decreased, although less than in the bathing medium, and the K+ concentration is increased. When Na+ is replaced by K+, the Na+ and the K+ concentration in the secreted fluid are approximately equal to their bathing medium concentrations. In the Li+ and choline medium, stimulation of the pancreas by carbachol or CCK-8 increases the fluid secretion rate. In addition, it increases the Li+ or choline concentration, and decreases the Na+ and K+ concentrations in the secreted fluid. In normal and K+ medium, stimulation causes only a slight increase in fluid secretion rate, with no change in the secretory Na+ concentration. In normal medium, stimulation leads to a decrease in the secretory K+ concentration. The effects of replacing Na+ appear to be the result of a direct inhibition of the active HCO3- transport underlying secretion, and an indirect inhibition related to the permeability of the pancreas for the various cations. The stimulants are likely to act by increasing the permeability of the tight junctions.

Effects of environment factors on initiation of sperm motility in sea cucumber Apostichopus japonicus (Selenka)

NASA Astrophysics Data System (ADS)

Yu, Li; Shao, Mingyu; Bao, Zhenmin; Hu, Jingjie; Zhang, Zhifeng

2011-06-01

Sperm of sea cucumber Apostichopus japonicus (Selenka) were quiescent in electrolyte NaCl solution and artificial seawater (ASW) and nonelectrolyte glucose and mannitol solutions when the osmolality was less than 200 mOsm kg-1. The sperm started to be motile as a result of increased osmolality, indicating an osmolality-dependent initiation of sperm motility in sea cucumber. After a brief incubation in hypotonic NaCl and glucose solutions with osmolalities of 200 and 400 mOsm kg-1, sperm lost partial motile ability. Sperm became immobilized when pH was 6.0 in NaCl, glucose and mannitol solutions, suggesting that an H+ release is involved in sperm activation. The decreased pH had no effect on the percentage of motile sperm in ASW, whereas it delayed the time period to reach the maximum motility (motilitymax). Extracellular Ca2+ in electrolyte solutions was not essential for motility stimulation but shortened the time of reaching motilitymax. When Ca2+ was mixed in nonelectrolyte solutions the sperm motility was completely suppressed. The K+ channel blocker, quinine, suppressed the sperm motility in electrolyte solution, showing a possible involvement of K+ transport in the process. High K+ concentration did not affect the sperm motility in NaCl solution, but decreased it in ASW and almost entirely suppressed it in nonelectrolyte solutions. The different effects of pH and K+ in ASW and NaCl solution indicate that external ions may also regulate sperm motility.

Most effective way to improve the hydrogen storage abilities of Na-decorated BN sheets: applying external biaxial strain and an electric field.

PubMed

Tang, Chunmei; Zhang, Xue; Zhou, Xiaofeng

2017-02-15

Density functional calculations were used to investigate the hydrogen storage abilities of Na-atoms-decorated BN sheets under both external biaxial strain and a vertical electric field. The Na atom generally has the weakest binding strength to a given substrate compared with the other elements in the periodic table [PANS, 2016, 113, 3735]. Consequently, it is understudied in comparison to other elements and there are few reports about the hydrogen storage abilities of Na-decorated nanomaterials. We calculated that the average binding energy (E b ) of Na atoms to the pure BN sheet is 1.08 eV, which is smaller than the cohesive energy of bulk Na (1.11 eV). However, the E b can be increased to 1.15 eV under 15% biaxial strain, and further up to 1.53 eV with the control of both 15% biaxial strain and a 5.14 V nm -1 electric field (E-field). Therefore, the application of biaxial strain and an external upward E-field can prevent clustering of the Na atoms on the surface of a BN sheet, which is crucial for the hydrogen storage. Each Na atom on the surface of a BN sheet can adsorb only one H 2 molecule when no strain or E-field is applied; however, the absorption increases to five H 2 molecules under 15% biaxial strain and six H 2 molecules under both 15% biaxial strain combined with a 5.14 V nm -1 E-field. The average adsorption energies for H 2 of BN-(Na-mH 2 ) (m = 1-6) are within the range of practical applications (0.2-0.6 eV). The hydrogen gravimetric density of the periodic BN-(Na-6H 2 ) 4 structure is 9 wt%, which exceeds the 5.5 wt% value that should be met by 2017 as specified by the US Department of Energy. On the other side, removal of the biaxial strain and E-field can help to desorb the H 2 molecule. These findings suggest a new route to design hydrogen storage materials under near-ambient conditions.

DOE Office of Scientific and Technical Information (OSTI.GOV)

He, Mingfu; Lau, Kah Chun; Ren, Xiaodi

Alkali metal-oxygen batteries are of great interests for energy storage because of their unparalleled theoretical energy densities. Particularly attractive is the emerging Na-O 2 battery because of the formation of superoxide as the discharge product. Dimethyl sulfoxide (DMSO) is a promising solvent for this battery but its instability towards Na makes it impractical in the Na-O 2 battery. Here in this paper, we report the enhanced stability of Na in DMSO solutions containing concentrated sodium trifluoromethanesulfonimide (NaTFSI) salts (>3molkg -1). Raman spectra of NaTFSI/DMSO electrolytes and abinitio molecular dynamics simulation reveal the Na + solvation number in DMSO and themore » formation of Na(DMSO) 3(TFSI)-like solvation structure. The majority of DMSO molecules solvating Na + in concentrated solutions reduces the available free DMSO molecules that can react with Na and renders the TFSI anion decomposition, which protects Na from reacting with the electrolyte. Using these concentrated electrolytes, Na-O 2 batteries can be cycled forming sodium superoxide (NaO 2) as the sole discharge product with improved long cycle life, highlighting the beneficial role of concentrated electrolytes for Na-based batteries.« less

Transmembrane Na+ and Ca2+ electrochemical gradients in cardiac muscle and their relationship to force development

PubMed Central

1982-01-01

Na+- and CA2+-sensitive microelectrodes were used to measure intracellular Na+ and Ca2+ activities (alpha iCa) of sheep ventricular muscle and Purkinje strands to study the interrelationship between Na+ and Ca2+ electrochemical gradients (delta muNa and delta muCa) under various conditions. In ventricular muscle, alpha iNa was 6.4 +/- 1.2 mM and alpha iCa was 87 +/- 20 nM ([Ca/+] = 272 nM). A graded decrease of external Na+ activity (alpha oNa) resulted in decrease of alpha iNa, and increase of alpha iCa. There was increase of twitch tension in low- alpha oNa solutions, and occasional increase of resting tension in 40% alpha oNa. Increase of external Ca2+ (alpha oCa) resulted in increase of alpha iCa and decrease of alpha iNa. Decrease of alpha oCa resulted in decrease of alpha iCa and increase of alpha iNa. The apparent resting Na-Ca energy ratio (delta muCa/delta muNa) was between 2.43 and 2.63. When the membrane potential (Vm) was depolarized by 50 mM K+ in ventricular muscle, Vm depolarized by 50 mV, alpha iNa decreased, and alpha iCa increased, with the development of a contracture. The apparent energy coupling ratio did not change with depolarization. 5 x 10(-6) M ouabain induced a large increase in alpha iNa ad alpha iCa, accompanied by an increase in twitch and resting tension. Under the conditions we have studied, delta muNa and delta muCa appeared to be coupled and n was nearly constant at 2.5, as would be expected if the Na-Ca exchange system was able to set the steady level of alpha iCa. Tension threshold was about 230 nM alpha iCa. The magnitude of twitch tension was directly related to alpha iCa. PMID:6292328

Short term effects of increasing dietary salt concentrations on urine composition in healthy cats.

PubMed

Paßlack, N; Burmeier, H; Brenten, T; Neumann, K; Zentek, J

2014-09-01

High dietary salt (NaCl) concentrations are assumed to be beneficial in preventing the formation of calcium oxalate (CaOx) uroliths in cats, since increased water intake and urine volume have been observed subsequent to intake. In human beings, dietary NaCl restriction is recommended for the prevention of CaOx urolith formation, since high NaCl intake is associated with increased urinary Ca excretion. The aim of the present study was to clarify the role of dietary NaCl in the formation of CaOx uroliths in cats. Eight cats received four diets that differed in Na and Cl concentrations (0.38-1.43% Na and 0.56-2.52% Cl dry matter, DM). Each feeding period consisted of a 21 day adaptation period, followed by a 7 day sampling period for urine collection. Higher dietary NaCl concentrations were associated with increased urine volume and renal Na excretion. Urinary Ca concentration was constant, but renal Ca excretion increased from 0.62 to 1.05 mg/kg bodyweight (BW)/day with higher dietary NaCl concentrations (P ≤ 0.05). Urinary oxalate (Ox), citrate, P and K concentrations decreased when NaCl intake was high (P ≤ 0.05), and urinary pH was low in all groups (6.33-6.45; P > 0.05). Relative supersaturation of CaOx in the urine was unaffected by dietary NaCl concentrations. In conclusion, the present study demonstrated several beneficial effects of high dietary NaCl intake over a relatively short time period. In particular, urinary Ca concentration remained unchanged because of increased urine volume. Decreased urinary Ox concentrations might help to prevent the formation of CaOx uroliths, but this should be verified in future studies in diseased or predisposed cats. Copyright © 2014 Elsevier Ltd. All rights reserved.

Influence of NaCl Concentrations on Coagulation, Temperature, and Electrical Conductivity Using a Perfusion Radiofrequency Ablation System: An Ex Vivo Experimental Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aube, Christophe, E-mail: ChAube@chu-angers.fr; Schmidt, Diethard; Brieger, Jens

2007-02-15

Purpose. To determine, by means of an ex vivo study, the effect of different NaCl concentrations on the extent of coagulation obtained during radiofrequency (RF) ablation performed using a digitally controlled perfusion device. Method. Twenty-eight RF ablations were performed with 40 W for 10 min using continuous NaCl infusion in fresh excised bovine liver. For perfusion, NaCl concentrations ranging from 0 (demineralized water) to 25% were used. Temperature, the amount of energy, and the dimensions of thermal-induced white coagulation were assessed for each ablation. These parameters were compared using the nonparametric Mann-Whitney test. Correlations were calculated according to the Spearmanmore » test. Results. RF ablation performed with 0.9% to 25% concentrations of NaCl produced a mean volume of coagulation of 30.7 {+-} 3.8 cm{sup 3}, with a mean short-axis diameter of 3.6 {+-} 0.2 cm. The mean amount of energy was 21,895 {+-} 1,674 W and the mean temperature was 85.4 {+-} 12.8 deg. C. Volume of coagulation, short-axis diameter, and amount of energy did not differ significantly among NaCl concentrations (p > 0.5). A correlation was found between the NaCl concentration and the short-axis diameter of coagulation (r = 0.64) and between the NaCl concentration and the mean temperature (r = 0.67), but not between the NaCl concentration and volume of coagulation. Conclusion. In an ex vivo model, continuous perfusion with high NaCl concentrations does not significantly improve the volume of thermal-induced coagulation. This may be because the use of a low-power generator cannot sufficiently exploit the potential advantage of better tissue conductivity provided by NaCl perfusion.« less

Facilitated giga-seal formation with a just originated glass surface.

PubMed

Böhle, T; Benndorf, K

1994-07-01

A simple technique of tip preparation in patch pipettes is described, which facilitates giga-seal formation. The pipettes were fabricated from thick-walled borosilicate glass tubing (external diameter 2.0 mm, internal diameter 0.5 mm) and the tips could be repeatedly broken in the bath. The pipette resistance correspondingly fell in steps of 3-20 M omega from about 80 M omega to about 2 M omega (double concentrated Tyrode). Scanning electron microscopy showed that the tip obtained after breaking was fairly plain. These broken tips were especially appropriate for patch-clamping. In cardiac myocytes in 11 out of 26 patches with Na+ channel activity, giga-seals developed spontaneously, i.e. without suction. In these patches the amplitude of the mean current with depolarizing pulses to -40 mV was significantly higher in comparison with patches formed under negative pressure. It is concluded that spontaneously sealed patches are most likely of planar configuration and the Na+ channel activity exceeds that in suction-induced patches.

Calcium and initial surface binding phase of pinocytosis in Amoeba proteus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prusch, R.D.

1986-08-01

The uptake of membrane-bound solute and external medium by bulk-phase pinocytosis in Amoeba proteus is influenced by the level of Ca/sup 2 +/ in the external medium. Increasing external Ca/sup 2 +/ to approx.10/sup -4/ M increases pinocytotic intensity, while increases in Ca/sup 2 +/ above this level decrease the intensity of pinocytosis. The initial interaction of pinocytotic inducers and Ca/sup +2/ at the surface of A moeba proteus was therefore examined. Alcain blue and Na/sup +/, both inducers of pinocytosis, differ in the manner with which they associate with the amoeba surface, suggesting the possibility of different pinocytosis-inducing sitesmore » on the amoeba surface. Low levels of external Ca/sup 2 +/ in the range of 3 x 10/sup -5/ to 4.5 x 10/sup -4/ M increase the amount of cationic inducer associated with the cell surface while, at the same time, decreasing anion association with the cell surface. It is suggested that Ca/sup 2 +/ influences ion association with the cell surface by controlling the availability of negative surface sites, which in turn influences pinocytotic intensity. Surface binding of Na/sup +/, Ca/sup 2 +/ and Cl/sup -/ was determined by adding /sup 22/Na, /sup 45/Ca or /sup 36/Cl.« less

Cytosolic Na+ Controls an Epithelial Na+ Channel Via the Go Guanine Nucleotide-Binding Regulatory Protein

NASA Astrophysics Data System (ADS)

Komwatana, P.; Dinudom, A.; Young, J. A.; Cook, D. I.

1996-07-01

In tight Na+-absorbing epithelial cells, the rate of Na+ entry through amiloride-sensitive apical membrane Na+ channels is matched to basolateral Na+ extrusion so that cell Na+ concentration and volume remain steady. Control of this process by regulation of apical Na+ channels has been attributed to changes in cytosolic Ca2+ concentration or pH, secondary to changes in cytosolic Na+ concentration, although cytosolic Cl- seems also to be involved. Using mouse mandibular gland duct cells, we now demonstrate that increasing cytosolic Na+ concentration inhibits apical Na+ channels independent of changes in cytosolic Ca2+, pH, or Cl-, and the effect is blocked by GDP-β -S, pertussis toxin, and antibodies against the α -subunits of guanine nucleotide-binding regulatory proteins (Go). In contrast, the inhibitory effect of cytosolic anions is blocked by antibodies to inhibitory guanine nucleotide-binding regulatory proteins (Gi1/Gi2. It thus appears that apical Na+ channels are regulated by Go and Gi proteins, the activities of which are controlled, respectively, by cytosolic Na+ and Cl-.

Analysis of bakery products by laser-induced breakdown spectroscopy.

PubMed

Bilge, Gonca; Boyacı, İsmail Hakkı; Eseller, Kemal Efe; Tamer, Uğur; Çakır, Serhat

2015-08-15

In this study, we focused on the detection of Na in bakery products by using laser-induced breakdown spectroscopy (LIBS) as a quick and simple method. LIBS experiments were performed to examine the Na at 589 nm to quantify NaCl. A series of standard bread sample pellets containing various concentrations of NaCl (0.025-3.5%) were used to construct the calibration curves and to determine the detection limits of the measurements. Calibration graphs were drawn to indicate functions of NaCl and Na concentrations, which showed good linearity in the range of 0.025-3.5% NaCl and 0.01-1.4% Na concentrations with correlation coefficients (R(2)) values greater than 0.98 and 0.96. The obtained detection limits for NaCl and Na were 175 and 69 ppm, respectively. Performed experimental studies showed that LIBS is a convenient method for commercial bakery products to quantify NaCl concentrations as a rapid and in situ technique. Copyright © 2015 Elsevier Ltd. All rights reserved.

Alternative Sodium Recovery Technology—High Hydroxide Leaching: FY10 Status Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahoney, Lenna A.; Neiner, Doinita; Peterson, Reid A.

2011-02-04

Boehmite leaching tests were carried out at NaOH concentrations of 10 M and 12 M, temperatures of 85°C and 60°C, and a range of initial aluminate concentrations. These data, and data obtained during earlier 100°C tests using 1 M and 5 M NaOH, were used to establish the dependence of the boehmite dissolution rate on hydroxide concentration, temperature, and initial aluminate concentration. A semi-empirical kinetic model for boehmite leaching was fitted to the data and used to calculate the NaOH additions required for leaching at different hydroxide concentrations. The optimal NaOH concentration for boehmite leaching at 85°C was estimated, basedmore » on minimizing the amount of Na that had to be added in NaOH to produce a given boehmite conversion.« less

Use of external fixators for damage-control orthopaedics in natural disasters like the 2005 Pakistan earthquake.

PubMed

Awais, Syed; Saeed, Ayesha; Ch, Asad

2014-08-01

In the 2005 Pakistan earthquake, the great many injured with multiple fractures and open wounds provided a unique opportunity to practice damage-control orthopaedics. External fixators remain a time-tested tools for operating surgeons on such occasions. The locally manufactured, readily available Naseer-Awais (NA) external fixator filled such needs of this disaster with good outcome. This is a retrospective descriptive study of 19,700 patients that presented over seven months to the two centres established by the lead author (SMA) in Muzaffarabad and Mansehra just one night after the 2005 earthquake. A series of local and foreign orthopaedic surgeon teams operated in succession. The computerised patient data collection of 1,145 operations was retrospectively analysed. Of the 19,700 patients presenting to the SMA centres, 50% had limb injuries. Total fracture fixations were 1,145, of which 295 were external fixations: 185 were applied on the lower limb and 90 on upper limb, the majority were applied on tibia. External fixators are valuable damage-control tools in natural disasters and warfare injuries. The locally manufactured NA external fixator served the needs of the many limb injuries during the 2005 Pakistan earthquake.

Molecular Dynamics Simulation of Surface Tension of NaCl Aqueous Solution at 298.15K: from Diluted to Highly Supersaturated Concentrations

NASA Astrophysics Data System (ADS)

Wang, Xiaoxiang; Chen, Chuchu; Poeschl, Ulirch; Su, Hang; Cheng, Yafang

2017-04-01

Sodium chloride (NaCl) is one of the key components of atmospheric aerosol particles. Concentration-depend surface tension of aqueous NaCl solution is essential to determine the equilibrium between droplet NaCl solution and water vapor, which is important in regards to aerosol-cloud interaction and aerosol climate effects. Although supersaturated NaCl droplets can be widely found under atmospheric conditions, the experimental determined concentration dependency of surface tension is limited up to the saturated concentration range due to technical difficulties, i.e., heterogeneous nucleation since nearly all surface tension measurement techniques requires contact of the sensor and solution surface. In this study, the surface tension of NaCl aqueous solution with solute mass fraction from 0 to 1 was calculated using molecular dynamics (MD) simulation. The surface tension increases monotonically and near linearly when mass fraction of NaCl (xNaCl) is lower than 0.265 (saturation point), which follows theoretical predictions (e.g., E-AIM, SP parameterization, and PK parameterization). Once entering into the supersaturated concentration range, the calculated surface tension starts to deviate from the near-linear extrapolation and adopts a slightly higher increasing rate until xNaCl of 0.35. We found that these two increasing phases (xNaCl 0.35) is mainly driven by the increase of excessive surface enthalpy when the solution becomes concentrated. After that, the surface tension remains almost unchanged until xNaCl of 0.52. This phenomenon is supported by the results from experiment based Differential Koehler Analyses. The stable surface tension in this concentration range is attributed to a simultaneous change of surface excess enthalpy and entropy at similar degree. When the NaCl solution is getting more concentrated than xNaCl of 0.52, the simulated surface tension regains an even faster growing momentum and shows the tendency of ultimately approaching the surface tension of molten NaCl at 298.15 K ( 148.4 mN/m by MD simulation). Energetic analyses imply that this fast increase is primarily still an excessive surface enthalpy-driven process, although concurrent fluctuation of excessive surface entropy is also expected but in a much smaller scale. Our results unfold the global landscape of concentration dependence of aqueous NaCl solution and its driven forces: a water surface tension dominated regime (xNaCl from 0 to 0.35), a transition regime (xNaCl from 0.35 to 0.52) and a molten NaCl surface tension dominated regime (xNaCl beyond 0.52).

U. S. EPA’S NA APPROACH FOR PETROLEUM HYDROCARBONS

EPA Science Inventory

Most evaluations of NA of petroleum hydrocarbons use geochemical data to document the NA through biodegradation. The expected trends during biodegradation (plume interior vs. background concentrations) are Dissolved oxygen concentrations below background, Nitrate concentrations ...

Determination of homocysteine in human saliva by liquid chromatography and electrospray ionization quadrupole time-of-flight mass spectrometry: profiles in healthy adults.

PubMed

Abaye, Daniel A; Nielsen, Birthe; Boateng, Joshua S

2013-12-01

Homocysteine (Hcys) is a non-essential amino acid associated with a range of diseased and abnormal metabolic conditions. Hcys concentration in saliva is routinely determined by enzyme assays, which are broadly specific, but can be expensive and suffer from cross-reactivity. Total Hcys (tHcys) concentrations in eight healthy adults were determined to establish the inter-day variation during resting, normal and intensive physical activity, using the more sensitive analytical techniques of liquid chromatography and tandem mass spectrometry without prior derivatization. Saliva (~ 1.5 mL) was collected over four days; early morning (EA), normal activity (NA) and during physical activity (PA). Samples were processed by disulphide reduction, acetonitrile precipitation and then centrifugation-filtration. Extracts were chromatographically resolved and analysed on a quadrupole time- of-flight (QToF) mass spectrometer. The protonated [M+H]+, m/z 136.101 and product ([M+H]+- HCOOH) m/z 90.103 ions were then monitored against an internal standard (13CHcys) and external set of calibration standards. Mean tHcys concentration for the whole group, including exercise was 6.6 ± 8.0 (range 0.2 - 29.6 nmol/mL). Overall, concentration of tHcys was greater in males than the females but not significantly (p > 0.05). The mean EA concentration was significantly (p < 0.05) greater than NA for both males (p = 0340) and females (p = 0.0045). There were large within-subject variations (coefficient of variation; CV%; 24% to 103%). The limits of detection (LOD) and quantification (LOQ) were 0.07 and 0.22 nmol/mL, respectively. The procedure potentially provides a convenient means of analyzing salivary Hcys as a diagnostic disease marker.

Sodium Carbonate is Saltier Than Sodium Chloride to Sodium-Depleted Rats.

PubMed

St John, Steven J; McBrayer, Anya M; Krauskopf, Erin E

2017-10-01

In a series of behavioral experiments in the 1960s, G.R. Morrison identified several unique features of the taste of Na2CO3 to rats; namely, it is 1) considerably more intense than NaCl at isomolar concentrations, 2) avoided at 10 times lower concentrations than NaCl to thirsty rats, 3) preferred at 10 times lower concentrations than NaCl in sodium-depleted rats. He also demonstrated its qualitatively similarity to NaCl. In Experiment 1, we confirmed and extended many of Morrison's observations. Rats were injected with furosemide on 3 occasions to stimulate a sodium appetite. After each depletion, rats were given a brief-access taste test in a lickometer presenting, in random order, water and 7 concentrations of salt. One test used NaCl (0.028-0.89 M, quarter log steps), another used Na2CO3, and the third used Na2CO3, but at a tenfold lower concentration range (0.0028-0.089 M). Rats licked NaCl in an inverted-U shaped concentration-response function peaking at 0.158-0.281 M. As Morrison's results predicted, rats licked Na2CO3 in nearly identical fashion, but at a tenfold lower concentration range (peak at 0.0158-0.028 M). In a second experiment, furosemide-treated rats were repeatedly tested with the lower Na2CO3 range but mixed in the epithelial sodium channel blocker amiloride at various concentrations (3-300 μM, half log steps). Amiloride reduced licking for Na2CO3 and shifted the peak response rightward up to about half a log unit. Thus, this "super-saltiness" of Na2CO3 to rats is at least partly amiloride-dependent. © The Author 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

[Cellular and intracellular transport of vitamin C. The physiologic aspects].

PubMed

Szarka, András; Lőrincz, Tamás

2013-10-20

Vitamin C requirement is satisfied by natural sources and vitamin C supplements in the ordinary human diet. The two major forms of vitamin C in the diet are L-ascorbic acid and L-dehydroascorbic acid. Both ascorbate and dehydroascorbate are absorbed along the entire length of the human intestine. The reduced form, L-ascorbic acid is imported by an active mechanism, requiring two sodium-dependent vitamin C transporters (SVCT1 and SVCT2). The transport of the oxidized form, dehydroascorbate is mediated by glucose transporters GLUT1, GLUT3 and possibly GLUT4. Initial rate of uptake of both ascorbate and dehydroascorbate is saturable with increasing external substrate concentration. Vitamin C plasma concentrations are tightly controlled when the vitamin is taken orally. It has two simple reasons, on the one hand, the capacity of the transporters is limited, on the other hand the two Na+-dependent transporters can be down-regulated by an elevated level of ascorbate.

Palytoxin isolated from marine coelenterates. The inhibitory action on (Na,K)-ATPase.

PubMed

Ishida, Y; Takagi, K; Takahashi, M; Satake, N; Shibata, S

1983-07-10

Palytoxin (PTX), C129H223N3O54, a highly toxic substance isolated from zoanthids of Palythoa tuberculosa, inhibited (Na,K)-ATPase (ATP phosphohydrolase, EC 3.6.1.3) prepared from guinea pig heart and hog cerebral cortex in a dose-dependent manner at concentrations greater than 10(-8) M. In the presence of Na (100 mM) and K (20 mM), PTX showed potency nearly equal to that of ouabain. When the ATPase was activated by the various Na concentrations at a constant K concentration, both PTX and ouabain inhibited the ATPase activity noncompetitively. On the other hand, when K concentration was changed at a constant Na concentration, PTX caused a competitive inhibition in all ranges of K concentrations employed, whereas ouabain caused a competitive inhibition at low concentrations and a noncompetitive inhibition at high concentrations.

Extremely Stable Sodium Metal Batteries Enabled by Localized High-Concentration Electrolytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Jianming; Chen, Shuru; Zhao, Wengao

Sodium (Na) metal is a promising anode for Na ion batteries. However, the high reactivity of Na metal with electrolytes and the low Na metal cycling efficiency have limited its practical application in rechargeable Na metal batteries. High concentration electrolytes (HCE, ≥4 M) consisting of sodium bis(fluorosulfonyl)imide (NaFSI) and ether solvent could ensure the stable cycling of Na metal with high coulombic efficiency, but suffer from high viscosity, poor wetting ability, and high salt cost. Here, we report that the salt concentration could be significantly reduced (≤ 1.5 M) by diluting with a hydrofluoroether (HFE) as ‘inert’ diluent, which maintainsmore » the solvation structures of HCE, thereby forming a localized high concentration electrolyte (LHCE). A LHCE (2.1 M NaFSI/DME-BTFE (solvent molar ratio 1:2)) has been demonstrated to enable the dendrite-free Na deposition with high coulombic efficiency of > 99%, fast-charging (20C) and stable cycling (90.8% retention after 40,000 cycles) of Na||Na3V2(PO4)3 batteries.« less

Induced Pacemaker Activity on Toad Skin

PubMed Central

Bueno, Enrique J.; Corchs, Lelio

1968-01-01

The electrical transients produced on the isolated abdominal skin obtained from Bufo arenarum Hensel, under the influence of inward current pulses of constant intensity have been studied. When both faces of the skin are bathed with Ringer's solution, short pulses of inward current give rise to transient variations of the potential difference between both faces of the skin with "all-or-nothing" characteristics (action potentials, AP). When the outer face is bathed with a modified Ringer solution with low sodium content (2.4 mM), the transients are longer and they are only evident when the pulse is several hundred milliseconds long. With even longer pulses (several seconds) a repetitive activity can be elicited, with the electrical characteristics of a "pacemaker" activity. In all these "excitability" phenomena Na+ may be replaced by Li+ in the outer solution. The logarithm of the duration of AP's is inversely related to the logarithm of the increase in concentration of Na+ or Li+ in the solution bathing the external face of the skin. The duration of AP's is increased when the Ca++ concentration in the outer solution is raised. This effect is more evident with low sodium concentration on the outside. The evolution of the slope conductance during repetitive activity has been determined. The site and mechanisms of the "excitable" behavior of the skin and the induced repetitive activity are discussed. Under the experimental conditions employed the behavior of the skin is compared with that of normally excitable plasma membranes. PMID:5692095

Fundamental investigations of clay/polymer nanocomposites and applications in co-extruded microlayered systems

NASA Astrophysics Data System (ADS)

Decker, Jeremy John

The second and fourth generations of hydroxylated dendritic polyesters (HBP2, HBP4) were combined with unmodified sodium montmorillonite clay (Na +MMT) in water to generate a broad range of polymer clay nanocomposites from 0 to 100% wt/wt Na+MMT. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to investigate intercalation states of the clay galleries. It was shown that interlayer spacings were independent of generation number and changed over the composition range from 0.5 nm to 3.5 nm in 0.5 nm increments that corresponded to a flattened HBP conformation within the clay tactoids. The HBP4/Na+MMT systems were investigated to study the vitrified Rigid Amorphous Fraction (RAF) induced by the clay surfaces. Differential Scanning Calorimetry (DSC) showed changes in heat capacity, Delta Cp, at Tg, that decreased with clay content, until completely suppressed at 80 wt% Na+MMT due to confinement. RAF was quantified from these changes in heat capacity and verified by the analysis of orthopositronium lifetime temperature scans utilizing positron annihilation lifetime spectroscopy (PALS): verifying the glassy nature of the RAF at elevated temperatures. Mathematical relationships allowed for correlation of the interlayer spacings with DeltaC p. RAF formation correlated to intercalated HBP4, and external surfaces of the clay tactoids. The interdiffusion of a polymer pair in microlayers was exploited to increase the concentration of nanoclay particles. When microlayers of a nanocomposite composed of organically modified montmorillonite (M2(HT)2 ) inside maleic anhydride grafted linear low-density polyethylene (LLDPE-g-MA) and low-density polyethylene (LDPE) were taken into the melt, the greater mobility of the linear LLDPE-g-MA chains compared to the branched LDPE chains caused shrinkage of the nanocomposite microlayers, concentrating the M 2(HT)2 contained within. Analysis of the clay morphology within these layers demonstrated an increase in clay particle lengths and aspect ratios, which was attributed to the growth of skewed aggregates during concentration. The melt induced clay concentration and increased clay particle dimensions caused significant decreases in the permeability of the nanocomposite microlayers and reduced the overall permeability of the multilayered films. Morphology and transport behavior of these microlayered films were compared to a series of bulk nanocomposites using a second LLDPE-g-MA containing M 2(HT)2 with varying clay content.

Physiological sodium concentrations enhance the iodide affinity of the Na+/I- symporter

NASA Astrophysics Data System (ADS)

Nicola, Juan P.; Carrasco, Nancy; Mario Amzel, L.

2014-06-01

The Na+/I- symporter (NIS) mediates active I- transport—the first step in thyroid hormonogenesis—with a 2Na+:1I- stoichiometry. NIS-mediated 131I- treatment of thyroid cancer post-thyroidectomy is the most effective targeted internal radiation cancer treatment available. Here to uncover mechanistic information on NIS, we use statistical thermodynamics to obtain Kds and estimate the relative populations of the different NIS species during Na+/anion binding and transport. We show that, although the affinity of NIS for I- is low (Kd=224 μM), it increases when Na+ is bound (Kd=22.4 μM). However, this Kd is still much higher than the submicromolar physiological I- concentration. To overcome this, NIS takes advantage of the extracellular Na+ concentration and the pronounced increase in its own affinity for I- and for the second Na+ elicited by binding of the first. Thus, at physiological Na+ concentrations, ~79% of NIS molecules are occupied by two Na+ ions and ready to bind and transport I-.

PEP Support Laboratory Leaching and Permeate Stability Tests

DOE Office of Scientific and Technical Information (OSTI.GOV)

Russell, Renee L.; Peterson, Reid A.; Rinehart, Donald E.

2009-09-25

Pacific Northwest National Laboratory (PNNL) has been tasked by Bechtel National Inc. (BNI) on the River Protection Project-Hanford Tank Waste Treatment and Immobilization Plant (RPP-WTP) project to perform research and development activities to resolve technical issues identified for the Pretreatment Facility (PTF). The Pretreatment Engineering Platform (PEP) was designed, constructed, and operated as part of a plan to respond to issue M12, "Undemonstrated Leaching Processes," of the External Flowsheet Review Team (EFRT) issue response plan.( ) The PEP is a 1/4.5-scale test platform designed to simulate the WTP pretreatment caustic leaching, oxidative leaching, ultrafiltration solids concentration, and slurry washing processes.more » The PEP replicates the WTP leaching processes using prototypic equipment and control strategies. A simplified flow diagram of the PEP system is shown in Figure 1.1. Two operating scenarios are currently being evaluated for the ultrafiltration process (UFP) and leaching operations. The first scenario has caustic leaching performed in the UFP-2 ultrafiltration feed vessels (i.e., vessel UFP-VSL-T02A in the PEP and vessels UFP-VSL-00002A and B in the WTP PTF). The second scenario has caustic leaching conducted in the UFP-1 ultrafiltration feed preparation vessels (i.e., vessels UFP-VSL-T01A and B in the PEP and vessels UFP-VSL-00001A and B in the WTP PTF). In both scenarios, 19-M sodium hydroxide solution (NaOH, caustic) is added to the waste slurry in the vessels to leach solid aluminum compounds (e.g., gibbsite, boehmite). Caustic addition is followed by a heating step that uses direct injection of steam to accelerate the leach process. Following the caustic leach, the vessel contents are cooled using vessel cooling jackets and/or external heat exchangers. The main difference between the two scenarios is that for leaching in UFP-VSL-T01A and B, the 19-M NaOH is added to un-concentrated waste slurry (3 to 8 wt% solids), while for leaching in UFP-VSL-T02A, the slurry is concentrated to nominally 20 wt% solids using cross-flow ultrafiltration before adding caustic.« less

radiation and electric field induced effects on the order-disorder phase in lithium sodium sulphate crystals

NASA Astrophysics Data System (ADS)

Hamed, A. E.; Kassem, M. E.; El-Wahidy, E. F.; El-Abshehy, M. A.

1995-03-01

The temperature dependence of specific heat at constant pressure, Cp(T), has been measured for lithium sodium sulphate, LiNaSo4 crystals, at different ?-radiation doses and external bias electric field (Eb), in the temperature range 300-900 K. A nonlinear dependence of transition temperature, T1 and a remarkable change in the thermodynamic parameters, were obtained as the effect of both electric field and ?-radiation. The effect of ?-radiation doses on the phase transition in LiNaSO4 crystals was explained as due to an internal bias field, Eb, originating from the interaction of polar defects with the order parameter of the host lattice. The internal bias field effect on the behaviour of Cp(T) in LiNaSO4 crystals was similar to that of the external electric field (E).

Reduction of interferences in graphite furnace atomic absorption spectrometry by multiple linear regression modelling

NASA Astrophysics Data System (ADS)

Grotti, Marco; Abelmoschi, Maria Luisa; Soggia, Francesco; Tiberiade, Christian; Frache, Roberto

2000-12-01

The multivariate effects of Na, K, Mg and Ca as nitrates on the electrothermal atomisation of manganese, cadmium and iron were studied by multiple linear regression modelling. Since the models proved to efficiently predict the effects of the considered matrix elements in a wide range of concentrations, they were applied to correct the interferences occurring in the determination of trace elements in seawater after pre-concentration of the analytes. In order to obtain a statistically significant number of samples, a large volume of the certified seawater reference materials CASS-3 and NASS-3 was treated with Chelex-100 resin; then, the chelating resin was separated from the solution, divided into several sub-samples, each of them was eluted with nitric acid and analysed by electrothermal atomic absorption spectrometry (for trace element determinations) and inductively coupled plasma optical emission spectrometry (for matrix element determinations). To minimise any other systematic error besides that due to matrix effects, accuracy of the pre-concentration step and contamination levels of the procedure were checked by inductively coupled plasma mass spectrometric measurements. Analytical results obtained by applying the multiple linear regression models were compared with those obtained with other calibration methods, such as external calibration using acid-based standards, external calibration using matrix-matched standards and the analyte addition technique. Empirical models proved to efficiently reduce interferences occurring in the analysis of real samples, allowing an improvement of accuracy better than for other calibration methods.

Assessing carbon and nitrogen removal in a novel anoxic-aerobic cyanobacterial-bacterial photobioreactor configuration with enhanced biomass sedimentation.

PubMed

de Godos, I; Vargas, V A; Guzmán, H O; Soto, R; García, B; García, P A; Muñoz, R

2014-09-15

The carbon and nitrogen removal potential of an innovative anoxic-aerobic photobioreactor configuration operated with both internal and external recyclings was evaluated under different cyanobacterial-bacterial sludge residence times (9-31 days) during the treatment of wastewaters with low C/N ratios. Under optimal operating conditions, the two-stage photobioreactor was capable of providing organic carbon and nitrogen removals over 95% and 90%, respectively. The continuous biomass recycling from the settler resulted in the enrichment and predominance of rapidly-settling cyanobacterial-bacterial flocs and effluent suspended solid concentrations lower than 35 mg VSS L(-1). These flocs exhibited sedimentation rates of 0.28-0.42 m h(-1) but sludge volumetric indexes of 333-430 ml/g. The decoupling between the hydraulic retention time and sludge retention time mediated by the external recycling also avoided the washout of nitrifying bacteria and supported process operation at biomass concentrations of 1000-1500 mg VSS L(-1). The addition of additional NaHCO3 to the process overcame the CO2 limitation resulting from the intense competition for inorganic carbon between cyanobacteria and nitrifying bacteria in the photobioreactor, which supported the successful implementation of a nitrification-denitrification process. Unexpectedly, this nitrification-denitrification process occurred both simultaneously in the photobioreactor alone (as a result of the negligible dissolved oxygen concentrations) and sequentially in the two-stage anoxic-aerobic configuration with internal NO3(-)/NO2(-) recycling. Copyright © 2014 Elsevier Ltd. All rights reserved.

Predicting Salt Permeability Coefficients in Highly Swollen, Highly Charged Ion Exchange Membranes.

PubMed

Kamcev, Jovan; Paul, Donald R; Manning, Gerald S; Freeman, Benny D

2017-02-01

This study presents a framework for predicting salt permeability coefficients in ion exchange membranes in contact with an aqueous salt solution. The model, based on the solution-diffusion mechanism, was tested using experimental salt permeability data for a series of commercial ion exchange membranes. Equilibrium salt partition coefficients were calculated using a thermodynamic framework (i.e., Donnan theory), incorporating Manning's counterion condensation theory to calculate ion activity coefficients in the membrane phase and the Pitzer model to calculate ion activity coefficients in the solution phase. The model predicted NaCl partition coefficients in a cation exchange membrane and two anion exchange membranes, as well as MgCl 2 partition coefficients in a cation exchange membrane, remarkably well at higher external salt concentrations (>0.1 M) and reasonably well at lower external salt concentrations (<0.1 M) with no adjustable parameters. Membrane ion diffusion coefficients were calculated using a combination of the Mackie and Meares model, which assumes ion diffusion in water-swollen polymers is affected by a tortuosity factor, and a model developed by Manning to account for electrostatic effects. Agreement between experimental and predicted salt diffusion coefficients was good with no adjustable parameters. Calculated salt partition and diffusion coefficients were combined within the framework of the solution-diffusion model to predict salt permeability coefficients. Agreement between model and experimental data was remarkably good. Additionally, a simplified version of the model was used to elucidate connections between membrane structure (e.g., fixed charge group concentration) and salt transport properties.

Conductive choline transport by alveolar epithelial plasma membrane vesicles.

PubMed

Oelberg, D G; Xu, F

1998-11-01

Choline is an important substrate in alveolar epithelia for both surfactant production and cellular maintenance. The underlying mechanisms of uptake and sites of membrane transport remain uncertain. To test the hypothesis that choline transport occurs at the basolateral side of alveolar epithelia by both Na+-independent and -dependent mechanisms, plasma membrane vesicles were prepared from the apical and basolateral membranes of mature porcine type II pneumocytes. Choline+ transport was assayed by uptake of [3H]choline+ by enriched apical or basolateral vesicles. In the presence of imposed, inside-negative charge gradients, basolateral vesicles exhibited early overshoot of [3H]choline+ uptake unaffected by the presence or absence of external Na+ (541 +/- 53 vs 564 +/- 79 pmol/mg protein (NS)). High sensitivity to hemicholinium-3 was observed in the presence or absence of Na+. In the absence of inside-negative charge gradients, uptake was reduced 12-fold in the presence or absence of Na+, and external choline+ induced internal alkalization of acidified basolateral vesicles. Accumulative [3H]choline+ uptakes by apical vesicles in the presence or absence of inside-negative charge gradients and Na+ were insignificant. We conclude that predominant choline+ uptake by type II pneumocytes occurs at the basolateral membrane by Na+-independent, electrogenic choline+ conductance. The presence of electroneutral choline+/H+ exchange is suggested. Copyright 1998 Academic Press.

Why double-stranded RNA resists condensation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tolokh, Igor S.; Pabit, Suzette; Katz, Andrea M.

2014-09-15

The addition of small amounts of multivalent cations to solutions containing double-stranded DNA leads to attraction between the negatively charged helices and eventually to condensation. Surprisingly, this effect is suppressed in double-stranded RNA, which carries the same charge as the DNA, but assumes a different double helical form. However, additional characterization of short (25 base-pairs) nucleic acid (NA) duplex structures by circular dichroism shows that measured differences in condensation are not solely determined by duplex helical geometry. Here we combine experiment, theory, and atomistic simulations to propose a mechanism that connects the observed variations in condensation of short NA duplexesmore » with the spatial variation of cobalt hexammine (CoHex) binding at the NA duplex surface. The atomistic picture that emerged showed that CoHex distributions around the NA reveals two major NA-CoHex binding modes -- internal and external -- distinguished by the proximity of bound CoHex to the helical axis. Decreasing trends in experimentally observed condensation propensity of the four studied NA duplexes (from B-like form of homopolymeric DNA, to mixed sequence DNA, to DNA:RNA hybrid, to A-like RNA) are explained by the progressive decrease of a single quantity: the fraction of CoHex ions in the external binding mode. Thus, while NA condensation depends on a complex interplay between various structural and sequence features, our coupled experimental and theoretical results suggest a new model in which a single parameter connects the NA condensation propensity with geometry and sequence dependence of CoHex binding.« less

Reflex cardioventilatory responses to hypoxia in the flathead gray mullet (Mugil cephalus) and their behavioral modulation by perceived threat of predation and water turbidity.

PubMed

Shingles, A; McKenzie, D J; Claireaux, G; Domenici, P

2005-01-01

In hypoxia, gray mullet surface to ventilate well-oxygenated water in contact with air, an adaptive response known as aquatic surface respiration (ASR). Reflex control of ASR and its behavioral modulation by perceived threat of aerial predation and turbid water were studied on mullet in a partly sheltered aquarium with free surface access. Injections of sodium cyanide (NaCN) into either the bloodstream (internal) or ventilatory water stream (external) revealed that ASR, hypoxic bradycardia, and branchial hyperventilation were stimulated by chemoreceptors sensitive to both systemic and water O2 levels. Sight of a model avian predator elicited bradycardia and hypoventilation, a fear response that inhibited reflex hyperventilation following external NaCN. The time lag to initiation of ASR following NaCN increased, but response intensity (number of events, time at the surface) was unchanged. Mullet, however, modified their behavior to surface under shelter or near the aquarium edges. Turbid water abolished the fear response and effects of the predator on gill ventilation and timing of ASR following external NaCN, presumably because of reduced visibility. However, in turbidity, mullet consistently performed ASR under shelter or near the aquarium edges. These adaptive modulations of ASR behavior would allow mullet to retain advantages of the chemoreflex when threatened by avian predators or when unable to perceive potential threats in turbidity.

NUTRITION AND METABOLISM OF MARINE BACTERIA1

PubMed Central

Takacs, Frank P.; Matula, Tibor I.; MacLeod, Robert A.

1964-01-01

Takacs, Frank P. (McGill University, Montreal, Quebec, Canada), Tibor I. Matula, and Robert A. MacLeod. Nutrition and metabolism of marine bacteria. XIII. Intracellular concentrations of sodium and potassium ions in a marine pseudomonad. J. Bacteriol. 87:510–518. 1964.—Washed cells of a marine pseudomonad were suspended in buffered salt solutions containing, in addition to MgSO4, NaCl and KCl at various concentrations. The cells were centrifuged from the medium and analyzed for Na+ and K+. Inulin and C14-carboxypolyglucose were employed to estimate the volume of extracellular fluid associated with the packed cells. Intracellular Na+ and K+ concentrations were determined by correcting for the amount of Na+ and K+ in the extracellular fluid. At all levels of Na+ in the suspending medium (0 to 1 m), the intracellular and extracellular Na+ concentrations within the limits of experimental error were the same. The intracellular K+ concentrations were approximately double the extracellular concentrations at the two levels of K+ tested (0.01 and 0.15 m) and were not influenced by the amount of Na+ present. Intracellular and extracellular Cl− concentrations were the same at the one level of Cl− examined. The intracellular fluid volume varied with the NaCl or KCl concentration of the suspending medium, being greatest in the absence of added salts, decreasing to a minimum at 0.3 m salt, and then increasing slightly at higher salt concentrations. Most of the intracellular Na+ could be removed by washing with solutions of MgSO4 or sucrose, but a small amount [10 to 15 μmoles/g (dry weight)] remained bound to the cells. PMID:14129666

Physiological indices of seawater readiness in postspawning steelhead kelts

USGS Publications Warehouse

Buelow, Jessica; Moffitt, Christine M.

2015-01-01

Management goals to improve the recovery of steelhead (Oncorhynchus mykiss) stocks at risk of extinction include increasing the proportion of postspawning fish that survive and spawn again. To be successful, postspawning steelhead (kelts) migrating downstream to the ocean must prepare physiologically and physically for a seawater transition. We sampled blood, gill filaments, and evaluated the external condition of migrating kelts from an ESA-listed population in the Snake/Columbia River system over two consecutive years to evaluate their physiological readiness for transition to seawater. We chose attributes often considered as measures of preparation for seawater in juveniles, including gill Na+,K+ ATPase activity, plasma electrolytes and hormones to consider factors related to external condition, size and sex. We found kelts in good external condition had plasma profiles similar to downstream-migrating smolts. In addition, we found more than 80% of kelts ranked in good external condition had smolt-like body silvering. We compared measures from migrating kelts with samples obtained from hatchery fish at the time of spawning to confirm that Na+, K+ ATPase activity in kelts was significantly elevated over spawning fish. We found significant differences in gill Na+, K+ ATPase activity in migrating kelts between the years of sampling, but little indication of influence of fish condition. We conclude that the postspawning steelhead sampled exhibited a suite of behaviours, condition and physiology characteristic of fish prepared for successful transition to a seawater environment.

Discovery of talatisamine as a novel specific blocker for the delayed rectifier K+ channels in rat hippocampal neurons.

PubMed

Song, M-K; Liu, H; Jiang, H-L; Yue, J-M; Hu, G-Y; Chen, H-Z

2008-08-13

Blocking specific K+ channels has been proposed as a promising strategy for the treatment of neurodegenerative diseases. Using a computational virtual screening approach and electrophysiological testing, we found four Aconitum alkaloids are potent blockers of the delayed rectifier K+ channel in rat hippocampal neurons. In the present study, we first tested the action of the four alkaloids on the voltage-gated K+, Na+ and Ca2+ currents in rat hippocampal neurons, and then identified that talatisamine is a specific blocker for the delayed rectifier K+ channel. External application of talatisamine reversibly inhibited the delayed rectifier K+ current (IK) with an IC50 value of 146.0+/-5.8 microM in a voltage-dependent manner, but exhibited very slight blocking effect on the voltage-gated Na+ and Ca2+ currents even at the high concentration of 1-3 mM. Moreover, talatisamine exerted a significant hyperpolarizing shift of the steady-state activation, but did not influence the steady state inactivation of IK and its recovery from inactivation, suggesting that talatisamine had no allosteric action on IK channel and was a pure blocker binding to the external pore entry of the channel. Our present study made the first discovery of potent and specific IK channel blocker from Aconitum alkaloids. It has been argued that suppressing K+ efflux by blocking IK channel may be favorable for Alzheimer's disease therapy. Talatisamine can therefore be considered as a leading compound worthy of further investigations.

X-ray microanalysis of rotavirus-infected mouse intestine: A new concept of diarrhoeal secretion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spencer, A.J.; Osborne, M.P.; Haddon, S.J.

1990-05-01

Neonatal mice were infected at 7 days of age with rotavirus (epizootic diarrhea of infant mice (EDIM) virus) and killed at 24-h intervals postinfection (PI). Cytoplasmic concentrations of Na, Mg, P, S, Cl, K, and Ca intestinal epithelial cells from infected and age-matched control animals were measured by x-ray microanalysis. In villus tip cells, Ca concentration increased at 24-96 h PI; Na concentration increased at 24-72 h PI; Ca and Na concentrations were near normal by 168 h PI. K concentration decreased 24-72 h PI, and Cl concentration decreased 48-96 h PI. In crypt cells, changes were observed without amore » discernible pattern: at 96 h PI, Na, Mg, S, and Cl concentrations increased and K concentration decreased; at 120 h PI, the concentrations of all elements except Na and Ca increased. In villus base cells, the mean concentrations of all elements except Ca peaked at 48-72 h PI and at 120 h PI. Na and Cl concentrations increased dramatically in some cells from 48 h PI onward. All the above concentration values were obtained from freeze-dried specimens and expressed in millimoles per kilogram of dry weight. Conversion of a limited number of data, pertaining to villus base cells, from dry weight to wet weight was possible. This conversion revealed that villus base cells in infected animals were more hydrated than corresponding cells from control animals. Also, the Na and Cl concentrations in mmol/kg H2O were significantly higher in villus base cells from infected animals than in those from corresponding controls: 137 +/- 7 versus 38 +/- 4 (Na) and 121 +/- 5 versus 89 +/- 6 (Cl). Wet weight concentrations of other elements were either the same (Mg) or lower (P, S, and K) after infection with virus.« less

Why double-stranded RNA resists condensation

PubMed Central

Tolokh, Igor S.; Pabit, Suzette A.; Katz, Andrea M.; Chen, Yujie; Drozdetski, Aleksander; Baker, Nathan; Pollack, Lois; Onufriev, Alexey V.

2014-01-01

The addition of small amounts of multivalent cations to solutions containing double-stranded DNA leads to inter-DNA attraction and eventual condensation. Surprisingly, the condensation is suppressed in double-stranded RNA, which carries the same negative charge as DNA, but assumes a different double helical form. Here, we combine experiment and atomistic simulations to propose a mechanism that explains the variations in condensation of short (25 base-pairs) nucleic acid (NA) duplexes, from B-like form of homopolymeric DNA, to mixed sequence DNA, to DNA:RNA hybrid, to A-like RNA. Circular dichroism measurements suggest that duplex helical geometry is not the fundamental property that ultimately determines the observed differences in condensation. Instead, these differences are governed by the spatial variation of cobalt hexammine (CoHex) binding to NA. There are two major NA-CoHex binding modes—internal and external—distinguished by the proximity of bound CoHex to the helical axis. We find a significant difference, up to 5-fold, in the fraction of ions bound to the external surfaces of the different NA constructs studied. NA condensation propensity is determined by the fraction of CoHex ions in the external binding mode. PMID:25123663

Fabrication of large binary colloidal crystals with a NaCl structure

PubMed Central

Vermolen, E. C. M.; Kuijk, A.; Filion, L. C.; Hermes, M.; Thijssen, J. H. J.; Dijkstra, M.; van Blaaderen, A.

2009-01-01

Binary colloidal crystals offer great potential for tuning material properties for applications in, for example, photonics, semiconductors and spintronics, because they allow the positioning of particles with quite different characteristics on one lattice. For micrometer-sized colloids, it is believed that gravity and slow crystallization rates hinder the formation of high-quality binary crystals. Here, we present methods for growing binary colloidal crystals with a NaCl structure from relatively heavy, hard-sphere-like, micrometer-sized silica particles by exploring the following external fields: electric, gravitational, and dielectrophoretic fields and a structured surface (colloidal epitaxy). Our simulations show that the free-energy difference between the NaCl and NiAs structures, which differ in their stacking of the hexagonal planes of the larger spheres, is very small (≈0.002 kBT). However, we demonstrate that the fcc stacking of the large spheres, which is crucial for obtaining the pure NaCl structure, can be favored by using a combination of the above-mentioned external fields. In this way, we have successfully fabricated large, 3D, oriented single crystals having a NaCl structure without stacking disorder. PMID:19805259

A combined physicochemical-biological method of NaCl extraction from the irrigation solution in the BTLSS

NASA Astrophysics Data System (ADS)

Trifonov, Sergey V.; Tikhomirov, Alexander A.; Ushakova, Sofya; Tikhomirova, Natalia

2016-07-01

The use of processed human wastes as a source of minerals for plants in closed biotechnical life support systems (BTLSS) leads to high salt levels in the irrigation solution, as urine contains high concentrations of NaCl. It is important to develop a process that would effectively decrease NaCl concentration in the irrigation solution and return this salt to the crew's diet. The salt-tolerant plants (Salicornia europea) used to reduce NaCl concentration in the irrigation solution require higher salt concentrations than those of the solution, and this problem cannot be resolved by concentrating the solution. At the same time, NaCl extracted from mineralized wastes by physicochemical methods is not pure enough to be included in the crew's diet. This study describes an original physicochemical method of NaCl extraction from the solution, which is intended to be used in combination with the biological method of NaCl extraction by using saltwort plants. The physicochemical method produces solutions with high NaCl concentrations, and saltwort plants serve as a biological filter in the final phase, to produce table salt. The study reports the order in which physicochemical and biological methods of NaCl extraction from the irrigation solution should be used to enable rapid and effective inclusion of NaCl into the cycling of the BTLSS with humans. This study was carried out in the IBP SB RAS and supported by the grant of the Russian Science Foundation (Project No. 14-14-00599).

Ion Permeability of a Microtubule in Neuron Environment.

PubMed

Shen, Chun; Guo, Wanlin

2018-04-19

Microtubules, constituted by end-to-end negatively charged α- and β-tubulin dimers, are long, hollow, pseudohelical cylinders with internal and external diameters of about 16 and 26 nm, respectively, and widely exist in cell cytoplasm, neuron axons, and dendrites. Although their structural functions in physiological processes, such as cell mitosis, cell motility, and motor protein transport, have been widely accepted, their role in neuron activity remains attractively elusive. Here we show a new function of microtubules: they can generate instant response to a calcium pulse because of their specific permeability for ions. Our comprehensive simulations from all-atom molecular dynamics to potential of mean force and continuum modeling reveal that K + and Na + ions can permeate through the nanopores in the microtubule wall easily, while Ca 2+ ions are blocked by the wall with a much higher free energy barrier. These cations are adsorbed to the surfaces of the wall with affinity decreasing in the sequence Ca 2+ , Na + , and K + . As a result, when the concentration of Ca 2+ ions increases outside the microtubule during neuronal excitation, K + and Na + ions will be driven into the microtubule, triggering subsequent axial ion redistribution within the microtubule. The results shed light on the possibility of the ion-permeable microtubules being involved in neural signal processing.

Effect of super-oxidized water, sodium hypochlorite and EDTA on dentin microhardness.

PubMed

Ghisi, Alexandre Corrêa; Kopper, Patrícia Maria Poli; Baldasso, Flávia E R; Stürmer, Caroline P; Rossi-Fedele, Giampiero; Steier, Liviu; Figueiredo, José Antonio Poli de; Morgental, Renata Dornelles; Vier-Pelisser, Fabiana Vieira

2014-01-01

The present study aimed to evaluate the influence of the following irrigating solutions on the microhardness of root canal dentin: 2% sodium hypochlorite (2NaOCl), 5% sodium hypochlorite (5NaOCl), super-oxidized water (400 ppm Sterilox - Sx) and 17% EDTA (E). Eighty roots from bovine incisors were randomly divided into 8 groups (n=10): 2NaOCl, 5NaOCl, Sx, and 2NaOCl + E, 5NaOCl + E, Sx + E (associated with E as final irrigant for 5 min), E solely and distilled water (dH2O) as the negative control. Root canal preparation was performed by hand instruments, using one of the irrigation protocols for 30 min. Then, 5 mm of the cervical root third were cut out from each sample and subjected to the Vickers microhardness test, at two points, one at approximately 500-1000 µm from the root canal lumen (distance 1), and the other at approximately 500-1000 µm from the external root surface (distance 2). Data were analyzed by Wilcoxon and Kruskal-Wallis tests at 5% significance level. Microhardness values at distance 1 were significantly lower than those at distance 2 for all groups, except 5NaOCl and 5NaOCl + E groups (p>0.05). EDTA showed the lowest microhardness values. However, no statistically significant difference was detected among groups at distance 1 and EDTA was significantly different only from Sx at distance 2. In conclusion, all tested solutions showed lower microhardness at the most superficial root canal dentin layer compared to the one found near the external root surface, except 5NaOCl and 5NaOCl + E; EDTA promoted lower microhardness values in comparison to Sterilox at this site.

EFFECT OF NONCLASSICAL POLARIZATION OF Na+ AND K+ ON THE STABILITY OF SOIL COLLOIDAL PARTICLES IN SUSPENSION

NASA Astrophysics Data System (ADS)

Wu-Quan, Ding; Jia-Hong, He; Lei, Wang; Xin-Min, Liu; Hang, Li

The study of soil colloids is essential because the stability of soil colloidal particles are important processes of interest to researchers in environmental fields. The strong nonclassical polarization of the adsorbed cations (Na+ and K+) decreased the electric field and the electrostatic repulsion between adjacent colloidal particles. The decrease of the absolute values of surface potential was greater for K+ than for Na+. The lower the concentration of Na+ and K+ in soil colloids, the greater the electrostatic repulsion between adjacent colloidal particles. The net pressure and the electrostatic repulsion was greater for Na+ than for K+ at the same ion concentration. For K+ and Na+ concentrations higher than 50mmol L-1 or 100 mmol L-1, there was a net negative (or attractive) pressure between two adjacent soil particles. The increasing total average aggregation (TAA) rate of soil colloids with increasing Na+ and K+ concentrations exhibited two stages: the growth rates of TAA increased rapidly at first and then increased slowly and eventually almost negligibly. The critical coagulation concentrations of soil colloids in Na+ and K+ were 91.6mmol L-1 and 47.8mmol L-1, respectively, and these were similar to the concentrations at the net negative pressure.

Relaxation of Isolated Ventricular Cardiomyocytes by a Voltage-Dependent Process

NASA Astrophysics Data System (ADS)

Bridge, John H. B.; Spitzer, Kenneth W.; Ershler, Philip R.

1988-08-01

Cell contraction and relaxation were measured in single voltage-clamped guinea pig cardiomyocytes to investigate the contribution of sarcolemmal Na+-Ca2+ exchange to mechanical relaxation. Cells clamped from -80 to 0 millivolts displayed initial phasic and subsequent tonic contractions; caffeine reduced or abolished the phasic and enlarged the tonic contraction. The rate of relaxation from tonic contractions was steeply voltage-dependent and was significantly slowed in the absence of a sarcolemmal Na+ gradient. Tonic contractions elicited in the absence of a Na+ gradient promptly relaxed when external Na+ was applied, reflecting activation of Na+-Ca2+ exchange. It appears that a voltage-dependent Na+-Ca2+ exchange can rapidly mechanically relax mammalian heart muscle.

Effect of Na+ on surface fractal dimension of compacted bentonite

NASA Astrophysics Data System (ADS)

Xiang, G. S.; Xu, Y. F.; Jiang, H.

2015-05-01

Compacted Tsukinuno bentonite was immersed into NaCl solutions of different concentrations in oedometers, and the surface fractal dimension of bentonite-saline association was measured by nitrogen adsorption isotherms. The application of the Frenkel-Halsey-Hill equation and the Neimark thermodynamic method to nitrogen adsorption isotherms indicated that the surface roughness was greater for the bentonite-saline association. The surface fractal dimension of bentonite increased in the NaCl solution with low Na+ concentration, but decreased at high Na+ concentration. This process was accompanied by the same tendency in specific surface area and microporosity with the presence of Na+ coating in the clay particles.

Solar thermal electricity generation

NASA Astrophysics Data System (ADS)

Gasemagha, Khairy Ramadan

1993-01-01

This report presents the results of modeling the thermal performance and economic feasibility of large (utility scale) and small solar thermal power plants for electricity generation. A number of solar concepts for power systems applications have been investigated. Each concept has been analyzed over a range of plant power ratings from 1 MW(sub e) to 300 MW(sub e) and over a range of capacity factors from a no-storage case (capacity factor of about 0.25 to 0.30) up to intermediate load capacity factors in the range of 0.46 to 0.60. The solar plant's economic viability is investigated by examining the effect of various parameters on the plant costs (both capital and O & M) and the levelized energy costs (LEC). The cost components are reported in six categories: collectors, energy transport, energy storage, energy conversion, balance of plant, and indirect/contingency costs. Concentrator and receiver costs are included in the collector category. Thermal and electric energy transport costs are included in the energy transport category. Costs for the thermal or electric storage are included in the energy storage category; energy conversion costs are included in the energy conversion category. The balance of plant cost category comprises the structures, land, service facilities, power conditioning, instrumentation and controls, and spare part costs. The indirect/contingency category consists of the indirect construction and the contingency costs. The concepts included in the study are (1) molten salt cavity central receiver with salt storage (PFCR/R-C-Salt); (2) molten salt external central receiver with salt storage (PFCR/R-E-Salt); (3) sodium external central receiver with sodium storage (PFCR/RE-Na); (4) sodium external central receiver with salt storage (PFCR/R-E-Na/Salt); (5) water/steam external central receiver with oil/rock storage (PFCR/R-E-W/S); (6) parabolic dish with stirling engine conversion and lead acid battery storage (PFDR/SLAB); (7) parabolic dish with stirling engine conversion and redox advanced battery storage (PFDR/S-RAB); and (8) parabolic trough with oil/rock storage (LFDR/R-HT-45). Key annual efficiency and economic results of the study are highlighted in tabular format for plant sizes and capacity factor that resulted in the lowest LEC over the analysis range.

Long-lasting potassium channel inactivation in myoepithelial fibres is related to characteristics of swimming in diphyid siphonophores.

PubMed

Inoue, Isao; Tsutsui, Izuo; Bone, Quentin

2005-12-01

Diphyid siphonophores swim using bursts of propulsive jets, which are produced by contractions of a monolayer of subumbrellar myoepithelial fibres lining the nectophore. This swimming behaviour is characterised by successive increases in the force generating the jets during the initial jets of the burst. Action potentials that generate the contractions propagate throughout the myoepithelial layer: both their amplitude and duration successively increase during the first part of the burst. To investigate the ionic mechanism of this action potential augmentation, single myoepithelial cells were enzymatically dissociated and whole-cell voltage clamped. Na+, Ca2+ and K+ currents were recorded under different internal and external salt compositions. The Na+ current was blocked by a relatively high concentration (4 micromol l-1 or higher) of tetrodotoxin (TTX), indicating that the Na+ channel belongs to a group of TTX-resistant Na+ channels. The Ca2+ current was blocked by nifedipine (10 micromol l-1) and Co2+ (5 mmol l-1), indicating that the Ca2+ channel is L-type. The K+ current possessed a unique property of long-lasting inactivation. The K+ current fully inactivated during a depolarisation to +30 mV with a time-constant of approximately 9 ms, and the time constant of recovery from inactivation at -70 mV was 13.2 s. This long-lasting inactivation of the K+ channel was the major factor in the augmentation of both action potentials and contractions of the myoepithelial sheet during the initial part of the burst.

Cracking characteristics of alloy 690 in thiosulfate containing chloride solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, H.H.; Tsai, W.T.

1999-07-01

The cracking characteristics of Alloy 690 in deaerated 1wt% NaCl solution with different Na{sub 2}S{sub 2}O{sub 2} concentrations, namely 0.01, 0.1, 0.2 and 0.5 M, at controlled anodic potentials was investigated by using slow strain rate testing (SSRT) with a strain rate of 1 x 10{sup {minus}6} s{sup {minus}1}. The results showed that the ultimate tensile strength and the ductility increased with increasing the concentration of Na{sub 2}S{sub 2}O{sub 3} at the same anodic potential, but decreased with increasing potential at a fixed concentration of Na{sub 2}S{sub 2}O{sub 3}. Pitting corrosion could occur on Alloy 690 in 1wt% NaCl solutionmore » with the concentration of Na{sub 2}S{sub 2}O{sub 3} {le} 0.1 M, depending on the potential. The susceptibilities of Alloy 690 to pitting corrosion and environmentally-assisted cracking in 1wt% NaCl solution were inhibited with the concentration of Na{sub 2}S{sub 2}O{sub 3} {ge} 0.2M, regardless of the potential.« less

Gustatory Plasticity in "C. elegans" Involves Integration of Negative Cues and NaCl Taste Mediated by Serotonin, Dopamine, and Glutamate

ERIC Educational Resources Information Center

Hukema, Renate K.; Rademakers, Suzanne; Jansen, Gert

2008-01-01

While naive "Caenorhabditis elegans" individuals are attracted to 0.1-200 mM NaCl, they become strongly repelled by these NaCl concentrations after prolonged exposure to 100 mM NaCl. We call this behavior gustatory plasticity. Here, we show that "C. elegans" displays avoidance of low NaCl concentrations only when pre-exposure to NaCl is combined…

Assessment of nickel titanium and beta titanium corrosion resistance behavior in fluoride and chloride environments.

PubMed

Kassab, Elisa J; Gomes, José Ponciano

2013-09-01

To assess the influence of fluoride concentration on the corrosion behavior of nickel titanium (NiTi) superelastic wire and to compare the corrosion resistance of NiTi with that of beta titanium alloy in physiological solution with and without addition of fluoride. NiTi corrosion resistance was investigated through electrochemical impedance spectroscopy and anodic polarization in sodium chloride (NaCl 0.15 M) with and without addition of 0.02 M sodium fluoride (NaF), and the results were compared with those associated with beta titanium. The influence of fluoride concentration on NiTi corrosion behavior was assessed in NaCl (0.15 M) with and without 0.02, 0.04, 0.05, 0.07, and 0.12 M NaF solution. Galvanic corrosion between NiTi and beta titanium were investigated. All samples were characterized by scanning electron microscopy. Polarization resistance decreased when NaF concentration was increased, and, depending on NaF concentration, NiTi can suffer localized or generalized corrosion. In NaCl solution with 0.02 M NaF, NiTi suffer localized corrosion, while beta titanium alloys remained passive. Current values near zero were observed by galvanic coupling of NiTi and beta titanium. There is a decrease in NiTi corrosion resistance in the presence of fluoride. The corrosion behavior of NiTi alloy depends on fluoride concentration. When 0.02 and 0.04 M of NaF were added to the NaCl solution, NiTi presented localized corrosion. When NaF concentration increased to 0.05, 0.07, and 0.12 M, the alloy presented general corrosion. NiTi corrosion resistance behavior is lower than that of beta titanium. Galvanic coupling of these alloys does not increase corrosion rates.

Comparative sodium transport patterns provide clues for understanding salinity and metal responses in aquatic insects.

PubMed

Scheibener, S A; Richardi, V S; Buchwalter, D B

2016-02-01

The importance of insects in freshwater ecosystems has led to their extensive use in ecological monitoring programs. As freshwater systems are increasingly challenged by salinization and metal contamination, it is important to understand fundamental aspects of aquatic insect physiology (e.g., osmoregulatory processes) that contribute to insect responses to these stressors. Here we compared the uptake dynamics of Na as NaCl, NaHCO3 and Na2SO4 in the caddisfly Hydropsyche betteni across a range of Na concentrations (0.06-15.22 mM) encompassing the vast majority of North American freshwater ecosystems. Sulfate as the major anion resulted in decreased Na uptake rates relative to the chloride and bicarbonate salts. A comparison of Na (as NaHCO3) turnover rates in the caddisfly Hydropsyche sparna and the mayfly Maccaffertium sp. revealed different patterns in the 2 species. Both species appeared to tightly regulate their whole body sodium concentrations (at ∼47±1.8 μmol/g wet wt) across a range of Na concentrations (0.06-15.22 mM) over 7 days. However, at the highest Na concentration (15.22 mM), Na uptake rates in H. sparna (419.1 μM Na g(-1) hr(-1) wet wt) appeared close to saturation while Na uptake rates in Maccaffertium sp. were considerably faster (715 g μM Na g(-1) hr(-1) wet wt) and appeared to not be close to saturation. Na efflux studies in H. sparna revealed that loss rates are commensurate with uptake rates and are responsive to changes in water Na concentrations. A comparison of Na uptake rates (at 0.57 mM Na) across 9 species representing 4 major orders (Ephemeroptera, Plecoptera, Trichoptera and Diptera) demonstrated profound physiological differences across species after accounting for the influence of body weight. Faster Na uptake rates were associated with species described as being sensitive to salinization in field studies. The metals silver (Ag) and copper (Cu), known to be antagonistic to Na uptake in other aquatic taxa did not generally exhibit this effect in aquatic insects. Ag only reduced Na uptake at extremely high concentrations, while Cu generally stimulated Na uptake in aquatic insects, rather than suppress it. These results help explain the lack of insect responses to dissolved metal exposures in traditional toxicity testing and highlight the need to better understand fundamental physiological processes in this ecologically important faunal group. Copyright © 2015 Elsevier B.V. All rights reserved.

pH changes in frog rods upon manipulation of putative pH-regulating transport mechanisms.

PubMed

Kalamkarov, G; Pogozheva, I; Shevchenko, T; Koskelainen, A; Hemila, S; Donner, K

1996-10-01

Rod intracellular pH (pHi) in the intact frog retina was measured fluorometrically with the dye 2',7'-bis(2-carboxyethyl)-5(and-6)-carboxyfluorescein under treatments chosen to affect putative pH-regulating transport mechanisms in the plasma membrane. The purpose was to relate possible pHi changes to previously reported effects on photoresponses. In nominally bicarbonate-free Ringer, application of amiloride (1 mM) or substitution of 95 mM external Na+ by K+ or choline triggered monotonic but reversible acidifications, consistent with inhibition of Na+/H+ exchange. Bicarbonate-dependent mechanisms were characterized as follows: (1) Replacing half of a 12 mM phosphate buffer by bicarbonate caused a sustained rise of pHi. (2) Subsequent application of the anion transport inhibitor 4,4'-diisothiocyanatostilbene-2',2'-disulphonic acid (DIDS, 0.2 mM) set off a slow acidification. (3) Substitution of external Cl- by gluconate (95 mM) caused a rapid pHi rise both in normal Na+ and low-Na+ perfusion. (4) This effect was inhibited by DIDS. The results support a consistent explanation of parallel electrophysiological experiments on the assumption that intracellular acidifications reduce and alkalinizations (in a certain range) augment photoresponses. It is concluded that both Na+/H+ exchange and bicarbonate transport control rod pHi, modulating the light-sensitive current. Part of the bicarbonate transport is by Na(+)-independent HCO3-/Cl- exchange, but a further Na(+)-coupled bicarbonate import mechanism is implicated.

Inorganic ion composition in Tardigrada: cryptobionts contain a large fraction of unidentified organic solutes.

PubMed

Halberg, Kenneth Agerlin; Larsen, Kristine Wulff; Jørgensen, Aslak; Ramløv, Hans; Møbjerg, Nadja

2013-04-01

Many species of tardigrades are known to tolerate extreme environmental stress, yet detailed knowledge of the mechanisms underlying the remarkable adaptations of tardigrades is still lacking, as are answers to many questions regarding their basic biology. Here, we present data on the inorganic ion composition and total osmotic concentration of five different species of tardigrades (Echiniscus testudo, Milnesium tardigradum, Richtersius coronifer, Macrobiotus cf. hufelandi and Halobiotus crispae) using high-performance liquid chromatography and nanoliter osmometry. Quantification of the ionic content indicates that Na(+) and Cl(-) are the principal inorganic ions in tardigrade fluids, albeit other ions, i.e. K(+), NH4(+), Ca(2+), Mg(2+), F(-), SO4(2-) and PO4(3-) were also detected. In limno-terrestrial tardigrades, the respective ions are concentrated by a large factor compared with that of the external medium (Na(+), ×70-800; K(+), ×20-90; Ca(2+) and Mg(2+), ×30-200; F(-), ×160-1040, Cl(-), ×20-50; PO4(3-), ×700-2800; SO4(2-), ×30-150). In contrast, in the marine species H. crispae, Na(+), Cl(-) and SO4(2-) are almost in ionic equilibrium with (brackish) salt water, while K(+), Ca(2+), Mg(2+) and F(-) are only slightly concentrated (×2-10). An anion deficit of ~120 mEq l(-1) in M. tardigradum and H. crispae indicates the presence of unidentified ionic components in these species. Body fluid osmolality ranges from 361±49 mOsm kg(-1) in R. coronifer to 961±43 mOsm kg(-1) in H. crispae. Concentrations of most inorganic ions are largely identical between active and dehydrated groups of R. coronifer, suggesting that this tardigrade does not lose large quantities of inorganic ions during dehydration. The large osmotic and ionic gradients maintained by both limno-terrestrial and marine species are indicative of a powerful ion-retentive mechanism in Tardigrada. Moreover, our data indicate that cryptobiotic tardigrades contain a large fraction of unidentified organic osmolytes, the identification of which is expected to provide increased insight into the phenomenon of cryptobiosis.

Novel naïve Bayes classification models for predicting the chemical Ames mutagenicity.

PubMed

Zhang, Hui; Kang, Yan-Li; Zhu, Yuan-Yuan; Zhao, Kai-Xia; Liang, Jun-Yu; Ding, Lan; Zhang, Teng-Guo; Zhang, Ji

2017-06-01

Prediction of drug candidates for mutagenicity is a regulatory requirement since mutagenic compounds could pose a toxic risk to humans. The aim of this investigation was to develop a novel prediction model of mutagenicity by using a naïve Bayes classifier. The established model was validated by the internal 5-fold cross validation and external test sets. For comparison, the recursive partitioning classifier prediction model was also established and other various reported prediction models of mutagenicity were collected. Among these methods, the prediction performance of naïve Bayes classifier established here displayed very well and stable, which yielded average overall prediction accuracies for the internal 5-fold cross validation of the training set and external test set I set were 89.1±0.4% and 77.3±1.5%, respectively. The concordance of the external test set II with 446 marketed drugs was 90.9±0.3%. In addition, four simple molecular descriptors (e.g., Apol, No. of H donors, Num-Rings and Wiener) related to mutagenicity and five representative substructures of mutagens (e.g., aromatic nitro, hydroxyl amine, nitroso, aromatic amine and N-methyl-N-methylenemethanaminum) produced by ECFP_14 fingerprints were identified. We hope the established naïve Bayes prediction model can be applied to risk assessment processes; and the obtained important information of mutagenic chemicals can guide the design of chemical libraries for hit and lead optimization. Copyright © 2017 Elsevier B.V. All rights reserved.

Inhibitory effects of palmitoylcarnitine and lysophosphatidylcholine on the sodium current of cardiac ventricular cells.

PubMed

Sato, T; Kiyosue, T; Arita, M

1992-01-01

We investigated the effects of ischemia-related amphipathic compounds, palmitoylcarnitine (PamCar, 0.5-50 microM) and lysophosphatidylcholine (lysoPtdCho, 5-50 microM) on sodium current (INa) of guinea-pig ventricular myocytes. The cells were perfused with low-Na+ (60 mM) Tyrode's solution, and Ca2+ and K+ currents were blocked by external Co2+ (3 mM) and internal Cs+ (140 mM), respectively. INa was elicited by depolarizing voltage steps from a holding potential of -100 mV at a temperature of 33 degrees C. PamCar (5 microM) decreased the peak INa (attained at -20 mV or -30 mV) from 6.1 +/- 2.1 nA to 3.9 +/- 1.4 nA (n = 11), or by 36.1% within 2 min, and shifted the curve of steady-state INa inactivation by 5.4 mV in the positive direction (from -76.3 +/- 4.6 mV, control to -70.9 +/- 4.0 mV, in PamCar, n = 4). Partial restoration of the amplitude and the shift of the steady-state inactivation curve of INa was attained after washout of PamCar. In contrast, lysoPtdCho at concentrations over 10 microM irreversibly depressed the INa within 0.5-3 min and the reduction of INa was followed by cell contracture or cell death (n = 9). The survival time, defined as a period from the start of lysoPtdCho application to the time of the last successful recording of the INa (before evolution of sudden changes in the holding current), depended on the concentrations of lysoPtdCho. Both PamCar and lysoPtdCho retarded the time course of activation and inactivation of INa.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship between maternal sodium intake and blood lead concentration during pregnancy.

PubMed

Lee, Yo A; Hwang, Ji-Yun; Kim, Hyesook; Kim, Ki Nam; Ha, Eun-Hee; Park, Hyesook; Ha, Mina; Kim, Yangho; Hong, Yun-Chul; Chang, Namsoo

2013-03-14

Pb is released from bone stores during pregnancy, which constitutes a period of increased bone resorption. A high Na intake has been found to be negatively associated with Ca and adversely associated with bone metabolism. It is possible that a high Na intake during pregnancy increases the blood Pb concentration; however, no previous study has reported on the relationship between Na intake and blood Pb concentration. We thus have investigated this relationship between Na intake and blood Pb concentrations, and examined whether this relationship differs with Ca intake in pregnant Korean women. Blood Pb concentrations were analysed in 1090 pregnant women at mid-pregnancy. Dietary intakes during mid-pregnancy were estimated by a 24 h recall method covering the use of dietary supplements. Blood Pb concentrations in whole-blood samples were analysed using graphite furnace atomic absorption spectrophotometry. Multiple regression analysis performed after adjustment for covariates revealed that maternal Na intake was positively associated with blood Pb concentration during pregnancy, but only when Ca intake was below the estimated average requirement for pregnant Korean women (P= 0·001). The findings of the present study suggest that blood Pb concentration during pregnancy could be minimised by dietary recommendations that include decreased Na and increased Ca intakes.

Sequential Combination of Electro-Fenton and Electrochemical Chlorination Processes for the Treatment of Anaerobically-Digested Food Wastewater.

PubMed

Shin, Yong-Uk; Yoo, Ha-Young; Kim, Seonghun; Chung, Kyung-Mi; Park, Yong-Gyun; Hwang, Kwang-Hyun; Hong, Seok Won; Park, Hyunwoong; Cho, Kangwoo; Lee, Jaesang

2017-09-19

A two-stage sequential electro-Fenton (E-Fenton) oxidation followed by electrochemical chlorination (EC) was demonstrated to concomitantly treat high concentrations of organic carbon and ammonium nitrogen (NH 4 + -N) in real anaerobically digested food wastewater (ADFW). The anodic Fenton process caused the rapid mineralization of phenol as a model substrate through the production of hydroxyl radical as the main oxidant. The electrochemical oxidation of NH 4 + by a dimensionally stable anode (DSA) resulted in temporal concentration profiles of combined and free chlorine species that were analogous to those during the conventional breakpoint chlorination of NH 4 + . Together with the minimal production of nitrate, this confirmed that the conversion of NH 4 + to nitrogen gas was electrochemically achievable. The monitoring of treatment performance with varying key parameters (e.g., current density, H 2 O 2 feeding rate, pH, NaCl loading, and DSA type) led to the optimization of two component systems. The comparative evaluation of two sequentially combined systems (i.e., the E-Fenton-EC system versus the EC-E-Fenton system) using the mixture of phenol and NH 4 + under the predetermined optimal conditions suggested the superiority of the E-Fenton-EC system in terms of treatment efficiency and energy consumption. Finally, the sequential E-Fenton-EC process effectively mineralized organic carbon and decomposed NH 4 + -N in the real ADFW without external supply of NaCl.

Elemental analysis and radiation hazards parameters of bauxite located in Saudi Arabia

NASA Astrophysics Data System (ADS)

Alashrah, S.; E Taher, A.

2017-04-01

Since Bauxite has been widely used in industry and in scientific investigations for producing Aluminum, it is important to measure the radionuclides concentrations to determine the health effect. The Bauxite mine is located in Az Zabirah city in Saudi Arabia. The concentrations of the radionuclides in the bauxite samples were measured using γ-ray spectrometer NaI (Tl). The average and range values of the concentrations of 226Ra, 232Th and 40K were 102.2 (141.1-62.7), 156.3 (202.8-102.8) and 116.8 (191.7- 48.9) Bq/kg respectively. These results were compared with the reported ranges in the literature from other locations around the world. The radiation hazard parameters; radium equivalent activity, annual dose, external hazard were also calculated and compared with the recommended levels by International Commission on Radiological Protection (ICRP-60) and united nations scientific committee on the effects of atomic radiation UNSCEAR reports. There are no studies for the natural radioactivity in the bauxite mine in Az Zabirah city, so these results are a start to establishing a database in this location.

Effect of Chorda Tympani Nerve Transection on Salt Taste Perception in Mice

PubMed Central

Ishiwatari, Yutaka; Theodorides, Maria L.; Bachmanov, Alexander A.

2011-01-01

Effects of gustatory nerve transection on salt taste have been studied extensively in rats and hamsters but have not been well explored in the mouse. We examined the effects of chorda tympani (CT) nerve transection on NaCl taste preferences and thresholds in outbred CD-1 mice using a high-throughput phenotyping method developed in our laboratory. To measure taste thresholds, mice were conditioned by oral self-administration of LiCl or NaCl and then presented with NaCl concentration series in 2-bottle preference tests. LiCl-conditioned and control NaCl-exposed mice were given bilateral transections of the CT nerve (LiCl-CTX, NaCl-CTX) or were left intact as controls (LiCl-CNT, NaCl-CNT). After recovery from surgery, mice received a concentration series of NaCl (0–300 mM) in 48-h 2-bottle tests. CT transection increased NaCl taste thresholds in LiCl-conditioned mice and eliminated avoidance of concentrated NaCl in control NaCl-exposed mice. This demonstrates that in mice, the CT nerve is important for detection and recognition of NaCl taste and is necessary for the normal avoidance of high concentrations of NaCl. The results of this experiment also show that the method of high-throughput phenotyping of salt taste thresholds is suitable for detecting changes in the taste periphery in mouse genetic studies. PMID:21743094

Sodium ion-dependent amino acid transport in membrane vesicles of Bacillus stearothermophilus.

PubMed Central

Heyne, R I; de Vrij, W; Crielaard, W; Konings, W N

1991-01-01

Amino acid transport in membrane vesicles of Bacillus stearothermophilus was studied. A relatively high concentration of sodium ions is needed for uptake of L-alanine (Kt = 1.0 mM) and L-leucine (Kt = 0.4 mM). In contrast, the Na(+)-H(+)-L-glutamate transport system has a high affinity for sodium ions (Kt less than 5.5 microM). Lithium ions, but no other cations tested, can replace sodium ions in neutral amino acid transport. The stimulatory effect of monensin on the steady-state accumulation level of these amino acids and the absence of transport in the presence of nonactin indicate that these amino acids are translocated by a Na+ symport mechanism. This is confirmed by the observation that an artificial delta psi and delta mu Na+/F but not a delta pH can act as a driving force for uptake. The transport system for L-alanine is rather specific. L-Serine, but not L-glycine or other amino acids tested, was found to be a competitive inhibitor of L-alanine uptake. On the other hand, the transport carrier for L-leucine also translocates the amino acids L-isoleucine and L-valine. The initial rates of L-glutamate and L-alanine uptake are strongly dependent on the medium pH. The uptake rates of both amino acids are highest at low external pH (5.5 to 6.0) and decline with increasing pH. The pH allosterically affects the L-glutamate and L-alanine transport systems. The maximal rate of L-glutamate uptake (Vmax) is independent of the external pH between pH 5.5 and 8.5, whereas the affinity constant (Kt) increases with increasing pH. A specific transport system for the basic amino acids L-lysine and L-arginine in the membrane vesicles has also been observed. Transport of these amino acids occurs most likely by a uniport mechanism. PMID:1670936

Natural Radioactivity of Boron Added Clay Samples

NASA Astrophysics Data System (ADS)

Akkurt, I.; ćanakciı, H.; Mavi, B.; Günoǧlu, K.

2011-12-01

Clay, consisting fine-grained minerals, is an interesting materials and can be used in a variety of diferent fields especially in dermatology application. Using clay such a field it is important to measure its natural radioacitivty. Thus the purpose of this study is to measure 226Ra, 232Th and 40K concentration in clay samples enriched with boron. Three different types of clay samples were prepared where boron is used in different rate. The measurements have been determined using a gamma-ray spectrometry consists of a 3″×3″ NaI(Tl) detector. From the measured activity the radium equivalent activities (Raeq), external hazard index (Hex), absorbed dose rate in air (D) and annual effective dose (AED) have also been obtained.

Simultaneous measurements of magnesium, calcium and sodium influxes in perfused squid giant axons under membrane potential control.

PubMed

Rojas, E; Taylor, R E

1975-10-01

1. Giant axons from the squids Dosidicus gigas, Loligo forbesi and Loligo vulgaris were internally perfused with 550 or 275 mM KF plus sucrose and bathed in artificial sea water containing 45Ca, 28Mg or mixtures of 45Ca-28Mg or 45Ca-22Na. Resting influxes and extra influxes during voltage-clamp pulses were measured by collecting and counting the internal perfusate. 2. For Dosidicus axons in 10 mM-CaCl2 the resting influx of calcium was 0-016 +/- 0-007 p-mole/cm2 sec and a linear function of external concentration. For two experiments in 10 and 84-7 mM-CaCl2, 100 nM tetrodotoxin had no effect. Resting calcium influx in 10 mM-CaCl2 was 0-017 +/- 0-013 p-mole/cm2 sec for Loligo axons. 3. With 55 mM-MgCl2 outside the average resting magnesium influx was 0-124 +/- 0-080 p-mole/cm2 sec for Loligo axons. Discarding one aberrant point the value is 0-105 +/- 0-046 which is not significantly different from the resting calcium influx for Dosidicus fibres in 55 mM-CaCl2, given as 0-094 p-mole/cm2 sec by the regression line shown in Fig. 1. In two experiments 150 nM tetrodotoxin had no effect. 4. With 430 mM-NaCl outside 100 nM tetrodotoxin reduced the average resting influx of sodium in Dosidicus axon from 27-7 +/- 4-5 to 25-1 +/- 6-2 p-mole/cm2 sec and for Loligo fibres in 460 mM-NaCl from 50-5 +/- 4 to 20 +/- 8 p-mole/cm2 sec. 5. Using depolarizing pulses of various durations, the extra calcium influx occurred in two phases. The early phase was eliminated by external application of tetrodotoxin. The results of analysis are consistent with, but do not rigorously demonstrate, the conclusion that the tetrodotoxin sensitive calcium entry is flowing through the normal sodium channels (cf. Baker, Hodgkin & Ridgway, 1971). 6. Measurements of extra influxes using 22Na and 45Ca simultaneously indicate that the time courses of tetrodotoxin sensitive calcium and sodium entry are similar but not necessarily identical. It is very doubtful that any significant calcium entry occurs before the sodium or is involved in the activation of the sodium system. 7. These measurements confirm for Loligo, as previously shown for Dosidicus axons, that the magnitude and time course of the sodium entry during a depolarizing pulse deduced from electrical measurements is the same as that measured with 22Na. 8. Using 28Mg, or mixtures of 45Ca and 28Mg, we observed a single phase of magnesium entry which was insensitive to external tetrodotoxin or internal tetraethyl ammonium. The magnitude of the magnesium influx was considerably greater than the calcium extra entry and large enough to have been detected in the experiments of Meves & Vogel (1973) if it represented current. 9. We suggest the possibility that the calcium and magnesium extra influxes, after external treatment with tetrodotoxin, during a depolarizing pulse, do not contribute to the measured current.

Simultaneous measurements of magnesium, calcium and sodium influxes in perfused squid giant axons under membrane potential control.

PubMed Central

Rojas, E; Taylor, R E

1975-01-01

1. Giant axons from the squids Dosidicus gigas, Loligo forbesi and Loligo vulgaris were internally perfused with 550 or 275 mM KF plus sucrose and bathed in artificial sea water containing 45Ca, 28Mg or mixtures of 45Ca-28Mg or 45Ca-22Na. Resting influxes and extra influxes during voltage-clamp pulses were measured by collecting and counting the internal perfusate. 2. For Dosidicus axons in 10 mM-CaCl2 the resting influx of calcium was 0-016 +/- 0-007 p-mole/cm2 sec and a linear function of external concentration. For two experiments in 10 and 84-7 mM-CaCl2, 100 nM tetrodotoxin had no effect. Resting calcium influx in 10 mM-CaCl2 was 0-017 +/- 0-013 p-mole/cm2 sec for Loligo axons. 3. With 55 mM-MgCl2 outside the average resting magnesium influx was 0-124 +/- 0-080 p-mole/cm2 sec for Loligo axons. Discarding one aberrant point the value is 0-105 +/- 0-046 which is not significantly different from the resting calcium influx for Dosidicus fibres in 55 mM-CaCl2, given as 0-094 p-mole/cm2 sec by the regression line shown in Fig. 1. In two experiments 150 nM tetrodotoxin had no effect. 4. With 430 mM-NaCl outside 100 nM tetrodotoxin reduced the average resting influx of sodium in Dosidicus axon from 27-7 +/- 4-5 to 25-1 +/- 6-2 p-mole/cm2 sec and for Loligo fibres in 460 mM-NaCl from 50-5 +/- 4 to 20 +/- 8 p-mole/cm2 sec. 5. Using depolarizing pulses of various durations, the extra calcium influx occurred in two phases. The early phase was eliminated by external application of tetrodotoxin. The results of analysis are consistent with, but do not rigorously demonstrate, the conclusion that the tetrodotoxin sensitive calcium entry is flowing through the normal sodium channels (cf. Baker, Hodgkin & Ridgway, 1971). 6. Measurements of extra influxes using 22Na and 45Ca simultaneously indicate that the time courses of tetrodotoxin sensitive calcium and sodium entry are similar but not necessarily identical. It is very doubtful that any significant calcium entry occurs before the sodium or is involved in the activation of the sodium system. 7. These measurements confirm for Loligo, as previously shown for Dosidicus axons, that the magnitude and time course of the sodium entry during a depolarizing pulse deduced from electrical measurements is the same as that measured with 22Na. 8. Using 28Mg, or mixtures of 45Ca and 28Mg, we observed a single phase of magnesium entry which was insensitive to external tetrodotoxin or internal tetraethyl ammonium. The magnitude of the magnesium influx was considerably greater than the calcium extra entry and large enough to have been detected in the experiments of Meves & Vogel (1973) if it represented current. 9. We suggest the possibility that the calcium and magnesium extra influxes, after external treatment with tetrodotoxin, during a depolarizing pulse, do not contribute to the measured current. PMID:1202193

Effect of sodium chloride concentration on elemental analysis of brines by laser-induced breakdown spectroscopy (LIBS).

PubMed

Goueguel, Christian; Singh, Jagdish P; McIntyre, Dustin L; Jain, Jinesh; Karamalidis, Athanasios K

2014-01-01

Leakage of injected carbon dioxide (CO2) or resident fluids, such as brine, is a major concern associated with the injection of large volumes of CO2 into deep saline formations. Migration of brine could contaminate drinking water resources by increasing their salinity or endanger vegetation and animal life as well as human health. The main objective of this study was to investigate the effect of sodium chloride (NaCl) concentration on the detection of calcium and potassium in brine samples using laser-induced breakdown spectroscopy (LIBS). The ultimate goals were to determine the suitability of the LIBS technique for in situ measurements of metal ion concentrations in NaCl-rich solution and to develop a chemical sensor that can provide the early detection of brine intrusion into formations used for domestic or agricultural water production. Several brine samples of NaCl-CaCl2 and NaCl-KCl were prepared at NaCl concentrations between 0.0 and 3.0 M. The effect of NaCl concentration on the signal-to-background ratio (SBR) and signal-to-noise ratio (SNR) for calcium (422.67 nm) and potassium (769.49 nm) emission lines was evaluated. Results show that, for a delay time of 300 ns and a gate width of 3 μs, the presence of and changes in NaCl concentration significantly affect the SBR and SNR for both emission lines. An increase in NaCl concentration from 0.0 to 3.0 M produced an increase in the SNR, whereas the SBR dropped continuously. The detection limits obtained for both elements were in the milligrams per liter range, suggesting that a NaCl-rich solution does not severely limit the ability of LIBS to detect trace amount of metal ions.

Effects of neutral sodium hydrogen phosphate on setting reaction and mechanical strength of hydroxyapatite putty.

PubMed

Ishikawa, K; Miyamoto, Y; Takechi, M; Ueyama, Y; Suzuki, K; Nagayama, M; Matsumura, T

1999-03-05

The setting reaction and mechanical strength in terms of diametral tensile strength (DTS) of hydroxyapatite (HAP) putty made of tetracalcium phosphate, dicalcium phosphate anhydrous, and neutral sodium hydrogen phosphate (Na1.8H1.2PO4) solution containing 8 wt % sodium alginate were evaluated as a function of the Na1.8H1.2PO4 concentration. In one condition, HAP putty was placed in an incubator kept at 37 degrees C and 100% relative humidity. In the other condition, immediately after mixing HAP putty was immersed in serum kept at 37 degrees C. Longer setting times and lower DTS values were observed when HAP putty was immersed in serum regardless of the Na1.8H1.2PO4 concentration. The setting times of the HAP putty in both conditions became shorter with an increase in the Na1. 8H1.2PO4 concentration, reaching approximately 7-13 min when the Na1. 8H1.2PO4 concentration was 0.6 mol/L or higher. The DTS value of HAP putty was relatively constant (10 MPa) regardless of the Na1.8H1. 2PO4 concentration (0.2-1.0 mol/L) when HAP putty was kept in an incubator. In contrast, when HAP putty was immersed in serum, the DTS value was dependent on the Na1.8H1.2PO4 concentration. It increased with the Na1.8H1.2PO4 concentration and reached approximately 5 MPa when the Na1.8H1.2PO4 concentration was 0.6 mol/L, after which it showed a relatively constant DTS value. We therefore would recommend a HAP putty that uses 0.6 mol/L Na1.8H1. 2PO4 since at that concentration the putty's setting time (approximately 10 min) is proper for clinical use and it shows good DTS value (approximately 5 MPa) even when it is immersed in serum immediately after mixing. Copyright 1999 John Wiley & Sons, Inc.

Measurement of the cytosolic sodium ion concentration in rat brain synaptosomes by a fluorescence method.

PubMed

Kongsamut, S; Nachshen, D A

1988-05-24

A method for the measurement of the cytosolic Na+ concentration in intact synaptosomes is described. This method makes use of a pH sensitive dye (BCECF) that can be loaded into the cytosol and a relatively specific ionophore (monensin) that can exchange Na+ for H+ across the synaptosomal membrane. By setting conditions such that there is no electrochemical potential difference for H+ across the membrane (no membrane potential and pHi = pHo), addition of ionophore would induce a H+ flux only if there is a concentration difference for Na+. Thus, when there is no fluorescence change (no cytosolic pH change) extracellular [Na+] equals intrasynaptosomal [Na+]. The intrasynaptosomal [Na+] concentration was determined to be 7 +/- 3 mM (n = 5; mean +/- S.E.). The results obtained with this fluorescence method are compared with estimates obtained by atomic absorption spectrometry. Limitations and applications of the method are discussed.

Japanese Papilio butterflies puddle using Na+ detected by contact chemosensilla in the proboscis

NASA Astrophysics Data System (ADS)

Inoue, Takashi A.; Hata, Tamako; Asaoka, Kiyoshi; Ito, Tetsuo; Niihara, Kinuko; Hagiya, Hiroshi; Yokohari, Fumio

2012-12-01

Many butterflies acquire nutrients from non-nectar sources such as puddles. To better understand how male Papilio butterflies identify suitable sites for puddling, we used behavioral and electrophysiological methods to examine the responses of Japanese Papilio butterflies to Na+, K+, Ca2+, and Mg2+. Based on behavioral analyses, these butterflies preferred a 10-mM Na+ solution to K+, Ca2+, and Mg2+ solutions of the same concentration and among a tested range of 1 mM to 1 M NaCl. We also measured the ion concentrations of solutions sampled from puddling sites in the field. Na+ concentrations of the samples were up to 6 mM, slightly lower than that preferred by butterflies in the behavioral experiments. Butterflies that sipped the 10 mM Na+ solution from the experimental trays did not continue to puddle on the ground. Additionally, butterflies puddled at sites where the concentrations of K+, Ca2+, and/or Mg2+ were higher than that of Na+. This suggests that K+, Ca2+, and Mg2+ do not interfere with the detection of Na+ by the Papilio butterfly. Using an electrophysiological method, tip recordings, receptor neurons in contact chemosensilla inside the proboscis evoked regularly firing impulses to 1, 10, and 100 mM NaCl solutions but not to CaCl2 or MgCl2. The dose-response patterns to the NaCl solutions were different among the neurons, which were classified into three types. These results showed that Japanese Papilio butterflies puddle using Na+ detected by the contact chemosensilla in the proboscis, which measure its concentration.

Assessment of radiological hazard parameters due to natural radioactivity in soils from granite-rich regions in Kütahya Province, Turkey.

PubMed

Sahin, Latife; Hafızoğlu, Nurgül; Çetinkaya, Hakan; Manisa, Kaan; Bozkurt, Engin; Biçer, Ahmet

2017-05-01

The analysis of natural radioactivity from 238 U, 232 Th and 40 K in 357 soil samples collected from the province of Kütahya was carried out using a NaI(Tl) gamma-ray spectroscopy system at the Nuclear Physics Research Laboratory, Dumlupınar University, Kütahya, Turkey. The specific activities of 238 U, 232 Th and 40 K in the soil samples were evaluated. From the activity concentrations of 238 U, 232 Th and 40 K, the total absorbed outdoor gamma-ray dose rates and the corresponding annual effective dose rates were determined. The corresponding values of the external and internal hazard indices of all the soil samples were also calculated. The external gamma-ray dose rate at 1 m above the ground was directly measured at each collected soil sample location. The results obtained in this study were compared within the limits of values obtained in other cities of Turkey, those in other countries. Radiological maps of Kütahya Province were constructed from the results of this study.

Carbachol regulates pacemaker activities in cultured interstitial cells of Cajal from the mouse small intestine.

PubMed

So, Keum Young; Kim, Sang Hun; Sohn, Hong Moon; Choi, Soo Jin; Parajuli, Shankar Prasad; Choi, Seok; Yeum, Cheol Ho; Yoon, Pyung Jin; Jun, Jae Yeoul

2009-05-31

We studied the effect of carbachol on pacemaker currents in cultured interstitial cells of Cajal (ICC) from the mouse small intestine by muscarinic stimulation using a whole cell patch clamp technique and Ca2+-imaging. ICC generated periodic pacemaker potentials in the current-clamp mode and generated spontaneous inward pacemaker currents at a holding potential of-70 mV. Exposure to carbachol depolarized the membrane and produced tonic inward pacemaker currents with a decrease in the frequency and amplitude of the pacemaker currents. The effects of carbachol were blocked by 1-dimethyl-4-diphenylacetoxypiperidinium, a muscarinic M(3) receptor antagonist, but not by methotramine, a muscarinic M(2) receptor antagonist. Intracellular GDP-beta-S suppressed the carbachol-induced effects. Carbachol-induced effects were blocked by external Na+-free solution and by flufenamic acid, a non-selective cation channel blocker, and in the presence of thapsigargin, a Ca2+-ATPase inhibitor in the endoplasmic reticulum. However, carbachol still produced tonic inward pacemaker currents with the removal of external Ca2+. In recording of intracellular Ca2+ concentrations using fluo 3-AM dye, carbachol increased intracellular Ca2+ concentrations with increasing of Ca2+ oscillations. These results suggest that carbachol modulates the pacemaker activity of ICC through the activation of non-selective cation channels via muscarinic M(3) receptors by a G-protein dependent intracellular Ca2+ release mechanism.

Fluoride exposure changed the structure and the expressions of Y chromosome related genes in testes of mice.

PubMed

Cao, Jinling; Chen, Yan; Chen, Jianjie; Yan, Hanghang; Li, Meiyan; Wang, Jundong

2016-10-01

It is known that during spermatogenesis, pluripotent germ cells differentiate to become efficient delivery vehicles to the oocyte of paternal DNA, and the process is easily damaged by external poison. In this study, the effects of fluoride on the body weight, fluoride content in femur, testosterone levels in serum and testis, sperm quality, and the expressions of Y chromosome microdeletion genes and protein levels were examined in testes of Kunming male mice treated with different concentrations of 0, 25, 50, 100 mg/L of NaF in drinking water for 11 weeks, respectively. The results showed that compared with the control group, fluoride contents in three treatment groups were significantly increased and the structure of testes was seriously injured. The testosterone contents and the sperm count were decreased. Sperm malformation ratio was distinctly elevated. The expressions of Sly and HSF2 mRNA were markedly reduced in 100 mg/L NaF group and Ssty2 mRNA expression was dramatically decreased in 50 and 100 mg/L NaF groups. Meanwhile, the protein levels of Ssty2 and Sly were significantly reduced in 50 and 100 mg/L NaF groups and HSF2 protein levels were significantly decreased in 100 mg/L NaF group. These studies indicated that fluoride had toxic effects on male reproductive system by reducing the testosterone and sperm count, and increasing the sperm malformation ratio, supported by the damage of testicular structure, as a consequence of depressed HSF2 level, which resulted in the down-regulation of Ssty2 and Sly mRNA and protein. Copyright © 2016 Elsevier Ltd. All rights reserved.

Silver ion (Ag+)-induced increases in cell membrane K+ and Na+ permeability in the renal proximal tubule: reversal by thiol reagents.

PubMed

Kone, B C; Kaleta, M; Gullans, S R

1988-04-01

The initial mechanisms of injury to the proximal tubule following exposure to nephrotoxic heavy metals are not well established. We studied the immediate effects of silver (Ag+) on K+ transport and respiration with extracellular K+ and O2 electrodes in suspensions of renal cortical tubules. Addition of silver nitrate (AgNO3) to tubules suspended in bicarbonate Ringer's solution caused a rapid, dose-dependent net K+ efflux (Km = 10(-4) M, Vmax = 379 nmol K+/min/mg protein) which was not inhibited by furosemide, barium chloride, quinine, tetraethylammonium, or tolbutamide. An increase in the ouabain-sensitive oxygen consumption rate (QO2) (13.9 +/- 1.1 to 25.7 +/- 4.4 nmol O2/min/mg, P less than 0.001), was observed 19 sec after the K+ efflux induced by AgNO3 (10(-4) M), suggesting a delayed increase in Na+ entry into the cell. Ouabain-insensitive QO2, nystatin-stimulated QO2, and CCCP-uncoupled QO2 were not significantly affected, indicating preserved function of the Na+,K+-ATPase and mitochondria. External addition of the thiol reagents dithiothreitol (1 mM) and reduced glutathione (1 mM) prevented and/or immediately reversed the effects on K+ transport and QO2. We conclude that Ag+ causes early changes in the permeability of the cell membrane to K+ and then to Na+ at concentrations that do not limit Na+,K+-ATPase activity or mitochondrial function. These alterations are likely the result of a reversible interaction of Ag+ with sulfhydryl groups of cell membrane proteins and may represent initial cytotoxic effects common to other sulfhydryl-reactive heavy metals on the proximal tubule.

Cytotoxicity of peracetic acid: evaluation of effects on metabolism, structure and cell death.

PubMed

Viola, K S; Rodrigues, E M; Tanomaru-Filho, M; Carlos, I Z; Ramos, S G; Guerreiro-Tanomaru, J M; Faria, G

2017-01-30

To evaluate the cytotoxicity and the mechanism of cell aggression of peracetic acid (PA) in comparison with sodium hypochlorite (NaOCl). L929 fibroblasts were exposed to 1% PA and 2.5% NaOCl, at several dilutions for 10 min. The following parameters were evaluated: cell metabolism by methylthiazol tetrazolium assay, external morphology by scanning electron microscopy, ultrastructure by transmission electron microscopy, the cytoskeleton by means of actin and α-tubulin labelling, and the type of cell death by flow cytometry (apoptosis/necrosis). The data were analysed by two-way anova and the Bonferroni post-test (α = 0.05). The PA group had lower cell viability and a higher percentage of necrotic cells than the NaOCl group (P < 0.05). Both solutions diminished cell metabolism, led to destructuring of the cytoskeleton, created changes in the external morphology, resulted in the accumulation of proteins in the rough endoplasmic reticulum and induced cell death predominantly by necrosis. However, these changes were observed in lower doses of PA when compared with NaOCl. Although they had the same mechanism of cytotoxicity, 1% PA had greater cytotoxic potential than 2.5% NaOCl. © 2017 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Astrocytic and neuronal accumulation of elevated extracellular K+ with a 2/3 K+/Na+ flux ratio—consequences for energy metabolism, osmolarity and higher brain function

PubMed Central

Hertz, Leif; Xu, Junnan; Song, Dan; Yan, Enzhi; Gu, Li; Peng, Liang

2013-01-01

Brain excitation increases neuronal Na+ concentration by 2 major mechanisms: (i) Na+ influx caused by glutamatergic synaptic activity; and (ii) action-potential-mediated depolarization by Na+ influx followed by repolarizating K+ efflux, increasing extracellular K+ concentration. This review deals mainly with the latter and it concludes that clearance of extracellular K+ is initially mainly effectuated by Na+,K+-ATPase-mediated K+ uptake into astrocytes, at K+ concentrations above ~10 mM aided by uptake of Na+,K+ and 2 Cl− by the cotransporter NKCC1. Since operation of the astrocytic Na+,K+-ATPase requires K+-dependent glycogenolysis for stimulation of the intracellular ATPase site, it ceases after normalization of extracellular K+ concentration. This allows K+ release via the inward rectifying K+ channel Kir4.1, perhaps after trans-astrocytic connexin- and/or pannexin-mediated K+ transfer, which would be a key candidate for determination by synchronization-based computational analysis and may have signaling effects. Spatially dispersed K+ release would have little effect on extracellular K+ concentration and allow K+ accumulation by the less powerful neuronal Na+,K+-ATPase, which is not stimulated by increases in extracellular K+. Since the Na+,K+-ATPase exchanges 3 Na+ with 2 K+, it creates extracellular hypertonicity and cell shrinkage. Hypertonicity stimulates NKCC1, which, aided by β-adrenergic stimulation of the Na+,K+-ATPase, causes regulatory volume increase, furosemide-inhibited undershoot in [K+]e and perhaps facilitation of the termination of slow neuronal hyperpolarization (sAHP), with behavioral consequences. The ion transport processes involved minimize ionic disequilibria caused by the asymmetric Na+,K+-ATPase fluxes. PMID:23986689

Voltage dependence of the rat chorda tympani response to Na+ salts: implications for the functional organization of taste receptor cells.

PubMed

Ye, Q; Heck, G L; DeSimone, J A

1993-07-01

1. Voltage-clamp and current-clamp data were obtained from a circumscribed region of the anterior rat lingual epithelium while simultaneously monitoring the afferent, stimulus-evoked, neural response from the same receptive field. 2. Chorda tympani (CT) responses at constant Na(+)-salt concentration were enhanced by submucosa negative voltage clamp and suppressed by positive voltage clamp. The complete CT response profile, including the time course of adaptation, was not uniquely determined by NaCl concentration alone. The response could be reproduced at different NaCl concentrations by applying a compensating voltage. 3. The form of the concentration and voltage dependence of the CT response indicates that the complete stimulus energy is the Na+ electrochemical potential difference across receptor cell apical membranes, and not Na+ concentration alone. This is the underlying principal behind the equivalence of chemical and electric taste for Na+ salts. 4. CT responses to sodium gluconate (25 and 200 mM) and 25 mM NaCl produced amiloride-insensitive components (AIC) of low magnitude. NaCl at 200 mM produced a significantly larger AIC. The AIC was voltage-clamp independent. The relative magnitude of the AIC was positively correlated with the transepithelial conductance of each salt. This suggests that the large AIC for 200 mM NaCl results from its relatively high permeability through the paracellular pathway. 5. Analysis of the CT response under voltage clamp revealed two anion effects on Na(+)-salt taste, both of which act through the paracellular shunt. 1) Anions modify the transepithelial potential (TP) across tight junctions and thereby modulate the cell receptor potential. This anion effect can be eliminated by voltage clamping the TP. 2) Sufficiently mobile anions facilitate electroneutral diffusion of Na+ salts through tight junctions. This effect is observed especially when Cl- is the anion and when the stimulus concentration favors NaCl influx, allowing Na+ to stimulate receptor cells from the submucosal side. Because the submucosal intercellular spaces are nearly isopotential regions, this effect is insensitive to voltage clamp of the TP. The large AIC associated with this anion effect is due to the low permeability of amiloride.

Studies on improvement of pharmaceutical preparations prescribed in hospitals. IV. Dibekacin sulfate viscous solution for treatment of mouth and throat wounds.

PubMed

Namiki, N; Yokoyama, H; Moriya, K; Fukuda, M; Takashima, T; Uchida, Y; Yuasa, H; Kanaya, Y

1986-11-01

For the purpose of preventing suppuration of wounds of the oral cavity and throat, we attempted to develop a viscous solution of dibekacin sulfate (DKB) as a suitable medication. Solutions of different viscosity and antibacterial potency were prepared by mixing DKB, sodium carboxymethyl cellulose (CMC-Na), and water in varying proportions. Studies were then performed to ascertain relationships between the concentration of CMC-Na pH and viscosity, and between the viscosity and diffusion of DKB. The concentration of CMC-Na giving rise to optimal clinical efficacy was determined, and the concentration of DKB necessary for clinical treatment was estimated on the basis of the ionic binding constant between DKB and CMC-Na. As a result, the optimum CMC-Na concentration was found to be 2%, while the optimum DKB concentration was estimated to be 100 micrograms/ml.

Sodium chloride concentration determines exoelectrogens in anode biofilms occurring from mangrove-grown brackish sediment.

PubMed

Miyahara, Morio; Kouzuma, Atsushi; Watanabe, Kazuya

2016-10-01

Single-chamber microbial fuel cells (MFCs) were inoculated with mangrove-grown brackish sediment (MBS) and continuously supplied with an acetate medium containing different concentrations of NaCl (0-1.8M). Different from MFCs inoculated with paddy-field soil (high power outputs were observed between 0.05 and 0.1M), power outputs from MBS-MFCs were high at NaCl concentrations from 0 to 0.6M. Amplicon-sequence analyses of anode biofilms suggest that different exoelectrogens occurred from MBS depending on NaCl concentrations; Geobacter occurred abundantly below 0.1M, whereas Desulfuromonas was abundant from 0.3M to 0.6M. These results suggest that NaCl concentration is the major determinant of exoelectrogens that occur in anode biofilms from MBS. It is also suggested that MBS is a potent source of microbes for MFCs to be operated in a wide range of NaCl concentrations. Copyright © 2016 Elsevier Ltd. All rights reserved.

Assessment of sodium status in large ruminants by measuring the sodium-to-potassium ratio in muzzle secretions.

PubMed

Singh, S P; Rani, D

1999-09-01

To develop a simple diagnostic test to assess sodium status in large ruminants on the basis of the sodium-to-potassium ratio (Na:K) and to determine its relevance. 7 buffalo heifers and 21 lactating, pregnant, and nonpregnant dairy cows and heifers. Buffalo heifers were subjected in 2 experiments to variable dietary sodium intake or sodium depletion and changes in sodium and potassium concentrations; Na:K was simultaneously monitored in various body fluids to study its value for indicating sodium status. Validity of the muzzle secretion test was assessed. Muzzle secretion and urinary Na:K and sodium concentration, but not serum electrolyte concentrations, reflected the sodium status of buffalo heifers in response to the widely variable intake of sodium (0.03 to 0.16% of dry matter [DM]). Progressive sodium depletion during an 11-day period, using saliva deprivation caused reciprocal changes in sodium and potassium concentrations in saliva and muzzle secretion, but not in urine. Decreasing urine sodium concentration was associated with decreasing urine potassium concentration. Saliva, urine, and muzzle secretion Na:K closely reflected the degree of sodium deficit. Buffaloes or dairy cows maintained on optimal sodium intake had muzzle secretion and urine Na:K > 0.30. Muzzle secretion or urine Na:K < 0.20 or < 0.10, respectively, was indicative of sodium deficiency. Analysis of muzzle secretion Na:K, and to a large extent urine Na:K, may be used as a convenient diagnostic tool to assess sodium status in large ruminants. It has accuracy similar to that of saliva Na:K.

Light-driven Na + pump from Gillisia limnaea: A high-affinity Na + binding site is formed transiently in the photocycle

DOE PAGES

Balashov, Sergei P.; Imasheva, Eleonora S.; Dioumaev, Andrei K.; ...

2014-11-06

A group of microbial retinal proteins most closely related to the proton pump xanthorhodopsin has a novel sequence motif and a novel function. Instead of, or in addition to, proton transport, they perform light-driven sodium ion transport, as reported for one representative of this group (KR2) from Krokinobacter. In this paper, we examine a similar protein, GLR from Gillisia limnaea, expressed in Escherichia coli, which shares some properties with KR2 but transports only Na +. The absorption spectrum of GLR is insensitive to Na + at concentrations of ≤3 M. However, very low concentrations of Na + cause profound differencesmore » in the decay and rise time of photocycle intermediates, consistent with a switch from a “Na +-independent” to a “Na +-dependent” photocycle (or photocycle branch) at ~60 μM Na +. The rates of photocycle steps in the latter, but not the former, are linearly dependent on Na + concentration. This suggests that a high-affinity Na + binding site is created transiently after photoexcitation, and entry of Na + from the bulk to this site redirects the course of events in the remainder of the cycle. A greater concentration of Na + is needed for switching the reaction path at lower pH. The data suggest therefore competition between H + and Na + to determine the two alternative pathways. The idea that a Na + binding site can be created at the Schiff base counterion is supported by the finding that upon perturbation of this region in the D251E mutant, Na + binds without photoexcitation. Furthermore, binding of Na+ to the mutant shifts the chromophore maximum to the red like that of H +, which occurs in the photocycle of the wild type.« less

Open external circuit for microbial fuel cell sensor to monitor the nitrate in aquatic environment.

PubMed

Wang, Donglin; Liang, Peng; Jiang, Yong; Liu, Panpan; Miao, Bo; Hao, Wen; Huang, Xia

2018-07-15

This study employed an open external circuit, rather than a closed circuit applied in previous studies, to operate an microbial fuel cell (MFC) sensor for real-time nitrate monitoring, and achieved surprisingly greater sensitivity (4.42 ± 0.3-6.66 ± 0.4 mV/(mg/L)) when the nitrate was at a concentration of 10-40 mg/L, compared to that of the MFC sensor with a closed circuit (0.8 ± 0.05-1.6 ± 0.1 mV/(mg/L)). The MFC sensor operated in open circuit (O-MFC sensor) delivered much more stable performance than that operated in closed circuit (C-MFC sensor) when affected by organic matter (NaAc). The sensitivity of O-MFC sensor was twice that of C-MFC sensor at a low background concentration of organic matter. When organic matter reached a high concentration, the sensitivity of O-MFC sensor remained at an acceptable level, while that of C-MFC sensor dropped to almost zero. Challenged by a combined shock of organic matter and nitrate, O-MFC sensor delivered evident electrical signals for nitrate warning, while C-MFC failed. Another novel feature of this study lies in a new mathematical model to examine the bioanode process of nitrate monitoring. It revealed that lower capacitance of the bioanode in O-MFC was the major contributor to the improved sensitivity of the device. Copyright © 2018 Elsevier B.V. All rights reserved.

Na-KATPase activity and intracellular ion concentrations in the lactating guinea pig mammary gland. Studies on Na-K activated adenosine triphosphatase, XXXVI.

PubMed

Vreeswijk, J H; de Pont, J J; Bonting, S L

1975-01-01

The intracellular sodium, potassium and chloride concentrations in slices of lactating guinea pig mammary gland have been determined by chemical analysis and the use of appropriate values for extracellular space. These ion concentrations after 1 hr incubation at 37 degrees C in a Krebs-Ringer bicarbonate solution are 45mM Na+, 138 mM K+ and 44 mM Cl-, which values are in agreement with those found in fresh mammary gland slices. Inhibition of the NaK activated ATPase cation pump system of the tissue by 10(-4)M ouabain, anoxia or cooling to 0 degrees C Causes a gain of Na+ and an equimolar loss of K+ without a significant change in chloride concentration. The effect of cooling (0 degrees C) is reversible by reincubation at 37 degrees C. Water content of the tissue (76.5% of wet weight) and extracellular space (40.5%) do not change under these conditions. The results permit the conclusion that the NaK activated ATPase system is responsible for the maintenance of the intracellular Na+ and K+ concentrations, but do not support the presence of a chloride pump.

Novel duplex vapor-electrochemical method for silicon solar cells

NASA Technical Reports Server (NTRS)

Nanis, L.; Sanjurjo, A.; Westphal, S.

1979-01-01

Optimization studies were carried out for the SiF4-Na reaction with solid Na feed. The goals of the study were the consistent production of high purity reaction products and the gathering of relevant information needed to scale-up the reactor. Parameters studied include: (1) effect of surface to volume ratio of Na slices on the extent of reaction; (2) effect of Na surface oxidation on the extent of reaction; (3) effect of external heating on the extent of SiF4-Na reaction; (4) effect of Na slice addition rate on extent of the reaction; and (5) SiF4-Na reaction - high pressure experiments. An investigation was also made of the possible role played by NaF as a fluxing agent during the separation of silicon by melting of the reaction product (Si + NaF) mixture. Since silicon can be produced by the thermite reaction between Na2SiF6 and Na, studies were initiated to gather information on parameters which control the efficiency of the thermite reaction.

[Synergistic effects of lysozyme with EDTA-2Na on antibacterial activity].

PubMed

Li, Xiao-man; Wang, Xiao-yan; Gao, Xue-jun

2015-02-18

To evaluate the synergistic antibacterial effects of lysozyme with ethylenediaminetetraacetic acid disodium salt (EDTA-2Na) on Enterococcus faecalis (E. faecalis) and Porphyromonas endodontalis (P. endodontalis). E. faecalis and P. endodontalis were cultured and adjusted to 10(8) CFU/mL. Then 0.3, 0.5, 1, 2, 5, 10, 50, 100, 150 and 300 g/L of lysozyme were prepared with deionized water; and the lysozyme solutions were mixed with 0.5, 1.0, 2.0 g/L of EDTA-2Na, respectively. The bacteria and lysosome with/without EDTA-2Na interacted for 15 min, then water-soluble tetrazolium (WST) working solution was added and the activity of the bacteria was calculated by measuring optical densities at 450 nm and 630 nm with microplate spectrophotometer. Regarding the pure lysozyme from 0.5 g/L to 150 g/L, more E. faecalis and P. endodontalis were inhibited when the concentration of lysozyme was higher, especially for E. faecalis. There was synergistic effect of lysozyme with EDTA-2Na on antibacterial activity, which was related to the concentration of lysozyme. On E. faecalis, the antibacterial activity of lysozyme with EDTA-2Na was 1.2-3.7 folds than the pure lysozyme when the concentration of lysozyme was 0.5-50 g/L (P<0.05), and on P. endodontalis, the antibacterial activity of lysozyme with EDTA-2Na was 1.3-3.5 folds than the pure lysozyme when the concentration of lysozyme was 0.5-10 g/L (P<0.05). When the concentration of lysozyme was higher than 100 g/L, EDTA-2Na did not show synergistic effect on the antibacterial activity (P>0.05). For E. faecalis and P. endodontalis, a low concentration of lysozyme with EDTA-2Na showed significant synergistic antibacterial activity, while a high concentration of lysozyme with EDTA-2Na did not.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Josephson, Gary B.; Geeting, John GH; Bredt, Ofelia P.

Pacific Northwest National Laboratory (PNNL) has been tasked by Bechtel National Inc. (BNI) on the River Protection Project-Waste Treatment Plant (RPP-WTP) project to perform research and development activities to resolve technical issues identified for the Pretreatment Facility (PTF). The Pretreatment Engineering Platform (PEP) was designed, constructed, and operated as part of a plan to respond to issue M12, "Undemonstrated Leaching Processes." The PEP is a 1/4.5-scale test platform designed to simulate the WTP pretreatment caustic leaching, oxidative leaching, ultrafiltration solids concentration, and slurry washing processes. The PEP replicates the WTP leaching processes using prototypic equipment and control strategies. The PEPmore » also includes non-prototypic ancillary equipment to support the core processing. Two operating scenarios are currently being evaluated for the ultrafiltration process (UFP) and leaching operations. The first scenario has caustic leaching performed in the UFP-2 ultrafiltration feed vessels (i.e., vessel UFP-VSL-T02A in the PEP; and vessels UFP-VSL-00002A and B in the WTP PTF). The second scenario has caustic leaching conducted in the UFP-1 ultrafiltration feed preparation vessels (i.e., vessels UFP-VSL-T01A and B in the PEP; vessels UFP-VSL-00001A and B in the WTP PTF). In both scenarios, 19-M sodium hydroxide solution (NaOH, caustic) is added to the waste slurry in the vessels to leach solid aluminum compounds (e.g., gibbsite, boehmite). Caustic addition is followed by a heating step that uses direct injection of steam to accelerate the leach process. Following the caustic leach, the vessel contents are cooled using vessel cooling jackets and/or external heat exchangers. The main difference between the two scenarios is that for leaching in UFP-1, the 19-M NaOH is added to un-concentrated waste slurry (3-8 wt% solids), while for leaching in UFP-2, the slurry is concentrated to nominally 20 wt% solids using cross-flow ultrafiltration before the addition of caustic. In both scenarios, following the caustic leach, the slurry was then concentrated to 17 wt% and washed with inhibited water to remove NaOH and other soluble salts. Next, the slurry was oxidatively leached using sodium permanganate to solubilize chrome. The slurry was then washed to remove the dissolved chrome and concentrated.« less

Injection of sodium borohydride and nzvi solutions into homogeneous sands: H2 gas production and implications

NASA Astrophysics Data System (ADS)

Mohammed, O.; Mumford, K. G.; Sleep, B. E.

2016-12-01

Gases are commonly introduced into the subsurface via external displacement (drainage). However, gases can also be produced by internal drainage (exsolution). One example is the injection of reactive solutions for in situ groundwater remediation, such as nanoscale zero-valent iron (nzvi), which produces hydrogen gas (H2). Effective implementation of nzvi requires an understanding of H2 gas generation and dynamics, and their effects on aqueous permeability, contaminant mass transfer and potential flow diversion. Several studies have reported using excess sodium borohydride (NaBH4) in nzvi applications to promote complete reaction and to ensure uniform nzvi particle growth, which also produces H2 gas. The aim of this study was to visualize and quantify H2 produced by exsolution from the injection of NaBH4 and nzvi solutions into homogeneous sands, and to investigate the reduction of hydraulic conductivity caused by the H2 gas and the subsequent increase in hydraulic conductivity as the gas dissolved. Bench-scale experiments were performed using cold (4 °C) NaBH4 solutions injected in sand packed in a 22 cm × 34 cm × 1 cm flow cell. The injected solution was allowed to warm to room temperature, for controlled production of a uniform distribution of exsolved gas. A light transmission method was used to quantify gas production and dissolution over time. The results indicate a reduction of hydraulic conductivity due to the existence of H2 and increased hydraulic conductivity as H2 gas dissolves, which could be represented using traditional relative permeability expressions. Additional experiments were performed in the flow cell to compare H2 gas exsolving from nzvi and NaBH4 solutions injected as either a point injection or a well injection. The results indicated greater amounts of H2 gas produced when injecting nzvi solutions prepared with high concentrations of excess NaBH4. H2 gas pooling at the top of the flow cell, and H2 gas trapped near the injection point created preferential flow through the middle of the cell. These results demonstrate that H2 gas produced during remediation by nzvi injection can be controlled by limiting the excess NaBH4 concentrations. The trapped H2 gas produced by injection of nzvi, or NaBH4 alone may provide a source of H2 that could facilitate bioremediation as a secondary treatment.

Preliminary studies on the concentration of Na+,K(+)-ATPase in skeletal muscle of draught cattle in Mozambique: effect of sex, age and training.

PubMed

Veeneklaas, R J; Verkleij, C B; van Schie, B; Harun, M A S; Everts, M E

2002-09-01

The effect of training on the potential for work in draught cattle was assessed by measuring the Na+,K(+)-ATPase in the muscle cell membrane and the elevation in the concentration of K+ in plasma during exercise. Biopsies of the semitendinosus muscle and venous blood samples were taken from the cattle used for draught work in Mozambique. No differences were found in the plasma ion or Na+,K(+)-ATPase concentrations in samples taken from Nguni, Africander and Angoni breeds. There were no significant differences in plasma ions (Na+,K+ and Cl-) or muscle Na+,K(+)-ATPase concentrations between the Angoni males and females, although the males showed an increase in Na+,K(+)-ATPase with age, while the females showed a decrease. The increase in males might be attributed to their higher level of activity in the herds than that of females. After a training period of 15 days, a significant increase in Na+,K(+)-ATPase concentration in semitendinosus muscle was found in Angoni cattle. In females, this was significant after 8 days of training (about 30%); in males after 15 days of training (about 16%). On day 15, there was a reduction in the elevation of plasma K+ during the 2 h of draught work, indicating an increased capacity of the Na+,K+ pumps to maintain the extracellular K+ concentration in working muscles and a possible delay in the moment of fatigue.

Tissue-specific changes in OGG1 and SOD mRNA expression caused by NaOCl exposure in black seabream ( Acanthopagrus schlegelii)

NASA Astrophysics Data System (ADS)

Park, Ho-Ra; Kim, Yong; Yeo, Won-Jun; Kim, Ji-Hye; Han, Kyung-Nam

2017-09-01

The DNA-damage defense mechanism was studied in black seabreams after oxidative stress caused by exposure to sodium hypochlorite (NaOCl). Liver, muscle, and brain tissues were obtained after different NaOCl-exposure times (0, 24, 48, 72, and 96 h) and concentrations (0.5, 1, 1.5, 2, and 3 mg/L), after which oxoguanine glycosylase (OGG1) and superoxide dismutase (SOD) mRNA-expression levels were analyzed. At all NaOCl concentrations tested, liver OGG1 expression increased to a maximum in a time-dependent manner after NaOCl exposure and then decreased. In muscles, OGG1 expression increased over time following exposure to a low concentration of NaOCl (0.5, 1, and 1.5 mg/L), whereas it showed a mixed pattern (both increases and decreases observed) in the high-concentration groups (2 and 3 mg/L). SOD mRNA expression increased over time, both in the liver and muscles. In the brain, both OGG1 and SOD mRNA expression levels were highest after exposure to the lowest NaOCl concentration (0.5 mg/L), whereas basal levels were maintained over time at higher concentrations. These results indicate that OGG1 and SOD provide resistance to oxidative stress in black seabreams. In addition, continuous exposure to oxidative stress can suppress enzyme expression, suggesting a risk for long-term exposure to NaOCl.

The Role of Dopant Ions on Charge Injection and Transport in Electrochemically Doped Quantum Dot Films.

PubMed

Gudjonsdottir, Solrun; van der Stam, Ward; Kirkwood, Nicholas; Evers, Wiel H; Houtepen, Arjan J

2018-05-16

Control over the charge density is very important for implementation of colloidal semiconductor nanocrystals into various optoelectronic applications. A promising approach to dope nanocrystal assemblies is charge injection by electrochemistry, in which the charge compensating electrolyte ions can be regarded as external dopant ions. To gain insight into the doping mechanism and the role of the external dopant ions, we investigate charge injection in ZnO nanocrystal assemblies for a large series of charge compensating electrolyte ions with spectroelectrochemical and electrochemical transistor measurements. We show that charge injection is limited by the diffusion of cations in the nanocrystal films as their diffusion coefficient are found to be ∼7 orders of magnitude lower than those of electrons. We further show that the rate of charge injection depends strongly on the cation size and cation concentration. Strikingly, the onset of electron injection varies up to 0.4 V, depending on the size of the electrolyte cation. For the small ions Li + and Na + the onset is at significantly less negative potentials. For larger ions (K + , quaternary ammonium ions) the onset is always at the same, more negative potential, suggesting that intercalation may take place for Li + and Na + . Finally, we show that the nature of the charge compensating cation does not affect the source-drain electronic conductivity and mobility, indicating that shallow donor levels from intercalating ions fully hybridize with the quantum confined energy levels and that the reorganization energy due to intercalating ions does not strongly affect electron transport in these nanocrystal assemblies.

The Role of Dopant Ions on Charge Injection and Transport in Electrochemically Doped Quantum Dot Films

PubMed Central

2018-01-01

Control over the charge density is very important for implementation of colloidal semiconductor nanocrystals into various optoelectronic applications. A promising approach to dope nanocrystal assemblies is charge injection by electrochemistry, in which the charge compensating electrolyte ions can be regarded as external dopant ions. To gain insight into the doping mechanism and the role of the external dopant ions, we investigate charge injection in ZnO nanocrystal assemblies for a large series of charge compensating electrolyte ions with spectroelectrochemical and electrochemical transistor measurements. We show that charge injection is limited by the diffusion of cations in the nanocrystal films as their diffusion coefficient are found to be ∼7 orders of magnitude lower than those of electrons. We further show that the rate of charge injection depends strongly on the cation size and cation concentration. Strikingly, the onset of electron injection varies up to 0.4 V, depending on the size of the electrolyte cation. For the small ions Li+ and Na+ the onset is at significantly less negative potentials. For larger ions (K+, quaternary ammonium ions) the onset is always at the same, more negative potential, suggesting that intercalation may take place for Li+ and Na+. Finally, we show that the nature of the charge compensating cation does not affect the source-drain electronic conductivity and mobility, indicating that shallow donor levels from intercalating ions fully hybridize with the quantum confined energy levels and that the reorganization energy due to intercalating ions does not strongly affect electron transport in these nanocrystal assemblies. PMID:29718666

Altervalent substitution of sodium for calcium in biogenic calcite and aragonite

NASA Astrophysics Data System (ADS)

Yoshimura, Toshihiro; Tamenori, Yusuke; Suzuki, Atsushi; Kawahata, Hodaka; Iwasaki, Nozomu; Hasegawa, Hiroshi; Nguyen, Luan T.; Kuroyanagi, Azumi; Yamazaki, Toshitsugu; Kuroda, Junichiro; Ohkouchi, Naohiko

2017-04-01

Sodium concentrations in biogenic CaCO3 are several thousands of parts per million, and, on a molar basis, Na is among the most abundant constituent minor element in these carbonates. Nevertheless, the chemical form of Na in CaCO3 is not well constrained. We used synchrotron X-ray spectroscopy to identify the dominant molecular host sites for Na in biogenic calcite and aragonite precipitated by corals, bivalves, and foraminifera. We also used the K-edge X-ray absorption near-edge structure to investigate the chemical environment of Na in biogenic calcium carbonates and identify the altervalent substitution of Na into Ca sites in the lattice structures of calcite and aragonite. Minor cation and anion concentrations in biogenic CaCO3 suggest that the principal substitution mechanism involves charge compensation through the creation of CO32- vacancies. The mostly homogeneous Na concentrations in the skeletal microstructures of the various biota we examined indicate that environmental and biological controls, such as temperature, skeletal microstructure, and calcification rates, have only minor influences on skeletal Na concentrations. A decrease of Na:Ca ratios with increasing age of foraminiferal shells picked from a Quaternary sediment core, indicates progressive release of Na, which suggests that structurally-substituted Na in biogenic CaCO3 is readily leached during burial diagenesis. Whereas the sediment that undergo diagenesis release some Na back to the water column, sodium co-precipitation in biogenic CaCO3 serves as a potential sink of Na for the ocean.

Low pH-Induced Pore Formation by the T Domain of Botulinum Toxin Type A is Dependent upon NaCl Concentration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lai, B.; Swaminathan, S.; Agarwal, R.

2010-07-19

Botulinum neurotoxins (BoNTs) undergo low pH-triggered membrane insertion, resulting in the translocation of their light (catalytic) chains into the cytoplasm. The T (translocation) domain of the BoNT heavy chain is believed to carry out translocation. Here, the behavior of isolated T domain from BoNT type A has been characterized, both in solution and when associated with model membranes. When BoNT T domain prepared in the detergent dodecylmaltoside was diluted into aqueous solution, it exhibited a low pH-dependent conformational change below pH 6. At low pH the T domain associated with, and formed pores within, model membrane vesicles composed of 30more » mol% dioleoylphosphatidylglycerol/70 mol% dioleoylphosphatidylcholine. Although T domain interacted with vesicles at low (50 mM) and high (400 mM) NaCl concentrations, the interaction required much less lipid at low salt. However, even at high lipid concentrations pore formation was much more pronounced at low NaCl concentrations than at high NaCl concentration. Increasing salt concentration after insertion in the presence of 50 mM NaCl did not decrease pore formation. A similar effect of NaCl concentration upon pore formation was observed in vesicles composed solely of dioleoylphosphatidylcholine, showing that the effect of NaCl did not solely involve modulation of electrostatic interactions between protein and anionic lipids. These results indicate that some feature of membrane-bound T domain tertiary structure critical for pore formation is highly dependent upon salt concentration.« less

Inhibition of nitrate reduction by NaCl adsorption on a nano-zero-valent iron surface during a concentrate treatment for water reuse.

PubMed

Hwang, Yuhoon; Kim, Dogun; Shin, Hang-Sik

2015-01-01

Nanoscale zero-valent iron (NZVI) has been considered as a possible material to treat water and wastewater. However, it is necessary to verify the effect of the matrix components in different types of target water. In this study, different effects depending on the sodium chloride (NaCl) concentration on reductions of nitrates and on the characteristics of NZVI were investigated. Although NaCl is known as a promoter of iron corrosion, a high concentration of NaCl (>3 g/L) has a significant inhibition effect on the degree of NZVI reactivity towards nitrate. The experimental results were interpreted by a Langmuir-Hinshelwood-Hougen-Watson reaction in terms of inhibition, and the decreased NZVI reactivity could be explained by the increase in the inhibition constant. As a result of a chloride concentration analysis, it was verified that 7.7-26.5% of chloride was adsorbed onto the surface of NZVI. Moreover, the change of the iron corrosion product under different NaCl concentrations was investigated by a surface analysis of spent NZVI. Magnetite was the main product, with a low NaCl concentration (0.5 g/L), whereas amorphous iron hydroxide was observed at a high concentration (12 g/L). Though the surface was changed to permeable iron hydroxide, the Fe(0) in the core was not completely oxidized. Therefore, the inhibition effect of NaCl could be explained as the competitive adsorption of chloride and nitrate.

Physico-chemical changes in karkade (Hibiscus sabdariffa L.) seedlings responding to salt stress.

PubMed

Galal, Abdelnasser

2017-03-01

Salinity is one of the major abiotic stress factors affecting series of morphological, physiological, metabolic and molecular changes in plant growth. The effect of different concentrations (0, 25, 50, 100 and 150 mM) of NaCl on the vegetative growth and some physiological parameters of karkade (Hibiscus sabdariffa var. sabdariffa) seedling were investigated. NaCl affected the germination rate, delayed emergence and retarded vegetative growth of seedlings. The length of seedling as well as the leaf area was significantly reduced. The fresh weight remained lower in NaCl treated seedlings compared to control. NaCl at 100 and 150 mM concentrations had significant effect on the dry matter contents of the treated seedlings. The chloroplast pigments in the treated seedlings were affected, suggesting that the NaCl had a significant effect on the chlorophyll and carotenoid biosynthesis. The results showed that the salt treatments induced an increase in proline concentration of the seedlings. The osmotic potential (ψs) of NaCl treated seedlings decreased with increasing NaCl concentrations. Salt treatments resulted in dramatic quantitative reduction in the total sterol percent compared with control ones. Salt stress resulted in increase and decrease of Na + and K + ions, respectively. NaCl salinity increased lipid peroxidation. SDS-PAGE was used to evaluate protein pattern after applying salt stress. High molecular weight proteins were intensified, while low molecular weight proteins were faint. NaCl at 100 and 150 mM concentration distinguished with new protein bands. Salt stress induced a new peroxidase bands and increased the band intensity, indicating the protective role of peroxidase enzyme.

Assessment of natural radioactivity and associated radiation hazards in some building materials used in Kilpenathur, Tiruvannamalai dist, Tamilnadu, India

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raghu, Y.; Harikrishnan, N.; Ravisankar, R., E-mail: ravisankarphysics@gmail.com

The present study aimed to measure the radioactivity concentration of naturally occuring radionuclides in the locally used building materials from Kilpenthaur, Tiruvannmalai Dist, Tamilnadu, India. This study will also evaluate the radiation hazard arising due to the use of these materials in the construction of dwellings. The concentrations of natural radionuclides {sup 226}Ra, {sup 232}Th and {sup 40}K in five types of building materials have been measured by gamma spectrometry using NaI (Tl) 3” x 3”detector. The estimated radium equivalent activities (Ra{sub eq}), indoor absorbed gamma dose rate (D{sub R}), annual effective dose rate (H{sub R}) and the external hazardmore » indexes(H{sub ex}) were lower than the recommended safe limit and are comparable with results from similar studies conducted in other countries. Therefore, the use of these building material samples under investigation in the construction of dwellings is considered to be safe for inhabitants.« less

Sodium: some effects on bluegreen algal growth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ward, A.K.; Wetzel, R.G.

The growth of heterocystous bluegreen algae in various concentrations of sodium was examined in axenic culture as well as in situ studies. Anabaena cylindrica Lemm, with no Na/sup +/ added, suffered from decreased rates of acetylene reduction, /sup 14/C assimilation, excretion of organic C as well as lower concentrations of chlorophyll a and particulate organic C compared to cultures supplied with 5, 10, and 50 mg Na/sup +/ . l/sup -1/. Sodium deficient algae released extracellularly a higher percentage of previously fixed C as organic C. No differences in any parameter measured were demonstrable among cultures grown with 5, 10,more » and 50 mg Na/sup +/ . l/sup -1/. High nitrate concentrations (20 mg NO/sub 3/- . /sup -1/) resulted in decreased rates of acetylene reduction and heterocyst numbers in Na sufficient and Na deficient cultures; however, decreased cellular Na content at high NO/sub 3/- levels occurred only in N deficient cultures. Higher percentages of excreted organic C occurred with increasing NO/sub 3/- concentrations in Na deficient cultures. Sodium enrichment of natural bluegreen populations with the addition of 50, 100, and 200 mg Na/sup +/ . l/sup -1/ elicited neither a stimulatory nor an inhibitory response in photosynthetic C fixation. In contrast, the addition of small amounts of Na/sup +/ (5 mg . l/sup -1/) resulted in increased C fixation. However, since the Na concentration of the lake water, at ca. 5 mg Na/sup +/ . l/sup -1/, was sufficient for growth of the bluegreens present, sodium is not assumed to be limiting under most natural conditions. No increase in in situ acetylene reduction rates occurred with additions of sodium.« less

Japanese Papilio butterflies puddle using Na+ detected by contact chemosensilla in the proboscis.

PubMed

Inoue, Takashi A; Hata, Tamako; Asaoka, Kiyoshi; Ito, Tetsuo; Niihara, Kinuko; Hagiya, Hiroshi; Yokohari, Fumio

2012-12-01

Many butterflies acquire nutrients from non-nectar sources such as puddles. To better understand how male Papilio butterflies identify suitable sites for puddling, we used behavioral and electrophysiological methods to examine the responses of Japanese Papilio butterflies to Na(+), K(+), Ca(2+), and Mg(2+). Based on behavioral analyses, these butterflies preferred a 10-mM Na(+) solution to K(+), Ca(2+), and Mg(2+) solutions of the same concentration and among a tested range of 1 mM to 1 M NaCl. We also measured the ion concentrations of solutions sampled from puddling sites in the field. Na(+) concentrations of the samples were up to 6 mM, slightly lower than that preferred by butterflies in the behavioral experiments. Butterflies that sipped the 10 mM Na(+) solution from the experimental trays did not continue to puddle on the ground. Additionally, butterflies puddled at sites where the concentrations of K(+), Ca(2+), and/or Mg(2+) were higher than that of Na(+). This suggests that K(+), Ca(2+), and Mg(2+) do not interfere with the detection of Na(+) by the Papilio butterfly. Using an electrophysiological method, tip recordings, receptor neurons in contact chemosensilla inside the proboscis evoked regularly firing impulses to 1, 10, and 100 mM NaCl solutions but not to CaCl(2) or MgCl(2). The dose-response patterns to the NaCl solutions were different among the neurons, which were classified into three types. These results showed that Japanese Papilio butterflies puddle using Na(+) detected by the contact chemosensilla in the proboscis, which measure its concentration.

Comparative evaluation of effectiveness of sodium dichloroisocyanurate and calcium hydroxide against Candida albicans.

PubMed

Kurian, Jacob; Bolla, Nagesh; Damaraju, Bhargavi

2012-09-01

Candida albicans is the most commonly isolated fungi from the oral cavity. It is the most infective to various intracanal medicaments and is considered as invasive yeast. Sodium dichloroisocyanurate (NaDCC) which is used as a disinfectant and as a biocide in treating potable water has similar action to that of sodium hypochlorite against microbes. The aim of the present study is to compare the effectiveness of calcium hydroxide and NaDCC against Candida albicans. After obtaining the stock cultures of Candida, the isolates were divided into six groups which were exposed to different concentrations of NaDCC and calcium hydroxide Ca(OH)₂. Group 1 consisted of the isolates which were subdivided into three groups, subjected to three different concentrations of NaDCC. Group 2 also consisted of three subgroups exposed to three different concentrations of Ca(OH)₂. Group three consisted of three subgroups which were exposed to three different concentrations of combinations of both NaDCC and Ca(OH)₂. The results of the present study show that calcium hydroxide was totally ineffective at all concentrations and NaDCC was effective and also the combination of both was shown to be effective. NaDCC alone was effective at all concentrations and the combination with Ca(OH)₂ was found to be less effective. Ca(OH)₂ was totally ineffective.

Chemokinetic behavior of the infective third-stage larvae of Strongyloides ratti on a sodium chloride gradient.

PubMed

Tobata-Kudo, H; Higo, H; Koga, M; Tada, I

2000-09-01

The movements of the infective third-stage larvae (L3) of a rodent parasitic nematode Strongyloides ratti were examined on a sodium chloride (NaCl) gradient set up on agarose plates. The movements of larvae were followed by observing their tracks on the surface of the agarose. The direction of movement depended on the NaCl concentration at the point of their initial placement on the gradient. Larvae placed at between 230 and 370 mM NaCl tended to migrate towards areas of lower concentration. On the other hand, when placed at concentrations less than 20 mM NaCl, larvae tended to migrate initially towards higher concentrations but did not linger in areas where the concentration was over approximately 80 mM NaCl. It seems that S. ratti L3, tested in vitro, prefer regions with a concentration of NaCl below 80 mM NaCl. Two typical chemokinetic behaviors are seen; a unidirectional avoidance movement when initially placed in unfavorable environmental conditions and a random dispersal movement when placed within an area of favorable conditions. Track patterns were straight in the avoidance movement but included multiple changes of direction and loops in the dispersal movement. This study introduces an assay system suitable for studying chemokinetic behavior of larvae of Strongyloides ratti.

Polyol concentrations in Aspergillus repens grown under salt stress.

PubMed

Kelavkar, U P; Chhatpar, H S

1993-09-01

Na(+), K(+) and the ratio of Na(+)/K(+) were higher in cells of the halotolerant Aspergillus repens grown with 2 M NaCl than without NaCl. The osmolytes, proline, glycerol, betaine and glutamate, did not affect the Na(+)/K(+) ratio, nor the polyol content of cells under any conditions. The concentrations of polyols, consisting of glycerol, arabitol, erythritol and mannitol, changed markedly during growth, indicating that they have a crucial role in osmotic adaptation.

Functional coupling between sodium-activated potassium channels and voltage-dependent persistent sodium currents in cricket Kenyon cells.

PubMed

Takahashi, Izumi; Yoshino, Masami

2015-10-01

In this study, we examined the functional coupling between Na(+)-activated potassium (KNa) channels and Na(+) influx through voltage-dependent Na(+) channels in Kenyon cells isolated from the mushroom body of the cricket Gryllus bimaculatus. Single-channel activity of KNa channels was recorded with the cell-attached patch configuration. The open probability (Po) of KNa channels increased with increasing Na(+) concentration in a bath solution, whereas it decreased by the substitution of Na(+) with an equimolar concentration of Li(+). The Po of KNa channels was also found to be reduced by bath application of a high concentration of TTX (1 μM) and riluzole (100 μM), which inhibits both fast (INaf) and persistent (INaP) Na(+) currents, whereas it was unaffected by a low concentration of TTX (10 nM), which selectively blocks INaf. Bath application of Cd(2+) at a low concentration (50 μM), as an inhibitor of INaP, also decreased the Po of KNa channels. Conversely, bath application of the inorganic Ca(2+)-channel blockers Co(2+) and Ni(2+) at high concentrations (500 μM) had little effect on the Po of KNa channels, although Cd(2+) (500 μM) reduced the Po of KNa channels. Perforated whole cell clamp analysis further indicated the presence of sustained outward currents for which amplitude was dependent on the amount of Na(+) influx. Taken together, these results indicate that KNa channels could be activated by Na(+) influx passing through voltage-dependent persistent Na(+) channels. The functional significance of this coupling mechanism was discussed in relation to the membrane excitability of Kenyon cells and its possible role in the formation of long-term memory. Copyright © 2015 the American Physiological Society.

Aerosol composition, chemistry, and source characterization during the 2008 VOCALS Experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Y.; Springston, S.; Jayne, J.

2010-03-15

Chemical composition of fine aerosol particles over the northern Chilean coastal waters was determined onboard the U.S. DOE G-1 aircraft during the VOCALS (VAMOS Ocean-Cloud-Atmosphere-Land Study) field campaign between October 16 and November 15, 2008. SO42-, NO3-, NH4+, and total organics (Org) were determined using an Aerodyne Aerosol Mass Spectrometer, and SO42-, NO3-, NH4+, Na+, Cl-, CH3SO3-, Mg2+, Ca2+, and K+ were determined using a particle-into-liquid sampler-ion chromatography technique. The results show the marine boundary layer (MBL) aerosol mass was dominated by non- sea-salt SO42- followed by Na+, Cl-, Org, NO3-, and NH4+, in decreasing importance; CH3SO3-, Ca2+, and K+more » rarely exceeded their respective limits of detection. The SO42- aerosols were strongly acidic as the equivalent NH4+ to SO42- ratio was only {approx}0.25 on average. NaCl particles, presumably of sea-salt origin, showed chloride deficits but retained Cl- typically more than half the equivalency of Na+, and are externally mixed with the acidic sulfate aerosols. Nitrate was observed only on sea-salt particles, consistent with adsorption of HNO3 on sea-salt aerosols, responsible for the Cl- deficit. Dust particles appeared to play a minor role, judging from the small volume differences between that derived from the observed mass concentrations and that calculated based on particle size distributions. Because SO42- concentrations were substantial ({approx}0.5 - {approx}3 {micro}g/m3) with a strong gradient (highest near the shore), and the ocean-emitted dimethylsulfide and its unique oxidation product, CH3SO3-, were very low (i.e., {le} 40 parts per trillion and <0.05 {micro}g/m3, respectively), the observed SO42- aerosols are believed to be primarily of terrestrial origin. Back trajectory calculations indicate sulfur emissions from smelters and power plants along coastal regions of Peru and Chile are the main sources of these SO4- aerosols. However, compared to observations, model calculations appeared to underestimate sulfate concentrations based on an existing emission inventory. The agreement between observations and model predictions of CO as well as total sulfur is reexamined in this work with a new emission inventory made available recently.« less

High-pressure versus isoelectronic doping effect on the honeycomb iridate Na2IrO3

NASA Astrophysics Data System (ADS)

Hermann, V.; Ebad-Allah, J.; Freund, F.; Pietsch, I. M.; Jesche, A.; Tsirlin, A. A.; Deisenhofer, J.; Hanfland, M.; Gegenwart, P.; Kuntscher, C. A.

2017-11-01

We study the effect of isoelectronic doping and external pressure in tuning the ground state of the honeycomb iridate Na2IrO3 by combining optical spectroscopy with synchrotron x-ray diffraction measurements on single crystals. The obtained optical conductivity of Na2IrO3 is discussed in terms of a Mott-insulating picture versus the formation of quasimolecular orbitals and in terms of Kitaev interactions. With increasing Li content x , (Na1 -xLix )2IrO3 moves deeper into the Mott-insulating regime, and there are indications that up to a doping level of 24% the compound comes closer to the Kitaev limit. The optical conductivity spectrum of single-crystalline α -Li2IrO3 does not follow the trends observed for the series up to x =0.24 . There are strong indications that α -Li2IrO3 is not as close to the Kitaev limit as Na2IrO3 and lies closer to the quasimolecular orbital picture instead. Except for the pressure-induced hardening of the phonon modes, the optical properties of Na2IrO3 seem to be robust against external pressure. Possible explanations of the unexpected evolution of the optical conductivity with isolectronic doping and the drastic change between x =0.24 and x =1 are given by comparing the pressure-induced changes of lattice parameters and the optical conductivity with the corresponding changes induced by doping.

Luminescence upconversion under hydrostatic pressure in the 3d-metal systems Ti2+:NaCl and Ni2+:CsCdCl3

NASA Astrophysics Data System (ADS)

Wenger, Oliver S.; Salley, G. Mackay; Valiente, Rafael; Güdel, Hans U.

2002-06-01

We present a study of upconversion materials and processes under external hydrostatic pressure. The near-infrared to visible photon upconversion properties of Ti2+-doped NaCl and Ni2+-doped CsCdCl3 at 15 K are studied as a function of external hydrostatic pressure. It is found that in Ti2+:NaCl pressure can be used to switch on an efficient upconversion mechanism, which is inactive at ambient pressure, leading to an order-of-magnitude enhancement of the overall upconversion efficiency of this material. For Ni2+:CsCdCl3 it is demonstrated that upconversion luminescence excitation spectroscopy can be used to study the pressure dependence of excited state absorption transitions. The results demonstrate the ability to tune upconversion properties by altering the local crystal field of active ions, in addition to probing the pressure dependence of excited state absorption transitions via upconversion spectroscopy.

Kinetics Study on the Effect of NaCl on the CaSO4 Dissolution Behavior

NASA Astrophysics Data System (ADS)

Song, Jingyao; Shi, Peiyang; Wang, Yeguang; Jiang, Maofa

2018-01-01

The study of the dissolution kinetics of CaSO4 is essential for the control of the dissolution and recrystallization behavior of CaSO4. In this work, the kinetic behavior of CaSO4 dissolved in NaCl solution was investigated by means of conductivity meter. The results show that with the increase of concentration of NaCl, the temperature rise and the time prolonged, the dissolution rate of dihydrate CaSO4 gradually increases, and the dissolved apparent activation energy is gradually decreased. When the NaCl concentration is 1.8%, the dissolution kinetic equation is 1-(1-α) 1/3=5.46*10-4exp (-9147/RT) t; When the NaCl concentration is 3.0%, the dissolution kinetic equation is 1-(1-α) 1/3=2.81×10-4 exp (-6753/RT)t; When the NaCl concentration is 3.6%, the dissolution kinetic equation is 1-(1-α) 1/3=3.07×l0-4exp(-6103/RT)t.

In vivo sodium, potassium, and sperm concentrations in the rat epididymis.

PubMed

Turner, T T; Hartmann, P K; Howards, S S

1977-02-01

In vivo samples of epididymal fluids were obtained through the use of micropuncture techniques. Microsamples from four areas of the rat epididymis were analyzed for Na+ and K+ concentrations and for sperm density. Na+ values declined significantly from caput to corpus epididymidis (P less than 0.01), while K+ and sperm concentrations increased significantly (P less than 0.01). A large water loss from the epididymal lumen was calculated, as well as net losses of both cations. Water losses may be explained on the basis of an active Na+ pump; however, the effect of the absolute values of epididymal Na+ and K+ concentrations on sperm motility and fertility remains unresolved.

Concentration dependence of Li+/Na+ diffusion in manganese hexacyanoferrates

NASA Astrophysics Data System (ADS)

Takachi, Masamitsu; Fukuzumi, Yuya; Moritomo, Yutaka

2016-06-01

Manganese hexacyanoferrates (Mn-HCFs) with a jungle-gym-type structure are promising cathode materials for Li+/Na+ secondary batteries (LIBs/SIBs). Here, we investigated the diffusion constants D Li/D Na of Li+/Na+ against the Li+/Na+ concentration x Na/x Li and temperature (T) of A 1.32Mn[Fe(CN)6]0.833.6H2O (A = Li and Na). We evaluated the activation energy E\\text{a}\\text{Li}/E\\text{a}\\text{Na} of D Li/D Na against x Na/x Li. We found that E\\text{a}\\text{Na} steeply increases with x Na from 0.41 eV at x Na = 0.69 to 0.7 eV at 1.1. The increase in E\\text{a}\\text{Na} is ascribed to the occupancy effect of the Na+ site. The increase in E\\text{a}\\text{Li} is suppressed, probably because the number of Li+ sites is three times that of Na+ sites.

Interindividual variability in sweat electrolyte concentration in marathoners.

PubMed

Lara, Beatriz; Gallo-Salazar, César; Puente, Carlos; Areces, Francisco; Salinero, Juan José; Del Coso, Juan

2016-01-01

Sodium (Na(+)) intake during exercise aims to replace the Na(+) lost by sweat to avoid electrolyte imbalances, especially in endurance disciplines. However, Na(+) needs can be very different among individuals because of the great inter-individual variability in sweat electrolyte concentration. The aim of this investigation was to determine sweat electrolyte concentration in a large group of marathoners. A total of 157 experienced runners (141 men and 16 women) completed a marathon race (24.4 ± 3.6 °C and 27.7 ± 4.8 % of humidity). During the race, sweat samples were collected by using sweat patches placed on the runners' forearms. Sweat electrolyte concentration was measured by using photoelectric flame photometry. As a group, sweat Na(+) concentration was 42.9 ± 18.7 mmol·L(-1) (minimal-maximal value = 7.0-95.5 mmol·L(-1)), sweat Cl(-) concentration was 32.2 ± 15.6 mmol·L(-1) (7.3-90.6 mmol·L(-1)) and sweat K(+) concentration was 6.0 ± 0.9 mmol·L(-1) (3.1-8.0 mmol·L(-1)). Women presented lower sweat Na(+) (33.9 ± 12.1 vs 44.0 ± 19.1 mmol·L(-1); P = 0.04) and sweat Cl(-) concentrations (22.9 ± 10.5 vs 33.2 ± 15.8 mmol·L(-1); P = 0.01) than men. A 20 % of individuals presented a sweat Na(+) concentration higher than 60 mmol·L(-1) while this threshold was not surpassed by any female marathoner. Sweat electrolyte concentration did not correlate to sweat rate, age, body characteristics, experience or training. Although there was a significant correlation between sweat Na(+) concentration and running pace (r = 0.18; P = 0.03), this association was weak to interpret that sweat Na(+) concentration increased with running pace. The inter-individual variability in sweat electrolyte concentration was not explained by any individual characteristics except for individual running pace and sex. An important portion (20 %) of marathoners might need special sodium intake recommendations due to their high sweat salt losses.

Increased cell membrane permeability to Na+ and K+ induced by thyroid hormone in rat skeletal muscle.

PubMed

Asano, Y

1978-01-01

Thyroid hormone (T3) increased Na+ dependent respiration accompanied by an increase in NaK-ATPase activity. Administration of T3 increased intracellular K+ concentration and Na/K ratio in thyroidectomized rats, and the Na+ efflux rate constant incubated in oxygenized Na+, K+-Ringers in euthyroid rats. However, the magnitude of the changes in intracellular K+ concentration was modest or invisible in comparison to the changes in QO2(t) and NaK-ATPase activity. The Na+ and K+ efflux rate constants in K+-free +ouabain Ringers were increased by T3 in both thyroidectomized and euthyroid rats. Thus, thyroid hormone stimulates not only Na pump but also the permeability of cell membrane to Na+ and K+. The both effects might contribute to the thyroid thermogenesis.

Effects of water hardness on the physiological responses to chronic waterborne silver exposure in early life stages of rainbow trout (Oncorhynchus mykiss).

PubMed

Morgan, T P; Guadagnolo, C M; Grosell, M; Wood, C M

2005-09-30

Early life stages of rainbow trout were exposed to 0, 0.1 and 1 microg/L Ag (as AgNO(3)) in very soft water (2mg/L CaCO(3)), moderately hard water (150 mg/L CaCO(3)) and hard water (400mg/L CaCO(3)) of low dissolved organic carbon concentration (0.5mg C/L) from fertilization to swim-up (64 days) under flow-through conditions, and monitored for whole embryo/larval silver accumulation, Na(+) and Cl(-) concentrations, Na(+) uptake and Na(+)K(+)-ATPase activity. The objective of the study was to investigate potential protective effects of water hardness on the physiological responses to chronic silver exposure. In the absence of silver, there was little effect of hardness on the ionoregulatory parameters studied, though higher hardness did improve survival post-hatch. At all three water hardness levels, whole embryo/larval Na(+) uptake was low and relatively constant prior to 50% hatch, but dramatically increased following 50% hatch, whereas Na(+)K(+)-ATPase activity steadily increased over development. Whole embryo/larval Na(+) and Cl(-) concentrations were low and constant prior to 50% hatch, but following 50% hatch Na(+) concentration increased, while Cl(-) concentration decreased. Following 50% hatch, exposure to 0.1 and 1 microg/L Ag resulted in a decrease in whole embryo/larval Na(+) concentration, Cl(-) concentration, Na(+) uptake and Na(+)K(+)-ATPase activity, indicating that the mechanism of chronic silver toxicity involves an ionoregulatory disturbance, and is similar to the mechanism of acute silver toxicity. An increase in water hardness reduced or eliminated the effect of silver on these parameters while enhancing survival, suggesting that the nature of the protective effect of hardness involves effects on the ionoregulatory disturbance associated with silver exposure. An increase in water hardness did not fully protect against the accumulation of silver associated with silver exposure. These results suggest that it may be possible to model chronic silver toxicity using a biotic ligand type model, and that a physiologically based model may be more appropriate because Na(+)K(+)-ATPase activity or Na(+) uptake is an endpoint for prediction rather than whole embryo or larval silver accumulation.

Bovine serum albumin partitioning in an aqueous two-phase system: effect of pH and sodium chloride concentration.

PubMed

Gündüz, U; Korkmaz, K

2000-06-23

The partitioning of bovine serum albumin (BSA) in a polyethylene glycol 3350 (8% w/w)-dextran 37 500 (6% w/w)-0.05 M phosphate aqueous two-phase was investigated at different pHs, at varying concentrations of sodium chloride at 20 degrees C. The effect of NaCl concentration on the partition coefficient of BSA was studied for the PEG-dx systems with initial pH values of 4.2, 5.0, 7.0, 9.0, and 9.8. The NaCl concentrations in the phase systems with constant pH value were 0.06, 0.1, 0.2, 0.3, and 0.34 M. It was observed that the BSA partition coefficient decreased at concentrations smaller than 0.2 M NaCl and increased at concentrations greater than 0.2 M NaCl for all systems with initial pHs of 4.2, 5.0, 7.0, 9.0, and 9.8. It was also seen that the partition coefficient of BSA decreased as the pH of the aqueous two-phase systems increased at any NaCl salt concentration studied.

Interaction of NaOH solutions with silica surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rimsza, Jessica M.; Jones, Reese E.; Criscenti, Louise J.

Sodium adsorption on silica surfaces depends on the solution counter-ion. Here, we use NaOH solutions to investigate basic environments. Sodium adsorption on hydroxylated silica surfaces from NaOH solutions were investigated through molecular dynamics with a dissociative force field, allowing for the development of secondary molecular species. Furthermore, across the NaOH concentrations (0.01 M – 1.0 M), ~50% of the Na + ions were concentrated in the surface region, developing silica surface charges between –0.01 C/m 2 (0.01 M NaOH) and –0.76 C/m 2 (1.0 M NaOH) due to surface site deprotonation. Five inner-sphere adsorption complexes were identified, including monodentate, bidentate,more » and tridentate configurations and two additional structures, with Na + ions coordinated by bridging oxygen and hydroxyl groups or water molecules. Coordination of Na + ions by bridging oxygen atoms indicates partial or complete incorporation of Na + ions into the silica surface. Residence time analysis identified that Na + ions coordinated by bridging oxygen atoms stayed adsorbed onto the surface four times longer than the mono/bi/tridentate species, indicating formation of relatively stable and persistent Na + ion adsorption structures. Such inner-sphere complexes form only at NaOH concentrations of > 0.5 M. Na + adsorption and lifetimes have implications for the stability of silica surfaces.« less

Interaction of NaOH solutions with silica surfaces

DOE PAGES

Rimsza, Jessica M.; Jones, Reese E.; Criscenti, Louise J.

2018-01-16

Sodium adsorption on silica surfaces depends on the solution counter-ion. Here, we use NaOH solutions to investigate basic environments. Sodium adsorption on hydroxylated silica surfaces from NaOH solutions were investigated through molecular dynamics with a dissociative force field, allowing for the development of secondary molecular species. Furthermore, across the NaOH concentrations (0.01 M – 1.0 M), ~50% of the Na + ions were concentrated in the surface region, developing silica surface charges between –0.01 C/m 2 (0.01 M NaOH) and –0.76 C/m 2 (1.0 M NaOH) due to surface site deprotonation. Five inner-sphere adsorption complexes were identified, including monodentate, bidentate,more » and tridentate configurations and two additional structures, with Na + ions coordinated by bridging oxygen and hydroxyl groups or water molecules. Coordination of Na + ions by bridging oxygen atoms indicates partial or complete incorporation of Na + ions into the silica surface. Residence time analysis identified that Na + ions coordinated by bridging oxygen atoms stayed adsorbed onto the surface four times longer than the mono/bi/tridentate species, indicating formation of relatively stable and persistent Na + ion adsorption structures. Such inner-sphere complexes form only at NaOH concentrations of > 0.5 M. Na + adsorption and lifetimes have implications for the stability of silica surfaces.« less

Effects of non-uniform root zone salinity on water use, Na+ recirculation, and Na+ and H+ flux in cotton

PubMed Central

Kong, Xiangqiang; Luo, Zhen; Dong, Hezhong; Eneji, A. Egrinya

2012-01-01

A new split-root system was established through grafting to study cotton response to non-uniform salinity. Each root half was treated with either uniform (100/100 mM) or non-uniform NaCl concentrations (0/200 and 50/150 mM). In contrast to uniform control, non-uniform salinity treatment improved plant growth and water use, with more water absorbed from the non- and low salinity side. Non-uniform treatments decreased Na+ concentrations in leaves. The [Na+] in the ‘0’ side roots of the 0/200 treatment was significantly higher than that in either side of the 0/0 control, but greatly decreased when the ‘0’ side phloem was girdled, suggesting that the increased [Na+] in the ‘0’ side roots was possibly due to transportation of foliar Na+ to roots through phloem. Plants under non-uniform salinity extruded more Na+ from the root than those under uniform salinity. Root Na+ efflux in the low salinity side was greatly enhanced by the higher salinity side. NaCl-induced Na+ efflux and H+ influx were inhibited by amiloride and sodium orthovanadate, suggesting that root Na+ extrusion was probably due to active Na+/H+ antiport across the plasma membrane. Improved plant growth under non-uniform salinity was thus attributed to increased water use, reduced leaf Na+ concentration, transport of excessive foliar Na+ to the low salinity side, and enhanced Na+ efflux from the low salinity root. PMID:22200663

Concentration-dependent effect of sodium hypochlorite on stem cells of apical papilla survival and differentiation.

PubMed

Martin, David E; De Almeida, Jose Flavio A; Henry, Michael A; Khaing, Zin Z; Schmidt, Christine E; Teixeira, Fabricio B; Diogenes, Anibal

2014-01-01

Intracanal disinfection is a crucial step in regenerative endodontic procedures. Most published cases suggest the use of sodium hypochlorite (NaOCl) as the primary irrigant. However, the effect of clinically used concentrations of NaOCl on the survival and differentiation of stem cells is largely unknown. In this study, we tested the effect of various concentrations of NaOCl on the stem cells of the apical papilla (SCAPs) survival and dentin sialophosphoprotein (DSPP) expression. Standardized root canals were created in extracted human teeth and irrigated with NaOCl (0.5%, 1.5%, 3%, or 6%) followed by 17% EDTA or sterile saline. SCAPs in a hyaluronic acid-based scaffold were seeded into the canals and cultured for 7 days. Next, viable cells were quantified using a luminescence assay, and DSPP expression was evaluated using quantitative real-time polymerase chain reaction. There was a significant reduction in survival and DSPP expression in the group treated with 6% NaOCl compared with the untreated control group. Comparable survival was observed in the groups treated with the lower concentrations of NaOCl, but greater DSPP expression was observed in the 1.5% NaOCl group. In addition, 17% EDTA resulted in increased survival and DSPP expression partially reversing the deleterious effects of NaOCl. Collectively, the results suggest that dentin conditioning with high concentrations of NaOCl has a profound negative effect on the survival and differentiation of SCAPs. However, this effect can be prevented with the use of 1.5% NaOCl followed by 17% EDTA. The inclusion of this irrigation regimen might be beneficial in regenerative endodontic procedures. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Study of Co0.5Zn0.5Fe2O4 nanoparticles for magnetic hyperthermia

NASA Astrophysics Data System (ADS)

Kamzin, A. S.; Nikam, D. S.; Pawar, S. H.

2017-01-01

The structural characteristics, magnetic properties, and processes of magnetic heating in an alternating magnetic field of magnetic nanoparticles (MNPs) Co0.5Zn0.5Fe2O4 (cobalt-zinc ferrite, CZF) are studied to explore the possibilities of their application in medicine, namely, for magnetic hyperthermia treatment (the heating of particles with external alternating magnetic field). CZF magnetic nanoparticles were obtained by coprecipitation using sodium hydroxide (NaOH) as a precipitating agent. Based on the data obtained by transmission electron microscopy in the transmission geometry, it is found that CZF magnetic nanoparticles have an almost spherical shape with an average particle size of 13 nm. X-ray diffraction and Mössbauer studies showed that CZF magnetic nanoparticles are single-phase, and their structure corresponds to a cubic spinel structure. The saturation magnetization M s of CZF nanoparticles is measured at room temperature using a vibrating sample magnetometer. The possibility of heating CZF magnetic nanoparticles with an external alternating magnetic field was studied using an induction heating system. The specific absorption rate is determined by applying an external alternating magnetic field in the range of 167.5 to 335.2 Oe at a fixed frequency of 265 kHz. It is found that the maximum amount of heat (114.98 W/g) is produced at a concentration of 5 mg/L under a field of 335.2 Oe.

Combined activity of post-exercise concentrations of NA and eHsp72 on human neutrophil function: role of cAMP.

PubMed

Giraldo, Esther; Hinchado, María D; Ortega, Eduardo

2013-09-01

Extracellular heat shock proteins of 72 kDa (eHsp72) and noradrenaline (NA) can act as "danger signals" during exercise-induced stress by activating neutrophil function (chemotaxis, phagocytosis, and fungicidal capacity). In addition, post-exercise concentrations of NA increase the expression and release of Hsp72 by human neutrophils, and adrenoreceptors and cAMP are involved in the stimulation of neutrophils by eHsp72. This suggests an interaction between the two molecules in the modulation of neutrophils during exercise-induced stress. Given this context, the aim of the present investigation was to study the combined activity of post-exercise circulating concentrations of NA and eHsp72 on the neutrophil phagocytic process, and to evaluate the role of cAMP as intracellular signal in these effects. Results showed an accumulative stimulation of chemotaxis induced by NA and eHsp72. However, while NA and eHsp72, separately, stimulate the phagocytosis and fungicidal activity of neutrophils, when they act together they do not modify these capacities of neutrophils. Similarly, post-exercise concentrations of NA and eHsp72 separately increased the intracellular level of cAMP, but NA and eHsp72 acting together did not modify the intracellular concentration of cAMP. These results confirm that cAMP can be involved in the autocrine/paracrine physiological regulation of phagocytosis and fungicidal capacity of human neutrophils mediated by NA and eHsp72 in the context of exercise-induced stress. Copyright © 2013 Wiley Periodicals, Inc.

Natural Radioactivity of Boron Added Clay Samples

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akkurt, I.; Guenoglu, K.; Canakcii, H.

2011-12-26

Clay, consisting fine-grained minerals, is an interesting materials and can be used in a variety of different fields especially in dermatology application. Using clay such a field it is important to measure its natural radioactivity. Thus the purpose of this study is to measure {sup 226}Ra, {sup 232}Th and {sup 40}K concentration in clay samples enriched with boron. Three different types of clay samples were prepared where boron is used in different rate. The measurements have been determined using a gamma-ray spectrometry consists of a 3''x3'' NaI(Tl) detector. From the measured activity the radium equivalent activities (Ra{sub eq}), external hazardmore » index (H{sub ex}), absorbed dose rate in air (D) and annual effective dose (AED) have also been obtained.« less

Growth of Aeromonas species on increasing concentrations of sodium chloride.

PubMed

Delamare, A P; Costa, S O; Da Silveira, M M; Echeverrigaray, S

2000-01-01

The growth of 16 strains of Aeromonas, representing 12 species of the genera, were examined at different salt levels (0-1.71 M NaCl). All the strains grew on media with 0.34 M NaCl, and nine on media with 0.68 M. Two strains, Aer. enteropelogenes and Aer. trota, were able to grow on media with 0.85 M and 1.02 M NaCl, respectively. Comparison of the growth curves of Aer. hydrophila ATCC7966 and Aer. trota ATCC 49657 on four concentrations of NaCl (0.08, 0.34, 0.68 and 1.02 M) confirm the high tolerance of Aer. trota, and indicate that high concentrations of salt increase the lag time and decrease the maximum growth rate. However, both strains were able to grow, slowly, in at least 0.68 M NaCl, a sodium chloride concentration currently used as food preservative.

Shelf-Life of Chlorine Solutions Recommended in Ebola Virus Disease Response.

PubMed

Iqbal, Qais; Lubeck-Schricker, Maya; Wells, Emma; Wolfe, Marlene K; Lantagne, Daniele

2016-01-01

In Ebola Virus Disease (EVD) outbreaks, it is widely recommended to wash living things (handwashing) with 0.05% (500 mg/L) chlorine solution and non-living things (surfaces, personal protective equipment, dead bodies) with 0.5% (5,000 mg/L) chlorine solution. Chlorine solutions used in EVD response are primarily made from powdered calcium hypochlorite (HTH), granular sodium dichloroisocyanurate (NaDCC), and liquid sodium hypochlorite (NaOCl), and have a pH range of 5-11. Chlorine solutions degrade following a reaction highly dependent on, and unusually sensitive to, pH, temperature, and concentration. We determined the shelf-life of 0.05% and 0.5% chlorine solutions used in EVD response, including HTH, NaDCC, stabilized NaOCl, generated NaOCl, and neutralized NaOCl solutions. Solutions were stored for 30 days at 25, 30, and 35°C, and tested daily for chlorine concentration and pH. Maximum shelf-life was defined as days until initial concentration fell to <90% of initial concentration in ideal laboratory conditions. At 25-35°C, neutralized-NaOCl solutions (pH = 7) had a maximum shelf-life of a few hours, NaDCC solutions (pH = 6) 2 days, generated NaOCl solutions (pH = 9) 6 days, and HTH and stabilized NaOCl solutions (pH 9-11) >30 days. Models were developed for solutions with maximum shelf-lives between 1-30 days. Extrapolating to 40°C, the maximum predicted shelf-life for 0.05% and 0.5% NaDCC solutions were 0.38 and 0.82 hours, respectively; predicted shelf-life for 0.05% and 0.5% generated NaOCl solutions were >30 and 5.4 days, respectively. Each chlorine solution type offers advantages and disadvantages to responders, as: NaDCC is an easy-to-import high-concentration effervescent powder; HTH is similar, but forms a precipitate that may clog pipes; and, NaOCl solutions can be made locally, but are difficult to transport. We recommend responders chose the most appropriate source chlorine compound for their use, and ensure solutions are stored at appropriate temperatures and used or replaced before expiring.

Prediction of Intrinsic Cesium Desorption from Na-Smectite in Mixed Cation Solutions.

PubMed

Fukushi, Keisuke; Fukiage, Tomo

2015-09-01

Quantitative understanding of the stability of sorbed radionuclides in smectite is necessary to assess the performance of engineering barriers used for nuclear waste disposal. Our previous study demonstrated that the spatial organization of the smectite platelets triggered by the divalent cations led to the apparent fixation of intrinsic Cs in smectite, because some Cs is retained inside the formed tactoids. Natural water is usually a mixture of Na(+) and divalent cations (Ca(2+) and Mg(2+)). This study therefore investigated the desorption behavior of intrinsic Cs in Na-smecite in mixed Na(+)-divalent cation solutions under widely various cation concentrations using batch experiments, grain size measurements, and cation exchange modeling (CEM). Results show that increased Na(+) concentrations facilitate Cs desorption because Na(+) serves as the dispersion agent. A linear relation was obtained between the logarithm of the Na(+) fraction and the accessible Cs fraction in smectite. That relation enables the prediction of accessible Cs fraction as a function of solution cationic compositions. The corrected CEM considering the effects of the spatial organization suggests that the stability of intrinsic Cs in the smectite is governed by the Na(+) concentration, and suggests that it is almost independent of the concentrations of divalent cations in natural water.

Ca2+ ion permeability properties of (R,S) alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptors in isolated interneurons from the olfactory bulb of the rat.

PubMed

Jardemark, K; Nilsson, M; Muyderman, H; Jacobson, I

1997-02-01

The aim of the study was to investigate the divalent cation permeability of native alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionate (AMPA) receptors expressed in interneurons of the olfactory bulb. Kainic acid (KA) was used as agonist to activate AMPA-receptor-mediated currents, which were recorded with the use of the patch-clamp technique. In interneurons acutely isolated from the olfactory bulb, the current responses to KA showed linear/outwardly rectifying current-voltage (I-V) relationships with a positive average reversal potential of +7 mV in normal external medium (1 mM Ca2+, 1 mM Mg2+). Raising the external Ca2+ concentration to 10 mM suppressed the amplitude, whereas omission of Ca2+ enhanced the amplitude of the current. Spectral analysis of the increase in current variance produced by KA indicated that the decreased amplitude observed in 10 mM Ca2+ was accompanied by a reduction in the apparent single-channel conductance. Raising the concentration of Mg2+ from 1 to 10 mM had a weak depressant effect on the KA-evoked current amplitude. No shift in the reversal potential was observed when the concentration of Ca2+ or Mg2+ was changed from 1 to 10 mM. Increasing the external medium concentration of Ca2+ to 60 mM not only further depressed the amplitudes of the KA-evoked currents but also gave a pronounced leftward shift in the average reversal potential to -32 +/- 9 (SE) mV (N = 7). For neurons in primary culture, current responses to KA also showed linear/outwardly rectifying I-V relationships with a positive average reversal potential in normal external medium. Substituting N-methylglucamine for Na+ and increasing the Ca2+ concentration to 10 mM gave a leftward shift in the average reversal potential from +9 +/- 3 mV to -47 +/- 4 mV (N = 11) and caused a marked reduction in the amplitude of the KA-evoked currents at negative potentials. The permeability properties of the studied AMPA receptors were well predicted by the Eyring rate model (symmetrical, 2 barriers, 1 site). The model gave a pCa2+/pK+ permeability ratio of 0.06 for acutely isolated interneurons and 0.14 for interneurons in primary culture. The constant field theory, which failed to successfully reproduce all the experimental data, gave corresponding low permeability ratios of 0.18 and 0.40 for acutely isolated cells and cells in primary culture, respectively. Thus it is concluded that interneurons in the olfactory bulb mainly express AMPA receptors with low permeability to Ca2+ ions.

Evidence for the role of a Na(+)/HCO(3)(-) cotransporter in trout hepatocyte pHi regulation.

PubMed

Furimsky, M; Moon, T W; Perry, S F

2000-07-01

The mechanisms of intracellular pH (pHi) regulation were examined in hepatocytes of the rainbow trout Oncorhynchus mykiss. pHi was monitored using the pH-sensitive fluorescent dye BCECF, and the effects of various media and pharmacological agents were examined for their influence on baseline pHi and recovery rates from acid and base loading. Rates of Na(+) uptake were measured using (22)Na, and changes in membrane potential were examined using the potentiometric fluorescent dye Oxonol VI. The rate of proton extrusion following acid loading was diminished by the blockade of either Na(+)/H(+) exchange (using amiloride) or anion transport (using DIDS). The removal of external HCO(3)(-) and the abolition of outward K(+) diffusion by the channel blocker Ba(2+) also decreased the rate of proton extrusion following acid load. Depolarization of the cell membrane with 50 mmol l(-)(1) K(+), however, did not affect pHi. The rate of recovery from base loading was significantly diminished by the blockade of anion transport, removal of external HCO(3)(-) and, to a lesser extent, by blocking Na(+)/H(+) exchange. The blockade of K(+) conductance had no effect. The decrease in Na(+) uptake rate observed in the presence of the anion transport blocker DIDS and the DIDS-sensitive hyperpolarization of membrane potential during recovery from acid loading suggest that a Na(+)-dependent electrogenic transport system is involved in the restoration of pHi after intracellular acidification. The effects on baseline pHi indicate that the different membrane exchangers are tonically active in the maintenance of steady-state pHi. This study confirms the roles of a Na(+)/H(+) exchanger and a Cl(-)/HCO(3)(-) exchanger in the regulation of trout hepatocyte pHi and provides new evidence that a Na(+)/HCO(3)(-) cotransporter contributes to pHi regulation.

Controlled synthesis and luminescence properties of β-NaGdF4: Yb3+, Er3+ upconversion nanoparticles

NASA Astrophysics Data System (ADS)

Zhang, Yueli; Yao, Lu; Xu, Dekang; Lin, Hao; Yang, Shenghong

2018-06-01

β-NaGdF4:Yb3+,Er3+ upconversion (UC) nanoparticles (UCNPs) were prepared by a facile hydrothermal process with the assistance of sodium ethylene diaminetetraacetate salt (EDTA-2Na). The morphologies of the β-NaGdF4 UCNPs were controlled by changing the doses of EDTA-2Na and NaOH in precursor. With increasing concentration of EDTA-2Na in precursor, the size of crystals decreased, resulting in the decreasing of luminescence intensity. With increasing concentration of NaOH in precursor, the morphology became more homogeneous. However, due to the reduction of grain size and crystal quality, the luminescence intensity decreased. Nevertheless, the above results demonstrated a simple route to fabricate homogeneous UCNPs.

Rapid tissue dissolution efficiency of electrically-activated sodium hypochlorite on bovine muscle.

PubMed

Ertugrul, Ihsan Furkan; Maden, Murat; Orhan, Ekim Onur; Ozkorucuklu, Sabriye Percin; Aglarca, Ali Vasfi

2014-10-01

Sodium hypochlorite (NaOCl) is a common antimicrobial and tissue-dissolving irrigant. The aim of this in vitro study is to evaluate and compare dissolution capacities of sodium hypochlorite solutions after electrically activation (E-NaOCl) on bovine muscle specimens at various time periods and concentrations. Three sodium hypochlorite solutions of 1.25%, 2.5%, and 5% were tested at 3-min. and 5-min. with and without activation by electrically. Distilled water and NaOCl solutions without electrically activation were used as controls. Pieces of bovine muscle tissue (34 ± 2 mg) were placed in 10 mL of each solution at room temperature. In the group of E-NaOCl, electrically activation was performed through the potentiostat. The tissue specimens were weighed before and after treatment, and the percentage of weight loss was calculated. Weight loss of the tissue increased with the concentration of E-NaOCl and NaOCl. Higher concentration and electrically activation considerably enhanced the efficacy of sodium hypochlorite. The effect of electrically activation on tissue dissolution was much greater than that of same concentrations in the groups of NaOCl (P < 0.001). Tissue weight loss was significantly higher in 2.5% and 5% E-NaOCl at 3 min. than in 2.5% and 5% NaOCl at 5 min. (P < 0.05). There were not any significant differences between the 2.5% E-NaOCl and 5% NaOCl at 5 min. (P > 0.05). Electrically activation can improve the tissue-dissolving effectiveness of sodium hypochlorite.

Effect of salt and surfactant concentration on the structure of polyacrylate gel/surfactant complexes.

PubMed

Nilsson, Peter; Unga, Johan; Hansson, Per

2007-09-20

Small-angle X-ray scattering was used to elucidate the structure of crosslinked polyacrylate gel/dodecyltrimethylammonium bromide complexes equilibrated in solutions of varying concentrations of surfactant and sodium bromide (NaBr). Samples were swollen with no ordering (micelle free), or they were collapsed with either several distinct peaks (cubic Pm3n) or one broad correlation peak (disordered micellar). The main factor determining the structure of the collapsed complexes was found to be the NaBr concentration, with the cubic structure existing up to approximately 150 mM NaBr and above which only the disordered micellar structure was found. Increasing the salt concentration decreases the polyion mediated attractive forces holding the micelles together causing swelling of the gel. At sufficiently high salt concentration the micelle-micelle distance in the gel becomes too large for the cubic structure to be retained, and it melts into a disordered micellar structure. As most samples were above the critical micelle concentration, the bulk of the surfactant was in the form of micelles in the solution and the surfactant concentration thereby had only a minor influence on the structure. However, in the region around 150 mM NaBr, increasing the surfactant concentration, at constant NaBr concentration, was found to change the structure from disordered micellar to ordered cubic and back to disordered again.

Differential effects of dietary sodium intake on blood pressure and atherosclerosis in hypercholesterolemic mice.

PubMed

Lu, Hong; Wu, Congqing; Howatt, Deborah A; Balakrishnan, Anju; Charnigo, Richard J; Cassis, Lisa A; Daugherty, Alan

2013-01-01

The amount of dietary sodium intake regulates the renin angiotensin system (RAS) and blood pressure, both of which play critical roles in atherosclerosis. However, there are conflicting findings regarding the effects of dietary sodium intake on atherosclerosis. This study applied a broad range of dietary sodium concentrations to determine the concomitant effects of dietary sodium intake on the RAS, blood pressure, and atherosclerosis in mice. Eight-week-old male low-density lipoprotein receptor -/- mice were fed a saturated fat-enriched diet containing selected sodium concentrations (Na 0.01%, 0.1%, or 2% w/w) for 12 weeks. Mice in these three groups were all hypercholesterolemic, although mice fed Na 0.01% and Na 0.1% had higher plasma cholesterol concentrations than mice fed Na 2%. Mice fed Na 0.01% had greater abundances of renal renin mRNA than those fed Na 0.1% and 2%. Plasma renin concentrations were higher in mice fed Na 0.01% (14.2 ± 1.7 ng/ml/30 min) than those fed Na 0.1% or 2% (6.2 ± 0.6 and 5.8 ± 1.6 ng/ml per 30 min, respectively). However, systolic blood pressure at 12 weeks was higher in mice fed Na 2% (138 ± 3 mm Hg) than those fed Na 0.01% and 0.1% (129 ± 3 and 128 ± 4 mmHg, respectively). In contrast, mice fed Na 0.01% (0.17 ± 0.02 mm(2)) had larger atherosclerotic lesion areas in aortic roots than those fed Na 2% (0.09 ± 0.01 mm(2)), whereas lesion areas in mice fed Na 0.1% (0.12 ± 0.02 mm(2)) were intermediate between and not significantly different from those in Na 0.01% and Na 2% groups. In conclusion, while high dietary sodium intake led to higher systolic blood pressure, low dietary sodium intake augmented atherosclerosis in hypercholesterolemic mice. Copyright © 2013 Elsevier Inc. All rights reserved.

Differential effects of dietary sodium intake on blood pressure and atherosclerosis in hypercholesterolemic mice☆

PubMed Central

Lu, Hong; Wu, Congqing; Howatt, Deborah A.; Balakrishnan, Anju; Charnigo, Richard J.; Cassis, Lisa A.; Daugherty, Alan

2012-01-01

The amount of dietary sodium intake regulates the renin angiotensin system (RAS) and blood pressure, both of which play critical roles in atherosclerosis. However, there are conflicting findings regarding the effects of dietary sodium intake on atherosclerosis. This study applied a broad range of dietary sodium concentrations to determine the concomitant effects of dietary sodium intake on the RAS, blood pressure, and atherosclerosis in mice. Eight-week-old male low-density lipoprotein receptor −/− mice were fed a saturated fat-enriched diet containing selected sodium concentrations (Na 0.01%, 0.1%, or 2% w/w) for 12 weeks. Mice in these three groups were all hypercholesterolemic, although mice fed Na 0.01% and Na 0.1% had higher plasma cholesterol concentrations than mice fed Na 2%. Mice fed Na 0.01% had greater abundances of renal renin mRNA than those fed Na 0.1% and 2%. Plasma renin concentrations were higher in mice fed Na 0.01% (14.2±1.7 ng/ml/30 min) than those fed Na 0.1% or 2% (6.2±0.6 and 5.8±1.6 ng/ml per 30 min, respectively). However, systolic blood pressure at 12 weeks was higher in mice fed Na 2% (138±3 mm Hg) than those fed Na 0.01% and 0.1% (129±3 and 128±4 mmHg, respectively). In contrast, mice fed Na 0.01% (0.17±0.02 mm2) had larger atherosclerotic lesion areas in aortic roots than those fed Na 2% (0.09±0.01 mm2), whereas lesion areas in mice fed Na 0.1% (0.12±0.02 mm2) were intermediate between and not significantly different from those in Na 0.01% and Na 2% groups. In conclusion, while high dietary sodium intake led to higher systolic blood pressure, low dietary sodium intake augmented atherosclerosis in hypercholesterolemic mice. PMID:22705323

[Effects of carrier liquid and flow rate on the separation in gravitational field-flow fractionation].

PubMed

Guo, Shuang; Zhu, Chenqi; Gao-Yang, Yaya; Qiu, Bailing; Wu, Di; Liang, Qihui; He, Jiayuan; Han, Nanyin

2016-02-01

Gravitational field-flow fractionation is the simplest field-flow fractionation technique in terms of principle and operation. The earth' s gravity is its external field. Different sized particles are injected into a thin channel and carried by carrier fluid. The different velocities of the carrier liquid in different places results in a size-based separation. A gravitational field-flow fractionation (GrFFF) instrument was designed and constructed. Two kinds of polystyrene (PS) particles with different sizes (20 µm and 6 µm) were chosen as model particles. In this work, the separation of the sample was achieved by changing the concentration of NaN3, the percentage of mixed surfactant in the carrier liquid and the flow rate of carrier liquid. Six levels were set for each factor. The effects of these three factors on the retention ratio (R) and plate height (H) of the PS particles were investigated. It was found that R increased and H decreased with increasing particle size. On the other hand, the R and H increased with increasing flow rate. The R and H also increased with increasing NaN3 concentration. The reason was that the electrostatic repulsive force between the particles and the glass channel wall increased. The force allowed the samples approach closer to the channel wall. The results showed that the resolution and retention time can be improved by adjusting the experimental conditions. These results can provide important values to the further applications of GrFFF technique.

[Effects of NaCl stress on photosynthesis characteristics and fast chlorophyll fluorescence induction dynamics of Pistacia chinensis leaves].

PubMed

Li, Xu-Xin; Liu, Bing-Xiang; Guo, Zhi-Tao; Chang, Yue-Xia; He, Lei; Chen, Fang; Lu, Bing-She

2013-09-01

By using fast chlorophyll fluorescence induction dynamics analysis technique (JIP-test), this paper studied the photosynthesis characteristics and fast chlorophyll fluorescence induction dynamics of 1-year old Pistacia chinensis seedlings under the stress of NaCl at the concentrations 0% (CK), 0.15%, 0.3%, 0.45%, and 0.6%. With the increasing concentration of NaCl, the contents of Chl a, Chl b, and Chl (a+b) in the seedlings leaves decreased, the Chl a/b ratio decreased after an initial increase, and the carotenoid content increased. The net photosynthetic rate (P(n)) and stomatal conductance (g(s)) decreased gradually with increasing NaCl concentration. The decrease of P(n) was mainly attributed to the stomatal limitation when the NaCl concentration was lower than 0.3%, and to the non-stomatal limitation when the NaCl concentration was higher than 0.3%. The trapped energy flux per RC (TR0/CS0), electron transport flux per RC (ET0/CS0), density of RCs (RC/CS0), and yield or flux ratio (psi(0) or phi(E0)) decreased, but the absorption flux per CS (ABS/CS0) and the K phase (W(k)) and J phase (V) in the O-J-I-P chlorophyll fluorescence induction curves increased distinctly, indicating that NaCl stress damaged the leaf oxygen-evolving complex (OEC), donor sides, and PS II reaction centers. When the NaCl concentration reached 0.3%, the maximum photochemical efficiency (F(v)/F(m)) and performance index (PI(ABS)) decreased 17.7% and 36.6%, respectively, as compared with the control.

The Na+-Responsive ntp Operon Is Indispensable for Homeostatis of K+ and Na+ in Enterococcus hirae at Limited Proton Potential

PubMed Central

Kawano, Miyuki; Igarashi, Kazuei; Kakinuma, Yoshimi

1998-01-01

Enterococcus hirae ATCC 9790 grew well in Na+-deficient, low-K+ medium, but growth was inhibited by carbonylcyanide m-chlorophenylhydrazone (CCCP). Growth inhibition and decrease of cellular K+ levels in the presence of CCCP were relieved by the addition of Na+ and a high concentration of K+. In contrast, in the mutant defective in Na+-ATPase or the NtpJ component of the KtrII K+ uptake system, CCCP-induced growth inhibition was rescued by a high concentration of K+ but not of Na+. These transporters are thus indispensable for homeostatis of K+ and Na+ at low proton potential. PMID:9733699

Taste and acceptance of pyrophosphates by rats and mice.

PubMed

McCaughey, Stuart A; Giza, Barbara K; Tordoff, Michael G

2007-06-01

The palatability and taste quality of pyrophosphates were evaluated in a series of behavioral and electrophysiological experiments. In two-bottle choice tests with water, rats strongly preferred some concentrations of Na3HP2O7 and Na4P2O7, moderately preferred some concentrations of K4P2O7 and Fe4(P2O7)3, and were indifferent to or avoided all concentrations of Ca2P2O7 and Na2H2P2O7. The contribution of sodium to the preference for sodium pyrophosphates was ascertained: 1) Rats with a choice between Na4P2O7 and NaCl preferred 1 mM Na4P2O7 to 4 mM NaCl but preferred 40 or 150 mM NaCl to 10 mM Na4P2O7, 2) blocking salt taste transduction by mixing Na4P2O7 with amiloride reduced preferences but did not eliminate them, and 3) three mouse strains (FVB/J, C57BL/6J, and CBA/J) known to differ in sodium preference had the same rank order of preferences for Na3HP2O7 and NaCl, but peak preferences were higher for Na3HP2O7 than for NaCl. The taste qualities of pyrophosphates were determined by measuring taste-evoked responses of neurons in the nucleus of the solitary tract of rats. Across-neuron patterns of activity for sodium pyrophosphates were similar to that of NaCl but the pattern of Na3HP2O7 plus amiloride was unique from those of sweet, salty, sour, bitter, and umami stimuli. Taken together, the results indicate that the high palatability of some concentrations of Na3HP2O7 and Na4P2O7 is due partially to their salty taste, but there must also be another cause, which may include a novel orosensory component distinct from the five major taste qualities.

Transport mechanism and regulatory properties of the human amino acid transporter ASCT2 (SLC1A5).

PubMed

Scalise, Mariafrancesca; Pochini, Lorena; Panni, Simona; Pingitore, Piero; Hedfalk, Kristina; Indiveri, Cesare

2014-11-01

The kinetic mechanism of the transport catalyzed by the human glutamine/neutral amino acid transporter hASCT2 over-expressed in P. pastoris was determined in proteoliposomes by pseudo-bi-substrate kinetic analysis of the Na(+)-glutamineex/glutaminein transport reaction. A random simultaneous mechanism resulted from the experimental analysis. Purified functional hASCT2 was chemically cross-linked to a stable dimeric form. The oligomeric structure correlated well with the kinetic mechanism of transport. Half-saturation constants (Km) of the transporter for the other substrates Ala, Ser, Asn and Thr were measured both on the external and internal side. External Km were much lower than the internal ones confirming the asymmetry of the transporter. The electric nature of the transport reaction was determined imposing a negative inside membrane potential generated by K(+) gradients in the presence of valinomycin. The transport reaction resulted to be electrogenic and the electrogenicity originated from external Na(+). Internal Na(+) exerted a stimulatory effect on the transport activity which could be explained by a regulatory, not a counter-transport, effect. Native and deglycosylated hASCT2 extracted from HeLa showed the same transport features demonstrating that the glycosyl moiety has no role in transport function. Both in vitro and in vivo interactions of hASCT2 with the scaffold protein PDZK1 were revealed.

Coacervation and aggregate transitions of a cationic ammonium gemini surfactant with sodium benzoate in aqueous solution.

PubMed

Wang, Ruijuan; Tian, Maozhang; Wang, Yilin

2014-03-21

Coacervation in an aqueous solution of cationic ammonium gemini surfactant hexamethylene-1,6-bis(dodecyldimethylammonium bromide) (C12C6C12Br2) with sodium benzoate (NaBz) has been investigated at 25 °C by turbidity titration, light microscopy, dynamic light scattering, cryogenic temperature transmission electron microscopy (Cryo-TEM), scanning electron microscopy (SEM), isothermal titration calorimetry, ζ potential and (1)H NMR measurements. There is a critical NaBz concentration of 0.10 M, only above which coacervation can take place. However, if the NaBz concentration is too large, coacervation also becomes difficult. Coacervation takes place at a very low concentration of C12C6C12Br2 and exists in a very wide concentration region of C12C6C12Br2. The phase behavior in the NaBz concentration from 0.15 to 0.50 M includes spherical micelles, threadlike micelles, coacervation, and precipitation. With increasing NaBz concentration, the phase boundaries of coacervation shift to higher C12C6C12Br2 concentration. Moreover, the C12C6C12Br2-NaBz aggregates in the coacervate are found to be close to charge neutralized. The Cryo-TEM and SEM images of the coacervate shows a layer-layer stacking structure consisting of a three-dimensional network formed by the assembly of threadlike micelles. Long, dense and almost uncharged threadlike micelles are the precursors of coacervation in the system.

Influence of lorcainide on microsomal Na+, K(+)-ATPase in guinea-pig isolated heart preparations.

PubMed Central

Almotrefi, A. A.; Dzimiri, N.

1991-01-01

1. The effects of lorcainide on the myocardial Mg2(+)-dependent, Na+ and K(+)-activated adenosine triphosphatase (Na+, K(+)-ATPase) were compared in guinea-pig heart preparations with those of ouabain, a specific inhibitor of the enzyme activity. 2. Both ouabain and lorcainide inhibited the microsomal Na+, K(+)-ATPase activity in a concentration-dependent fashion. Their inhibitory effective ranges were 0.05-100 microM and 0.15-125 microM, respectively, and the concentrations for half maximal inhibition (IC50 values) were 2.1 +/- 0.3 and 33.5 +/- 7.3 microM, respectively. 3. In a second series of experiments, the combined effects of the two drugs on the enzyme activity were studied. In these experiments, lorcainide produced a concentration-dependent potentiation of the inhibitory effects of ouabain on Na+, K(+)-ATPase activity. 4. The present study demonstrates that lorcainide is a potent inhibitor of myocardial Na+, K(+)-ATPase. PMID:1849773

[Different NaCl-dependence of the circadian CO2-gas-exchange of some halophil growing coastal plants].

PubMed

Treichel, Siegfried; Bauer, Peter

1974-03-01

CO 2 -exchange, diurnal changes in malate- and ion concentrations of the halophytes Carpobrotus edulis, Crithmum maritimum, Mesembryanthemum nodiflorum, Salicornia fruticosa, Suaeda maritima, and Trifolium fragiferum were investigated after culture at different NaCl concentrations. In Carp. edulis and Mes. nodiflorum the diurnal rhythm of CO 2 -exchange is in accordance with that of crassulacean acid metabolism (CAM), in Sal. fruticosa, Crithm. maritimum, Suaeda maritima, and Trif. fragiferum with that of Benson-Calvin metabolism (C 3 ). Malate concentration and CO 2 uptake in the sap latter group are not influenced. On the other hand, Carp. edulis and Mes. nodiflorum show an accumulation of malate during the night, which can be interpreted as a further indication of CAM.The two species most resistant to NaCl, Carp. edulis and Sal. fruticosa, greatly differ very much in their NaCl content. NaCl concentration in Salicornia is four times higher than in Carpobrotus.The different metabolic properties studied might be of ecological importance for the plants in their natural habitats. The effect of NaCl on metabolic processes is discussed.

The chemical kinetics and thermodynamics of sodium species in oxygen-rich hydrogen flames

NASA Technical Reports Server (NTRS)

Hynes, A. J.; Steinberg, M.; Schofield, K.

1984-01-01

Results are presented which, it is claimed, lead to a correction of previous misconceptions over the relative importance and kinetics of NaO2. It is shown that its rapid conversion to NaO and NaOH is such that it can severely perturb the NaOH/Na ratio and produce significant concentration overshoots over that predicted from the balance of the reaction of Na with H2O. This becomes increasingly the case in flames of large O2 concentrations and temperatures below 2500 K; and the corresponding large rate constants for the termolecular formation of the other alkali peroxides imply that similar considerations will be necessary for them. Depending on the rate constants for the exothermic conversions of MO2 to MO or MOH, the steady-state concentrations of MO2 could be more or less significant than for sodium. Owing to numerous reactions that produce these conversions, the MOH species will probably be the dominant species in all cases in oxygen-rich hydrogen or hydrocarbon flames, with MO concentrations at not greater than 1 percent of the bound metal.

Early Detection of Salt Stress Damage by Biophotons in Red Bean Seedling

NASA Astrophysics Data System (ADS)

Ohya, Tomoyuki; Kurashige, Hideaki; Okabe, Hirotaka; Kai, Shoichi

2000-06-01

The optical detection of the stress damage to plants by NaCl solutions was attempted during germination of a seed and growth of a root. We compared the photon intensity of red beans before and after NaCl treatment and found that the photon intensity after NaCl treatment decreased as the NaCl concentration increased. For the saturated NaCl concentration (4.5 M), however, the observed photon intensity drastically increased, and the simultaneous destruction of cell membranes was observed. The intensity of biophoton emission from red beans showed characteristic change with salt concentrations. When the salt stress was applied to the red beans at an early growth stage, their root elongations were suppressed and photon intensity from the root decreased. This was not the case for the root at the late stage. This shows that biophoton intensity due to salt stress depends on not only NaCl concentration but also the growth stage of the plant. We may conclude that the extent of damage to roots by salt stress can be evaluated from biophoton response.

Influence of sodium chloride on the colloidal and rennet coagulation properties of concentrated casein micelle suspensions.

PubMed

Zhao, Z; Corredig, M

2016-08-01

The research investigated the influence of NaCl on the colloidal and rennet coagulation properties of concentrated milk. Milk was concentrated to 1×, 3×, and 5× using ultrafiltration. Rennet gelation was followed by rheology and diffusing wave spectroscopy. Soluble protein, total and diffusible calcium and phosphate, size, and zeta potential were also measured as a function of concentration history. In the presence of 300mM NaCl, colloidal calcium phosphate solubilized and pH and the negative charge on the surface of casein micelles decreased. Increasing the volume fraction caused the formation of stiffer gels for both samples with or without NaCl. The addition of NaCl caused a significant increase in the bulk viscosity of the milk concentrated 5× and a decrease in turbidity. The concentration had no effect on the gelation time of control samples, nor on the kinetics of caseinomacropeptide release. On the other hand, rennet gelation was retarded by the addition of NaCl, and the gels showed lower elastic moduli compared with those obtained with control milk. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Rapid removal of copper with magnetic poly-acrylic weak acid resin: quantitative role of bead radius on ion exchange.

PubMed

Fu, Lichun; Shuang, Chendong; Liu, Fuqiang; Li, Aimin; Li, Yan; Zhou, Yang; Song, Haiou

2014-05-15

A novel magnetic weak acid resin NDMC was self-synthesized for the removal of Cu(2+) from aqueous solutions. NDMC showed superior properties on the removal of Cu(2+) compared to commercial resins C106 and IRC-748, which was deeply investigated by adsorption isotherms and kinetic tests. The equilibrium adsorption amount of Cu(2+) onto NDMC (267.2mg/g) was almost twice as large as that onto IRC-748 (120.0mg/g). The adsorption kinetics of Cu(2+) onto the three resins fitted well with the pseudo-second-order equation. The initial adsorption rate h of NDMC was about 4 times that of C106 and nearly 8 times that of IRC-748 at the initial concentration of 500mg/L. External surface area was determined to be the key factor in rate-controlling by further analyzing the adsorption thermodynamics, kinetics parameters and physicochemical properties of the resins. NDMC resin with the smallest bead radius possessed the largest external surface and therefore exhibited the fastest kinetics. The adsorption amount of Cu(2+) onto NDMC was not influenced as the concentration of Na(+) increased from 1.0 to 10.0mM/L. Dilute HCl solution could effectively desorb Cu(2+). NDMC demonstrated high stability during 10 adsorption/desorption cycles, showing great potential in the rapid removal of Cu(2+) from wastewater. Copyright © 2014 Elsevier B.V. All rights reserved.

Reduction and conversion of 2,4,6-trinitrotoluene (TNT) by sulfide under simulated anaerobic conditions.

PubMed

Qiao, Hua; Wang, He-ling; Feng, Hua-jun; Yao, Jun; Shen, Dong-sheng; Tang, Zhi-jian

2010-07-15

To account for the fast disappearance of TNT in anaerobic fermentative liquid, we investigated TNT (TNT(0)=50 mg/L) reduction by Na(2)S at 30+/-1 degrees C in two types of buffer systems, a phosphate buffer (PB, system A) and a CH(3)COOH-NaHCO(3) buffer (system B). The effects of pH, sulfide concentration and buffer system on the conversion and reaction rate of TNT were investigated. The effect of different variables on the conversion of TNT decreased in the following order: Na(2)S concentration>pH>buffer system. A kinetics study showed that TNT reduction by Na(2)S occurred in two stages separated by a change point. The observed rate constants of the first stage K(obs-1) were 1 order of magnitude lower than those of the second stage. The TNT conversion rate increased and the time to reach the change point became shorter with increasing Na(2)S concentration and pH. A 5-fold increase in Na(2)S concentration above the theoretical stoichiometric concentration was optimum. Observed rate constants of the first stage K(obs-1) were proportional to the hydrosulfide ion concentration and the conversion rate of TNT was greater and faster in buffer system B than in system A. 2010 Elsevier B.V. All rights reserved.

Effects of environmental conditions on growth and survival of Salmonella in pasteurized whole egg.

PubMed

Jakočiūnė, Džiuginta; Bisgaard, Magne; Hervé, Gaëlle; Protais, Jocelyne; Olsen, John Elmerdahl; Chemaly, Marianne

2014-08-01

This study investigated the influence of three parameters (time, temperature and NaCl concentration) on survival and four parameters (temperature, NaCl and lysozyme concentrations and pH) on growth of Salmonella enterica serovar Enteritidis (S. Enteritidis) in pasteurized whole egg (PWE). Doehlert uniform shell design was employed to choose conditions for trials and data was fitted to polynomial models and were presented as estimated response surfaces. A model for prediction of reduction of S. Enteritidis in PWE within temperatures between 50 and 58°C, NaCl concentrations of 0-12%, and heating times between 30 and 210s and a model for prediction of growth rate of S. Enteritidis in PWE in the temperature range of 1-25°C, NaCl concentration of 0-12%, pH between 5 and 9, and lysozyme concentrations of 107-1007 U/mg proteins were developed. The maximum reduction condition was 58°C, 0% of NaCl at a fixed heating time of 120s, while maximum growth rate was estimated at 25°C and 0% of NaCl. pH and lysozyme concentration were shown not to influence growth performance significantly in the range of values studied. Results inform industry of the optimal pasteurization and storage parameters for liquid whole egg. Copyright © 2014 Elsevier B.V. All rights reserved.

Prenatal programming of adult mineral metabolism: relevance to blood pressure, dietary prevention strategies, and cardiovascular disease.

PubMed

Schulter, Günter; Goessler, Walter; Papousek, Ilona

2012-01-01

Mounting evidence indicates that adult health outcomes such as the development of cardiovascular disease or diabetes can trace some of their roots back to prenatal development. This study investigated the epigenetic impact of a particular prenatal hormonal condition on specific health-related consequences, i.e., on concentrations of minerals and mineral metabolism in adults. In 70 university students, the second-to-fourth digit length (2D:4D) was measured as a proxy of prenatal sex steroid action, and the concentrations of sodium (Na), potassium (K), magnesium (Mg), and calcium (Ca) were determined in hair samples by inductively coupled plasma-mass spectrometry. Mineral concentrations and the mineral ratios Na/K, Na/Mg, and Na/Ca were analyzed in multivariate analyses of variance, with digit ratios and sex of participants as grouping variables. The results were validated in a replication cohort from the general population, and with a wider age-range. In addition, the correlation of mineral concentrations and mineral ratios with blood pressure was examined. Men with relatively lower (i.e., more masculine) and women with relatively higher (i.e., more feminine) digit ratios had higher Na/K, Na/Mg, and Na/Ca ratios than their counterparts. Virtually identical results were obtained in the replication study. Moreover, Na concentrations and Na/K ratios were significantly correlated with systolic blood pressure. The findings suggest that the individual variation in mineral metabolism can be predicted by 2D:4D, indicating that prenatal sex steroid action may be involved in the epigenetic programming of specific metabolic conditions which are highly relevant to adult health and disease. 2011 Wiley Periodicals, Inc.

Response to non-uniform salinity in the root zone of the halophyte Atriplex nummularia: growth, photosynthesis, water relations and tissue ion concentrations.

PubMed

Bazihizina, Nadia; Colmer, Timothy D; Barrett-Lennard, Edward G

2009-09-01

Soil salinity is often heterogeneous, yet the physiology of halophytes has typically been studied with uniform salinity treatments. An evaluation was made of the growth, net photosynthesis, water use, water relations and tissue ions in the halophytic shrub Atriplex nummularia in response to non-uniform NaCl concentrations in a split-root system. Atriplex nummularia was grown in a split-root system for 21 d, with either the same or two different NaCl concentrations (ranging from 10 to 670 mm), in aerated nutrient solution bathing each root half. Non-uniform salinity, with high NaCl in one root half (up to 670 mm) and 10 mm in the other half, had no effect on shoot ethanol-insoluble dry mass, net photosynthesis or shoot pre-dawn water potential. In contrast, a modest effect occurred for leaf osmotic potential (up to 30 % more solutes compared with uniform 10 mm NaCl treatment). With non-uniform NaCl concentrations (10/670 mm), 90 % of water was absorbed from the low salinity side, and the reduction in water use from the high salinity side caused whole-plant water use to decrease by about 30 %; there was no compensatory water uptake from the low salinity side. Leaf Na(+) and Cl(-) concentrations were 1.9- to 2.3-fold higher in the uniform 670 mm treatment than in the 10/670 mm treatment, whereas leaf K(+) concentrations were 1.2- to 2.0-fold higher in the non-uniform treatment. Atriplex nummularia with one root half in 10 mm NaCl maintained net photosynthesis, shoot growth and shoot water potential even when the other root half was exposed to 670 mm NaCl, a concentration that inhibits growth by 65 % when uniform in the root zone. Given the likelihood of non-uniform salinity in many field situations, this situation would presumably benefit halophyte growth and physiology in saline environments.

Effects of sodium chloride exposure on ion regulation in larvae (glochidia) of the freshwater mussel Lampsilis fasciola.

PubMed

Nogueira, Lygia S; Bianchini, Adalto; Wood, Chris M; Loro, Vania L; Higgins, Sarah; Gillis, Patricia L

2015-12-01

The salinization of freshwater can have negative effects on ecosystem health, with heightened effects in salt-sensitive biota such as glochidia, the larvae of freshwater mussels. However, the toxicological mechanism underlying this sensitivity is unknown. Therefore, Lampsilis fasciola glochidia were exposed to NaCl (nominally 0.25 and 1.0 g/L) prepared in reconstituted moderately-hard water (control), as well as to a dilution of that water (1:4) with ultrapure reference water (diluted control). Unidirectional Na(+) influx (measured with (22)Na) was evaluated after 1, 3 and 48 h of exposure. In addition, unidirectional Cl(-) influx (measured with (36)Cl), whole-body ion (Cl(-) and Na(+)) concentrations, and glochidia viability (measured as the ability to close valves) were assessed after 48 h of exposure. Significantly reduced glochidia viability (56%) was observed after exposure to 1.0 g/L NaCl. Na(+) influx was significantly higher in glochidia exposed to both 0.25 and 1.0 g/L NaCl for 1h than in those kept under control conditions. After 3 and 48 h of exposure, differences in Na(+) influx rate between salt-exposed and control glochidia were generally reduced, indicating that larvae may be able to, at least temporarily, recover their ability to regulate Na(+) influx when exposed to elevated NaCl concentration. Compared to the moderately-hard water control, whole-body Na(+) and Cl(-) concentrations were relatively unchanged in glochidia exposed to 0.25 g/L NaCl, but were significantly elevated in glochidia exposed to 1.0 g/L NaCl and the diluted control. While Na(+) influx rate had recovered to the control level after 48 h of exposure to 1.0 g/L NaCl, Cl(-) influx rate remained elevated, being ~7-fold higher than the Na(+) influx rate. These findings suggest that the loss of viability observed when glochidia were exposed to a high NaCl concentration (1.0 g/L) could be caused by ionoregulatory disturbances mainly associated with an elevated Cl(-) influx. Copyright © 2015 Elsevier Inc. All rights reserved.

Size-controlled synthesis of Pd nanocrystals using a specific multifunctional peptide

NASA Astrophysics Data System (ADS)

Chiu, Chin-Yi; Li, Yujing; Huang, Yu

2010-06-01

Here we report a peptide-mediated synthesis of Pd NCs in aqueous solution with controllable size in the sub-10 nanometre regime. The specific multifunctional peptide Q7 selected using the phage display technique can bind to the Pd NC surface and act as a stabilizer to mediate Pd crystal nucleation and growth. At the nucleation stage, Q7 bound to and helped stabilize the different-sized small Pd NC nuclei achieved using different concentrations of the external reducing agent, NaBH4. At the growth stage, Q7 played the dual role of binding to and reducing the precursor onto the existing nuclei, which led to the further controllable growth of the Pd NCs. By using the variable sizes of nuclei as seeds, and by introducing different amounts of precursors Pd NCs with tunable sizes from 2.6 to 6.6 nm were achieved with good size distribution.Here we report a peptide-mediated synthesis of Pd NCs in aqueous solution with controllable size in the sub-10 nanometre regime. The specific multifunctional peptide Q7 selected using the phage display technique can bind to the Pd NC surface and act as a stabilizer to mediate Pd crystal nucleation and growth. At the nucleation stage, Q7 bound to and helped stabilize the different-sized small Pd NC nuclei achieved using different concentrations of the external reducing agent, NaBH4. At the growth stage, Q7 played the dual role of binding to and reducing the precursor onto the existing nuclei, which led to the further controllable growth of the Pd NCs. By using the variable sizes of nuclei as seeds, and by introducing different amounts of precursors Pd NCs with tunable sizes from 2.6 to 6.6 nm were achieved with good size distribution. Electronic Supplementary Information (ESI) available. Experimental details for peptide selection, peptide synthesis and Pd NCs synthesis; Q7 peptide sequence molecular structure and characterization; TEM images of Pd NCs. See DOI: 10.1039/c0nr00194e/

The use of nicotinic acid to induce sustained low plasma nonesterified fatty acids in feed-restricted Holstein cows.

PubMed

Pires, J A A; Grummer, R R

2007-08-01

The objectives were to determine the effects of nicotinic acid (NA) on blood metabolites (experiment 1) and whether successive doses of NA could induce sustained reductions of plasma nonesterified fatty acids (NEFA; experiment 2) in feed-restricted, nonlactating Holstein cows. Experiment 1 was a single 4 x 4 Latin square with 1-wk periods. Each period consisted of 2.5 d of feed restriction to increase plasma NEFA and 4.5 d of ad libitum feeding. Treatments were abomasal administration of 0, 6, 30, or 60 mg of NA/kg of body weight (BW), given as a single bolus 48 h after initiation of feed restriction. Plasma NEFA concentration decreased from 546 microEq/L to 208 +/- 141 microEq/L at 1 h after the infusion of 6 mg of NA/kg of BW, and to less than 100 +/- 148 microEq/L at 3 h after the abomasal infusion of the 2 highest doses of NA. A rebound occurred after the initial decrease of plasma NEFA concentration. The rebound lasted up to 9 h for the 30-mg dose of NA, and up to 6 h for the 6-mg dose. Experiment 2 was a randomized complete block design with 3 treatments and 6 cows. Starting at 48 h of feed restriction, cows received 9 hourly abomasal infusions of 0, 6, or 10 mg of NA/kg of BW. Plasma NEFA concentrations decreased from 553 microEq/L +/- 24 immediately before the initiation of treatments to <100 microEq/L during hourly infusions of 6 or 10 mg of NA/kg. Data suggest that the maximal antilipolytic response was achieved with the lowest dose of NA. A rebound of NEFA started 2 to 3 h after NA infusions were terminated. In both experiments, the NEFA rebound period coincided with increases in insulin and no change or increased glucose concentrations, suggesting a state of insulin resistance induced by elevated NEFA. This model for reducing plasma NEFA concentration by abomasal infusions of NA can be used to study the metabolic ramifications of elevated vs. reduced NEFA concentrations. The data demonstrate potential benefits and pitfalls of using NA to regulate plasma NEFA and prevent lipid-related metabolic disorders.

Weakening of ion-channel interactions of Na+ and Li+ in acetylcholine-receptor channels of frog skeletal muscle with an increase in agonist concentration.

PubMed

Manthey, A A

1998-05-01

The possibility that increases in agonist concentration beyond threshold levels may force changes in the character of high-conductance open states of skeletal muscle nicotinic acetylcholine receptor channels (nAChR) was examined by seeing whether differences in several critical ionic properties of nAChR currents could be detected with changes in agonist level. Single- and bi-ionic whole-cell currents of Na+ and Li+ in voltage-clamped frog (Rana pipiens) muscle fibers were measured during local superfusion of endplates with carbamylcholine (carb) at concentrations of 54 microm (low-carb) and 270 microM (high-carb). Three ionic properties that would be affected by changes in the open-state configuration of channel subunits were tested. First, ion-saturation characteristics. Peak Na+ and Li+ currents in low-carb trials showed sublinear dependence on ion concentrations from 0 to 60 mM with Km values of 78 (Na+) and 49 (Li+) mM and a power function slope of 0. 75 on double-log plot. In contrast, the concentration dependence of Na+ and Li+ currents in high-carb tests was linear through the origin with a power function slope of 1.02. Second, Na+/Li+ selectivity. The ratio of peak Na+ and Li+ currents in low-carb tests varied from 1.86 to 2.28 for ion concentrations of from 20 to 60 mM [mean = 2.02 +/- 0.06 (SEM)] whereas the ratio for high-carb trials ranged from only 1.29 to 1.52 [mean = 1.42 +/- 0.40 (SEM)]. Third, competitive interactions of Na+ and Li+ currents. Equimolar mixtures of Na+ and Li+ in low-carb tests produced bi-ionic inward currents which were never larger than the single-ion Na+ current alone, but bi-ionic currents at the high-carb level were always greater than the single-ion Na+ current, approximating the sum of the single-ion Na+ and Li+ currents in most cases. The results are consistent with a decrease in ion-channel binding at the high-carb level and support the possibility of agonist-induced changes in the high-conductance open-state configuration of nAChR subunits which result in a weakening of constraints on cation movements through the channel.

Enrichment of fluoride in groundwater under the impact of saline water intrusion at the salt lake area of Yuncheng basin, northern China

NASA Astrophysics Data System (ADS)

Gao, Xubo; Wang, Yanxin; Li, Yilian; Guo, Qinghai

2007-12-01

Long-term intake of high-fluoride groundwater causes endemic fluorosis. This study, for the first time, discovered that the salt lake water intrusion into neighboring shallow aquifers might result in elevation of fluoride content of the groundwater. Two cross-sections along the groundwater flow paths were selected to study the geochemical processes controlling fluoride concentration in Yuncheng basin, northern China. There are two major reasons for the observed elevation of fluoride content: one is the direct contribution of the saline water; the other is the undersaturation of the groundwater with respect to fluorite due to salt water intrusion, which appears to be more important reason. The processes of the fluorine activity reduction and the change of Na/Ca ratio in groundwater induced by the intrusion of saline water favor further dissolution of fluorine-bearing mineral, and it was modeled using PHREEQC. With the increase in Na concentration (by adding NaCl or Na2SO4 as Na source, calcium content kept invariable), the increase of NaF concentration was rapid at first and then became slower; and the concentrations of HF, HF{2/-}, CaF+, and MgF+ were continuously decreasing. The geochemical conditions in the study area are advantageous to the complexation of F- with Na+ and the decline of saturation index of CaF2, regardless of the water type (Cl-Na or SO4-Na type water).

Control of xylem Na+ loading and transport to the shoot in rice and barley as a determinant of differential salinity stress tolerance.

PubMed

Ishikawa, Tetsuya; Shabala, Sergey

2018-05-15

Control of xylem Na + loading has often been named as the essential components of salinity tolerance mechanism. However, it is less clear to what extent the difference in this trait may determine differential salinity tolerance between species. In this study barley (Hordeum vulgare L. cv. CM72) and rice (Oryza sativa L. cv Dongjin) plants were grown under two levels of salinity. Na + and K + concentrations in the xylem sap, and shoot and root tissues were measured at different time points after stress onset. Salt-exposed rice plants prevented xylem Na + loading for several days, but failed to control this process in the longer term, ultimately resulting in a massive Na + shoot loading. Barley plants quickly increased xylem Na + concentration and its delivery to the shoot (most likely for the purpose of osmotic adjustment) but were able to reduce this process later on, keeping most of accumulated Na + in the root, thus maintaining non-toxic shoot Na + level. Rice plants increased shoot K + concentration, while barley plants maintained higher root K + concentration. Control of xylem Na + loading is remarkably different between rice and barley; this difference may differentiate the extent of the salinity tolerance between species. This trait should be investigated in more details to be used in the breeding programs aimed to improve salinity tolerance in crops. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Effect of salinity stress on growth, lipid productivity, fatty acid composition, and biodiesel properties in Acutodesmus obliquus and Chlorella vulgaris.

PubMed

Pandit, Priti Raj; Fulekar, Madhusudan H; Karuna, Mallampalli Sri Lakshmi

2017-05-01

Two microalgae strains including Chlorella vulgaris and Acutodesmus obliquus were grown on BG11 medium with salinity stress ranging from 0.06 to 0.4 M NaCl. Highest lipid content in C. vulgaris and A. obliquus was 49 and 43% in BG11 amended with 0.4 M NaCl. The microalgal strains C. vulgaris and A. obliquus grow better at 0.06 M NaCl concentration than control condition. At 0.06 M NaCl, improved dry biomass content in C. vulgaris and A. obliquus was 0.92 and 0.68 gL -1 , respectively. Stress biomarkers like reactive oxygen species, antioxidant enzyme catalase, and ascorbate peroxidase were also lowest at 0.06 M NaCl concentration revealing that both the microalgal strains are well acclimatized at 0.06 M NaCl concentration. The fatty acid composition of the investigated microalgal strains was also improved by increased NaCl concentration. At 0.4 M NaCl, palmitic acid (37%), oleic acid (15.5%), and linoleic acid (20%) were the dominant fatty acids in C. vulgaris while palmitic acid (54%) and stearic acid (26.6%) were major fatty acids found in A. obliquus. Fatty acid profiling of C. vulgaris and A. obliquus significantly varied with salinity concentration. Therefore, the study showed that salt stress is an effective stress that could increase not only the lipid content but also improved the fatty acid composition which could make C. vulgaris and A. obliquus potential strains for biodiesel production.

Enzymatic properties of separated isozymes of the Na,K-ATPase. Substrate affinities, kinetic cooperativity, and ion transport stoichiometry.

PubMed

Sweadner, K J

1985-09-25

There are two isozymes of the Na,K-ATPase, which can be purified separately from rat renal medulla and brainstem axolemma. Here the basic kinetic properties of the two Na,K-ATPases have been compared in conditions permitting enzyme turnover. The two isozymes are half-maximally activated at different concentrations of ATP, the axolemma Na,K-ATPase having the higher affinity. They are half-maximally activated by Na+ and K+ at very similar concentrations but show differences in cooperativity toward Na+. The affinities of both isozymes for ATP and Na+ are affected in a qualitatively similar way by variations in the concentration of K+. Both isozymes transport 22Na+ and 42K+ in a ratio close to 3:2 in artificial lipid vesicles. The two isozymes differ most strikingly in the inhibition of ATPase activity by ouabain. The axolemma Na,K-ATPase has a high affinity for ouabain with positive cooperativity, while the renal medulla Na,K-ATPase has a lower affinity with negative cooperativity. It is likely that the cooperativity differences are due to kinetic effects, reflecting different rates of conformation transitions during enzyme turnover. The functional result of the contrasting cooperativities is that the difference in sensitivity to ouabain is amplified.

Movements of labelled sodium ions in isolated rat superior cervical ganglia

PubMed Central

Brown, D. A.; Scholfield, C. N.

1974-01-01

1. Isolated rat superior cervical ganglia were incubated in Krebs solution containing 24Na and carbachol for 4 min at 25° C. They were then washed at 3° C for 15 min to remove extracellular 24Na and the efflux of residual intracellular 24Na stimulated by warming to 25° C. 2. During the 15 min wash at 3° C desaturation curves became exponential with a rate constant of 0·012 ± 0·001 min-1 (n = 24). This was assumed to represent loss of intracellular 24Na, and initial uptake of 24Na was calculated therefrom by back-extrapolation to zero wash-time. After 4 min in 24Na + 180 μM carbachol intracellular [24Na] so calculated was 61·6 ± 3·1 mM (n = 18), representing 83% labelling of intracellular Na. In the absence of carbachol intracellular [24Na] was 10·0 ± 0·5 mM, representing 49% labelling. Extracellular Na was labelled by > 90% after 4 min in 24Na. The apparent rate constant for washout of extracellular 24Na was 0·6 min-1 at 3° C and 0·95 min-1 at 25° C. 3. The loss of the residual intracellular 24Na during temperature stimulation was interpreted quantitatively in terms of an exponential decline of the bulk of intracellular 24Na with an extrusion rate constant of 0·39 ± 0·1 min-1 (n = 18), efflux being delayed by passage through the extracellular space with an effective rate constant of 0·8-1·2 min-1. 4. The peak rate constant (kC) for the desaturation curve at 25° C was 0·35 ± 0·01 min-1. An Arrhenius plot of log kC/T° K-1 yielded a two-stage linear regression with a transition at 20° C. Activation energies of 8 and 31 kcal. mole-1 were calculated above and below this transition respectively. 5. Omission of K from the 25° C temperature-stimulating solution reduced kC by 62%. The K-sensitive component of extrusion rate constant was a hyperbolic function of [K]e with half-saturation at 5·6 mM-[K]e and maximum kC of 0·58 min-1. 6. Cyanide (2 mM), 2,4-dinitrophenol (1 mM) and ouabain (1·4 mM) reduced kC by 50-90%. The half-maximally inhibiting concentration of ouabain was about 60 μM. 7. Substitution of sucrose, Li or choline for external Na did not reduce the extrusion rate of 24Na in either 6 mM-[K]e or 0 mM-[K]e. Li stimulated 24Na extrusion in Na-free, K-free solution. 8. The properties of the ganglionic Na pump deduced from rates of temperature-stimulated 24Na extrusion accord with the view that the ganglion hyperpolarization observed after Na loading by exposure to nicotinic depolarizing agents results from electrogenic Na extrusion. A comparable hyperpolarization is observed after temperature stimulation following Na loading. PMID:4455816

Coupled phase and aqueous species equilibrium of the H 2O-CO 2-NaCl-CaCO 3 system from 0 to 250 °C, 1 to 1000 bar with NaCl concentrations up to saturation of halite

NASA Astrophysics Data System (ADS)

Duan, Zhenhao; Li, Dedong

2008-10-01

A model is developed for the calculation of coupled phase and aqueous species equilibrium in the H 2O-CO 2-NaCl-CaCO 3 system from 0 to 250 °C, 1 to 1000 bar with NaCl concentrations up to saturation of halite. The vapor-liquid-solid (calcite, halite) equilibrium together with the chemical equilibrium of H +, Na +, Ca 2+, CaHCO3+, Ca(OH) +, OH -, Cl -, HCO3-, CO32-, CO 2(aq) and CaCO 3(aq) in the aqueous liquid phase as a function of temperature, pressure, NaCl concentrations, CO 2(aq) concentrations can be calculated, with accuracy close to those of experiments in the stated T- P- m range, hence calcite solubility, CO 2 gas solubility, alkalinity and pH values can be accurately calculated. The merit and advantage of this model is its predictability, the model was generally not constructed by fitting experimental data. One of the focuses of this study is to predict calcite solubility, with accuracy consistent with the works in previous experimental studies. The resulted model reproduces the following: (1) as temperature increases, the calcite solubility decreases. For example, when temperature increases from 273 to 373 K, calcite solubility decreases by about 50%; (2) with the increase of pressure, calcite solubility increases. For example, at 373 K changing pressure from 10 to 500 bar may increase calcite solubility by as much as 30%; (3) dissolved CO 2 can increase calcite solubility substantially; (4) increasing concentration of NaCl up to 2 m will increase calcite solubility, but further increasing NaCl solubility beyond 2 m will decrease its solubility. The functionality of pH value, alkalinity, CO 2 gas solubility, and the concentrations of many aqueous species with temperature, pressure and NaCl (aq) concentrations can be found from the application of this model. Online calculation is made available on www.geochem-model.org/models/h2o_co2_nacl_caco3/calc.php.

Salty taste deficits in CALHM1 knockout mice.

PubMed

Tordoff, Michael G; Ellis, Hillary T; Aleman, Tiffany R; Downing, Arnelle; Marambaud, Philippe; Foskett, J Kevin; Dana, Rachel M; McCaughey, Stuart A

2014-07-01

Genetic ablation of calcium homeostasis modulator 1 (CALHM1), which releases adenosine triphosphate from Type 2 taste cells, severely compromises the behavioral and electrophysiological responses to tastes detected by G protein-coupled receptors, such as sweet and bitter. However, the contribution of CALHM1 to salty taste perception is less clear. Here, we evaluated several salty taste-related phenotypes of CALHM1 knockout (KO) mice and their wild-type (WT) controls: 1) In a conditioned aversion test, CALHM1 WT and KO mice had similar NaCl avoidance thresholds. 2) In two-bottle choice tests, CALHM1 WT mice showed the classic inverted U-shaped NaCl concentration-preference function but CALHM1 KO mice had a blunted peak response. 3) In brief-access tests, CALHM1 KO mice showed less avoidance than did WT mice of high concentrations of NaCl, KCl, NH(4)Cl, and sodium lactate (NaLac). Amiloride further ameliorated the NaCl avoidance of CALHM1 KO mice, so that lick rates to a mixture of 1000 mM NaCl + 10 µM amiloride were statistically indistinguishable from those to water. 4) Relative to WT mice, CALHM1 KO mice had reduced chorda tympani nerve activity elicited by oral application of NaCl, NaLac, and sucrose but normal responses to HCl and NH(4)Cl. Chorda tympani responses to NaCl and NaLac were amiloride sensitive in WT but not KO mice. These results reinforce others demonstrating that multiple transduction pathways make complex, concentration-dependent contributions to salty taste perception. One of these pathways depends on CALHM1 to detect hypertonic NaCl in the mouth and signal the aversive taste of concentrated salt. © The Author 2014. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

The effect of 8.25% sodium hypochlorite on dental pulp dissolution and dentin flexural strength and modulus.

PubMed

Cullen, James K T; Wealleans, James A; Kirkpatrick, Timothy C; Yaccino, John M

2015-06-01

The purpose of this study was to evaluate the effect of various concentrations of sodium hypochlorite (NaOCl), including 8.25%, on dental pulp dissolution and dentin flexural strength and modulus. Sixty dental pulp samples and 55 plane parallel dentin bars were retrieved from extracted human teeth. Five test groups (n = 10) were formed consisting of a pulp sample and dentin bar immersed in various NaOCl solutions. The negative control group (n = 5) consisted of pulp samples and dentin bars immersed in saline. The positive control group (n = 5) consisted of pulp samples immersed in 8.25% NaOCl without a dentin bar. Every 6 minutes for 1 hour, the solutions were refreshed. The dentin bars were tested for flexural strength and modulus with a 3-point bend test. The time until total pulp dissolution and any changes in dentin bar flexural strength and modulus for the different NaOCl solutions were statistically analyzed. An increase in NaOCl concentration showed a highly significant decrease in pulp dissolution time. The pulp dissolution property of 8.25% NaOCl was significantly faster than any other tested concentration of NaOCl. The presence of dentin did not have a significant effect on the dissolution capacity of NaOCl if the solutions were refreshed. NaOCl concentration did not have a statistically significant effect on dentin flexural strength or modulus. Dilution of NaOCl decreases its pulp dissolution capacity. Refreshing the solution is essential to counteract the effects of dentin. In this study, NaOCl did not have a significant effect on dentin flexural strength or modulus. Published by Elsevier Inc.

Salty Taste Deficits in CALHM1 Knockout Mice

PubMed Central

Ellis, Hillary T.; Aleman, Tiffany R.; Downing, Arnelle; Marambaud, Philippe; Foskett, J. Kevin; Dana, Rachel M.; McCaughey, Stuart A.

2014-01-01

Genetic ablation of calcium homeostasis modulator 1 (CALHM1), which releases adenosine triphosphate from Type 2 taste cells, severely compromises the behavioral and electrophysiological responses to tastes detected by G protein–coupled receptors, such as sweet and bitter. However, the contribution of CALHM1 to salty taste perception is less clear. Here, we evaluated several salty taste–related phenotypes of CALHM1 knockout (KO) mice and their wild-type (WT) controls: 1) In a conditioned aversion test, CALHM1 WT and KO mice had similar NaCl avoidance thresholds. 2) In two-bottle choice tests, CALHM1 WT mice showed the classic inverted U-shaped NaCl concentration-preference function but CALHM1 KO mice had a blunted peak response. 3) In brief-access tests, CALHM1 KO mice showed less avoidance than did WT mice of high concentrations of NaCl, KCl, NH4Cl, and sodium lactate (NaLac). Amiloride further ameliorated the NaCl avoidance of CALHM1 KO mice, so that lick rates to a mixture of 1000mM NaCl + 10 µM amiloride were statistically indistinguishable from those to water. 4) Relative to WT mice, CALHM1 KO mice had reduced chorda tympani nerve activity elicited by oral application of NaCl, NaLac, and sucrose but normal responses to HCl and NH4Cl. Chorda tympani responses to NaCl and NaLac were amiloride sensitive in WT but not KO mice. These results reinforce others demonstrating that multiple transduction pathways make complex, concentration-dependent contributions to salty taste perception. One of these pathways depends on CALHM1 to detect hypertonic NaCl in the mouth and signal the aversive taste of concentrated salt. PMID:24846212

Influence of halogenides on luminescence from silver molecular clusters in photothermorefractive glasses

NASA Astrophysics Data System (ADS)

Dubrovin, V. D.; Ignat'ev, A. I.; Nikonorov, N. V.; Sidorov, A. I.

2014-05-01

It is shown experimentally that a rise in the sodium halogenide (NaCl, NaBr) concentration in photothermorefractive glasses increases the intensity of luminescence from silver neutral molecular clusters. Substitution of NaBr for NaCl with their concentration being the same shifts the luminescence band toward longer waves and raises its intensity. These findings can be explained by the formation of molecular clusters of type Ag n -Hal (Hal = Cl, Br) in photothermorefractive glass.

Crystallization Behavior and Heat Transfer of Fluorine-Free Mold Fluxes with Different Na2O Concentration

NASA Astrophysics Data System (ADS)

Yang, Jian; Zhang, Jianqiang; Sasaki, Yasushi; Ostrovski, Oleg; Zhang, Chen; Cai, Dexiang; Kashiwaya, Yoshiaki

2016-08-01

In this study, the crystallization behavior and heat transfer of CaO-SiO2-Na2O-B2O3-TiO2-Al2O3-MgO-Li2O fluorine-free mold fluxes with different Na2O contents (5 to 11 mass pct) were studied using single/double hot thermocouple technique (SHTT/DHTT) and infrared emitter technique (IET), respectively. Continuous cooling transformation (CCT) and time-temperature transformation (TTT) diagrams constructed using SHTT showed that crystallization temperature increased and incubation time shortened with the increase of Na2O concentration, indicating an enhanced crystallization tendency. The crystallization process of mold fluxes in the temperature field simulating the casting condition was also investigated using DHTT. X-ray diffraction (XRD) analysis of the quenched mold fluxes showed that the dominant phase changed from CaSiO3 to Ca11Si4B2O22 with the increasing concentration of Na2O. The heat transfer examined by IET showed that the increase of Na2O concentration reduced the responding heat flux when Na2O was lower than 9 mass pct but the further increase of Na2O to 11 mass pct enhanced the heat flux. The correlation between crystallinity and heat transfer was discussed in terms of crystallization tendency and crystal morphology.

Novel naïve Bayes classification models for predicting the carcinogenicity of chemicals.

PubMed

Zhang, Hui; Cao, Zhi-Xing; Li, Meng; Li, Yu-Zhi; Peng, Cheng

2016-11-01

The carcinogenicity prediction has become a significant issue for the pharmaceutical industry. The purpose of this investigation was to develop a novel prediction model of carcinogenicity of chemicals by using a naïve Bayes classifier. The established model was validated by the internal 5-fold cross validation and external test set. The naïve Bayes classifier gave an average overall prediction accuracy of 90 ± 0.8% for the training set and 68 ± 1.9% for the external test set. Moreover, five simple molecular descriptors (e.g., AlogP, Molecular weight (M W ), No. of H donors, Apol and Wiener) considered as important for the carcinogenicity of chemicals were identified, and some substructures related to the carcinogenicity were achieved. Thus, we hope the established naïve Bayes prediction model could be applied to filter early-stage molecules for this potential carcinogenicity adverse effect; and the identified five simple molecular descriptors and substructures of carcinogens would give a better understanding of the carcinogenicity of chemicals, and further provide guidance for medicinal chemists in the design of new candidate drugs and lead optimization, ultimately reducing the attrition rate in later stages of drug development. Copyright © 2016 Elsevier Ltd. All rights reserved.

Field-scale application of spent sulfidic caustic as a source of alternative electron donor for autotrophic denitrification.

PubMed

Lee, Jae-Ho; Park, Jeung-Jin; Choi, Gi-Choong; Byun, Im-Gyu; Park, Tae-Joo; Lee, Tae-Ho

2013-01-01

Biological reuse of spent sulfidic caustic (SSC) originating from oil refineries is a promising method for the petrochemical industry because of low handling cost. SSC typically contains high concentrations of sulfur, with the most dominant sulfur compounds being sulfide (S(2-)). SSC is also characterized by a high pH and elevated alkalinity up to 5-15% by weight. Because of these characteristics, SSC can be used for denitrification of NO3(-)-N in the biological nitrogen removal process as both the electron donor and buffering agent in sulfur-utilizing autotrophic denitrification. In this study, two kinds of SSC (SSC I, SSC II) produced from two petrochemical companies were used for autotrophic denitrification in a field-scale wastewater treatment plant (WWTP). The effluent total nitrogen (TN) concentration in this process was about 10.5 mg/L without any external carbon sources and the nitrification efficiency was low, about 93.0%, because of alkalinity deficiency in the influent. The injection of SSC I, but not SSC II, promoted nitrification efficiency, which was attributed to the difference in the NaOH/S ratio between SSC I and II. SSC was injected based on sulfide concentration of SSC required to denitrify NO3(-)-N in the WWTP. SSC I had higher NaOH/S than SSC II and thus could supply more alkalinity for nitrification than SSC II. On the other hand, additional TN removal of about 9.0% was achieved with the injection of both SSCs. However, denitrification efficiency was not proportionally increased with increasing SSC injection because of NO3(-)-N deficiency in the anoxic tank due to the limited capacity of the recycling pump. For the same reason, sulfate concentration, which is the end product of sulfur-utilizing autotrophic denitrificaiton in the effluent, was also not increased with increasing SSC injection.

Ionic mechanisms of transient inward current in the absence of Na(+)-Ca2+ exchange in rabbit cardiac Purkinje fibres.

PubMed Central

Han, X; Ferrier, G R

1992-01-01

1. Membrane currents were measured with a two-microelectrode technique in voltage clamped rabbit cardiac Purkinje fibres under conditions known to cause intracellular calcium overload and to eliminate or minimize Na(+)-Ca2+ exchange. 2. Increasing [Ca2+]o from 2.5 to 5 mM or above and substituting external sodium with either sucrose, choline or Li+ induced an oscillatory transient inward current (TI) which peaked 200-300 ms after repolarization from a previous depolarizing pulse. The TI quickly disappeared upon return to normal Tyrode solution. Both the rate and configuration of action potentials of Purkinje fibres also returned to control upon return to Tyrode solution after 30 min of high Ca2+ exposure, if the Ca2+ concentration was 30 mM or less. 3. The TI in Na(+)-free solution was Ca2+ dependent. Either zero or low (2.5 mM) [Ca2+]o, or replacement of [Ca2+]o by BaCl prevented induction of the TI current upon repolarization from a previous depolarizing pulse. 4. In the presence of 30 mM-CaCl2 and with choline chloride as the substitute for NaCl, TI had a distinct reversal potential (Erev) of -25 mV. The time-to-peak TI, either inward or outward, did not shift significantly with change in voltage. Both inward and outward TI were simultaneously abolished by exposure to 1 microM-ryanodine, suggesting they were both activated by transient release of Ca2+ from the sarcoplasmic reticulum. The occurrence of TI in the absence of [Na+]o is not compatible with an electrogenic Na(+)-Ca2+ exchange mechanism. The existence of a clear-cut reversal potential suggests that an ionic channel may be responsible for the TI under these conditions. 5. Both the magnitude of peak TI and the Erev were affected by changes of CaCl2 concentration. (i) Under steady-state conditions, peak inward TI was significantly increased when the [Ca2+]o was elevated from 5 to 15 mM. The peak TI in the outward direction was significantly increased when [Ca2+]o was elevated from 15 to 30 mM; however, the difference in peak inward TI at 15 and 30 mM [Ca2+]o was small. (ii) Clear-cut reversals of TI were found at Ca2+ concentrations of 10 mM (Erev = -19.5 mV) or greater, and elevation of [Ca2+]o to 20, 30, 50 and 105 mM shifted the Erev to more negative potentials. (iii) In the presence of 5 mM [Ca2+]o the inward TI declined to zero at about -30 mV, and test voltages between -55 and +5 mV failed to reveal a distinct outward TI.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:1284077

Fluoride induces apoptosis in H9c2 cardiomyocytes via the mitochondrial pathway.

PubMed

Yan, Xiaoyan; Wang, Lu; Yang, Xia; Qiu, Yulan; Tian, Xiaolin; Lv, Yi; Tian, Fengjie; Song, Guohua; Wang, Tong

2017-09-01

Numerous studies have shown that chronic excessive fluoride intake can adversely affect different organ systems. In particular, the cardiovascular system is susceptible to disruption by a high concentration of fluoride. The objectives of this study were to explore the mechanism of apoptosis by detecting the toxic effects of different concentrations of sodium fluoride (NaF) in H9c2 cells exposed for up to 96 h. NaF not only inhibited H9c2 cell proliferation but also induced apoptosis and morphological damage. With increasing NaF concentrations, early apoptosis of H9c2 cells was increased while the mitochondrial membrane potential was decreased. Compared with the control group, the mRNA levels of caspase-3, caspase-9, and cytochrome c all increased with increasing concentrations of NaF. In summary, these data suggest that apoptosis is involved in NaF-induced H9c2 cell toxicity and that activation of the mitochondrial pathway may occur. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ecophysiological response of Crambe maritima to airborne and soil-borne salinity

PubMed Central

de Vos, Arjen C.; Broekman, Rob; Groot, Maartje P.; Rozema, Jelte

2010-01-01

Background and Aims There is a need to evaluate the salt tolerance of plant species that can be cultivated as crops under saline conditions. Crambe maritima is a coastal plant, usually occurring on the driftline, with potential use as a vegetable crop. The aim of this experiment was to determine the growth response of Crambe maritima to various levels of airborne and soil-borne salinity and the ecophysiological mechanisms underlying these responses. Methods In the greenhouse, plants were exposed to salt spray (400 mm NaCl) as well as to various levels of root-zone salinity (RZS) of 0, 50, 100, 200 and 300 mm NaCl during 40 d. The salt tolerance of Crambe maritima was assessed by the relative growth rate (RGR) and its components. To study possible salinity effects on the tissue and cellular level, the leaf succulence, tissue Na+ concentrations, Na+ : K+ ratio, net K+/Na+ selectivity, N, P, K+, Ca2+, Mg2+, proline, soluble sugar concentrations, osmotic potential, total phenolics and antioxidant capacity were measured. Key Results Salt spray did not affect the RGR of Crambe maritima. However, leaf thickness and leaf succulence increased with salt spray. Root zone salinities up to 100 mm NaCl did not affect growth. However, at 200 mm NaCl RZS the RGR was reduced by 41 % compared with the control and by 56 % at 300 mm NaCl RZS. The reduced RGR with increasing RZS was largely due to the reduced specific leaf area, which was caused by increased leaf succulence as well as by increased leaf dry matter content. No changes in unit leaf rate were observed but increased RZS resulted in increased Na+ and proline concentrations, reduced K+, Ca2+ and Mg2+ concentrations, lower osmotic potential and increased antioxidant capacity. Proline concentrations of the leaves correlated strongly (r = 0·95) with RZS concentrations and not with plant growth. Conclusions Based on its growth response, Crambe maritima can be classified as a salt spray tolerant plant that is sensitive to root zone salinities exceeding 100 mm NaCl. PMID:20354071

Effects of Monovalent Cations on the Sodium-Alanine Interaction in Rabbit Ileum

PubMed Central

Frizzell, Raymond A.; Schultz, Stanley G.

1970-01-01

H, K, Rb, and Li inhibit Na-dependent alanine influx across the brush border of rabbit ileum. Kinetic analysis indicates that H and K behave as competitive inhibitors of influx so that increasing the concentration of H or K in the mucosal solution is kinetically indistinguishable from decreasing the Na concentration. In addition the coupling between alanine and Na influxes is markedly reduced at pH 2.5. With the exception of H and Li, none of these monovalent cations significantly affects carrier-mediated alanine influx in the absence of Na indicating that their inhibitory effects are largely restricted to the Na-dependent fraction of influx. Increasing H concentration from 0.03 to 3 mM does not affect influx in the absence of Na but markedly inhibits influx in the presence of Na. Li significantly enhances alanine influx in the absence of Na. Ag, UO2, and La also inhibit the Na-dependent fraction of alanine influx. These findings suggest that anionic groups having a pKa of approximately 4 are involved in the interaction between Na and the alanine-carrier complex; present evidence implicates carboxylate groups however, phosphoryl residues cannot be ruled out. The previously proposed kinetic model for the Na-alanine interaction has been extended to accommodate these effects of H and other monovalent cations. The mechanistic and physiological implications of these findings are discussed. PMID:5507092

In-vitro activity of sodium-hypochlorite gel on bacteria associated with periodontitis.

PubMed

Jurczyk, Karolina; Nietzsche, Sandor; Ender, Claudia; Sculean, Anton; Eick, Sigrun

2016-11-01

The aim of the present study was to assess the antimicrobial activity of a sodium hypochlorite formulation including its components against bacteria associated with periodontal disease. Sodium hypochlorite formulation (NaOCl gel), its components sodium hypochlorite (NaOCl), and the activating vehicle were compared with 0.1 % chlorhexidine digluconate (CHX) solution. The antimicrobial activity was proven by determination of minimal inhibitory concentrations (MIC), minimal bactericidal concentrations, and killing assays. Furthermore, the influence on formation as well as on a 4-day-old 6-species biofilm was tested. Except for one strain (Parvimonas micra ATCC 33270 in case of NaOCl gel), the MICs both of the CHX solution and NaOCl gel did not exceed 10 % of the formulations' concentration. In general, MICs of the NaOCl gel were equal as of the CHX solution against Gram-negatives but higher against Gram-positive bacteria. CHX but not NaOCl gel clearly inhibited biofilm formation; however, the activity of NaOCl gel was more remarkable on a 4-day-old biofilm. NaOCl killed bacteria in the biofilm and interfered with the matrix. The NaOCl gel acts antimicrobial in particular against Gram-negative species associated with periodontitis. Moreover, its component NaOCl hypochlorite is able to alter biofilm matrices. The NaOCl gel may represent a potential alternative for adjunctive topical antimicrobial treatment in periodontitis.

Toxicity assessment of sodium fluoride in Drosophila melanogaster after chronic sub-lethal exposure.

PubMed

Dutta, Moumita; Rajak, Prem; Khatun, Salma; Roy, Sumedha

2017-01-01

Sodium fluoride (NaF), one of the most frequently used fluoride compound is composed of Na + and F - . Apart from its use in water fluoridation, NaF also acts as a major component for different dental products like toothpastes, gels and mouth rinses etc. The present study was carried out to explore the toxic impact of chronic NaF exposure on a non-target organism, Drosophila melanogaster. The larvae exposed to different concentrations of NaF through food showed a significant increase in HSP70 expression both qualitatively and quantitatively. The altered tail length and tail intensity in Comet assay validate the increased DNA damage in treated larvae. The activity of AChE, oxidative stress marker enzymes, phase I and phase II detoxifying enzymes were found to be significantly inhibited in the treated larvae when compared to control though there was no evidence of dose dependent change in each case. The alterations in the mentioned parameters can be due to increased body Fluoride ion (F - ) concentration since the analysis with ion electrode analyzer revealed that F - concentration increased significantly with NaF treatment. Hence, the results suggest that D. melanogaster manifest prominent toxic response when subjected to chronic exposure to sub-lethal NaF concentrations. Copyright © 2016 Elsevier Ltd. All rights reserved.

The effect of cation source and dietary cation-anion difference on rumen ion concentrations in lactating dairy cows.

PubMed

Catterton, T L; Erdman, R A

2016-08-01

Many studies have focused on the influence of dietary cation-anion difference (DCAD) on animal performance but few have examined the effect of DCAD on the rumen ionic environment. The objective of this study was to examine the effects of DCAD, cation source (Na vs. K), and anion source (Cl vs. bicarbonate or carbonate) on rumen environment and fermentation. The study used 5 rumen-fistulated dairy cows and 5 dietary treatments that were applied using a 5×5 Latin square design with 2-wk experimental periods. Treatments consisted of (1) the basal total mixed ration (TMR); (2) the basal TMR plus 340mEq/kg of Na (dry matter basis) using NaCl; (3) the basal TMR plus 340mEq/kg of K using KCl; (4) the basal TMR plus 340mEq/kg of Na using NaHCO3; and (5) the basal TMR plus 340mEq/kg of K using K2CO3. On the last day of each experimental period, rumen samples were collected and pooled from 5 different locations at 0, 1.5, 3, 4.5, 6, 9, and 12h postfeeding for measurement of rumen pH and concentrations of strong ions and volatile fatty acids (VFA). Dietary supplementation of individual strong ions increased the corresponding rumen ion concentration. Rumen Na was decreased by 24mEq/L when K was substituted for Na in the diet, but added dietary Na had no effect on rumen K. Rumen Cl was increased by 10mEq/L in diets supplemented with Cl. Cation source had no effect on rumen pH or total VFA concentration. Increased DCAD increased rumen pH by 0.10 pH units and increased rumen acetate by 4mEq/L but did not increase total VFA. This study demonstrated that rumen ion concentrations can be manipulated by dietary ion concentrations. If production and feed efficiency responses to DCAD and ionophores in the diet are affected by rumen Na and K concentrations, then manipulating dietary Na and K could be used either to enhance or diminish those responses. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Differential tolerance of 3 self-rooted Citrus limon cultivars to NaCl stress.

PubMed

Tsabarducas, V; Chatzistathis, T; Therios, I; Koukourikou-Petridou, M; Tananaki, C

2015-12-01

One-year-old self-rooted cuttings of three Citrus limon cultivars (Nouvel Athos, Lisbon, Maglini) were grown in 1 L black plastic bags, containing a mixture of sand: perlite (1:1), in order to investigate: i) if genotypic differences to salt stress existed, ii) if KNO3 can alleviate salinity stress, iii) the role of carbohydrates (such as the sugars fructose, glucose and sucrose) and proline as possible osmoregulators in C. limon osmoprotection, and iv) if genotypic differences to salt stress tolerance exist among the 3 studied cultivars. The experiment included 3 treatments: i) control (C), i.e. 25% modified Hoagland (No2) solution (MHS)-NaCl, ii) T1, 25% MHS+80 mM NaCl, iii) T2, 25% MHS+80 mM NaCl+5 mM KNO3. Plant growth was negatively affected by high NaCl (T1); the highest Cl and Na quantities have been absorbed by Lisbon, while the lowest ones by Maglini. Salt stress reduced macronutrient and Zn concentrations, as well as the total carbohydrate concentration, and increased peroxidase (POD) activity and chlorophyll fluorescence in the leaves of the 3 C. limon cultivars studied; five mM KNO3 application alleviated the harmful effect of salt stress on leaf total carbohydrate concentration and leaf N and K concentrations. Sucrose was dramatically reduced in all the three genotypes studied, while leaf fructose concentration was significantly increased in Nouvel Nouvel Nouvel Athos and Maglini under salt stress. Leaf proline concentration of Maglini was significantly decreased by the high NaCl concentration, while Nouvel Athos and Lisbon had high proline concentration in their leaves. In conclusion, from the significantly decreased levels of proline for Maglini, together with the greatest reduction of the ratio Fv/Fm and the least enhancement of POD activity-compared to the other two cultivars-it can be concluded that Maglini was more susceptible to salinity, and should not be preferred for cultivation under NaCl stress. Finally, rich KNO3 application alleviated the harmful effect of NaCl stress, thus it is highly recommended for use by the growers in areas with salt problems. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

External concentration of organic acid anions and pH: key independent variables for studying how organic acids inhibit growth of bacteria in mildly acidic foods.

PubMed

Carpenter, C E; Broadbent, J R

2009-01-01

Although the mechanisms by which organic acids inhibit growth of bacteria in mildly acidic foods are not fully understood, it is clear that intracellular accumulation of anions is a primary contributor to inhibition of bacterial growth. We hypothesize that intracellular accumulation of anions is driven by 2 factors, external anion concentration and external acidity. This hypothesis follows from basic chemistry principles that heretofore have not been fully applied to studies in the field, and it has led us to develop a novel approach for predicting internal anion concentration by controlling the external concentration of anions and pH. This approach overcomes critical flaws in contemporary experimental design that invariably target concentration of either protonated acid or total acid in the growth media thereby leaving anion concentration to vary depending on the pK(a) of the acids involved. Failure to control external concentration of anions has undoubtedly confounded results, and it has likely led to misleading conclusions regarding the antimicrobial action of organic acids. In summary, we advocate an approach for directing internal anion levels by controlling external concentration of anions and pH because it presents an additional opportunity to study the mechanisms by which organic acids inhibit bacterial growth. Knowledge gained from such studies would have important application in the control of important foodborne pathogens such as Listeria monocytogenes, and may also facilitate efforts to promote the survival in foods or beverages of desirable probiotic bacteria.

Block of voltage-gated potassium channels by Pacific ciguatoxin-1 contributes to increased neuronal excitability in rat sensory neurons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Birinyi-Strachan, Liesl C.; Gunning, Simon J.; Lewis, Richard J.

2005-04-15

The present study investigated the actions of the polyether marine toxin Pacific ciguatoxin-1 (P-CTX-1) on neuronal excitability in rat dorsal root ganglion (DRG) neurons using patch-clamp recording techniques. Under current-clamp conditions, bath application of 2-20 nM P-CTX-1 caused a rapid, concentration-dependent depolarization of the resting membrane potential in neurons expressing tetrodotoxin (TTX)-sensitive voltage-gated sodium (Na{sub v}) channels. This action was completely suppressed by the addition of 200 nM TTX to the external solution, indicating that this effect was mediated through TTX-sensitive Na{sub v} channels. In addition, P-CTX-1 also prolonged action potential and afterhyperpolarization (AHP) duration. In a subpopulation of neurons,more » P-CTX-1 also produced tonic action potential firing, an effect that was not accompanied by significant oscillation of the resting membrane potential. Conversely, in neurons expressing TTX-resistant Na{sub v} currents, P-CTX-1 failed to alter any parameter of neuronal excitability examined in this study. Under voltage-clamp conditions in rat DRG neurons, P-CTX-1 inhibited both delayed-rectifier and 'A-type' potassium currents in a dose-dependent manner, actions that occurred in the absence of alterations to the voltage dependence of activation. These actions appear to underlie the prolongation of the action potential and AHP, and contribute to repetitive firing. These data indicate that a block of potassium channels contributes to the increase in neuronal excitability, associated with a modulation of Na{sub v} channel gating, observed clinically in response to ciguatera poisoning.« less

Synthesis-driven, structure-dependent optical behavior in phase-tunable NaYF 4:Yb,Er-based motifs and associated heterostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Haiqing; Han, Jinkyu; McBean, Coray

Understanding the key parameters necessary for generating uniform Er,Yb co-activated NaYF 4 possessing various selected phases (i.e. cubic or hexagonal) represents an important chemical strategy towards tailoring optical behavior in these systems. In this paper, we report on a straightforward hydrothermal synthesis in which the separate effects of reaction temperature, reaction time, and precursor stoichiometry in the absence of any surfactant were independently investigated. Interestingly, the presence and the concentration of NH 4OH appear to be the most critical determinants of the phase and morphology. For example, with NH 4OH as an additive, we have observed the formation of novelmore » hierarchical nanowire bundles which possess overall lengths of ~5 μm and widths of ~1.5 μm but are composed of constituent component sub-units of long, ultrathin (~5 nm) nanowires. These motifs have yet to be reported as distinctive morphological manifestations of fluoride materials. The optical properties of as-generated structures have also been carefully analyzed. Specifically, we have observed tunable, structure-dependent energy transfer behavior associated with the formation of a unique class of NaYF 4–CdSe quantum dot (QD) heterostructures, incorporating zero-dimensional (0D), one-dimensional (1D), and three-dimensional (3D) NaYF 4 structures. Our results have demonstrated the key roles of the intrinsic morphology-specific physical surface area and porosity as factors in governing the resulting opto-electronic behavior. Finally and specifically, the trend in energy transfer efficiency correlates well with the corresponding QD loading within these heterostructures, thereby implying that the efficiency of FRET appears to be directly affected by the amount of QDs immobilized onto the external surfaces of the underlying fluoride host materials.« less

Synthesis-driven, structure-dependent optical behavior in phase-tunable NaYF 4:Yb,Er-based motifs and associated heterostructures

DOE PAGES

Liu, Haiqing; Han, Jinkyu; McBean, Coray; ...

2017-01-03

Understanding the key parameters necessary for generating uniform Er,Yb co-activated NaYF 4 possessing various selected phases (i.e. cubic or hexagonal) represents an important chemical strategy towards tailoring optical behavior in these systems. In this paper, we report on a straightforward hydrothermal synthesis in which the separate effects of reaction temperature, reaction time, and precursor stoichiometry in the absence of any surfactant were independently investigated. Interestingly, the presence and the concentration of NH 4OH appear to be the most critical determinants of the phase and morphology. For example, with NH 4OH as an additive, we have observed the formation of novelmore » hierarchical nanowire bundles which possess overall lengths of ~5 μm and widths of ~1.5 μm but are composed of constituent component sub-units of long, ultrathin (~5 nm) nanowires. These motifs have yet to be reported as distinctive morphological manifestations of fluoride materials. The optical properties of as-generated structures have also been carefully analyzed. Specifically, we have observed tunable, structure-dependent energy transfer behavior associated with the formation of a unique class of NaYF 4–CdSe quantum dot (QD) heterostructures, incorporating zero-dimensional (0D), one-dimensional (1D), and three-dimensional (3D) NaYF 4 structures. Our results have demonstrated the key roles of the intrinsic morphology-specific physical surface area and porosity as factors in governing the resulting opto-electronic behavior. Finally and specifically, the trend in energy transfer efficiency correlates well with the corresponding QD loading within these heterostructures, thereby implying that the efficiency of FRET appears to be directly affected by the amount of QDs immobilized onto the external surfaces of the underlying fluoride host materials.« less

When Information Improves Information Security

NASA Astrophysics Data System (ADS)

Grossklags, Jens; Johnson, Benjamin; Christin, Nicolas

This paper presents a formal, quantitative evaluation of the impact of bounded-rational security decision-making subject to limited information and externalities. We investigate a mixed economy of an individual rational expert and several naïve near-sighted agents. We further model three canonical types of negative externalities (weakest-link, best shot and total effort), and study the impact of two information regimes on the threat level agents are facing.

Importance of plant species and external silicon concentration to active silicon uptake and transport.

PubMed

Liang, Yongchao; Hua, Haixia; Zhu, Yong-Guan; Zhang, Jie; Cheng, Chunmei; Römheld, Volker

2006-01-01

Here, we characterized silicon (Si) uptake and xylem loading in Oryza sativa, Zea mays, Helianthus annuus and Benincase hispida in a series of hydroponic experiments. Both active and passive Si-uptake components co-exist in all the plants tested. The active component is the major mechanism responsible for Si uptake in O. sativa and Z. mays. By contrast, passive uptake prevails in H. annuus and B. hispida at a higher external Si concentration (0.85 mM), while the active component constantly exists and contributes to the total Si uptake, especially at a lower external Si concentration (0.085 mM). Short experiments showed that Si uptake was significantly suppressed in O. sativa and Z. mays by metabolic inhibitors or low temperature, regardless of external Si concentrations. By contrast, Si uptake in H. annuus and B. hispida was inhibited more significantly by metabolic inhibitors or low temperature at lower (for example, 0.085 mM) than at higher (for example, 1.70 mM) external Si concentrations. It can be concluded that both active and passive Si-uptake components co-exist in O. sativa, Z. mays, H. annuus and B. hispida, with their relative contribution being dependent much upon both plant species and external Si concentrations.

Electrolytes as Cathode Interlayers in Inverted Organic Solar Cells: Influence of the Cations on Bias-Dependent Performance.

PubMed

Li, Yaru; Liu, Xiaohui; Li, Xiaodong; Zhang, Wenjun; Xing, Feifei; Fang, Junfeng

2017-03-08

The performance of organic solar cells (OSCs) with edetate electrolytes depends on external bias, and ions are speculated to be responsible for this phenomenon. To clarify the detailed relationship between the ions of electrolytes and the bias-dependent behaviors of devices, this work introduces four edetate cathode interlayers (EDTA-X, X = nH(4-n)Na, n = 0, 1, 2, and 4) containing different kinds and number of cations into inverted OSCs. The results show that the devices initial and saturated (after external bias treatment) power conversion efficiencies (PCEs) both decrease with the increase in the number of H + . Moreover, the bias-dependent degrees increase with the increase in H + number; with that, the PCE increment of EDTA-4H device is 53.4%, while that of the EDTA-4Na device is almost unchanged. The electrical impedance spectroscopy and capacitance-voltage tests reveal that the interfacial recombination is greatly suppressed by external bias treatment, which is not a result of the decreased density of defect states. The results indicate that the ion's motion, specifically the H + motion, under external electrical field is responsible for the bias-dependent behavior, which is conducive to the design of new efficient electrolytic interlayers without bias-dependent performance.

The Ionic Permeability Changes during Acetylcholine-Induced Responses of Aplysia Ganglion Cells

PubMed Central

Sato, Makoto; Austin, George; Yai, Hideko; Maruhashi, Juro

1968-01-01

ACh-induced depolarization (D response) in D cells markedly decreases as the external Na+ is reduced. However, when Na+ is completely replaced with Mg++, the D response remains unchanged. When Na+ is replaced with Tris(hydroxymethyl)aminomethane, the D response completely disappears, except for a slight decrease in membrane resistance. ACh-induced hyperpolarization (H response) in H cells is markedly depressed as the external Cl- is reduced. Frequently, the reversal of the H response; i.e., depolarization, is observed during perfusion with Cl--free media. In cells which show both D and H responses superimposed, it was possible to separate these responses from each other by perfusing the cells with either Na+-free or Cl--free Ringer's solution. High [K+]0 often caused a marked hyperpolarization in either D or H cells. This is due to the primary effect of high [K+]0 on the presynaptic inhibitory fibers. The removal of this inhibitory afferent interference by applying Nembutal readily disclosed the predicted K+ depolarization. In perfusates containing normal [Na+]0, the effects of Ca++ and Mg++ on the activities of postsynaptic membrane were minimal, supporting the current theory that the effects of these ions on the synaptic transmission are mainly presynaptic. The possible mechanism of the hyperpolarization produced by simultaneous perfusion with both high [K+]0 and ACh in certain H cells is explained quantitatively under the assumption that ACh induces exclusively an increase in Cl- permeability of the H membrane. PMID:5648831

Sodium-dependent magnesium uptake by ferret red cells.

PubMed Central

Flatman, P W; Smith, L M

1991-01-01

1. Magnesium uptake can be measured in ferret red cells incubated in media containing more than 1 mM-magnesium. Uptake is substantially increased if the sodium concentration in the medium is reduced. 2. Magnesium uptake is half-maximally activated by 0.37 mM-external magnesium when the external sodium concentration is 5 mM. Increasing the external sodium concentration increases the magnesium concentration needed to activate the system. 3. Magnesium uptake is increased by reducing the external sodium concentration. Uptake is half-maximum at sodium concentrations of 17, 22 and 62 nM when the external magnesium concentrations are 2, 5 and 10 mM respectively. 4. Replacement of external sodium with choline does not affect the membrane potential of ferret red cells over a 45 min period. 5. Magnesium uptake from media containing 5 mM-sodium is inhibited by amiloride, quinidine and imipramine. It is not affected by ouabain or bumetanide. Vanadate stimulates magnesium uptake but has no effect on magnesium efflux. 6. When cell ATP content is reduced to 19 mumol (1 cell)-1 by incubating cells for 3 h with 2-deoxyglucose, magnesium uptake falls by 50% in the presence of 5 mM-sodium and is completely abolished in the presence of 145 mM-sodium. Some of the inhibition may be due to the increase in intracellular ionized magnesium concentration ([Mg2+]i) from 0.7 to 1.0 mM which occurs under these conditions. 7. Magnesium uptake can be driven against a substantial electrochemical gradient if the external sodium concentration is reduced sufficiently. 8. These findings are discussed in terms of several possible models for magnesium transport. It is concluded that the majority of magnesium uptake observed in low-sodium media is via sodium-magnesium antiport. A small portion of uptake is through a parallel leak pathway. It is believed that the antiport is responsible for maintaining [Mg2+]i below electrochemical equilibrium in these cells at physiological external sodium concentration. Thus in ferret red cells the direction of magnesium transport can be reversed by reversing the sodium gradient. PMID:1822527

Drivers of Seasonal Variability in Marine Boundary Layer Aerosol Number Concentration Investigated Using a Steady State Approach

NASA Astrophysics Data System (ADS)

Mohrmann, Johannes; Wood, Robert; McGibbon, Jeremy; Eastman, Ryan; Luke, Edward

2018-01-01

Marine boundary layer (MBL) aerosol particles affect the climate through their interaction with MBL clouds. Although both MBL clouds and aerosol particles have pronounced seasonal cycles, the factors controlling seasonal variability of MBL aerosol particle concentration are not well constrained. In this paper an aerosol budget is constructed representing the effects of wet deposition, free-tropospheric entrainment, primary surface sources, and advection on the MBL accumulation mode aerosol number concentration (Na). These terms are then parameterized, and by assuming that on seasonal time scales Na is in steady state, the budget equation is rearranged to form a diagnostic equation for Na based on observable variables. Using data primarily collected in the subtropical northeast Pacific during the MAGIC campaign (Marine ARM (Atmospheric Radiation Measurement) GPCI (GCSS Pacific Cross-Section Intercomparison) Investigation of Clouds), estimates of both mean summer and winter Na concentrations are made using the simplified steady state model and seasonal mean observed variables. These are found to match well with the observed Na. To attribute the modeled difference between summer and winter aerosol concentrations to individual observed variables (e.g., precipitation rate and free-tropospheric aerosol number concentration), a local sensitivity analysis is combined with the seasonal difference in observed variables. This analysis shows that despite wintertime precipitation frequency being lower than summer, the higher winter precipitation rate accounted for approximately 60% of the modeled seasonal difference in Na, which emphasizes the importance of marine stratocumulus precipitation in determining MBL aerosol concentrations on longer time scales.

Direct Analysis of Proteins from Solutions with High Salt Concentration Using Laser Electrospray Mass Spectrometry

NASA Astrophysics Data System (ADS)

Karki, Santosh; Shi, Fengjian; Archer, Jieutonne J.; Sistani, Habiballah; Levis, Robert J.

2018-05-01

The detection of lysozyme, or a mixture of lysozyme, cytochrome c, and myoglobin, from solutions with varying salt concentrations (0.1 to 250 mM NaCl) is compared using laser electrospray mass spectrometry (LEMS) and electrospray ionization-mass spectrometry (ESI-MS). Protonated protein peaks were observed up to a concentration of 250 mM NaCl in the case of LEMS. In the case of ESI-MS, a protein solution with salt concentration > 0.5 mM resulted in predominantly salt-adducted features, with suppression of the protonated protein ions. The constituents in the mixture of proteins were assignable up to 250 mM NaCl for LEMS and were not assignable above a NaCl concentration of 0.5 mM for ESI. The average sodium adducts (< n >) bound to the 7+ charge state of lysozyme for LEMS measurements from salt concentrations of 2.5, 25, 50, and 100 mM NaCl are 1.71, 5.23, 5.26, and 5.11, respectively. The conventional electrospray measurements for lysozyme solution containing salt concentrations of 0.1, 1, 2, and 5 mM NaCl resulted in < n > of 2.65, 6.44, 7.57, and 8.48, respectively. LEMS displays an approximately two orders of magnitude higher salt tolerance in comparison with conventional ESI-MS. The non-equilibrium partitioning of proteins on the surface of the charged droplets is proposed as the mechanism for the high salt tolerance phenomena observed in the LEMS measurements. [Figure not available: see fulltext.

Direct Analysis of Proteins from Solutions with High Salt Concentration Using Laser Electrospray Mass Spectrometry

NASA Astrophysics Data System (ADS)

Karki, Santosh; Shi, Fengjian; Archer, Jieutonne J.; Sistani, Habiballah; Levis, Robert J.

2018-03-01

The detection of lysozyme, or a mixture of lysozyme, cytochrome c, and myoglobin, from solutions with varying salt concentrations (0.1 to 250 mM NaCl) is compared using laser electrospray mass spectrometry (LEMS) and electrospray ionization-mass spectrometry (ESI-MS). Protonated protein peaks were observed up to a concentration of 250 mM NaCl in the case of LEMS. In the case of ESI-MS, a protein solution with salt concentration > 0.5 mM resulted in predominantly salt-adducted features, with suppression of the protonated protein ions. The constituents in the mixture of proteins were assignable up to 250 mM NaCl for LEMS and were not assignable above a NaCl concentration of 0.5 mM for ESI. The average sodium adducts (< n >) bound to the 7+ charge state of lysozyme for LEMS measurements from salt concentrations of 2.5, 25, 50, and 100 mM NaCl are 1.71, 5.23, 5.26, and 5.11, respectively. The conventional electrospray measurements for lysozyme solution containing salt concentrations of 0.1, 1, 2, and 5 mM NaCl resulted in < n > of 2.65, 6.44, 7.57, and 8.48, respectively. LEMS displays an approximately two orders of magnitude higher salt tolerance in comparison with conventional ESI-MS. The non-equilibrium partitioning of proteins on the surface of the charged droplets is proposed as the mechanism for the high salt tolerance phenomena observed in the LEMS measurements. [Figure not available: see fulltext.

Cannabinoid findings in children hair - what do they really tell us? An assessment in the light of three different analytical methods with focus on interpretation of Δ9-tetrahydrocannabinolic acid A concentrations.

PubMed

Moosmann, Bjoern; Roth, Nadine; Hastedt, Martin; Jacobsen-Bauer, Andrea; Pragst, Fritz; Auwärter, Volker

2015-05-01

Hair analysis for drugs and drugs of abuse is increasingly applied in child protection cases. To determine the potential risk to a child living in a household where drugs are consumed, not only can the hair of the parents be analyzed but also the hair of the child. In the case of hair analysis for cannabinoids, the differentiation between external contamination and systemic uptake is particularly difficult, since the drug is quite often handled extensively prior to consumption (e.g. when preparing a joint) and smoke causes a further risk for an external contamination. Δ9-tetrahydrocannabinolic acid A (THCA-A), the non-psychoactive biogenetic precursor of Δ9-tetrahydrocannabinol (THC), is a suitable marker for external contamination since it is not incorporated into the hair matrix through the bloodstream in relevant amounts. In the presented study, hair samples from 41 children, 4 teenagers, and 34 drug-consuming parents were analyzed for THCA-A, THC and cannabinol (CBN) applying methanolic extraction and a fully validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method (Method 1). For comparison, a part of the samples was also analyzed applying alkaline hydrolysis followed by liquid/liquid extraction and gas chromatography-mass spectrometry (GC-M)S (Method 2), or by headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) (Method 3). Furthermore, 458 seized marihuana samples and 180 seized hashish samples were analyzed for the same cannabinoids by gas-chromatography-flame ionization detector (GC-FID). In all but one of the hair samples, the concentration of THCA-A was higher than the concentration of THC and in 14 cases no THC could be detected despite the presence of THCA-A, suggesting that in almost all cases a significant external contamination had occurred. Within-family comparison showed a higher THCA-A/THC ratio in hair of children than of their consuming caregivers. Mean and median of this ratio of all hair samples (6.7 and 4.2) were between those of marihuana (11.0 and 8.3) and hashish (2.8 and 2.1) with a large variation in all samples. Comparison of the Methods 1 to 3 showed clearly that the choice of the analytical procedure has a strong influence on the quantitative results, mainly because of decarboxylation of THCA-A during hair hydrolysis by NaOH and other analytical steps, which lead to artifactually elevated THC concentrations. In conclusion, these findings suggest that the major part of the cannabinoids detected in the hair samples from children arose from an external contamination through 'passive' transfer by e.g. contaminated hands or surfaces and not from inhalation or deposition of side stream smoke. Copyright © 2014 John Wiley & Sons, Ltd.

Ion Fluxes and Short-Circuit Current in Internally Perfused Cells of Valonia ventricosa

PubMed Central

Gutknecht, John

1967-01-01

Ion transport in the giant celled marine alga, Valonia ventricosa, was studied during internal perfusion and short-circuiting of the vacuole potential. The perfusing and bathing solutions were similar to natural Valonia sap and contained the following concentrations of major ions: Na 51, K 618, and Cl 652 mM. The average short-circuit current (I sc) was 97 pEq/cm2 sec (inward positive current), and the average open-circuit potential difference (PD) was 74 mv (vacuole positive to external solution). Perfused and short-circuited cells showed a small net influx of Na (2.0 pEq/cm2 sec) and large net influxes of K (80 pEq/cm2 sec) and Cl (50 pEq/cm2 sec). Unidirectional K influx was proportional to I sc, but more than one-half of the I sc remained unaccounted for. Both the I sc and PD were partly light-dependent, declining rapidly during the first 1–2 min of darkness. Ouabain (5 x 10-4 M) had little effect on the influx of Na or K and had no effect on I inf or PD. Fluid was absorbed at a rate of about 93 pliter/cm2 sec. Reversing the direction of fluid movement by adding mannitol to the outside solution had little effect on ion movements. The ionic and electrical properties of normal and perfused cells of Valonia are compared. PMID:6050968

Load- and polysaccharide-dependent activation of the Na+-type MotPS stator in the Bacillus subtilis flagellar motor.

PubMed

Terahara, Naoya; Noguchi, Yukina; Nakamura, Shuichi; Kami-Ike, Nobunori; Ito, Masahiro; Namba, Keiichi; Minamino, Tohru

2017-04-05

The flagellar motor of Bacillus subtilis possesses two distinct H + -type MotAB and Na + -type MotPS stators. In contrast to the MotAB motor, the MotPS motor functions efficiently at elevated viscosity in the presence of 200 mM NaCl. Here, we analyzed the torque-speed relationship of the Bacillus MotAB and MotPS motors over a wide range of external loads. The stall torque of the MotAB and MotPS motors at high load was about 2,200 pN nm and 220 pN nm, respectively. The number of active stators in the MotAB and MotPS motors was estimated to be about ten and one, respectively. However, the number of functional stators in the MotPS motor was increased up to ten with an increase in the concentration of a polysaccharide, Ficoll 400, as well as in the load. The maximum speeds of the MotAB and MotPS motors at low load were about 200 Hz and 50 Hz, respectively, indicating that the rate of the torque-generation cycle of the MotPS motor is 4-fold slower than that of the MotAB motor. Domain exchange experiments showed that the C-terminal periplasmic domain of MotS directly controls the assembly and disassembly dynamics of the MotPS stator in a load- and polysaccharide-dependent manner.

Load- and polysaccharide-dependent activation of the Na+-type MotPS stator in the Bacillus subtilis flagellar motor

PubMed Central

Terahara, Naoya; Noguchi, Yukina; Nakamura, Shuichi; Kami-ike, Nobunori; Ito, Masahiro; Namba, Keiichi; Minamino, Tohru

2017-01-01

The flagellar motor of Bacillus subtilis possesses two distinct H+-type MotAB and Na+-type MotPS stators. In contrast to the MotAB motor, the MotPS motor functions efficiently at elevated viscosity in the presence of 200 mM NaCl. Here, we analyzed the torque-speed relationship of the Bacillus MotAB and MotPS motors over a wide range of external loads. The stall torque of the MotAB and MotPS motors at high load was about 2,200 pN nm and 220 pN nm, respectively. The number of active stators in the MotAB and MotPS motors was estimated to be about ten and one, respectively. However, the number of functional stators in the MotPS motor was increased up to ten with an increase in the concentration of a polysaccharide, Ficoll 400, as well as in the load. The maximum speeds of the MotAB and MotPS motors at low load were about 200 Hz and 50 Hz, respectively, indicating that the rate of the torque-generation cycle of the MotPS motor is 4-fold slower than that of the MotAB motor. Domain exchange experiments showed that the C-terminal periplasmic domain of MotS directly controls the assembly and disassembly dynamics of the MotPS stator in a load- and polysaccharide-dependent manner. PMID:28378843

Effect of sucrose ester concentration on the interfacial characteristics and physical properties of sodium caseinate-stabilized oil-in-water emulsions.

PubMed

Zhao, Qiangzhong; Liu, Daolin; Long, Zhao; Yang, Bao; Fang, Min; Kuang, Wanmei; Zhao, Mouming

2014-05-15

The effect of sucrose ester (SE) concentration on interfacial tension and surface dilatational modulus of SE and sodium caseinate (NaCas)-SE solutions were investigated. The critical micelle concentration (CMC) of SE was presumed to be 0.05% by measuring interfacial tension of SE solution. The interfacial tension of NaCas-SE solution decreased with increased SE concentration. A sharp increase in surface dilatational modulus of NaCas solution was observed when 0.01% SE was added and a decline was occurred at higher SE level. The influence of SE concentration on droplet size and confocal micrograph, surface protein concentration, ζ-potential and rheological properties of oil-in-water (O/W) emulsions prepared with 1% NaCas was also examined. The results showed that addition of SE reduced droplet size and surface protein concentration of the O/W emulsions. The ζ-potential of the O/W emulsions increased initially and decreased afterward with increased SE concentration. All the O/W emulsions exhibited a shear-thinning behaviour and the data were well-fitted into the Herschel-Bulkley model. Copyright © 2013 Elsevier Ltd. All rights reserved.

Enhanced gelation of chitosan/β-sodium glycerophosphate thermosensitive hydrogel with sodium bicarbonate and biocompatibility evaluated.

PubMed

Deng, Aipeng; Kang, Xi; Zhang, Jing; Yang, Yang; Yang, Shulin

2017-09-01

The application of chitosan/β-sodium glycerophosphate (β-GP) thermosensitive hydrogel has been limited by the relatively slow gelation, weak mechanical resistance and poor cytocompatibility. In this study, sodium hydrogen carbonate (NaHCO 3 ) was applied with β-GP as gel agents to produce high-strength hydrogel. The hydrogels prepared with high NaHCO 3 concentration or more gel agents showed shorter gelation time, better thermostability, drastically enhanced resistance in compression. Meanwhile, the hydrogels presented obvious porous structures and excellent biocompatibility to HUVEC and NIH 3T3 cultured in vitro with higher NaHCO 3 concentration and moderate concentration of β-GP. Overall, appropriate concentration of β-GP combined with NaHCO 3 can be a good gel regent to improve properties of chitosan thermosensitive hydrogels. Copyright © 2017 Elsevier B.V. All rights reserved.

Salting-out and salting-in: competitive effects of salt on the aggregation behavior of soy protein particles and their emulsifying properties.

PubMed

Xu, Hua-Neng; Liu, Yang; Zhang, Lianfu

2015-08-07

Emulsions stabilized by protein particles have gained increasing research attention due to their combined advantages of biocompatibility and superior stability. In this study, colloidal particles consisting of soy protein isolates (SPIs) prepared through a heat-treatment procedure are used to make oil-in-water emulsions at a protein concentration of 10 g L(-1) and a pH of 5.91. We investigate parallelly the effects of NaCl on the stability and rheological properties of the particle suspensions and their stabilized emulsions at salt concentrations of 0, 100 and 400 mM. The aggregation behavior of the particles is strongly dependent on the NaCl concentration, showing signs of sedimentation at low NaCl concentration (100 mM) but redispersion again at high NaCl concentration (400 mM). The extensive particle aggregation is beneficial to the formation of a continuous interfacial film for the emulsions, and hence results in a remarkable increase of creaming stability and interfacial viscoelastic moduli. The results can be explained in terms of two competitive effects of NaCl: salting-out and salting-in, which are attributed to complex electrostatic interactions between the particles as a function of NaCl concentration. The delicate balance between salting-out and salting-in provides an interesting insight into the nature of underlying protein particle interactions in aqueous suspensions and a possible mechanism for tailoring their emulsifying properties via salt effects.

Evidence for a Na/H Antiporter in Membrane Vesicles Isolated from Roots of the Halophyte Atriplex nummularia.

PubMed

Braun, Y; Hassidim, M; Lerner, H R; Reinhold, L

1988-05-01

The ATP-dependent establishment of a positive membrane potential (measured as S(14)CN(-)-accumulation) in membrane vesicles isolated from the roots of Atriplex nummularia Lindl. was not inhibited by NaMes and KMes at concentrations up to 140 millimolar. On the other hand, the formation of DeltapH (measured as (14)C-methylamine accumulation or quenching of quinacrine fluorescence), was depressed by NaMes concentrations as low as 30 millimolar. Supply of NaMes after the DeltapH had been established brought about partial dissipation within 30 seconds. Extent of dissipation of DeltapH increased with NaMes concentration over the range tested (up to 180 millimolar). The H(+)/Na(+) exchange indicated by these results was not due to the creation of a Na(+) diffusion potential. Formation of DeltapH in these vesicles was stable to NO(3) (-) up to 100 millimolar; further, the dissipating effect of Na(+) supply was apparent on a DeltapH formed in the presence of 30 millimolar NO(3) (-). Additional evidence that the origin of the membrane vesicles observed in this investigation was not the tonoplast and was probably the plasmalemma included the vanadate sensitivity of the establishment of the membrane potential.

Effect of NaCl treatments on glucosinolate metabolism in broccoli sprouts*

PubMed Central

Guo, Rong-fang; Yuan, Gao-feng; Wang, Qiao-mei

2013-01-01

To understand the regulation mechanism of NaCl on glucosinolate metabolism in broccoli sprouts, the germination rate, fresh weight, contents of glucosinolates and sulforaphane, as well as myrosinase activity of broccoli sprouts germinated under 0, 20, 40, 60, 80, and 100 mmol/L of NaCl were investigated in our experiment. The results showed that glucoerucin, glucobrassicin, and 4-hydroxy glucobrassicin in 7-d-old broccoli sprouts were significantly enhanced and the activity of myrosinase was inhibited by 100 mmol/L of NaCl. However, the total glucosinolate content in 7-d-old broccoli sprouts was markedly decreased although the fresh weight was significantly increased after treatment with NaCl at relatively low concentrations (20, 40, and 60 mmol/L). NaCl treatment at the concentration of 60 mmol/L for 5 d maintained higher biomass and comparatively higher content of glucosinolates in sprouts of broccoli with decreased myrosinase activity. A relatively high level of NaCl treatment (100 mmol/L) significantly increased the content of sulforaphane in 7-d-old broccoli sprouts compared with the control. These results indicate that broccoli sprouts grown under a suitable concentration of NaCl could be desirable for human nutrition. PMID:23365011

Surface effects of corrosive media on hardness, friction, and wear of materials

NASA Technical Reports Server (NTRS)

Miyoshi, K.; Buckley, D. H.; Rengstorff, G. W. P.; Ishigaki, H.

1985-01-01

Hardness, friction, and wear experiments were conducted with magnesium oxide exposed to various corrosive media and also with elemental iron and nickel exposed to water and NaOH. Chlorides such as MgCl2 and sodium containing films were formed on cleaved magnesium oxide surfaces. The MgCl2 films softened the magnesium oxide surfaces and caused high friction and great deformation. Hardness was strongly influenced by the pH value of the HCl-containing solution. The lower the pH, the lower the microhardness. Neither the pH value of nor the immersion time in NaOH containing, NaCl containing, and HNO3 containing solutions influenced the microhardness of magnesium oxide. NaOH formed a protective and low friction film on iron surfaces. The coefficient of friction and the wear for iron were low at concentrations of NaOH higher than 0.01 N. An increase in NaOH concentration resulted in a decrease in the concentration of ferric oxide on the iron surface. It took less NaOH to form a protective, low friction film on nickel than on iron.

Assessing the integration of forward osmosis and anaerobic digestion for simultaneous wastewater treatment and resource recovery.

PubMed

Ansari, Ashley J; Hai, Faisal I; Price, William E; Ngo, Huu H; Guo, Wenshan; Nghiem, Long D

2018-07-01

This study assessed the performance and key challenges associated with the integration of forward osmosis (FO) and anaerobic digestion for wastewater treatment and resource recovery. Using a thin film composite polyamide FO membrane, maximising the pre-concentration factor (i.e. system water recovery) resulted in the enrichment of organics and salinity in wastewater. Biomethane potential evaluation indicated that methane production increased correspondingly with the FO pre-concentration factor due to the organic retention in the feed solution. At 90% water recovery, about 10% more methane was produced when using NaOAc compared with NaCl because of the contribution of biodegradable reverse NaOAc flux. No negative impact on anaerobic digestion was observed when wastewater was pre-concentrated ten-fold (90% water recovery) for both draw solutes. Interestingly, the unit cost of methane production using NaOAc was slightly lower than NaCl due to the lower reverse solute flux of NaOAc, although NaCl is a much cheaper chemical. Crown Copyright © 2018. Published by Elsevier Ltd. All rights reserved.

Transepithelial potential in the Magadi tilapia, a fish living in extreme alkalinity.

PubMed

Wood, Chris M; Bergman, Harold L; Bianchini, Adalto; Laurent, Pierre; Maina, John; Johannsson, Ora E; Bianchini, Lucas F; Chevalier, Claudine; Kavembe, Geraldine D; Papah, Michael B; Ojoo, Rodi O

2012-02-01

We investigated the transepithelial potential (TEP) and its responses to changes in the external medium in Alcolapia grahami, a small cichlid fish living in Lake Magadi, Kenya. Magadi water is extremely alkaline (pH = 9.92) and otherwise unusual: titratable alkalinity (290 mequiv L(-1), i.e. HCO(3) (-) and CO(3) (2-)) rather than Cl(-) (112 mmol L(-1)) represents the major anion matching Na(+) = 356 mmol L(-1), with very low concentrations of Ca(2+) and Mg(2+) (<1 mmol L(-1)). Immediately after fish capture, TEP was +4 mV (inside positive), but stabilized at +7 mV at 10-30 h post-capture when experiments were performed in Magadi water. Transfer to 250% Magadi water increased the TEP to +9.5 mV, and transfer to fresh water and deionized water decreased the TEP to -13 and -28 mV, respectively, effects which were not due to changes in pH or osmolality. The very negative TEP in deionized water was attenuated in a linear fashion by log elevations in [Ca(2+)]. Extreme cold (1 vs. 28°C) reduced the positive TEP in Magadi water by 60%, suggesting blockade of an electrogenic component, but did not alter the negative TEP in dilute solution. When fish were transferred to 350 mmol L(-1) solutions of NaHCO(3), NaCl, NaNO(3), or choline Cl, only the 350 mmol L(-1) NaHCO(3) solution sustained the TEP unchanged at +7 mV; in all others, the TEP fell. Furthermore, after transfer to 50, 10, and 2% dilutions of 350 mmol L(-1) NaHCO(3), the TEPs remained identical to those in comparable dilutions of Magadi water, whereas this did not occur with comparable dilutions of 350 mmol L(-1) NaCl-i.e. the fish behaves electrically as if living in an NaHCO(3) solution equimolar to Magadi water. We conclude that the TEP is largely a Na(+) diffusion potential attenuated by some permeability to anions. In Magadi water, the net electrochemical forces driving Na(+) inwards (+9.9 mV) and Cl(-) outwards (+3.4 mV) are small relative to the strong gradient driving HCO(3) (-) inwards (-82.7 mV). Estimated permeability ratios are P (Cl)/P (Na) = 0.51-0.68 and [Formula: see text] = 0.10-0.33. The low permeability to HCO(3) (-) is unusual, and reflects a unique adaptation to life in extreme alkalinity. Cl(-) is distributed close to Nernst equilibrium in Magadi water, so there is no need for lower P (Cl). The higher P (Na) likely facilitates Na(+) efflux through the paracellular pathway. The positive electrogenic component is probably due to active HCO(3) (-) excretion.

Characterization and determination of naphthenic acids species in oil sands process-affected water and groundwater from oil sands development area of Alberta, Canada.

PubMed

Huang, Rongfu; Chen, Yuan; Meshref, Mohamed N A; Chelme-Ayala, Pamela; Dong, Shimiao; Ibrahim, Mohamed D; Wang, Chengjin; Klamerth, Nikolaus; Hughes, Sarah A; Headley, John V; Peru, Kerry M; Brown, Christine; Mahaffey, Ashley; Gamal El-Din, Mohamed

2018-01-01

This work reports the monitoring and assessment of naphthenic acids (NAs) in oil sands process-affected water (OSPW), Pleistocene channel aquifer groundwater (PLCA), and oil sands basal aquifer groundwater (OSBA) from an active oil sands development in Alberta, Canada, using ultra performance liquid chromatography time-of-flight mass spectrometry (UPLC-TOF-MS) analysis with internal standard (ISTD) and external standard (ESTD) calibration methods and Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) for compositional analysis. PLCA was collected at 45-51 m depth and OSBA was collected at 67-144 m depth. Results of O x -NA concentrations follow an order as OSPW > OSBA > PLCA, indicating that occurrences of NAs in OSBA were likely related to natural bitumen deposits instead of OSPW. Liquid-liquid extraction (LLE) was applied to avoid the matrix effect for the ESTD method. Reduced LLE efficiency accounted for the divergence of the ISTD and ESTD calibrated results for oxidized NAs. Principle component analysis results of O 2 and O 4 species could be employed for differentiation of water types, while classical NAs with C13-15 and Z (-4)-(-6) and aromatic O 2 -NAs with C16-18 and Z (-14)-(-16) could be measured as marker compounds to characterize water sources and potential temporal variations of samples, respectively. FTICR-MS results revealed that compositions of NA species varied greatly among OSPW, PLCA, and OSBA, because of NA transfer and transformation processes. This work contributed to the understanding of the concentration and composition of NAs in various types of water, and provided a useful combination of analytical and statistical tools for monitoring studies, in support of future safe discharge of treated OSPW. Copyright © 2017 Elsevier Ltd. All rights reserved.

Excretion of NaCl and KCl loads in mosquitoes. 2. Effects of the small molecule Kir channel modulator VU573 and its inactive analog VU342

PubMed Central

Rouhier, Matthew F.; Hine, Rebecca M.; Park, Seokhwan Terry; Raphemot, Rene; Denton, Jerod; Piermarini, Peter M.

2014-01-01

The effect of two small molecules VU342 and VU573 on renal functions in the yellow fever mosquito Aedes aegypti was investigated in vitro and in vivo. In isolated Malpighian tubules, VU342 (10 μM) had no effect on the transepithelial secretion of Na+, K+, Cl−, and water. In contrast, 10 μM VU573 first stimulated and then inhibited the transepithelial secretion of fluid when the tubules were bathed in Na+-rich or K+-rich Ringer solution. The early stimulation was blocked by bumetanide, suggesting the transient stimulation of Na-K-2Cl cotransport, and the late inhibition of fluid secretion was consistent with the known block of AeKir1, an Aedes inward rectifier K+ channel, by VU573. VU342 and VU573 at a hemolymph concentration of about 11 μM had no effect on the diuresis triggered by hemolymph Na+ or K+ loads. VU342 at a hemolymph concentration of 420 μM had no effect on the diuresis elicited by hemolymph Na+ or K+ loads. In contrast, the same concentration of VU573 significantly diminished the Na+ diuresis by inhibiting the urinary excretion of Na+, Cl−, and water. In K+-loaded mosquitoes, 420 μM VU573 significantly diminished the K+ diuresis by inhibiting the urinary excretion of K+, Na+, Cl−, and water. We conclude that 1) the effects of VU573 observed in isolated Malpighian tubules are overwhelmed in vivo by the diuresis triggered with the coinjection of Na+ and K+ loads, and 2) at a hemolymph concentration of 420 μM VU573 affects Kir channels systemically, including those that might be involved in the release of diuretic hormones. PMID:25056106

Enteral administration of monosodium phosphate, monopotassium phosphate and monocalcium phosphate for the treatment of hypophosphataemia in lactating dairy cattle.

PubMed

Idink, M J; Grünberg, W

2015-05-09

Hypohosphataemia is a frequent finding in early lactating and anorectic dairy cows. Sodium phosphate is commonly used for oral phosphorus (P) supplementation, although other phosphate salts may present useful treatment alternatives. Objectives of this study were to compare the efficacy of monopotassium phosphate (KH2PO4) and monocalcium phosphate (Ca(H2PO4)2) to monosodium phosphate (NaH2PO4) in P-depleted cows. Furthermore, the effect of concentrated NaH2PO4 on the reticular groove reflex was studied. Six healthy but P-depleted dairy cows underwent four treatments in randomised order. Treatments consisted of intraruminal administration of NaH2PO4, KH2PO4 and Ca(H2PO4)2 providing the equivalent of 60 g P. A fourth treatment consisting of concentrated NaH2PO4 combined with acetaminophen as a marker substance was administered orally to determine whether the reticular groove reflex could be induced. Intraruminal administration of NaH2PO4 and KH2PO4 resulted in similar increases in plasma Pi concentrations ([Pi]) while intraruminal Ca(H2PO4)2 resulted in lower increases in plasma [Pi]. Oral and intraruminal administration of NaH2PO4 resulted in similar times to peak plasma [Pi] and acetaminophen concentration, indicating that concentrated NaH2PO4 administered orally did not trigger the reticular groove reflex. These results suggest that oral administration of KH2PO4 is equally effective as NaH2PO4. Oral administration of Ca(H2PO4)2 in contrast has a less pronounced effect on the plasma [Pi]. British Veterinary Association.

SABRE: A New NaI(T1) Dark Matter Direct Detection Experiment

NASA Astrophysics Data System (ADS)

Shields, Emily; Xu, Jingke; Calaprice, Frank

SABRE (Sodium-iodide with Active Background REjection) is a new NaI(Tl) experiment designed to test the DAMA/LIBRA claim for a positive WIMP-dark matter annual modulation signal. SABRE will consist of highly pure NaI(Tl) crystals in an active liquid scintillator veto that will be placed deep underground. The scintillator vessel will provide a veto against external backgrounds and those arising from detector components, especially the 3 keV signature from the decay of 40K in the crystal. Through the use of crystal purification techniques and the veto, we aim for a 40K background significantly lower than that of the DAMA/LIBRA experiment. We present our work developing low-background NaI(Tl) crystals using a highly pure NaI powder and the development of the veto.

Effect of Maillard Reacted Peptides on Human Salt Taste and the Amiloride-Insensitive Salt Taste Receptor (TRPV1t)

PubMed Central

Katsumata, Tadayoshi; Nakakuki, Hiroko; Tokunaga, Chikara; Fujii, Noboru; Egi, Makoto; Phan, Tam-Hao T.; Mummalaneni, Shobha; DeSimone, John A.

2008-01-01

Maillard reacted peptides (MRPs) were synthesized by conjugating a peptide fraction (1000–5000 Da) purified from soy protein hydrolyzate with galacturonic acid, glucosamine, xylose, fructose, or glucose. The effect of MRPs was investigated on human salt taste and on the chorda tympani (CT) taste nerve responses to NaCl in Sprague–Dawley rats, wild-type, and transient receptor potential vanilloid 1 (TRPV1) knockout mice. MRPs produced a biphasic effect on human salt taste perception and on the CT responses in rats and wild-type mice in the presence of NaCl + benzamil (Bz, a blocker of epithelial Na+ channels), enhancing the NaCl response at low concentrations and suppressing it at high concentrations. The effectiveness of MRPs as salt taste enhancers varied with the conjugated sugar moiety: galacturonic acid = glucosamine > xylose > fructose > glucose. The concentrations at which MRPs enhanced human salt taste were significantly lower than the concentrations of MRPs that produced increase in the NaCl CT response. Elevated temperature, resiniferatoxin, capsaicin, and ethanol produced additive effects on the NaCl CT responses in the presence of MRPs. Elevated temperature and ethanol also enhanced human salt taste perception. N-(3-methoxyphenyl)-4-chlorocinnamid (a blocker of TRPV1t) inhibited the Bz-insensitive NaCl CT responses in the absence and presence of MRPs. TRPV1 knockout mice demonstrated no Bz-insensitive NaCl CT response in the absence or presence of MRPs. The results suggest that MRPs modulate human salt taste and the NaCl + Bz CT responses by interacting with TRPV1t. PMID:18603652

The toxic effect of sodium fluoride on Spodoptera frugiperda 9 cells and differential protein analysis following NaF treatment of cells.

PubMed

Zuo, Huan; Chen, Liang; Kong, Ming; Yang, Yanhua; Lü, Peng; Qiu, Lipeng; Wang, Qiang; Ma, Shangshang; Chen, Keping

2018-05-01

Accumulation of excess fluoride has a destructive effect on the environment, endangering human health, affecting organism growth and development, and leading to damage to the biological chain, thereby affecting ecological environment balance. In recent years, numerous studies focused on the molecular mechanisms associated with fluoride toxicity; however, fluoride-toxicity mechanisms in insect cells remain unclear. This study explored the toxic impact of sodium fluoride (NaF) on Spodoptera frugiperda 9 (Sf9) insect cells. High concentrations of NaF (10 -4  M, 10 -3  M and 10 -2  M) resulted in cell enlargement, cell membrane blurring and breakage, and release of cellular contents. Dose-response curves indicated that NaF-specific inhibition rates on Sf9-cell activity increased along with increases in NaF concentration, with a half-inhibitory concentration (IC 50 ) for NaF of 5.919 × 10 -3  M at 72 h. Compared with controls, the percentages of early and late apoptotic and necrotic cells clearly increased based on observed increases in NaF concentrations. Two-dimensional gel electrophoresis combined with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was used to detect differentially expressed proteins in Sf9 cells treated with IC 50 NaF, identifying 17 proteins, seven of which were upregulated and 10 downregulated. These results demonstrated that Sf9 cells showed signs of NaF-mediated toxicity through alterations in cell morphology, apoptosis rates, and protein expression. Copyright © 2018 Elsevier Ltd. All rights reserved.

K+ Excretion: The Other Purpose for Puddling Behavior in Japanese Papilio Butterflies

PubMed Central

2015-01-01

To elucidate the purpose of butterfly puddling, we measured the amounts of Na+, K+, Ca2+, and Mg2+ that were absorbed or excreted during puddling by male Japanese Papilio butterflies through a urine test. All of the butterflies that sipped water with a Na+ concentration of 13 mM absorbed Na+ and excreted K+, although certain butterflies that sipped solutions with high concentrations of Na+ excreted Na+. According to the Na+ concentrations observed in naturally occurring water sources, water with a Na+ concentration of up to 10 mM appears to be optimal for the health of male Japanese Papilio butterflies. The molar ratio of K+ to Na+ observed in leaves was 43.94 and that observed in flower nectars was 10.93. The Na+ amount in 100 g of host plant leaves ranged from 2.11 to 16.40 mg, and the amount in 100 g of flower nectar ranged from 1.24 to 108.21 mg. Differences in host plants did not explain the differences in the frequency of puddling observed for different Japanese Papilio species. The amounts of Na+, K+, Ca2+, and Mg2+ in the meconium of both male and female butterflies were also measured, and both males and females excreted more K+ than the other three ions. Thus, the fluid that was excreted by butterflies at emergence also had a role in the excretion of the excessive K+ in their bodies. The quantities of Na+ and K+ observed in butterfly eggs were approximately 0.50 μg and 4.15 μg, respectively; thus, female butterflies required more K+ than male butterflies. Therefore, female butterflies did not puddle to excrete K+. In conclusion, the purpose of puddling for male Papilio butterflies is not only to absorb Na+ to correct deficiencies but also to excrete excessive K+. PMID:25955856

K+ excretion: the other purpose for puddling behavior in Japanese Papilio butterflies.

PubMed

Inoue, Takashi A; Ito, Tetsuo; Hagiya, Hiroshi; Hata, Tamako; Asaoka, Kiyoshi; Yokohari, Fumio; Niihara, Kinuko

2015-01-01

To elucidate the purpose of butterfly puddling, we measured the amounts of Na+, K+, Ca2+, and Mg2+ that were absorbed or excreted during puddling by male Japanese Papilio butterflies through a urine test. All of the butterflies that sipped water with a Na+ concentration of 13 mM absorbed Na+ and excreted K+, although certain butterflies that sipped solutions with high concentrations of Na+ excreted Na+. According to the Na+ concentrations observed in naturally occurring water sources, water with a Na+ concentration of up to 10 mM appears to be optimal for the health of male Japanese Papilio butterflies. The molar ratio of K+ to Na+ observed in leaves was 43.94 and that observed in flower nectars was 10.93. The Na+ amount in 100 g of host plant leaves ranged from 2.11 to 16.40 mg, and the amount in 100 g of flower nectar ranged from 1.24 to 108.21 mg. Differences in host plants did not explain the differences in the frequency of puddling observed for different Japanese Papilio species. The amounts of Na+, K+, Ca2+, and Mg2+ in the meconium of both male and female butterflies were also measured, and both males and females excreted more K+ than the other three ions. Thus, the fluid that was excreted by butterflies at emergence also had a role in the excretion of the excessive K+ in their bodies. The quantities of Na+ and K+ observed in butterfly eggs were approximately 0.50 μg and 4.15 μg, respectively; thus, female butterflies required more K+ than male butterflies. Therefore, female butterflies did not puddle to excrete K+. In conclusion, the purpose of puddling for male Papilio butterflies is not only to absorb Na+ to correct deficiencies but also to excrete excessive K+.

Studies of anions sorption on natural zeolites.

PubMed

Barczyk, K; Mozgawa, W; Król, M

2014-12-10

This work presents results of FT-IR spectroscopic studies of anions-chromate, phosphate and arsenate - sorbed from aqueous solutions (different concentrations of anions) on zeolites. The sorption has been conducted on natural zeolites from different structural groups, i.e. chabazite, mordenite, ferrierite and clinoptilolite. The Na-forms of sorbents were exchanged with hexadecyltrimethylammonium cations (HDTMA(+)) and organo-zeolites were obtained. External cation exchange capacities (ECEC) of organo-zeolites were measured. Their values are 17mmol/100g for chabazite, 4mmol/100g for mordenite and ferrierite and 10mmol/100g for clinoptilolite. The used initial inputs of HDTMA correspond to 100% and 200% ECEC of the minerals. Organo-modificated sorbents were subsequently used for immobilization of mentioned anions. It was proven that aforementioned anions' sorption causes changes in IR spectra of the HDTMA-zeolites. These alterations are dependent on the kind of anions that were sorbed. In all cases, variations are due to bands corresponding to the characteristic Si-O(Si,Al) vibrations (occurring in alumino- and silicooxygen tetrahedra building spatial framework of zeolites). Alkylammonium surfactant vibrations have also been observed. Systematic changes in the spectra connected with the anion concentration in the initial solution have been revealed. The amounts of sorbed CrO4(2-), AsO4(3-) and PO4(3-) ions were calculated from the difference between their concentrations in solutions before (initial concentration) and after (equilibrium concentration) sorption experiments. Concentrations of anions were determined by spectrophotometric method. Copyright © 2014 Elsevier B.V. All rights reserved.

Priming for immunologic memory in adults by meningococcal group C conjugate vaccination.

PubMed

Vu, David M; de Boer, Alberdina W; Danzig, Lisa; Santos, George; Canty, Bridget; Flores, Betty M; Granoff, Dan M

2006-06-01

Meningococcal group C polysaccharide-protein conjugate vaccines (MCV) prime infants and children for memory anticapsular responses upon subsequent exposure to unconjugated polysaccharide. The objective of this study was to determine whether MCV primes vaccine-naïve adults and adults previously vaccinated with meningococcal polysaccharide vaccine (MPSV) for memory antibody responses. Meningococcal vaccine-naïve adults were randomized to receive either MCV (MCV/naïve group) (n = 35) or pneumococcal conjugate vaccine (PCV) (PCV/naïve group) (n = 34). Participants with a history of receiving MPSV were given MCV (MCV/MPSV group) (n = 26). All subjects were challenged 10 months later with one-fifth of the usual dose of MPSV (10 mug of each polysaccharide). Sera were obtained before the conjugate vaccination and before and 7 days after the MPSV challenge and assayed for immunoglobulin G (IgG) anticapsular antibody concentrations and bactericidal titers. The MCV/naïve group had 7- to 10-fold-higher serum IgG and bactericidal responses after the MPSV challenge than the PCV/naïve group (P < 0.001). The increases (n-fold) in anticapsular antibody concentrations in the MCV/naïve group were greatest in subjects with antibody concentrations of 2 microg/ml before the challenge; P < 0.0001). Only 3 of 11 MCV-vaccinated subjects who had received MPSV before enrollment and who had antibody concentrations of

Effects of lead on Na+, K+-ATPase and hemolymph ion concentrations in the freshwater mussel Elliptio complanata

USGS Publications Warehouse

Mosher, Shad; Cope, W. Gregory; Weber, Frank X.; Shea, Damian; Kwak, Thomas J.

2012-01-01

Freshwater mussels are an imperiled fauna exposed to a variety of environmental toxicants such as lead (Pb) and studies are urgently needed to assess their health and condition to guide conservation efforts. A 28-day laboratory toxicity test with Pb and adult Eastern elliptio mussels (Elliptio complanata) was conducted to determine uptake kinetics and to assess the toxicological effects of Pb exposure. Test mussels were collected from a relatively uncontaminated reference site and exposed to a water-only control and five concentrations of Pb (as lead nitrate) ranging from 1 to 245 mu g/L in a static renewal test with a water hardness of 42 mg/L. Endpoints included tissue Pb concentrations, hemolymph Pb and ion (Na+, K+, Cl-, Ca2+) concentrations, and Na+, K+-ATPase enzyme activity in gill tissue. Mussels accumulated Pb rapidly, with tissue concentrations increasing at an exposure-dependent rate for the first 2 weeks, but with no significant increase from 2 to 4 weeks. Mussel tissue Pb concentrations ranged from 0.34 to 898 mu g/g dry weight, were strongly related to Pb in test water at every time interval (7, 14, 21, and 28 days), and did not significantly increase after day 14. Hemolymph Pb concentration was variable, dependent on exposure concentration, and showed no appreciable change with time beyond day 7, except for mussels in the greatest exposure concentration (245 mu g/L), which showed a significant reduction in Pb by 28 days, suggesting a threshold for Pb binding or elimination in hemolymph at concentrations near 1000 mu g/g. The Na+, K+-ATPase activity in the gill tissue of mussels was significantly reduced by Pb on day 28 and was highly correlated with tissue Pb concentration (R2 = 0.92; P = 0.013). The Na+, K+-ATPase activity was correlated with reduced hemolymph Na+ concentration at the greatest Pb exposure when enzyme activity was at 30% of controls. Hemolymph Ca2+ concentration increased significantly in mussels from the greatest Pb exposure and may be due to remobilization from the shell in an attempt to buffer the hemolymph against Pb uptake and toxicity. We conclude that Na+, K+-ATPase activity in mussels was adversely affected by Pb exposure, however, because the effects on activity were variable at the lower test concentrations, additional research is warranted over this range of exposures. (C) 2010 Wiley Periodicals, Inc. Environ Toxicol, 2012.

Lab-Scale Study of the Calcium Carbonate Dissolution and Deposition by Marine Cyanobacterium Phormidium subcapitatum

NASA Technical Reports Server (NTRS)

Karakis, S. G.; Dragoeva, E. G.; Lavrenyuk, T. I.; Rogochiy, A.; Gerasimenko, L. M.; McKay, D. S.; Brown, I. I.

2006-01-01

Suggestions that calcification in marine organisms changes in response to global variations in seawater chemistry continue to be advanced (Wilkinson, 1979; Degens et al. 1985; Kazmierczak et al. 1986; R. Riding 1992). However, the effect of [Na+] on calcification in marine cyanobacteria has not been discussed in detail although [Na+] fluctuations reflect both temperature and sea-level fluctuations. The goal of these lab-scale studies therefore was to study the effect of environmental pH and [Na+] on CaCO3 deposition and dissolution by marine cyanobacterium Phormidium subcapitatum. Marine cyanobacterium P. subcapitatum has been cultivated in ASN-III medium. [Ca2+] fluctuations were monitored with Ca(2+) probe. Na(+) concentrations were determined by the initial solution chemistry. It was found that the balance between CaCO3 dissolution and precipitation induced by P. subcapitatum grown in neutral ASN III medium is very close to zero. No CaCO3 precipitation induced by cyanobacterial growth occurred. Growth of P. subcapitatum in alkaline ASN III medium, however, was accompanied by significant oscillations in free Ca(2+) concentration within a Na(+) concentration range of 50-400 mM. Calcium carbonate precipitation occurred during the log phase of P. subcapitatum growth while carbonate dissolution was typical for the stationary phase of P. subcapitatum growth. The highest CaCO3 deposition was observed in the range of Na(+) concentrations between 200-400 mM. Alkaline pH also induced the clamping of P. subcapitatum filaments, which appeared to have a strong affinity to envelop particles of chemically deposited CaCO3 followed by enlargement of those particles size. EDS analysis revealed the presence of Mg-rich carbonate (or magnesium calcite) in the solution containing 10-100 mM Na(+); calcite in the solution containing 200 mM Na(+); and aragonite in the solution containing with 400 mM Na(+). Typical present-day seawater contains xxmM Na(+). Early (Archean) seawater was likely less saline. The division of marine cyanobacterium P. subcapitatum is associated with periodic deposition and dissolution of CaCO3, the rhythms and intensity of which are dependent on concentrations of both OH(-) and Na(+). Thus, the role of present-day marine cyanobacteria in the global carbonate cycle might be reduced to aggregation and recrystallization of available CaCO3 particles in marine water rather than long-term precipitation and accumulation of CaCO3 deposits. For lower Na(+) concentrations, precipitation of carbonates by cyanobacteria would be even less significant. These results suggest that the lack of calcified cyanobacteria in stromatalite-bearing Precambrian sequences can be explained not only by high dissolved inorganic carbon concentrations but also by lower salinity, as well as possible lower pH compared to present-day oceans.

Quadratic general rotary unitized design for doping concentrations and up-conversion luminescence properties of Er{sup 3+}/Yb{sup 3+} co-doped NaLa(MoO{sub 4}){sub 2} phosphors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Jiashi, E-mail: sunjs@dlmu.edu.cn; Shi, Linlin; Li, Shuwei

Highlights: • NaLa(MoO4)2: Er3+/Yb3+ phosphor is synthesized by solid state method. • QGRUD is first applied to the codoping concentration option. • Optimized phosphor presents more stable UC emissions than the commercial phosphor. - Abstract: It is still a great challenge that designing proper codoping concentrations of rare earth ions for achieving intensest expected emission from the studied phosphor. In this work, the quadratic general rotary unitized design (QGRUD) was introduced into the codoping concentration option of NaLa(MoO{sub 4}){sub 2}: Er{sup 3+}/Yb{sup 3+} phosphor for upconversion (UC) applications, and the optimum doping concentrations of Er{sup 3+} and Yb{sup 3+} formore » achieving maximum UC luminescence intensity, which is close to commercial NaYF{sub 4}:Er{sup 3+}/Yb{sup 3+} phosphor, were obtained. The two-photon process was assigned to the green UC emissions in the optimized NaLa(MoO{sub 4}){sub 2}: Er{sup 3+}/Yb{sup 3+} phosphor. It was also demonstrated that the optimized phosphor presented more stable upconversion emissions than the commercial NaYF{sub 4}:Er{sup 3+}/Yb{sup 3+} phosphor.« less

Hourly oral sodium chloride for the rapid and predictable treatment of hyponatremia.

PubMed

Kerns, Eric; Patel, Shweta; Cohen, David M

2014-12-01

Hypertonic NaCl is first-line therapy for acute, severe and symptomatic hyponatremia; however, its use is often restricted to the intensive care unit (ICU). A 35-year-old female inpatient with an optic chiasm glioma and ventriculoperitoneal shunt for hydrocephalus developed acute hyponatremia (sodium 122 mEq/l) perhaps coinciding with haloperidol treatment. The sum of her urinary sodium and potassium concentrations was markedly hypertonic vis-à-vis plasma; it was inferred that serum sodium concentration would continue to fall even in the complete absence of fluid intake. Intravenous (i.v.) 3% NaCl was recommended; however, a city-wide public health emergency precluded her transfer to the ICU. She was treated with hourly oral NaCl tablets in a dose calculated to deliver the equivalent of 0.5 ml/kg/h of 3% NaCl with an objective of increasing the serum sodium concentration by 6 mEq/l. She experienced a graded and predictable increase in serum sodium concentration. A slight overshoot to 129 mEq/l was rapidly corrected with 0.25 l of D5W, and she stabilized at 127 mEq/l. We conclude that hourly oral NaCl, in conjunction with careful monitoring of the serum sodium concentration, may provide an attractive alternative to i.v. 3% NaCl for selected patients with severe hyponatremia.

Naphthenic acids removal from high TDS produced water by persulfate mediated iron oxide functionalized catalytic membrane, and by nanofiltration.

PubMed

Aher, Ashish; Papp, Joseph; Colburn, Andrew; Wan, Hongyi; Hatakeyama, Evan; Prakash, Prakhar; Weaver, Ben; Bhattacharyya, Dibakar

2017-11-01

Oil industries generate large amounts of produced water containing organic contaminants, such as naphthenic acids (NA) and very high concentrations of inorganic salts. Recovery of potable water from produced water can be highly energy intensive is some cases due to its high salt concentration, and safe discharge is more suitable. Here, we explored catalytic properties of iron oxide (Fe x O y nanoparticles) functionalized membranes in oxidizing NA from water containing high concentrations of total dissolved solids (TDS) using persulfate as an oxidizing agent. Catalytic decomposition of persulfate by Fe x O y functionalized membranes followed pseudo-first order kinetics with an apparent activation energy of 18 Kcal/mol. Fe x O y functionalized membranes were capable of lowering the NA concentrations to less than discharge limits of 10 ppm at 40 °C. Oxidation state of iron during reaction was quantified. Membrane performance was investigated for extended period of time. A coupled process of advanced oxidation catalyzed by membrane and nanofiltration was also evaluated. Commercially available nanofiltration membranes were found capable of retaining NA from water containing high concentrations of dissolved salts. Commercial NF membranes, Dow NF270 (Dow), and NF8 (Nanostone) had NA rejection of 79% and 82%, respectively. Retentate for the nanofiltration was further treated with advanced oxidation catalyzed by Fe x O y functionalized membrane for removal of NA.

Phorbol esters inhibit smooth muscle contractions through activation of Na(+)-K(+)-ATPase.

PubMed Central

Sasaguri, T.; Watson, S. P.

1990-01-01

1. The role of protein kinase C (PKC) in agonist-induced contractions of guinea-pig ileum longitudinal smooth muscle has been investigated. 2. The phorbol esters, phorbol 12,13-dibutyrate (PDBu), phorbol 12,13-diacetate (PDA) and phorbol 12-myristate 13-acetate (PMA), relaxed tissues precontracted by submaximal concentrations of carbachol, histamine or substance P. 3. This inhibitory action of the phorbol esters was reversed following the application of ouabain, a specific inhibitor of Na(+)-K(+)-ATPase. Similarly, pretreatment with ouabain inhibited the ability of phorbol esters to relax tissues precontracted by the above agonists. 4. The slow relaxation of the tonic component of contraction induced by submaximal concentrations of carbachol and histamine, and all concentrations of substance P, was abolished in the presence of ouabain. 5. In Na(+)-loaded tissues, PDBu and carbachol caused a concentration-dependent increase of Na(+)-K(+)-ATPase activity, assessed by ouabain-sensitive 86Rb(+)-uptake. Extrusion of Na+, assessed by the cellular content of the ion, was also stimulated by PDBu (the effect of carbachol was not investigated). 6. We conclude that phorbol esters inhibit the tonic component of contractions induced by submaximal concentrations of these agonists through activation of Na(+)-K(+)-ATPase. We suggest that PKC may exert feedback control over the tonic component of agonist contractions through stimulation of the pump. PMID:1691673

Passive transport and binding of lead by human red blood cells.

PubMed

Simons, T J

1986-09-01

The uptake of Pb into human red blood cells has been studied using Pb buffers. Passive Pb movements can be studied conveniently when the cells are depleted of adenosine 5'-triphosphate (ATP), to eliminate active transport, and of inorganic phosphate, to prevent precipitation of lead phosphate. Pb can cross the membrane passively in either direction. Influx and efflux show similar properties. Passive Pb transport is strongly stimulated by HCO3-, and is reduced by replacing Cl- with ClO4-. It is inhibited by low concentrations of 4-acetamido-4'-isothiocyanostilbene-2,2'-disulphonic acid (SITS) and 4,4'-diisothiocyanostilbene-2.2'-disulphonic acid (DIDS), characteristic inhibitors of anion transport. Pb uptake is unaffected by varying the external concentrations of Na+, K+ and Ca2+. When Pb enters the cell, it binds mainly to haemoglobin. The ratio of bound Pb:free Pb2+ in the cytosol is estimated to be 6000:1. Pb binding to haemoglobin is unaffected by oxygenation. Binding to albumin is quantitatively similar to binding to haemoglobin. The implications of these results for the transport and binding of Pb in the blood are discussed.

Functional coupling between the Na+/Ca2+ exchanger and nonselective cation channels during histamine stimulation in guinea pig tracheal smooth muscle.

PubMed

Algara-Suárez, Paola; Romero-Méndez, Catalina; Chrones, Tom; Sánchez-Armass, Sergio; Meza, Ulises; Sims, Stephen M; Espinosa-Tanguma, Ricardo

2007-07-01

Airway smooth muscle (ASM) contracts partly due to an increase in cytosolic Ca(2+). In this work, we found that the contraction caused by histamine depends on external Na(+), possibly involving nonselective cationic channels (NSCC) and the Na(+)/Ca(2+) exchanger (NCX). We performed various protocols using isometric force measurement of guinea pig tracheal rings stimulated by histamine. We observed that force reached 53 +/- 1% of control during external Na(+) substitution by N-methyl-D-glucamine(+), whereas substitution by Li(+) led to no significant change (91 +/- 1%). Preincubation with KB-R7943 decreased the maximal force developed (52.3 +/- 5.6%), whereas preincubation with nifedipine did not (89.7 +/- 1.8%). Also, application of the nonspecific NCX blocker KB-R7943 and nifedipine on histamine-precontracted tracheal rings reduced force to 1 +/- 3%, significantly different from nifedipine alone (49 +/- 6%). Moreover, nonspecific NSCC inhibitors SKF-96365 and 2-aminoethyldiphenyl borate reduced force to 1 +/- 1% and 19 +/- 7%, respectively. Intracellular Ca(2+) measurements in isolated ASM cells showed that KB-R7943 and SKF-96365 reduced the peak and sustained response to histamine (0.20 +/- 0.1 and 0.19 +/- 0.09 for KB-R, 0.43 +/- 0.16 and 0.47 +/- 0.18 for SKF, expressed as mean of differences). Moreover, Na(+)-free solution only inhibited the sustained response (0.54 +/- 0.25). These data support an important role for NSCC and NCX during histamine stimulation. We speculate that histamine induces Na(+) influx through NSCC that promotes the Ca(2+) entry mode of NCX and Ca(V)1.2 channel activation, thereby causing contraction.

Multi-shell model of ion-induced nucleic acid condensation

NASA Astrophysics Data System (ADS)

Tolokh, Igor S.; Drozdetski, Aleksander V.; Pollack, Lois; Baker, Nathan A.; Onufriev, Alexey V.

2016-04-01

We present a semi-quantitative model of condensation of short nucleic acid (NA) duplexes induced by trivalent cobalt(iii) hexammine (CoHex) ions. The model is based on partitioning of bound counterion distribution around single NA duplex into "external" and "internal" ion binding shells distinguished by the proximity to duplex helical axis. In the aggregated phase the shells overlap, which leads to significantly increased attraction of CoHex ions in these overlaps with the neighboring duplexes. The duplex aggregation free energy is decomposed into attractive and repulsive components in such a way that they can be represented by simple analytical expressions with parameters derived from molecular dynamic simulations and numerical solutions of Poisson equation. The attractive term depends on the fractions of bound ions in the overlapping shells and affinity of CoHex to the "external" shell of nearly neutralized duplex. The repulsive components of the free energy are duplex configurational entropy loss upon the aggregation and the electrostatic repulsion of the duplexes that remains after neutralization by bound CoHex ions. The estimates of the aggregation free energy are consistent with the experimental range of NA duplex condensation propensities, including the unusually poor condensation of RNA structures and subtle sequence effects upon DNA condensation. The model predicts that, in contrast to DNA, RNA duplexes may condense into tighter packed aggregates with a higher degree of duplex neutralization. An appreciable CoHex mediated RNA-RNA attraction requires closer inter-duplex separation to engage CoHex ions (bound mostly in the "internal" shell of RNA) into short-range attractive interactions. The model also predicts that longer NA fragments will condense more readily than shorter ones. The ability of this model to explain experimentally observed trends in NA condensation lends support to proposed NA condensation picture based on the multivalent "ion binding shells."

Small synthetic peptides homologous to segments of the first external loop of occludin impair tight junction resealing.

PubMed

Lacaz-Vieira, F; Jaeger, M M; Farshori, P; Kachar, B

1999-04-01

This study shows that resealing of opened tight junctions (TJs) is impaired by interaction with oligopeptides homologous to the external domain of chick occludin. The experiments were carried out with confluent A6 cell monolayers grown on collagen supports under stable transepithelial electrical resistance (TER). The monolayers were bathed on the apical side with a 75 mm KCl solution and on the basolateral side by NaCl-Ringer's solution. TJ opening was induced by basolateral Ca2+ removal and was characterized by a marked drop of TER. The reintroduction of Ca2+ triggered junction resealing as indicated by an elevation of TER to control values. Custom-made peptides SNYYGSGLSY (corresponding to the residues 100 to 109) and SNYYGSGLS (residues 100 to 108), homologous to segments of the first external loop of chick occludin molecule, impaired junction resealing when the peptides were included in the apical bathing fluid (concentrations in the range of 0.5 to 1.5 mg/ml). Peptide removal from the apical solution usually triggered a slow recovery of TER, indicating a slow recovery of the TJ seal. Changes in localization of ZO-1, a cytoplasmic protein that underlies the membrane at the TJs, were evaluated immunocytochemically following Ca2+ removal and reintroduction. The presence or absence of the oligopeptides showed no influence on the pattern of change of ZO-1 localization. These observations support the hypothesis that the TJ seal results from the interaction of specific homologous segments of occludin on the surface of adjacent cells. Additionally, our results show that small peptides homologous to segments of the occludin first external loop can be used as specific reagents to manipulate the permeability of tight junctions.

Sodium-iodine symporter gene expression controlled by the EGR-1 promoter: biodistribution, imaging and in vitro radionuclide therapy with Na(131)I.

PubMed

Tang, Jun; Wang, Xiaoxia; Xu, Yuanqi; Shi, Yizhen; Liu, Zengli; Yang, Yi

2015-02-01

The objective of this study is to explore the feasibility of radioiodine treatment for cervical cancer using the early growth response (Egr-1) promoter to control sodium-iodine symporter (hNIS) gene expression. The hNIS gene was previously transfected into Hela cells under the control of either the cytomegalovirus (CMV) or Egr-1 promoters. Na(125)I uptake was measured in the presence or absence of NaClO4. Na(125)I efflux was measured. The effects of external beam radiation on iodine uptake and retention were studied. The cytotoxic effects of (131)I were measured by clonogenic assay. The Na(125)I biodistribution was obtained using mice bearing control and transfected cells. The %ID/g of tumor and major organs were obtained for a range of times up to 48 hours post injection and the ratio of tumor to non-tumor activity (T/NT) was calculated. Tumors were imaged with Na(131)I and (99m)TcO4 (-), and the ratio of tumor to background activity (T/B) was calculated. Na(125)I uptake in Hela cells was minimal in the absence of hNIS. Uptake in the transfected cells was strong, and could be blocked by NaClO4. The iodine uptake of Hela-Egr-1-hNIS cells increased after the irradiation, and the magnitude of this effect approximately matched the radiation dose delivered. The efflux of 125I was affected by neither the promoter sequence nor pre-irradiation. (131)I reduced the clonogenic survival of symporter expressing cells, relative to the parental line. The effect was greatest in cells where hNIS was driven by the CMV promoter. Tumors formed from Hela-Egr-1-hNIS concentrated Na(125)I over a 12 hour period, in contrast to untransfected cells. These tumors could also be successfully imaged using either Na(131)I or (99m)TcO4 (-). (131)I uptake peaked at 4h, while (99m)TcO4 (-) accumulated over approximately 20 hours. In vivo uptake of (131)I and (99m)TcO4 (-) was slightly higher in cells transfected with the Egr-1 promoter, compared to CMV. Hela-Egr-1-hNIS cells demonstrate highly enhanced iodine uptake, and this effect is further augmented by radiation, creating a positive feedback loop which may bolster radionuclide therapy in vivo. © The Author(s) 2014.

Synergistic enhancement in the co-gelation of salt-soluble pea proteins and whey proteins.

PubMed

Wong, Douglas; Vasanthan, Thava; Ozimek, Lech

2013-12-15

This paper investigated the enhancement of thermal gelation properties when salt-soluble pea proteins were co-gelated with whey proteins in NaCl solutions, using different blend ratios, total protein concentrations, pH, and salt concentrations. Results showed that the thermal co-gelation of pea/whey proteins blended in ratio of 2:8 in NaCl solutions showed synergistic enhancement in storage modulus, gel hardness, paste viscosity and minimum gelation concentrations. The highest synergistic enhancement was observed at pH 6.0 as compared with pH 4.0 and 8.0, and at the lower total protein concentration of 10% as compared with 16% and 22% (w/v), as well as in lower NaCl concentrations of 0.5% and 1.0% as compared with 1.5%, 2.0%, 2.5%, and 3.0% (w/v). The least gelation concentrations were also lower in the different pea/whey protein blend ratios than in pure pea or whey proteins, when dissolved in 1.0% or 2.5% (w/v) NaCl aqueous solutions. Copyright © 2013 Elsevier Ltd. All rights reserved.

Comparative evaluation of some commercially available brands of pharmaceutical preparations for Na, K and Mg concentrations.

PubMed

Hayat, Sikander; Chughtai, Muhammad Ismail; Ansari, Tariq Mahmood; Kamal, Ghulam Mustafa

2012-04-01

A study was carried out to investigate the concentrations of macro-elements (Na(+), K(+) and Mg(+2)) in twelve commercially available pharmaceutical preparations used as sex stimulant, by Atomic Absorption Spectrophotometer. A wet digestion method was adopted to prepare the samples. The results indicated that sodium concentration was maximum (3702 ± 29 μg g(-1)) in LB and minimum (495 ± 06 μg g(-1)) in H-E-H. Potassium concentration was maximum (6337 ± 13 μg g(-1)) in NBA while minimum (150 ± 06 μg g(-1)) in ZGRA. Magnesium concentration was maximum in V-100 (9226 ± 11 μg g(-1)) and minimum in FGRA (1194 ± 25 μg g(-1)). The concentration of macro-elements in the imported herbal preparations was in the order of Mg

Performance and microbial features of the partial nitritation-anammox process treating fish canning wastewater with variable salt concentrations.

PubMed

Val Del Rio, Angeles; Pichel, Andres; Fernandez-Gonzalez, Nuria; Pedrouso, Alba; Fra-Vázquez, Andrea; Morales, Nicolas; Mendez, Ramon; Campos, Jose Luis; Mosquera-Corral, Anuska

2018-02-15

The partial nitritation-anammox (PN-AMX) process applied to wastewaters with high NaCl concentration was studied until now using simulated media, without considering the effect of organic matter concentration and the shift in microbial populations. This research work presents results on the application of this process to the treatment of saline industrial wastewater. Obtained results indicated that the PN-AMX process has the capability to recover its initial activity after a sudden/acute salt inhibition event (up to 16 g NaCl/L). With a progressive salt concentration increase for 150 days, the PN-AMX process was able to remove the 80% of the nitrogen at 7-9 g NaCl/L. The microbiological data indicated that NaCl and ammonia concentrations and temperature are important factors shaping PN-AMX communities. Thus, the NOB abundance (Nitrospira) decreases with the increase of the salt concentration, while heterotrophic denitrifiers are able to outcompete anammox after a peak of organic matter in the feeding. Copyright © 2017 Elsevier Ltd. All rights reserved.

Impact of leather industries on fluoride dynamics in groundwater around a tannery cluster in South India.

PubMed

Sajil Kumar, P J

2013-03-01

The aim of this study was to investigate the controls of leather industries on fluoride contamination in and around a tannery cluster in Vaniyambadi. Hydrochemical analysis, mineral saturation indices and statistical methods were used to evaluate the intervening factors that controls the contamination processes. Fluoride in groundwater is exceeded the WHO guideline value (1.5 mg/L), in 62 % of the samples, mostly with Na-HCO3 and Na-Cl type of water. Results of the principal component analysis grouped Na, F, HCO3 and NO3 under component 1. This result was in agreement with the cross plot indicating high positive correlation between F and Na (r (2)  = 0.87), HCO3 (r (2)  = 0.84) and NO3 (r (2)  = 0.55). Fluorite (CaF2) and Halite (NaCl) was undersaturated, while calcite (CaCO3) was oversaturated for all the samples. This suggest more dissolution of F-rich minerals under the active supports of Na. Bivariate plots of Na versus Cl and Na + K versus HCO3 showed a combined origin of Na from tannery effluent as well as silicate weathering. Two major clusters, based on the Na, HCO3 and F concentration showed that groundwater is affected by tanneries and silicate weathering. Fluoride concentration in 38 % of samples (n = 5) have significantly affected by the high Na concentration from tanneries.

Issues and progress in determining background ozone and particle concentrations

NASA Astrophysics Data System (ADS)

Pinto, J. P.

2011-12-01

Exposure to ambient ozone is associated with a variety of health outcomes ranging from mild breathing discomfort to mortality. For the purpose of health risk and policy assessments EPA evaluates the anthropogenic increase in ozone above background concentrations and has defined the North American (NA) background concentration of O3 as that which would occur in the U.S. in the absence of anthropogenic emissions of precursors in the U.S., Canada, and Mexico. Monthly average NA background ozone has been used to evaluate health risks, but EPA and state air quality managers must also estimate day specific ozone background levels for high ozone episodes as part of urban scale photochemical modeling efforts to support ozone regulatory programs. The background concentration of O3 is of more concern than other air pollutants because it typically represents a much larger fraction of observed O3 than do the backgrounds of other criteria pollutants (particulate matter (PM), CO, NO2, SO2). NA background cannot be determined directly from ambient monitoring data because of the influence of NA precursor emissions on formation of ozone within NA. Instead, estimates of NA background O3 have been based on GEOS-Chem using simulations in which NA anthropogenic precursor emissions are zeroed out. Thus, modeled NA background O3 includes contributions from natural sources of precursors (including CH4, NMVOCs, NOx, and CO) everywhere in the world, anthropogenic sources of precursors outside of NA, and downward transport of O3 from the stratosphere. Although monitoring data cannot determine NA background directly, measurements by satellites, aircraft, ozonesondes and surface monitors have proved to be highly useful for identifying sources of background O3 and for evaluating the performance of the GEOS-Chem model. Model simulated NA background concentrations are strong functions of location and season with large inter-day variability and with values increasing with elevation and higher in spring than in summer, and tend to be highest in the Intermountain West during spring. Estimates of annual average NA and other background definitions that have been considered will be presented. Issues associated with modeling background concentrations for both health-risk assessments and for episodic regulatory air quality programs will be discussed, and proposals for new atmospheric measurements and model improvements needed to quantify more accurately background contributions to ozone will also be presented. The views expressed are those of the author and do not necessarily represent the views or policies of the U.S. Environmental Protection Agency.

Effects of sodium hydroxide treatment of dried distillers' grains on digestibility, ruminal metabolism, and metabolic acidosis of feedlot steers.

PubMed

Freitas, T B; Relling, A E; Pedreira, M S; Santana Junior, H A; Felix, T L

2016-02-01

The objectives were to determine the optimum inclusion of NaOH necessary to buffer the acidity of dried distillers' grains with solubles (DDGS) and its effects on digestibility, ruminal metabolism, and metabolic acidosis in feedlot steers. Rumen cannulated Angus-crossed steers were blocked by BW (small: 555 ± 42 kg initial BW, = 4; large: 703 ± 85 kg initial BW, = 4) over four 21-d periods in a replicated 4 × 4 Latin square design. Steers were assigned to 1 of 4 dietary treatments: 1) 50% untreated DDGS, 2) 50% DDGS treated with 0.5% (DM basis) sodium hydroxide (NaOH), 3) 50% DDGS treated with 1.0% (DM basis) NaOH, and 4) 50% DDGS treated with 1.5% (DM basis) NaOH. The remainder of the diets, on a DM basis, was composed of 20% corn silage, 20% dry-rolled corn, and 10% supplement. Ruminal pH was not affected by treatments ( = 0.56) or by a treatment × time interaction ( = 0.15). In situ NDF and ruminal DM disappearance did not differ ( ≥ 0.49 and ≥ 0.47, respectively) among treatments. Similar to in situ results, apparent total tract DM and NDF digestibility were not affected ( ≥ 0.33 and ≥ 0.21, respectively) by increasing NaOH inclusion in the diets. Urinary pH increased (linear, < 0.01) with increasing NaOH concentration in the diet. Blood pH was not affected ( ≥ 0.20), and blood total CO and partial pressure of CO were similar ( ≥ 0.56 and ≥ 0.17, respectively) as NaOH increased in the diet. Increasing NaOH in the diet did not affect ( ≥ 0.21) ruminal concentrations of total VFA. There were no linear ( = 0.20) or quadratic ( = 0.20) effects of treatment on ruminal acetate concentrations, nor was there a treatment × time interaction ( = 0.22) for acetate. Furthermore, there were no effects ( ≥ 0.90) of NaOH inclusion on ruminal propionate concentration. However, there was a quadratic response ( = 0.01) of ruminal butyrate concentrations as NaOH inclusion increased in the diet; ruminal butyrate concentrations were greatest with the 0.5 and 1.0% NaOH treatments of DDGS. In the current study, feeding DDGS treated with NaOH did not increase fiber digestibility nor was it necessary to alleviate a possible metabolic acidosis. Alkali treatment of DDGS did not increase average ruminal pH or blood pH.

Defect evolution and impurity migration in Na-implanted ZnO

NASA Astrophysics Data System (ADS)

Neuvonen, Pekka T.; Vines, Lasse; Venkatachalapathy, Vishnukanthan; Zubiaga, Asier; Tuomisto, Filip; Hallén, Anders; Svensson, Bengt G.; Kuznetsov, Andrej Yu.

2011-11-01

Secondary ion mass spectrometry (SIMS) and positron annihilation spectroscopy (PAS) have been applied to study impurity migration and open volume defect evolution in Na+ implanted hydrothermally grown ZnO samples. In contrast to most other elements, the presence of Na tends to decrease the concentration of open volume defects upon annealing and for temperatures above 600∘C, Na exhibits trap-limited diffusion correlating with the concentration of Li. A dominating trap for the migrating Na atoms is most likely Li residing on Zn site, but a systematic analysis of the data suggests that zinc vacancies also play an important role in the trapping process.

23Na NUCLEAR MAGNETIC RESONANCE RELAXATION STUDIES OF SODIUM ION INTERACTION WITH SOLUBLE RNA*

PubMed Central

James, Thomas L.; Noggle, Joseph H.

1969-01-01

Interactions between 23Na+ and soluble RNA in aqueous solution are studied with the use of 23Na nuclear magnetic resonance. At low concentrations of NaCl, the interactions obey a simple equilibrium model with a formation constant log (Kf)3 = 2.8 ± 0.3. The relaxation rate of the bound sodium is found to be T1B-1 = 222 ± 19 sec-1 compared to that of free sodium T1F-1 = 17.5 sec-1. At high NaCl concentrations, the system deviates from the model, possibly owing to aggregation of the soluble RNA. PMID:5256995

REACTOR HAVING NaK-UO$sub 2$ SLURRY HELICALLY POSITIONED IN A GRAPHITE MODERATOR

DOEpatents

Rodin, M.B.; Carter, J.C.

1962-05-15

A reactor utilizing 20% enriched uranium consists of a central graphite island in cylindrical form, with a spiral coil of tubing fitting against the central island. An external graphite moderator is placed around the central island and coil. A slurry of uranium dioxide dispersed in alkali metal passes through the coil to transfer heat externally to the reactor. There are also conventional controls for regulating the nuclear reaction. (AEC)

Response to non-uniform salinity in the root zone of the halophyte Atriplex nummularia: growth, photosynthesis, water relations and tissue ion concentrations

PubMed Central

Bazihizina, Nadia; Colmer, Timothy D.; Barrett-Lennard, Edward G.

2009-01-01

Background and Aims Soil salinity is often heterogeneous, yet the physiology of halophytes has typically been studied with uniform salinity treatments. An evaluation was made of the growth, net photosynthesis, water use, water relations and tissue ions in the halophytic shrub Atriplex nummularia in response to non-uniform NaCl concentrations in a split-root system. Methods Atriplex nummularia was grown in a split-root system for 21 d, with either the same or two different NaCl concentrations (ranging from 10 to 670 mm), in aerated nutrient solution bathing each root half. Key Results Non-uniform salinity, with high NaCl in one root half (up to 670 mm) and 10 mm in the other half, had no effect on shoot ethanol-insoluble dry mass, net photosynthesis or shoot pre-dawn water potential. In contrast, a modest effect occurred for leaf osmotic potential (up to 30 % more solutes compared with uniform 10 mm NaCl treatment). With non-uniform NaCl concentrations (10/670 mm), 90 % of water was absorbed from the low salinity side, and the reduction in water use from the high salinity side caused whole-plant water use to decrease by about 30 %; there was no compensatory water uptake from the low salinity side. Leaf Na+ and Cl− concentrations were 1·9- to 2·3-fold higher in the uniform 670 mm treatment than in the 10/670 mm treatment, whereas leaf K+ concentrations were 1·2- to 2·0-fold higher in the non-uniform treatment. Conclusions Atriplex nummularia with one root half in 10 mm NaCl maintained net photosynthesis, shoot growth and shoot water potential even when the other root half was exposed to 670 mm NaCl, a concentration that inhibits growth by 65 % when uniform in the root zone. Given the likelihood of non-uniform salinity in many field situations, this situation would presumably benefit halophyte growth and physiology in saline environments. PMID:19556265

Age related decreases in neural sensitivity to NaCl in SHR-SP.

PubMed

Osada, Kazumi; Komai, Michio; Bryant, Bruce P; Suzuki, Hitoshi; Tsunoda, Kenji; Furukawa, Yuji

2003-03-01

To determine whether neurophysiological taste responses of young and old rats are different, recordings were made from the whole chorda tympani nerve which innervates taste buds on the anterior tongue. SHR-SP (Stroke-Prone Spontaneously Hypertensive Rats) in two age groups were studied. Chemical stimuli included single concentrations of 250 mM NH(4)Cl, 100 mM NaCl, 100 mM KCl, 500 mM sucrose, 20 mM quinine-hydrochloride, 10 mM HCl, 10 mM monosodium glutamate (MSG), 10 mM L- glutamic acid (L-Glu) and an NaCl concentration series. The magnitude of the neural response (response ratio) was calculated by dividing the amplitude of the integrated response by the amplitude of the spontaneous activity that preceded it. Substantial neural responses to all chemicals were obtained at both ages. The responses to KCl, sucrose, quinine-hydrochloride, HCl, monosodium glutamate (MSG) and glutamic acid (Glu) did not change with age, but the response to NaCl did decrease significantly. The profile of the response/concentration function for NaCl differed with age. In particular, the responses to solutions more concentrated than 100 mM NaCl were significantly weaker in aged than in young SHR-SPs. We also observed that recovery from amiloride treatment on the tongue of SHR-SPs was faster in aged rats than in young ones, suggesting that there is some functional difference in the sodium-specific channels on the taste cell. These results suggest that aged SHR-SP may be less able than young SHR-SPs to discriminate among higher concentrations of NaCl solutions.

Evaluation of the antimicrobial activities of chlorhexidine gluconate, sodium hypochlorite and octenidine hydrochloride in vitro.

PubMed

Tirali, Resmiye E; Bodur, Haluk; Sipahi, Bilge; Sungurtekin, Elif

2013-04-01

The objective of this study was to compare the antimicrobial activity of sodium hypochlorite (NaOCl), chlorhexidine gluconate (CHX) and octenidine hydrochloride (OCT) in different concentrations against endodontic pathogens in vitro. Agar diffusion procedure was used to determine the antimicrobial activity of the tested materials. Enterococcus faecalis, Candida albicans and the mixture of these were used for this study. In the agar diffusion test, 5.25% NaOCl exhibited better antimicrobial effect than the other concentrations of NaOCl for all strains. All concentrations of OCT were effective against C. albicans and E. faecalis. Some 0.2% CHX was ineffective on all microorganisms. Antibacterial effectiveness of all experimental solutions decreased on the mixture of all strains. Decreasing concentrations of NaOCl resulted in significantly reduced antimicrobial effect. © 2010 The Authors. Australian Endodontic Journal © 2010 Australian Society of Endodontology.

Adsorption of goethite onto quartz and kaolinite

USGS Publications Warehouse

Goldberg, M.C.; Weiner, Eugene R.; Boymel, P.M.

1984-01-01

The adsorption of colloidal goethite onto quartz and kaolinite substrates has been studied as a function of pH and NaCl concentration. Goethite adsorption was measured quantitatively by Fourier-transform infrared spectroscopy. The results indicate that adsorption onto both substrates is due primarily to coulombic forces; however, the pH dependence of adsorption is very different for the two substrates. This is explained by the fact that the surface charge on quartz is entirely pH-dependent, while kaolinite has surface faces which carry a permanent negative charge. Adsorption of goethite on to kaolinite increases markedly with increasing NaCl concentration, while adsorption onto quartz is relatively independent of NaCl concentration. This can be explained by the influence of NaCl concentration upon the development of surface charge on the substrates. A method is described for separating surface-bound goethite from free goethite.

Effects of Etching Time and NaOH Concentration on the Production of Alumina Nanowires Using Porous Anodic Alumina Template

NASA Astrophysics Data System (ADS)

Sadeghpour-Motlagh, M.; Mokhtari-Zonouzi, K.; Aghajani, H.; Kakroudi, M. Ghassemi

2014-06-01

In this work, two-step anodizing of commercial aluminum foil in acid oxalic solution was applied for producing alumina film. Then the anodic alumina film was etched in sodium hydroxide (NaOH) solution resulting dense and aligned alumina nanowires. This procedure leads to splitting of alumina nanotubes. Subsequently nanowires are produced. The effects of NaOH solution concentration (0.2-1 mol/L) and etching time (60-300 s) at constant temperature on characteristic of nanotubes and produced nanowires were investigated using scanning electron microscopy. The results show that an increase in NaOH solution concentration increases the rate of nanowires production and in turn the manipulation process will be more specific.

The dependence of the action potential of the frog's heart on the external and intracellular sodium concentration

PubMed Central

Niedergerke, R.; Orkand, R. K.

1966-01-01

1. The overshoot of the action potential of the frog's heart was reduced when external sodium chloride was replaced by sucrose. However, the potential decrement was only 17·3 mV for a 10-fold reduction of sodium as compared with 58 mV expected on the basis of the sodium hypothesis of excitation. 2. Replacement of up to 75% of the external sodium by choline did not reduce the overshoot, provided atropine was present in sufficient concentrations to suppress any parasympathomimetic action. 3. The maximum rate of rise of the action potential markedly declined in low sodium fluids whether sucrose or choline chloride was used to replace sodium chloride. 4. The maximum rate of rise was reduced to only a small extent when external sodium was replaced by lithium. 5. Increasing the intracellular sodium concentration in exchange for lost potassium caused overshoots to decline. The effects resembled those obtained in similar experiments with skeletal muscle fibres (Desmedt, 1953). 6. Action potentials occurring under certain conditions even in the presence of very low external sodium concentrations (≤ 5% normal) also declined in height when the intracellular sodium concentration was increased. 7. The behaviour of the action potential in low external sodium concentrations may be explained by an action of calcium on the excitable membrane. PMID:5921833

Friction and wear of iron and nickel in sodium hydroxide solutions

NASA Technical Reports Server (NTRS)

Rengstorff, G. W. P.; Miyoshi, K.; Buckley, D. H.

1982-01-01

A loaded spherical aluminum oxider rider was made to slide, while in various solutions, on a flat iron or nickel surface reciprocate a distance of 1 cm. Time of experiments was 1 hr during which the rider passed over the rider passed over the center section of the track 540 times. Coefficients of friction were measured throughout the experiments. Wear was measured by scanning the track with a profilometer. Analysis of some of the wear tracks included use of the SEM (scanning electron microscrope) and XPS (X-ray photoelectron spectroscopy). Investigated were the effect of various concentractions of NaOH and of water. On iron, increasing NaOH concentration above 0.01 N caused the friction and wear to decrease. This decrease is accompanied by a decrease in surface concentration of ferric oxide (Fe2O3) while more complex iron-oxygen compounds, not clearly identified, also form. At low concentrations of NaOH, such as 0.01 N, where the friction is high, the wear track is badely torn up and the surface is broken. At high concentration, such as 10 N, where the friction is low, the wear track is smooth. The general conclusion is that NaOH forms a protective, low friction film on iron which is destroyed by wear at low concentrations but remains intact at high concentrations of NaOH. Nickel behaves differently than iron in that only a little NaOH gives a low coefficient of friction and a surface which, although roughened in the wear track, remains intact.

Friction and wear of iron and nickel in sodium hydroxide solutions

NASA Technical Reports Server (NTRS)

Rengstorff, G. P.; Miyoshi, K.; Buckley, D. H.

1983-01-01

A loaded spherical aluminum oxider rider was made to slide, while in various solutions, on a flat iron or nickel surface reciprocate a distance of 1 cm. Time of experiments was 1 hr during which the rider passed over the center section of the track 540 times. Coeficients of friction were measured throughout the experiments. Wear was measured by scanning the track with a profilometer. Analysis of some of the wear tracks included use of the SEM (scanning electron microscope) and XPS (X-ray photoelectron spectroscopy). Investigated were the effect of various concentrations of NaOH and of water. On iron, increasing NaOH concentration above 0.01 N caused the friction and wear to decrease. This decrease is accompanied by a decrease in surface concentration of ferric oxide (Fe2O3) while more complex iron-oxygen compounds, not clearly identified, also form. At low concentrations of NaOH, such as 0.01 N, where the friction is high, the wear track is badly torn up and the surface is broken. At high concentration, such as 10 N, where the friction is low, the wear track is smooth. The general conclusion is that NaOH forms a protective, low friction film on iron which is destroyed by wear at low concentrations but remains intact at high conentrations of NaOH. Nickel behaves differently than iron in that only a little NaOH gives a low coefficient of friction and a surface which, although roughened in the wear track, remains intact. Previously announced in STAR as N83-10171

Natural radionuclide concentrations in granite rocks in Aswan and Central-Southern Eastern Desert, Egypt and their radiological implications.

PubMed

Issa, Shams A M; Uosif, M A M; Abd el-Salam, L M

2012-07-01

Different types of granites, used extensively in local construction, were collected from five localities in Egypt, namely: Abu Ziran (Central Eastern Desert), Gabal El Maesala (Aswan) and three areas from Wadi Allaqi, (Gabal Abu Marw, Gabal Haumor and Gabal um Shalman), in the South Eastern Desert. Granite samples were studied radiologically, petrographically and geochemically. The contents of natural radionuclides ((226)Ra, (232)Th and (40)K) were measured in investigated samples by using gamma spectrometry [NaI (Tl) 3'×3']. The activity concentrations of (226)Ra, (232)Th and (40)K in the selected granite samples ranged from 9±0.5 to 111±7, 8±1 to 75±4 and 100±6 to 790±40 Bq kg(-1), respectively. The external hazard index (H(ex)), absorbed dose and annual effective dose rate were evaluated to assess the radiation hazard for people living in dwellings made of the materials studied. The calculated radium equivalents were lower than the values recommended for construction materials (370 Bq kg(-1)). The excess lifetime cancer risks were also calculated. Petrographically, the granites studied are varied in the form of potash-feldspar, quartz, plagioclase, mica and hornblende. The accessory minerals are zircon, apatite and allanite. Geochemically, the chemical composition of the granite is studied especially for major oxides. They are characterized to have SiO(2), K(2)O, Na(2)O and Al(2)O(3) with depletion in CaO, MgO, TiO(2) and P(2)O(5).

The permeability of endplate channels to monovalent and divalent metal cations

PubMed Central

1980-01-01

The relative permeability of endplate channels to monovalent and divalent metal ions was determined from reversal potentials. Thallium is the most permeant ion with a permeability ratio relative to Na+ of 2.5. The selectivity among alkali metals is weak with a sequence, Cs+ greater than Rb+ greater than K+ greater than Na+ greater than Li+, and permeability ratios of 1.4, 1.3, 1.1, 1.0, and 0.9. The selectivity among divalent ions is also weak, with a sequence for alkaline earths of Mg++ greater than Ca++ greater than Ba++ greater than Sr++. The transition metal ions Mn++, Co++, Ni++, Zn++, and Cd++ are also permeant. Permeability ratios for divalent ions decreased as the concentration of divalent ion was increased in a manner consistent with the negative surface potential theory of Lewis (1979 J. Physiol. (Lond.). 286: 417--445). With 20 mM XCl2 and 85.5 mM glucosamine.HCl in the external solution, the apparent permeability ratios for the alkaline earth cations (X++) are in the range 0.18--0.25. Alkali metal ions see the endplate channel as a water-filled, neutral pore without high-field-strength sites inside. Their permeability sequence is the same as their aqueous mobility sequence. Divalent ions, however, have a permeability sequence almost opposite from their mobility sequence and must experience some interaction with groups in the channel. In addition, the concentrations of monovalent and divalent ions are increased near the channel mouth by a weak negative surface potential. PMID:6247423

Effect of sodium accumulation on heterotrophic growth and polyhydroxybutyrate (PHB) production by Cupriavidus necator.

PubMed

Mozumder, Md Salatul Islam; Garcia-Gonzalez, Linsey; De Wever, Heleen; Volcke, Eveline I P

2015-09-01

This study evaluates the effect of sodium (Na(+)) concentration on the growth and PHB production by Cupriavidus necator. Both biomass growth and PHB production were inhibited by Na(+): biomass growth became zero at 8.9 g/L Na(+) concentration while PHB production was completely stopped at 10.5 g/L Na(+). A mathematical model for pure culture heterotrophic PHB production was set up to describe the Na(+) inhibition effect. The parameters related to Na(+) inhibition were estimated based on shake flask experiments. The accumulated Na(+) showed non-linear inhibition effect on biomass growth but linear inhibition effect on PHB production kinetics. Fed-batch experiments revealed that a high accumulation of Na(+) due to a prolonged growth phase, using NaOH for pH control, decreased the subsequent PHB production. The model was validated based on independent experimental data sets, showing a good agreement between experimental data and simulation results. Copyright © 2015 Elsevier Ltd. All rights reserved.

Physicochemical study of mixed systems composed by bovine caseinate and the galactomannan from Gleditsia amorphoides.

PubMed

López, Débora N; Galante, Micaela; Alvarez, Estela M; Risso, Patricia H; Boeris, Valeria

2017-10-01

Model systems formed by sodium caseinate (NaCAS) and espina corona gum (ECG) were studied. There was no evidence of attractive interactions between NaCAS and ECG macromolecules. Aqueous mixtures of NaCAS and ECG phase-separate segregatively over a wide range of concentrations. According to the images obtained by confocal laser scanning microscopy, NaCAS particles form larger protein aggregates when ECG is present in the system. An increase in the hydrodynamic diameter of NaCAS particles, as a result of ECG addition, was also observed by light scattering in diluted systems. A depletion-flocculation phenomenon, in which ECG is excluded from NaCAS surface, is proposed to occur in the concentrated mixed systems, resulting in NaCAS aggregation. ECG raises the viscosity of NaCAS dispersions without affecting the Newtonian flow behaviour of NaCAS. These results contribute to improve the knowledge of a barely-studied hydrocolloid which may be useful in the development of innovative food systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Dog red blood cells: Na and K diffusion potentials with extracellular ATP

PubMed Central

1977-01-01

External ATP causes a prompt increase in the Na and K permeability of dog red blood cells. By manipulating intra- and extracellular ion composition it is possible to observe ATP-induced net fluxes which can be explained in terms of the contribution of Na or K diffusion potentials to the membrane potential. Measurements of membrane voltage by a fluorescent dye technique confirm the existence of such potentials. A rough calculation of chloride permeability gives a value of the order of 10(-8) cm/s, which agrees with results in other species. The cells appear to be somewhat more permeable to bromide than to chloride. PMID:853285

The Antibiofilm efficacy of nitric oxide on soft contact lenses.

PubMed

Kim, Dong Ju; Park, Joo-Hee; Kim, Marth; Park, Choul Yong

2017-11-21

To investigate the antibiofilm efficacy of nitric oxide (NO) on soft contact lenses. Nitrite (NO precursor) release from various concentrations (0-1000 μM) of sodium nitrite (NaNO 2, NO donor) was measured by Griess Assay. Cell viability assay was performed using human corneal epithelial cell under various concentration (0-1000 μM) of NaNO 2 . Biofilm formation on soft contact lenses was achieved by adding Staphylococcus aureus or Pseudomonas aeruginosa to the culture media. Various concentrations of NaNO 2 (0-1000 μM) were added to the culture media, each containing soft contact lens. After incubation in NaNO 2 containing culture media for 1, 3, or 7 days, each contact lens was transferred to a fresh, bacteria-free media without NaNO 2 . The bacteria in the biofilm were dispersed in the culture media for planktonic growth. After reculturing the lenses in the fresh media for 24 h, optical density (OD) of media was measured at 600 nm and colony forming unit (CFU) was counted by spreading media on tryptic soy agar plate for additional 18 h. Nitrite release from NaNO 2 showed dose-dependent suppressive effect on biofilm formation. Most nitrite release from NaNO 2 tended to occur within 30 min. The viability of human corneal epithelial cells was well maintained at tested NaNO 2 concentrations. The bacterial CFU and OD showed dose-dependent decrease in the NaNO 2 treated samples on days 1, 3 and 7 for both Staphylococcus aureus and Pseudomonas aeruginosa. NO successfully inhibited the biofilm formation by Staphylococcus aureus or Pseudomonas aeruginosa on soft contact lenses in dose-dependent manner.

In vivo microdialysis of noradrenaline overflow: effects of alpha-adrenoceptor agonists and antagonists measured by cumulative concentration-response curves.

PubMed Central

van Veldhuizen, M. J.; Feenstra, M. G.; Heinsbroek, R. P.; Boer, G. J.

1993-01-01

1. The purpose of the present study was to compare the effects of several alpha-adrenoceptor agonists and antagonists on cerebral cortical overflow of endogenous noradrenaline (NA) in freely moving rats. One or two days after the implantation of transcerebral dialysis tubes in the frontoparietal cortex, extracellular NA levels were monitored on-line with high performance liquid chromatography and electrochemical detection. The drugs were applied locally via the dialysis membrane, and effects on NA overflow were determined in cumulative concentration-response curves. 2. The average basal cortical NA overflow of all experiments was 0.25 pg min-1. The alpha 2-adrenoceptor agonists caused a concentration-dependent decrease in NA levels. UK-14,304 was the most potent and B-HT 933 the least potent agonist. The maximal decrease in NA overflow was to 10-15% of control levels after UK-14,304 or moxonidine, to 30% after clonidine and to 50% after B-HT 933 administration. Continuous activation of the presynaptic alpha 2-adrenoceptor with 10(-6) M UK-14,304 caused a decrease in NA levels to 40-50% of basal levels. This decrease was reached within 1 h and remained stable for the entire 3 h measurement period. The alpha 1-adrenoceptor agonists, phenylephrine and methoxamine, induced an increase in NA levels to 225% and 300%, respectively, at a concentration of 10(-3) M. 3. Local application of alpha 2-adrenoceptor antagonists caused an increase in NA levels, with idazoxan being more potent than piperoxan. Yohimbine did not cause any significant change. 4. All drugs used in these in vivo experiments had in vitro recoveries across the dialysis membrane between 10 and 20%.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8102934

Evidence for a Na+/H+ Antiporter in Membrane Vesicles Isolated from Roots of the Halophyte Atriplex nummularia1

PubMed Central

Braun, Yael; Hassidim, Miriam; Lerner, Henri R.; Reinhold, Leonora

1988-01-01

The ATP-dependent establishment of a positive membrane potential (measured as S14CN−-accumulation) in membrane vesicles isolated from the roots of Atriplex nummularia Lindl. was not inhibited by NaMes and KMes at concentrations up to 140 millimolar. On the other hand, the formation of ΔpH (measured as 14C-methylamine accumulation or quenching of quinacrine fluorescence), was depressed by NaMes concentrations as low as 30 millimolar. Supply of NaMes after the ΔpH had been established brought about partial dissipation within 30 seconds. Extent of dissipation of ΔpH increased with NaMes concentration over the range tested (up to 180 millimolar). The H+/Na+ exchange indicated by these results was not due to the creation of a Na+ diffusion potential. Formation of ΔpH in these vesicles was stable to NO3− up to 100 millimolar; further, the dissipating effect of Na+ supply was apparent on a ΔpH formed in the presence of 30 millimolar NO3−. Additional evidence that the origin of the membrane vesicles observed in this investigation was not the tonoplast and was probably the plasmalemma included the vanadate sensitivity of the establishment of the membrane potential. PMID:16666082

Interaction of Bacillus subtilis spores with sodium hypochlorite, sodium dichloroisocyanurate and chloramine-T.

PubMed

Bloomfield, S F; Arthur, M

1992-02-01

Solutions of chlorine-releasing agents (CRAs) show varying activity against Bacillus subtilis spores; sodium hypochlorite (NaOCl) shows higher activity than sodium dichloroisocyanurate (NaDCC) which is more active than chloramine-T. Investigations with coat- and cortex-extracted spores indicate that resistance to CRAs depends not only on the spore coat but also the cortex. Whereas extraction of alkali-soluble coat protein increased sensitivity to NaOCl and NaDCC, degradation of coat and cortex material was required to achieve significant activity with chloramine-T. NaOCl (in the presence and absence of NaOH) and NaDCC (in the presence of NaOH only) produced degradation of spore coat and cortex material which may be related to their rapid sporicidal action at low concentrations under these conditions. By contrast, chloramine-T produced no degradation of cortex peptidoglycan and was only effective against normal and alkali-treated spores at high concentrations, requiring extraction of peptidoglycan with urea/dithiothreitol/sodium lauryl sulphate (UDS) or UDS/lysozyme to achieve significant activity at low concentrations. Results suggest that the sporicidal action of CRAs is associated with spore coat and cortex degradation causing rehydration of the protoplast allowing diffusion to the site of action on the underlying protoplast.

Effects of ampicillin/sulbactam and enrofloxacin on the blood pressure of isoflurane anesthetized dogs.

PubMed

Moorer, Jeremiah D; Towle-Millard, Heather A; Gross, Marjorie E; Payton, Mark E

2013-01-01

A blinded, prospective, randomized crossover study was performed to determine the effects of ampicillin Na/sulbactam Na and enrofloxacin on the blood pressure (BP) of healthy anesthetized dogs. Eight dogs were anesthetized three different times. They randomly received enrofloxacin, ampicillin Na/sulbactam Na, and saline. Systolic, diastolic, and mean arterial BPs (SAP, DAP, and MAP, respectively), heart rate (HR), O2 saturation of hemoglobin, end-tidal CO2 (ETCO2) concentration, inspired isoflurane concentration, end-tidal isoflurane (ETiso) concentration, respiratory rate, electrocardiogram, and body temperature were measured for 20 min prior to administration of treatment, during administration over 30 min, and for 30 min after administration. There was no significant difference in the SAP or ETiso. There was no significant change in the arterial pressure values over time in the enrofloxacin and ampicillin Na/sulbactam Na groups. The control group's MAP increased over time and was increased compared with the enrofloxacin group at times 25, 35, 45, and 55. The statistical difference between the enrofloxacin and the control groups was due to an increase in the MAP in the control group, not a decrease in the enrofloxacin group's BP. Neither enrofloxacin nor ampicillin Na/sulbactam Na caused hypotension in healthy dogs anesthetized with isoflurane and fentanyl.

An in vitro evaluation of the cytotoxicity of varying concentrations of sodium hypochlorite on human mesenchymal stem cells.

PubMed

Alkahtani, Ahmed; Alkahtany, Sarah M; Anil, Sukumaran

2014-07-01

To evaluate and compare the cytotoxicity of various concentrations of sodium hypochlorite on immortalized human bone marrow mesenchymal stem cells (MSCs). The 5.25 percent sodium hypochlo-rite (NaOCl) at concentrations of 0.5, 0.1, 0.025, 0.0125, and 0.005 mg/ml were used to assess the cytotoxic effect on MSCs. Immortalized human bone marrow mesenchymal stem cells (hTERT-MSCs) were exposed to NaOCl at 5 different concentrations. Cell viability was assessed by 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and alamarBlue assays. The cell morphology changes were assessed with scanning electron microscopy (SEM) after exposure to 2, 4, and 24 hour incubation. The ethidium bromide/acridine orange (EB/ AO) fuorescent stain was applied to the cells in the 8-chamber slides after they were incubated with the testing agents for 2 and 4 hours to detect live and dead cells. The observations were quantitatively and qualitatively analyzed. The cell viability study using MTT assay and AB assay showed significant reduction with varying concentration at 2 and 4 hours incubation period. The cell viability decreased with the higher percentage of NaOCl. The exposure time also revealed an inverse relation to the cell viability. The SEM analysis showed reduction in the number of cells and morphological alterations with 0.5 mg/ml at 2 and 4 hours compared to 0.025 mg/ml NaOCl. Destruction of the cells with structural alterations and lysis was evident under fuorescence microscope when the cells were exposed to 0.5 mg/ml NaOCl. Within the limitations of this in vitro study it can be concluded that NaOCl is toxic to the human bone marrow MSCs. The cell lysis was evident with higher concentration of sodium hypochlorite. From the observations, it can be concluded that a lower concentration of NaOCl may be used as endodontic irrigant due to its cytotoxic properties. Further studies are mandatory to evolve a consensus on the optimal concentration of sodium hypochlorite to be used as endodontic irrigant.

Effect of Pre-rigor Salting Levels on Physicochemical and Textural Properties of Chicken Breast Muscles.

PubMed

Kim, Hyun-Wook; Hwang, Ko-Eun; Song, Dong-Heon; Kim, Yong-Jae; Ham, Youn-Kyung; Yeo, Eui-Joo; Jeong, Tae-Jun; Choi, Yun-Sang; Kim, Cheon-Jei

2015-01-01

This study was conducted to evaluate the effect of pre-rigor salting level (0-4% NaCl concentration) on physicochemical and textural properties of pre-rigor chicken breast muscles. The pre-rigor chicken breast muscles were de-boned 10 min post-mortem and salted within 25 min post-mortem. An increase in pre-rigor salting level led to the formation of high ultimate pH of chicken breast muscles at post-mortem 24 h. The addition of minimum of 2% NaCl significantly improved water holding capacity, cooking loss, protein solubility, and hardness when compared to the non-salting chicken breast muscle (p<0.05). On the other hand, the increase in pre-rigor salting level caused the inhibition of myofibrillar protein degradation and the acceleration of lipid oxidation. However, the difference in NaCl concentration between 3% and 4% had no great differences in the results of physicochemical and textural properties due to pre-rigor salting effects (p>0.05). Therefore, our study certified the pre-rigor salting effect of chicken breast muscle salted with 2% NaCl when compared to post-rigor muscle salted with equal NaCl concentration, and suggests that the 2% NaCl concentration is minimally required to ensure the definite pre-rigor salting effect on chicken breast muscle.

Effect of Pre-rigor Salting Levels on Physicochemical and Textural Properties of Chicken Breast Muscles

PubMed Central

Choi, Yun-Sang

2015-01-01

This study was conducted to evaluate the effect of pre-rigor salting level (0-4% NaCl concentration) on physicochemical and textural properties of pre-rigor chicken breast muscles. The pre-rigor chicken breast muscles were de-boned 10 min post-mortem and salted within 25 min post-mortem. An increase in pre-rigor salting level led to the formation of high ultimate pH of chicken breast muscles at post-mortem 24 h. The addition of minimum of 2% NaCl significantly improved water holding capacity, cooking loss, protein solubility, and hardness when compared to the non-salting chicken breast muscle (p<0.05). On the other hand, the increase in pre-rigor salting level caused the inhibition of myofibrillar protein degradation and the acceleration of lipid oxidation. However, the difference in NaCl concentration between 3% and 4% had no great differences in the results of physicochemical and textural properties due to pre-rigor salting effects (p>0.05). Therefore, our study certified the pre-rigor salting effect of chicken breast muscle salted with 2% NaCl when compared to post-rigor muscle salted with equal NaCl concentration, and suggests that the 2% NaCl concentration is minimally required to ensure the definite pre-rigor salting effect on chicken breast muscle. PMID:26761884

Polymorphic Protein Crystal Growth: Influence of Hydration and Ions in Glucose Isomerase

PubMed Central

Gillespie, C. M.; Asthagiri, D.; Lenhoff, A. M.

2014-01-01

Crystal polymorphs of glucose isomerase were examined to characterize the properties and to quantify the energetics of protein crystal growth. Transitions of polymorph stability were measured in poly(ethylene glycol)/NaCl solutions, and one transition point was singled out for more detailed quantitative analysis. Single crystal x-ray diffraction was used to confirm space groups and identify complementary crystal structures. Crystal polymorph stability was found to depend on the NaCl concentration, with stability transitions requiring > 1 M NaCl combined with a low concentration of PEG. Both salting-in and salting-out behavior was observed and was found to differ for the two polymorphs. For NaCl concentrations above the observed polymorph transition, the increase in solubility of the less stable polymorph together with an increase in the osmotic second virial coefficient suggests that changes in protein hydration upon addition of salt may explain the experimental trends. A combination of atomistic and continuum models was employed to dissect this behavior. Molecular dynamics simulations of the solvent environment were interpreted using quasi-chemical theory to understand changes in protein hydration as a function of NaCl concentration. The results suggest that protein surface hydration and Na+ binding may introduce steric barriers to contact formation, resulting in polymorph selection. PMID:24955067

Age-dependent changes in diastolic Ca{sup 2+} and Na{sup +} concentrations in dystrophic cardiomyopathy: Role of Ca{sup 2+} entry and IP{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mijares, Alfredo; Altamirano, Francisco; Kolster, Juan

2014-10-03

Highlights: • Age-dependent increase in [Ca{sup 2+}]{sub d} and [Na{sup +}]{sub d} in mdx cardiomyocytes. • Gadolinium significantly reduced both [Ca{sup 2+}]{sub d} and [Na{sup +}]{sub d} at all ages. • IP{sub 3}-pathway inhibition reduced cations concentrations in dystrophic cardiomyocytes. - Abstract: Duchenne muscular dystrophy (DMD) is a lethal X-inherited disease caused by dystrophin deficiency. Besides the relatively well characterized skeletal muscle degenerative processes, DMD is also associated with a dilated cardiomyopathy that leads to progressive heart failure at the end of the second decade. The aim of the present study was to characterize the diastolic Ca{sup 2+} concentration ([Ca{supmore » 2+}]{sub d}) and diastolic Na{sup +} concentration ([Na{sup +}]{sub d}) abnormalities in cardiomyocytes isolated from 3-, 6-, 9-, and 12-month old mdx mice using ion-selective microelectrodes. In addition, the contributions of gadolinium (Gd{sup 3+})-sensitive Ca{sup 2+} entry and inositol triphosphate (IP{sub 3}) signaling pathways in abnormal [Ca{sup 2+}]{sub d} and [Na{sup +}]{sub d} were investigated. Our results showed an age-dependent increase in both [Ca{sup 2+}]{sub d} and [Na{sup +}]{sub d} in dystrophic cardiomyocytes compared to those isolated from age-matched wt mice. Gd{sup 3+} treatment significantly reduced both [Ca{sup 2+}]{sub d} and [Na{sup +}]{sub d} at all ages. In addition, blockade of the IP{sub 3}-pathway with either U-73122 or xestospongin C significantly reduced ion concentrations in dystrophic cardiomyocytes. Co-treatment with U-73122 and Gd{sup 3+} normalized both [Ca{sup 2+}]{sub d} and [Na{sup +}]{sub d} at all ages in dystrophic cardiomyocytes. These data showed that loss of dystrophin in mdx cardiomyocytes produced an age-dependent intracellular Ca{sup 2+} and Na{sup +} overload mediated at least in part by enhanced Ca{sup 2+} entry through Gd{sup 3+} sensitive transient receptor potential channels (TRPC), and by IP{sub 3} receptors.« less

Influence of methionine and vitamin E on fluoride concentration in bones and teeth of rats exposed to sodium fluoride in drinking water.

PubMed

Błaszczyk, Iwona; Birkner, Ewa; Gutowska, Izabela; Romuk, Ewa; Chlubek, Dariusz

2012-06-01

Increased exposure to fluorine-containing compounds leads to accumulation of fluorides in hard tissues of bones and teeth, which may result in numerous skeletal and dental disorders. This study evaluates the influence of methionine and vitamin E on fluoride concentration in bones and teeth of rats subjected to long-term exposure to sodium fluoride in drinking water. The study was conducted in 30 3-month-old female Wistar FL rats. The animals were divided into five groups, six rats per group. The control group consisted of rats receiving only distilled water as drinking water. All other groups received NaF in the amount of 10 mg/kg of body mass/day in their drinking water. In addition, respective animal groups received: NaF + Met group--10 mg of methionine/kg of body mass/day, NaF + Met + E group--10 mg of methionine/kg of body mass/day and 3 mg of vitamin E (tocopheroli acetas)/rat/day and NaF + E group--3 mg of vitamin E/rat/day. Femoral bones and incisor teeth were collected for the study, and the fluoride concentration was determined using a fluoride ion-selective electrode. Fluoride concentration in both bones and teeth was found to be higher in the NaF and NaF + Met groups compared to the control group. In groups NaF + Met + E and NaF + E, the study material contained much lower fluoride concentration compared to the NaF group, while the effect was more prominent in the NaF + E group. The results of the studies indicate that methionine and vitamin E have opposite effects on accumulation of fluorides in hard tissue in rats. By stimulating fluoride accumulation, methionine reduces the adverse effect of fluorides on soft tissue, while vitamin E, which prevents excessive accumulation of fluorides in bones and teeth, protects these tissues from fluorosis. Therefore, it seems that combined application of both compounds would be optimal for the prevention of the adverse effects of chronic fluoride intoxication.

An experimental study of Pb and Zn as a function of HCl at 300 and 500°C

NASA Astrophysics Data System (ADS)

Rock, M.; Frank, M. R.

2017-12-01

Hydrothermal galena (PbS) and sphalerite (ZnS) deposits are important sources of Pb and Zn and can be related to low-temperature Mississippi Valley (MVT), moderate temperature massive sulfides (VMS), and higher-temperature porphyry type deposits). Lead and Zn are thought to complex with chloride (PbCl2 and ZnCl2) in the hydrothermal fluid and can precipitate through a decrease in temperature, an increase in pH, or through the addition of reduce sulfur. There is, however, a dearth of data on the solubility of galena and sphalerite in acidic and sulfur-rich hydrothermal fluids over a range temperature that spans the MVT to porphyry systems The experiments were conducted in René 41 cold-seal pressure vessels at 300 and 500°C and 100 MPa to determine the concentrations of Pb and Zn in hydrothermal fluids as a function of HCl. Platinum capsules were loaded with natural galena and sphalerite and an aqueous fluid of 13-15 wt.% NaCl (eq.) containing HCl + NaCl. The [Na/H] of the aqueous fluid was varied from 1.75 to 340. The aqueous fluids were captured at the conclusion of the experiment and Pb and Zn concentrations were determined by using AA and ICP-OES. The data illustrate that the concentration of Pb and Zn in the fluid increased directly with temperature and total chloride while indirectly with [Na/H]. Lead and Zn concentrations at 300°C were highest at a [Na/H] of 1.75 with concentrations of 84 μg/g and 2200 ± 600 μg/g, respectively, and decreased to 4 μg/g and 241 μg/g, respectively, at a [Na/H] of 295. At 500°C, lead concentrations were 7600 ± 1600 μg/g at a [Na/H] of 1.75 and decreased to 1170 μg/g at a [Na/H] of 340. Zinc concentrations at 500°C were 1700 μg/g at a [Na/H] of 30 and 640 μg/g at a [Na/H] of 100. Decreasing acidity (increasing [Na/H]) and temperature are especially efficient at inducing the precipitation of galena and sphalerite and could produce variable Pb:Zn values in a given system depending on if temperature or acidity was more variable. Thus, galena and sphalerite can precipitate from a reduced sulfur-bearing fluid provided the acidity of the fluid was sufficiently high during transportation. Further, the variable Pb:Zn ratios observed in some ore-bearing systems could be a result of differences in the rate of change of temperature, acidity, and reduced sulfur and not from separate pulses of distinct mineralizing fluids.

External quality assessment for enterovirus 71 and coxsackievirus A16 detection by reverse transcription-PCR using armored RNA as a virus surrogate.

PubMed

Song, Liqiong; Sun, Shipeng; Li, Bo; Pan, Yang; Li, Wenli; Zhang, Kuo; Li, Jinming

2011-10-01

Three armored RNAs (virus-like particles [VLPs]) containing target sequences from enterovirus 71 (EV71) and coxsackievirus A16 (CA16) and a pan-enterovirus (pan-EV) sequence were constructed and used in an external quality assessment (EQA) to determine the performance of laboratories in the detection of EV71 and CA16. The EQA panel, which consisted of 20 samples, including 14 positive samples with different concentrations of EV and either EV71 or CA16 armored RNAs, 2 samples with all 3 armored RNAs, and 4 negative-control samples (NaN(3)-preserved minimal essential medium [MEM] without VLPs), was distributed to 54 laboratories that perform molecular diagnosis of hand, foot, and mouth disease (HFMD) virus infections. A total of 41 data sets from 41 participants were returned; 5 (12.2%) were generated using conventional in-house reverse transcription-PCR (RT-PCR) assays, and 36 (87.8%) were generated using commercial real-time RT-PCR assays. Performance assessments of laboratories differed; 12 (29.3%) showed a need for improvement. Surprisingly, 4 laboratories were unable to detect EV71 RNA in any samples, even those containing the highest concentration of 10(7) IU/ml. Furthermore, the detection sensitivity for EV71 among all laboratories (82.1%) was substantially lower than that for EV (97.4%) or CA16 (95.1%). Overall, the results of the present study indicate that EQA should be performed periodically to help laboratories monitor their ability to detect HFMD viruses and to improve the comparability of results from different laboratories.

External Quality Assessment for Enterovirus 71 and Coxsackievirus A16 Detection by Reverse Transcription-PCR Using Armored RNA as a Virus Surrogate▿†

PubMed Central

Song, Liqiong; Sun, Shipeng; Li, Bo; Pan, Yang; Li, Wenli; Zhang, Kuo; Li, Jinming

2011-01-01

Three armored RNAs (virus-like particles [VLPs]) containing target sequences from enterovirus 71 (EV71) and coxsackievirus A16 (CA16) and a pan-enterovirus (pan-EV) sequence were constructed and used in an external quality assessment (EQA) to determine the performance of laboratories in the detection of EV71 and CA16. The EQA panel, which consisted of 20 samples, including 14 positive samples with different concentrations of EV and either EV71 or CA16 armored RNAs, 2 samples with all 3 armored RNAs, and 4 negative-control samples (NaN3-preserved minimal essential medium [MEM] without VLPs), was distributed to 54 laboratories that perform molecular diagnosis of hand, foot, and mouth disease (HFMD) virus infections. A total of 41 data sets from 41 participants were returned; 5 (12.2%) were generated using conventional in-house reverse transcription-PCR (RT-PCR) assays, and 36 (87.8%) were generated using commercial real-time RT-PCR assays. Performance assessments of laboratories differed; 12 (29.3%) showed a need for improvement. Surprisingly, 4 laboratories were unable to detect EV71 RNA in any samples, even those containing the highest concentration of 107 IU/ml. Furthermore, the detection sensitivity for EV71 among all laboratories (82.1%) was substantially lower than that for EV (97.4%) or CA16 (95.1%). Overall, the results of the present study indicate that EQA should be performed periodically to help laboratories monitor their ability to detect HFMD viruses and to improve the comparability of results from different laboratories. PMID:21865426

Effect of Spacecraft Environmental Variables on the Flammability of Fire Resistant Fabrics

NASA Astrophysics Data System (ADS)

Osorio, A. F.; Fernandez-Pello, C.; Takahashi, S.; Rodriguez, J.; Urban, D. L.; Ruff, G.

2012-01-01

Fire resistant fabrics are used for firefighter, racecar drivers as well as astronaut suits. However, their fire resistant characteristics depend on the environment conditions and require study. Particularly important is the response of these fabrics to elevated oxygen concentration environments and radiant heat from a source such as an adjacent fire. In this work, experiments using two fire resistant fabrics were conducted to study the effect of oxygen concentration, external radiant flux and oxidizer flow velocity in concurrent flame spread. Results show that for a given fabric the minimum oxygen concentration for flame spread depends strongly on the magnitude of the external radiant flux. At increased oxygen concentrations the external radiant flux required for flame spread decreases. Oxidizer flow velocity influences the external radiant flux only when the convective heat flux from the flame has similar values to the external radiant flux. The results of this work provide further understanding of the flammability characteristics of fire resistant fabrics in environments similar to those of future spacecrafts.

Antagonistic Effect of Monovalent Cations in Maintenance of Cellular Integrity of a Marine Bacterium1

PubMed Central

De Voe, Irving W.; Oginsky, Evelyn L.

1969-01-01

The susceptibility of a marine bacterium, designated isolate c-A1, to lysis in distilled water and in salt solutions has been found to be a function of Na+ concentration. Optical densities of cells pre-exposed to 0.05 m MgCl2 were maintained in 1.0 m KCl, whereas those of cells pre-exposed to 1.0 m NaCl were not maintained at any KCl concentration tested. Cells transferred from MgCl2 to low concentrations of NaCl underwent more extensive lysis than did those transferred to distilled water. The degree of disruption of cells transferred to distilled water from mixtures of 0.05 m MgCl2 and NaCl (0 to 1.0 m) was dependent on the concentration of NaCl; similar results were obtained with LiCl, but not with KCl. In electron micrographs of thin sections, c-A1 cell envelopes consisted of two double-track layers which fractured and peeled apart on lysis after pre-exposure to NaCl-MgCl2 mixtures. Envelope eruptions or “hernias” occurred only in lysed cells pre-exposed to NaCl alone. No evidence for a functional lytic enzyme was found. Comparative studies on a terrestrial pseudomonad with a multilayered envelope indicated that preexposure to NaCl did not enhance the susceptibility of this cell to lysis in distilled water. The lytic susceptibility of the marine bacterium is considered to be the consequence of competition between specific monovalent cations and Mg++ for electrostatic interactions with components of the cell envelope of this organism. Images PMID:5788707

Free calcium ions in neurones of Helix aspersa measured with ion-selective micro-electrodes.

PubMed Central

Alvarez-Leefmans, F J; Rink, T J; Tsien, R Y

1981-01-01

1. Intracellular free calcium concentration, [Ca2+]i, was measured in giant neurones of the sub-oesophageal ganglia of Helix aspersa, using Ca-selective micro-electrodes containing a PVC-gelled, neutral-ligand sensor. 2. In calibration solutions the electrodes had a virtually ideal, Nernstian, response down to 1 microM-Ca2+ in the presence of 0.125 M-K+, 18-24 mV from 1 to 0.1 microM-Ca2+ and 8-14 mV from 0.1 to 0.01 microM-Ca2+. Interference from H+ and Mg2+ was negligible. The small response to Na+ at sub-micromolar Ca2+ was taken into account, when necessary, in measurement of [Ca2+]i. 3. Measurements of basal [Ca2+]i were made in ganglia from animals kept only a few weeks in captivity, in a bathing solution equilibrated with air and containing 2 mM-Ca2+. In thirteen measurements from impalements which met stringent criteria for electrode performance and cell viability, the mean basal pCa (--log10[Ca2+]) was 6.77 +/- 0.07 (S.E.), corresponding to a mean free Ca2+ concentration of 0.17 microM. 4. The basal [Ca2+]i in neurones from a group of snails kept hibernating for several months was higher, mean pCa 6.15, for ganglia handled in 2 mM-Ca2+ solution. 5. Intracellular injections of Ca2+ or EGTA raised and lowered, respectively, the indicated basal [Ca2+]i, showing that the electrodes responded appropriately inside the cells and that unknown or untested components of cytoplasm were not significantly interfering with the Ca-sensor. 6. Altering the external Ca2+ concentration between 0.1 and 10 mM usually produced only small, +/- 0.1 pCa units, changes in basal [Ca2+]i of satisfactorily impaled, quiescent cells. 7. In cell 1F, which has repetitive spikes with a substantial Ca current, changes in Ca gradient or blockade of voltage-dependent Ca channels sometimes markedly altered [Ca2+]i, showing that Ca entry with the spikes was elevating [Ca2+]i. 8. Replacing external Na+ with Li+ or bis(2-hydroxyethyl)dimethylammonium had little effect on [Ca2+]i. 9. Elevating CO2 to 5% or 79% lowered [Ca2+]i by an average of 0.16 and 0.26 pCa units respectively. PMID:6273543

Ionic currents of outer hair cells isolated from the guinea-pig cochlea.

PubMed

Housley, G D; Ashmore, J F

1992-03-01

1. Whole-cell currents were measured in outer hair cells isolated from each turn of the organ of Corti of the guinea-pig. 2. The slope input conductances at -70 mV of the cells ranged from 3.6 to 51 nS depending on the length of the cell. Shorter cells from the basal turns of the cochlea had the highest values. The membrane time constant of the cells varied from 3 to 0.2 ms from the apex to the base. 3. Irrespective of the position of the cells along the cochlea, three distinct currents were found. Each type of current was found in approximately the same proportion in all cells. 4. An outward K+ current was present which activated at potentials more positive than -35 mV. The current was sensitive to tetraethylammonium (30 mM), quinidine (100 microM) and nifedipine (50 microM). It could be removed by replacing external Ca2+ with Ba2+ or Mg2+. The current was also removed by substituting Nai+ or Csi+ for Ki+ pipette solution. This outwardly rectifying current appears similar to the calcium-activated K+ current described in other hair cells. 5. The main current present at membrane potentials from -90 mV to -50 mV was a second voltage-activated K+ current. It was 50% activated at -80 mV, and relaxed with a time constant of 20-40 ms on hyperpolarization to -120 mV. Near rest the kinetics were essentially time-dependent , but depended upon the external K+ concentration. The current was blocked by 5 mM external Cs+. 6. This current was highly selective for K+. Measured from reversal of the tail currents, the permeability ratio PK:PNa was approximately 30:1. Depolarization of the cell, presumed to lead to an elevation of intracellular calcium, produced a prolonged activation of the current. 7. A third current found in the cells was a cation current. By external ion replacement, the selectivity sequence was determined to be Ca2+ greater than Na+ approximately equal to K+ greater than choline+ greater than NMDG+ (respective permeabilities relative to Na: 2.9, 1.0, 0.99, 0.63 and 0.37). This current was reduced by external Ba2+ (3 mM) and by nifedipine (50 microM). The activation of this current appeared to depend upon raised levels of Cai2+. 8. These currents account for reported in vivo properties of cochlear outer hair cells as cells permeable to potassium at large negative resting potentials. The consequences for sound detection in the cochlea are briefly discussed.

On archaebacterial ATPase from Halobacterium saccharovorum

NASA Technical Reports Server (NTRS)

Kristjansson, H.; Ponnamperuma, C.; Hochstein, L.; Altekar, W.

1984-01-01

The energy transducing ATPase from Halobacterium saccharovorum was studied in order to define the origin of energy transducing systems. The ATPase required high salt concentration (4M NaCl) for activity; activity was rapidly lost when NaCl was below 1 Molar. At low salt concentration, the membrane bound ATPase activity could be stabilized in presence of spermine. However, following solubilization spermine was ineffective. Furthermore, F1 ATPase activity was stabilized by ammonium sulfate even when the NaCl concentration was less than 1 Molar. These studies suggest that stabilization by hydrophobic interactions preceded ionic ones in the evolution of the energy transducing ATPases.

Production and Rheological Properties of Welan Gum Produced by Sphingomonas sp. ATCC 31555 with Different Nitrogen Sources.

PubMed

Xu, Xiaopeng; Nie, Zuoming; Zheng, Zhiyong; Zhu, Li; Zhan, Xiaobei

2017-01-01

This study aimed to investigate the effect of nitrogen sources on the production and rheological properties of welan gum produced by Sphingomonas sp. ATCC 31555. Six different nitrogen sources were used for ATCC 31555 fermentation, and 2 of these were further analyzed due to their more positive influence on welan gum production and bacterial biomass. Bacterial biomass, welan gum yield, welan viscosity, molecular weight, monosaccharide composition, acyl content, and welan structure were analyzed. Welan gum production and the biomass concentration of ATCC 31555 were higher in media containing NaNO3 and beef extract. Welan viscosity decreased at higher temperatures of 30-90°C, and it increased with a higher welan concentration. In the media containing NaNO3 (3 g·L-1), welan viscosity was higher at 30-70°C and a welan solution concentration of 6-10 g·L-1. With a reduced NaNO3 concentration, the molecular weight of welan gum and the molar ratio of mannose decreased, but the molar ratio of glucuronic acid increased. With different nitrogen sources, the acetyl content of welan gum differed but its structure was similar. NaNO3 and beef extract facilitated welan production. A reduced NaNO3 concentration promoted welan viscosity. © 2017 S. Karger AG, Basel.

Effect of sodium hypochlorite on human pulp cells: an in vitro study

PubMed Central

Essner, Mark D.; Javed, Amjad; Eleazer, Paul D.

2014-01-01

Background The purpose of this study was to determine the effect of sodium hypochlorite (NaOCl) on human pulp cells to provide an aid in determining its optimum concentration in maintaining the viability of remaining pulp cells in the revascularization of immature permanent teeth with apical periodontitis. Study design Human pulp tissue cells taken from extracted third molars were plated, incubated, and subjected to various concentrations of NaOCl (0.33%, 0.16%, 0.08%, and 0.04%) for 5-, 10-, and 15-minute time intervals to simulate possible contact times in vivo. The Cell Titer–Glo Luminescent Cell Viability Assay was used to determine the number of viable cells present in culture following treatment. Results The results showed an increase in cell viability with the lowering of NaOCl concentration. The use of 0.04% NaOCl was similar to the control, indicating nearly complete preservation of cell viability at all time intervals tested. As sodium hypochlorite concentration increased from 0.04% to 0.33%, cell viability decreased correspondingly. Conclusions The results indicate that the lowest concentration of NaOCl tested did not affect the viability of cells. This may prove beneficial in developing a new treatment protocol to help preserve existing vital pulp cells in revascularization cases. PMID:21821446

Hybrid Molecule-Nanocrystal Photon Upconversion Across the Visible and Near-Infrared

DTIC Science & Technology

2015-07-10

applications in solar energy, biological imaging , and data storage. In this Letter, CdSe and PbSe semiconductor nanocrystals are combined with molecular...Goldschmidt, J. C. Absolute Upconversion Quantum Yield of β-NaYF4 Doped with Er3+ and External Quantum Efficiency of Upconverter Solar Cell Devices...C. Peak External Photocurrent Quantum Efficiency Exceeding 100% via MEG in a Quantum Dot Solar Cell . Science 2011, 334, 1530−1533. (37) Choi, J.-H

Formation of lactoferrin/sodium caseinate complexes and their adsorption behaviour at the air/water interface.

PubMed

Li, Quanyang; Zhao, Zhengtao

2017-10-01

This research investigated the complexation behaviour between lactoferrin (Lf) and sodium caseinate (NaCas) before and after heat treatment. The results showed that heating facilitated their interaction and different complexes were formed at different Lf/NaCas ratios. The presence of low concentrations of NaCas resulted in the rapid precipitation of Lf, while no precipitation was observed at the NaCas concentrations higher than Lf/NaCas ratio of 2:1. The formed complexes at the ratio of 2:1 have an average diameter of 194±9.0nm and they exhibited a great capacity in lowering the air/water interfacial tension. Further increase of NaCas concentration to ratios of 1:1 and 1:2 resulted in the formation of smaller complexes with average diameters of 60±2.5nm. The complexes formed at these two ratios showed similar adsorption behaviour at the air/water interface and they exhibited lower capacity in decreasing the interfacial tension than the ratio of 2:1. Copyright © 2017 Elsevier Ltd. All rights reserved.

The responses of cucumber plants subjected to different salinity or fertilizer concentrations and reproductive success of Tetranychus urticae mites on these plants.

PubMed

Khodayari, Samira; Abedini, Fatemeh; Renault, David

2018-05-01

The plant stress hypothesis posits that a herbivore's reproductive success increases when it feeds on stressed plants, while the plant vigor hypothesis predicts that a herbivore preferentially feeds on more vigorous plants. We examined these opposing hypotheses by growing spider mites (Tetranychus urticae) on the leaves of stressed and healthy (vigorous) cucumber plants. Host plants were grown under controlled conditions at low, moderate, and high concentrations of NaCl (to induce salinity stress), at low, moderate, and high fertilizer concentrations (to support growth), and without these additions (control). The effects of these treatments were evaluated by measuring fresh and dry plant biomass, carotenoid and chlorophyll content, antioxidant enzyme activity, and concentrations of PO 4 3- , K + , and Na + in plant tissues. The addition of low concentrations of fertilizer increased dry mass, protein, and carotenoid content relative to controls, suggesting a beneficial effect on plants. The highest NaCl treatment (2560 mg L -1 ) resulted in increased Na + and protein content relative to control plants, as well as reduced PO 4 3- , K + , and chlorophyll levels and reduced catalase and ascorbate peroxidase enzyme activity levels. Analysis of life table data of T. urticae mites raised on leaves from the aforementioned plant groups showed the intrinsic rate of increase (r) for mites was 0.167 day -1 in control specimens, 0.125 day -1 for mites reared on plants treated with a moderate concentration of fertilizer (10 mL L -1 ), and was highest (0.241 day -1 ) on plants grown under moderate salinity conditions (1920 mg L -1 NaCl). Reproductive success of T. urticae did not differ on plants watered with a moderate concentration of NaCl or a high concentration of fertilizer. The moderately-stressed plants formed a favorable environment for the development and reproduction of spider mites, supporting the plant stress hypothesis.

Effect of Ca sup 2+ on Cl sup minus transport in thin ascending limb of Henle's loop

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kondo, Yoshiaki; Yoshitomi, Koji; Imai, Masashi

1988-02-01

Effects of ambient Ca{sup 2+} concentration on Cl{sup {minus}} transport across the thin ascending limb of Henle's loop (TAL) were examined by the in vitro microperfusion technique. When Ca{sup 2+} concentration in the bathing fluid was decreased from 1.5 mM to nominally 0 mM at 37{degree}C, the relative permeability of Cl{sup {minus}} to Na{sup +} (P{sub Cl}/P{sub Na}) estimated from the NaCl diffusion voltage changed from 2.44 to 1.27. When Ca{sup 2+} concentration of the luminal fluid was reduced, P{sub Cl}/P{sub Na} was unchanged. When Ca{sup 2+} concentration in the bathing fluid was change from 4.5 to nominally 0 mM,more » the lumen-to-bath flux coefficient for {sup 36}Cl (K{sub 1{yields}b}{sup 36Cl}) was decreased, whereas the value of {sup 22}Na was unchanged, indicating that the reduction of Ca{sup 2+} concentration in the bathing fluid selectively inhibits Cl{sup {minus}} transport without affecting Na{sup +} transport. The pH titration curves of relative Cl{sup {minus}} permeability examined at three different Ca{sup 2+} concentrations at 37{degree}C revealed that the interaction between proton and Ca{sup +} was noncompetitive. Addition of quin 2-AM, which reduced intracellular Ca{sup 2+} concentration, to the bath caused an irreversible suppression of Cl{sup {minus}} permeability, suggesting that the decrease in intracellular Ca{sup 2+} concentration also inhibits the Cl{sup {minus}} transport across the TAL. From these observations the authors suggest: (1) Cl{sup {minus}} transport across the TAL is regulated by Ca{sup 2+} preferentially on the basolateral membrane; (2) this regulation depends on temperature; and (3) there is a noncompetitive interaction between Ca{sup 2+} and proton in the regulation of the conductive Cl{sup {minus}} pathway.« less

Cyclic variations in nitrogen uptake rate of soybean plants: effects of external nitrate concentration

NASA Technical Reports Server (NTRS)

Tolley-Henry, L.; Raper, C. D. Jr; Granato, T. C.; Raper CD, J. r. (Principal Investigator)

1988-01-01

Net uptake of NO3- by non-nodulated soybean plants [Glycine max (L.) Merr. cv. Ransom] growing in flowing hydroponic cultures containing 0.5, 1.0 and 10.0 mol m-3 NO3- was measured daily during a 24-d period of vegetative development to determine if amplitude of maximum and minimum rates of net NO3- uptake are responsive to external concentrations of NO3-. Removal of NO3- from the replenished solutions during each 24-h period was determined by ion chromatography. Neither dry matter accumulation nor the periodicity of oscillations in net uptake rate was altered by the external NO3- concentrations. The maxima of the oscillations in net uptake rate, however, increased nearly 3-fold in response to external NO3- concentrations. The maxima and minima, respectively, changed from 4.0 and 0.6 mmol NO3- per gram root dry weight per day at an external solution level of 0.5 mol m-3 NO3- to 15.2 and -2.7 mmol NO3- per gram root dry weight per day at an external solution level of 10.0 mol m-3 NO3-. The negative values for minimum net uptake rate from 10.0 mol m-3 NO3- solutions show that net efflux was occurring and indicate that the magnitude of the efflux component of net uptake was responsive to external concentration of NO3-.

Synthesis of copper nanocolloids using a continuous flow based microreactor

NASA Astrophysics Data System (ADS)

Xu, Lei; Peng, Jinhui; Srinivasakannan, C.; Chen, Guo; Shen, Amy Q.

2015-11-01

The copper (Cu) nanocolloids were prepared by sodium borohydride (NaBH4) reduction of metal salt solutions in a T-shaped microreactor at room temperature. The influence of NaBH4 molar concentrations on copper particle's diameter, morphology, size distribution, and elemental compositions has been investigated by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The ultraviolet-visible spectroscopy (UV-vis) was used to verify the chemical compounds of nanocolloids and estimate the average size of copper nanocolloids. The synthesized copper nanocolloids were uniform in size and non-oxidized. A decrease in the mean diameter of copper nanocolloids was observed with increasing NaBH4 molar concentrations. The maximum mean diameter (4.25 nm) occurred at the CuSO4/NaBH4 molar concentration ratio of 1:2.

Na(+)/Ca(2+) exchanger inhibition exerts a positive inotropic effect in the rat heart, but fails to influence the contractility of the rabbit heart.

PubMed

Farkas, A S; Acsai, K; Nagy, N; Tóth, A; Fülöp, F; Seprényi, G; Birinyi, P; Nánási, P P; Forster, T; Csanády, M; Papp, J G; Varró, A; Farkas, A

2008-05-01

The Na(+)/Ca(2+) exchanger (NCX) may play a key role in myocardial contractility. The operation of the NCX is affected by the action potential (AP) configuration and the intracellular Na(+) concentration. This study examined the effect of selective NCX inhibition by 0.1, 0.3 and 1.0 microM SEA0400 on the myocardial contractility in the setting of different AP configurations and different intracellular Na(+) concentrations in rabbit and rat hearts. The concentration-dependent effects of SEA0400 on I(Na/Ca) were studied in rat and rabbit ventricular cardiomyocytes using a patch clamp technique. Starling curves were constructed for isolated, Langendorff-perfused rat and rabbit hearts. The cardiac sarcolemmal NCX protein densities of both species were compared by immunohistochemistry. SEA0400 inhibited I(Na/Ca) with similar efficacy in the two species; there was no difference between the inhibitions of the forward or reverse mode of the NCX in either species. SEA0400 increased the systolic and the developed pressure in the rat heart in a concentration-dependent manner, for example, 1.0 microM SEA0400 increased the maximum systolic pressures by 12% relative to the control, whereas it failed to alter the contractility in the rabbit heart. No interspecies difference was found in the cardiac sarcolemmal NCX protein densities. NCX inhibition exerted a positive inotropic effect in the rat heart, but it did not influence the contractility of the rabbit heart. This implies that the AP configuration and the intracellular Na(+) concentration may play an important role in the contractility response to NCX inhibition.

Allergenic proteins are fragmented in low concentrations of sodium hypochlorite.

PubMed

Chen, P; Eggleston, P A

2001-07-01

To facilitate allergen removal from indoor environments, it would be helpful to have household cleaning products that modified allergenic activity. Because NaOCl dissolves proteins in high concentrations and is both capable of killing bacteria and viruses and inactivating viral antigens at somewhat lower concentrations, we explored its effects on Mus m 1 and other indoor allergens. To examine the ability of NaOCl to reduce the allergenicity of Mus m 1 and other indoor allergens. Using purified mouse urinary allergen, we examined the effect on protein measured by Coomassie protein assay and on Mus m 1 measured by ELISA. We also examined the effects using SDS/PAGE and Western blots probed with sheep anti-Mus m 1 and with allergic human serum. When NaOCl and Mus m 1 were combined in a molar ratio of 100 : 1, IgE binding to Mus m 1 on Western blot was significantly reduced. At higher NaOCl concentrations the protein appeared to fragment and eventually became undetectable. Fragmentation appeared to be random in that peptides of a wide range of apparent molecular weight were produced. The reaction was complete within 1-2 min at OCl : pr ratios of greater than 200 : 1 and was optimal at pH 7.4. Immunological activity of other allergens (Fel d 1, Bla g 1, Der p 1) was decreased in vitro and dried allergen extracts were removed from surfaces. Adding an extraneous protein, BSA, to NaOCl:Mus m 1 solutions decreased the effect of NaOCl on the allergen. We concluded that NaOCl at concentrations commonly used in household products is capable of dramatically affecting allergenic protein.

Dissolution of bovine pulp tissue in solutions consisting of varying NaOCl concentrations and combined with EDTA.

PubMed

Irala, Luis Eduardo Duarte; Grazziotin-Soares, Renata; Salles, Alexandre Azevedo; Munari, Aline Zen; Pereira, Joseani Santos

2010-01-01

This in vitro study evaluated (1) the dissolution of bovine pulp tissue in solutions consisting of varying NaOCl concentrations and combined with EDTA; and (2) the pH of these solutions before and after the experiment. The independent variables were the concentration and the volume of the solution. Thirty bovine pulps were divided in equal fragments, resulting in 90 fragments of pulp tissue. Each fragment was immersed in one of the following solutions: 1% NaOCl (4 ml), 2.5% NaOCl (4 ml), 1% NaOCl + 17% EDTA (2 ml : 2 ml), 1% NaOCl + 17% EDTA (1 ml : 3 ml), 2.5% NaOCl + 17% EDTA (2 ml : 2 ml), and 2.5% NaOCl + 17% EDTA (1 ml : 3 ml). The test solutions were dichotomized as either able or not able to dissolve the tissue, the latter being attributed when the dissolution of the pulp tissue was not complete within 48 hours. When the samples were able to dissolve the tissue, the time required for complete tissue dissolution was submitted to statistical analysis. The pH of the solutions was measured before and after the experiment. The pH variable was dichotomized as either changed or unchanged. The results demonstrated that the NaOCl solutions combined with 17% EDTA were not able to dissolve the tissue. The t-test revealed that the 2.5% NaOCl solution presented a lower mean dissolution time than the 1% NaOCl solution (p < 0.001). The pH of the solutions with equal volumes of NaOCl and EDTA decreased in 48 hours.

The Perceptual Characteristics of Sodium Chloride to Sodium-Depleted Rats.

PubMed

St John, Steven J

2017-02-01

Three experiments assessed potential changes in the rat's perception of sodium chloride (NaCl) during a state of sodium appetite. In Experiment 1, sodium-sufficient rats licking a range of NaCl concentrations (0.028-0.89M) in 15s trials showed an inverted U-shaped concentration response function peaking at 0.281M. Depleted rats (furosemide) showed an identical function, merely elevated, suggesting altered qualitative or hedonic perception but no change in perceived intensity. In Experiment 2, sodium-depleted rats were tested with NaCl, sodium gluconate, and potassium chloride (KCl; 0.028-0.89M) similar to Experiment 1. KCl was licked at the same rate as water except for a slight elevation at 0.158; sodium gluconate and NaCl were treated similarly, but rats showed more licking for hypertonic sodium gluconate than hypertonic NaCl. Sodium-depleted rats were also tested with NaCl mixed in amiloride (10-300 μM). Amiloride reduced licking but did not alter the shape of the concentration-response function. Collectively, these results suggest that transduction of sodium by epithelial sodium channels (which are blocked by amiloride and are more dominant in sodium gluconate than NaCl transduction) is crucial for the perception of sodium during physiological sodium depletion. In Experiment 3, sodium-deplete rats were tested with NaCl as in Experiment 1 but after taste aversion conditioning to 0.3M NaCl or sucrose. Rats conditioned to avoid NaCl but not sucrose failed to express a sodium appetite, strongly suggesting that NaCl does not undergo a change in taste quality during sodium appetite-rats show no confusion between sucrose and NaCl in this paradigm. Published by Oxford University Press on behalf of US Government 2016.

Quinone Reduction by the Na+-Translocating NADH Dehydrogenase Promotes Extracellular Superoxide Production in Vibrio cholerae▿ †

PubMed Central

Lin, Po-Chi; Türk, Karin; Häse, Claudia C.; Fritz, Günter; Steuber, Julia

2007-01-01

The pathogenicity of Vibrio cholerae is influenced by sodium ions which are actively extruded from the cell by the Na+-translocating NADH:quinone oxidoreductase (Na+-NQR). To study the function of the Na+-NQR in the respiratory chain of V. cholerae, we examined the formation of organic radicals and superoxide in a wild-type strain and a mutant strain lacking the Na+-NQR. Upon reduction with NADH, an organic radical was detected in native membranes by electron paramagnetic resonance spectroscopy which was assigned to ubisemiquinones generated by the Na+-NQR. The radical concentration increased from 0.2 mM at 0.08 mM Na+ to 0.4 mM at 14.7 mM Na+, indicating that the concentration of the coupling cation influences the redox state of the quinone pool in V. cholerae membranes. During respiration, V. cholerae cells produced extracellular superoxide with a specific activity of 10.2 nmol min−1 mg−1 in the wild type compared to 3.1 nmol min−1 mg−1 in the NQR deletion strain. Raising the Na+ concentration from 0.1 to 5 mM increased the rate of superoxide formation in the wild-type V. cholerae strain by at least 70%. Rates of respiratory H2O2 formation by wild-type V. cholerae cells (30.9 nmol min−1 mg−1) were threefold higher than rates observed with the mutant strain lacking the Na+-NQR (9.7 nmol min−1 mg−1). Our study shows that environmental Na+ could stimulate ubisemiquinone formation by the Na+-NQR and hereby enhance the production of reactive oxygen species formed during the autoxidation of reduced quinones. PMID:17322313

Hypernatremic Dehydration in Young Children: Is There a Solution?

PubMed

Ben-Shalom, Efrat; Toker, Ori; Schwartz, Shepard

2016-02-01

Hypernatremic dehydration is a common and potentially life-threatening condition in children. There is currently no consensus as to the optimal strategy for fluid management. To describe the relationship between the type, route and rate of fluids administered and the rate of decline in serum sodium (Na+) concentration. We reviewed the medical records of all children under the age of 2 years who were hospitalized with hypernatremic dehydration (serum Na+ ≥ 155 mEq/L) in Shaare Zedek Medical Center during the period 2001-2010. Collected data of 62 subjects included initial and subsequent serum Na+ levels, and rate and Na+ concentration of all intravenous and oral fluids administered until the serum Na+ reached ≤ 150 mEq/L. Median initial serum Na+ was 159.5 mEq/L (IQR 157-163, maximal value 170). The median rate of decline in serum Na+ until serum Na+ reached 150 mEq/L was 0.65 mEq/L/hr (IQR 0.45-0.95). Forty-two children received hypotonic oral fluids which accounted for approximately one-quarter of all fluids they received. There was no significant difference in the rate of decline in serum Na+ between those who consumed oral fluids and those who did not. Neither was there a correlation between the rate of IV fluids, receipt of oral fluids or the degree of dehydration, with the rate of decline in serum Na+. No child experienced an apparent short-term adverse outcome. A cumulative rate of 5.9 mI/kg/hr of IV fluid administration may reduce the serum Na+ by an acceptable rate (0.65 mEq/L/hr). Fluid therapy comprising up to 25% hypotonic oral fluids and 75% IV fluids high in Na+ concentration was not associated with any short-term adverse outcome in our patient population.

Reactive species modify NaV1.8 channels and affect action potentials in murine dorsal root ganglia neurons

PubMed Central

Schink, Martin; Leipolcf, Enrico; Schirmeyer, Jana; Schönherr, Roland; Hoshi, Toshinori; Heinemann, Stefan H.

2016-01-01

Dorsal root ganglia (DRG) neurons are important relay stations between the periphery and the central nervous system and are essential for somatosensory signaling. Reactive species are produced in a variety of physiological and pathophysiological conditions and are known to alter electric signaling. Here we studied the influence of reactive species on the electrical properties of DRG neurons from mice with the whole-cell patch-clamp method. Even mild stress induced by either low concentrations of chloramine-T (10 µM) or low-intensity blue-light irradiation profoundly diminished action potential frequency but prolonged single action potentials in wild-type neurons. The impact on evoked action potentials was much smaller in neurons deficient of the tetrodotoxin (TTX)-resistant voltage-gated sodium channel NaV1.8 (NaV1.8−/−), the channel most important for the action potential upstroke in DRG neurons. Low concentrations of chloramine-T caused a significant reduction of NaV1.8 peak current and at higher concentrations progressively slowed down inactivation. Blue light had a smaller effect on amplitude but slowed down NaV1.8 channel inactivation. The observed effects were less apparent for TTX-sensitive NaV channels. NaV1.8 is an important reactive-species-sensitive component in the electrical signaling of DRG neurons, potentially giving rise to loss-of-function and gain-of-function phenomena depending on the type of reactive species and their effective concentration and time of exposure. PMID:26383867

Reactive species modify NaV1.8 channels and affect action potentials in murine dorsal root ganglion neurons.

PubMed

Schink, Martin; Leipold, Enrico; Schirmeyer, Jana; Schönherr, Roland; Hoshi, Toshinori; Heinemann, Stefan H

2016-01-01

Dorsal root ganglion (DRG) neurons are important relay stations between the periphery and the central nervous system and are essential for somatosensory signaling. Reactive species are produced in a variety of physiological and pathophysiological conditions and are known to alter electric signaling. Here we studied the influence of reactive species on the electrical properties of DRG neurons from mice with the whole-cell patch-clamp method. Even mild stress induced by either low concentrations of chloramine-T (10 μM) or low-intensity blue light irradiation profoundly diminished action potential frequency but prolonged single action potentials in wild-type neurons. The impact on evoked action potentials was much smaller in neurons deficient of the tetrodotoxin (TTX)-resistant voltage-gated sodium channel NaV1.8 (NaV1.8(-/-)), the channel most important for the action potential upstroke in DRG neurons. Low concentrations of chloramine-T caused a significant reduction of NaV1.8 peak current and, at higher concentrations, progressively slowed down inactivation. Blue light had a smaller effect on amplitude but slowed down NaV1.8 channel inactivation. The observed effects were less apparent for TTX-sensitive NaV channels. NaV1.8 is an important reactive-species-sensitive component in the electrical signaling of DRG neurons, potentially giving rise to loss-of-function and gain-of-function phenomena depending on the type of reactive species and their effective concentration and time of exposure.

Caustic stress corrosion cracking of alloys 600 and 690 with NaOH concentrations

NASA Astrophysics Data System (ADS)

Park, In-Gyu; Lee, Chang-Soon; Hwang, Seong-Sik; Kim, Hong-Pyo; Kim, Joung-Soo

2005-10-01

In order to evaluate the stress corrosion cracking resistance for commercial alloys (C600MA, C600TT, C690TT) and Korean-made alloys (K600MA, K690TT), C-ring tests were performed in a caustic environment of 4, 10, 20, 30, and 50% NaOH solution at 315°C, for 480 h with an applied potential of 125 mV vs. OCP. Different stress corrosion cracking phenomena were observed according to the NaOH concentration. The rate of caustic IGSCC attack did not appear to increase monotonically with caustic concentrations, but peaked at a concentration between 4 and 50% caustic, or approximately 30% NaOH. Intergranular stress corrosion cracking was found for C600MA in 10, 20, and 30% NaOH solutions, while no cracking was observed in the 4 and 50% NaOH solutions. In 30% NaOH solution, transgrnular stress corrosion cracking was detected in C690TT, which may be related with the large amount of plastic strain (150% yield) and the applied potential (125 mV vs. OCP). The overall data clearly indicate that C600MA has the worst SCC resistance while K690TT offers the best resistance. There is also fairly good correlation between the caustic SCC susceptibility and some metallurgical parameters, particularly the grain size and the yield strength at room temperature. Specifically, materials having larger grain size and lower yield strength exhibited higher caustic SCC resistance.

Effects of dilute aqueous NaCl solution on caffeine aggregation

NASA Astrophysics Data System (ADS)

Sharma, Bhanita; Paul, Sandip

2013-11-01

The effect of salt concentration on association properties of caffeine molecule was investigated by employing molecular dynamics simulations in isothermal-isobaric ensemble of eight caffeine molecules in pure water and three different salt (NaCl) concentrations, at 300 K temperature and 1 atm pressure. The concentration of caffeine was taken almost at the solubility limit. With increasing salt concentration, we observe enhancement of first peak height and appearance of a second peak in the caffeine-caffeine distribution function. Furthermore, our calculated solvent accessible area values and cluster structure analyses suggest formation of higher order caffeine cluster on addition of salt. The calculated hydrogen bond properties reveal that there is a modest decrease in the average number of water-caffeine hydrogen bonds on addition of NaCl salt. Also observed are: (i) decrease in probability of salt contact ion pair as well as decrease in the solvent separated ion pair formation with increasing salt concentration, (ii) a modest second shell collapse in the water structure, and (iii) dehydration of hydrophobic atomic sites of caffeine on addition of NaCl.

Sodium Aluminate Concentration Effects on Microstructure and Corrosion Behavior of the Plasma Electrolytic Oxidation Coatings on Pure Titanium

NASA Astrophysics Data System (ADS)

Molaei, Maryam; Fattah-Alhosseini, Arash; Gashti, Seyed Omid

2018-01-01

Sodium aluminate (NaAlO2) concentration was varied in order to understand the influence of the chemical composition of electrolyte on the spark characteristics, microstructure, and corrosion behavior of plasma electrolytic oxidation (PEO) coatings. For this purpose, PEO coatings were formed on the pure titanium substrate surface using solutions of four diverse sodium aluminate concentrations (6, 8, 10, and 12 g/L). The PEO process was carried out at constant time and voltage (180 seconds and 420 V). Studying the microstructures of samples by scanning electron microscope (SEM) and their corrosion behavior in 3.5 wt pct NaCl solutions indicated that the increase in NaAlO2 concentration (up to 10 g/L) led to an increase in uniformity and compactness, thus decreasing the size of micro-pores and increment of corrosion resistance. However, at a certain level of NaAlO2 concentration (12 g/L), large and severe sparks were created on the surface of the sample during the process, worsening the corrosion resistance and microstructure of coating.

Accumulating pollutants in conifer needles on an Atlantic island - a case study with Pinus canariensis on Tenerife, Canary Islands.

PubMed

Tausz, Michael; Trummer, Walter; Goessler, Walter; Wonisch, Astrid; Grill, Dieter; Naumann, Simone; Jiménez, Maria Soledad; Morales, Domingo

2005-08-01

Concentrations of potential pollutant elements Na, Cl, and S were investigated in needles of Pinus canariensis grown at 55 field plots in Tenerife. Microelement concentrations (including heavy metals) were measured at a subset of 18 plots. Na and Cl concentrations were high at low elevations (up to 8 mg g(-1) Cl and 5.5 mg g(-1) Na). Na/Cl ratio close to standard seawater indicated sea spray influence up to 1200 m a.s.l. Only at few plots, sulphur concentrations indicated possible pollutant impact. Cluster and correlation analyses identified a related group of V, As, Cr, Fe, Mo, Ni, Cu, Pb, and Al, possibly related to traffic exhaust aggregated with soil particles. Mainly north-eastern, lower elevated plots were exposed to those immissions, but metal concentrations were generally low compared to data from other studies. In conclusion, seawater and soil particles explained most of the element distribution pattern in pine needles in Tenerife, but strong indications for some effect of local sources of air pollutants were detected.

Effects of dilute aqueous NaCl solution on caffeine aggregation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, Bhanita; Paul, Sandip, E-mail: sandipp@iitg.ernet.in

The effect of salt concentration on association properties of caffeine molecule was investigated by employing molecular dynamics simulations in isothermal-isobaric ensemble of eight caffeine molecules in pure water and three different salt (NaCl) concentrations, at 300 K temperature and 1 atm pressure. The concentration of caffeine was taken almost at the solubility limit. With increasing salt concentration, we observe enhancement of first peak height and appearance of a second peak in the caffeine-caffeine distribution function. Furthermore, our calculated solvent accessible area values and cluster structure analyses suggest formation of higher order caffeine cluster on addition of salt. The calculated hydrogenmore » bond properties reveal that there is a modest decrease in the average number of water-caffeine hydrogen bonds on addition of NaCl salt. Also observed are: (i) decrease in probability of salt contact ion pair as well as decrease in the solvent separated ion pair formation with increasing salt concentration, (ii) a modest second shell collapse in the water structure, and (iii) dehydration of hydrophobic atomic sites of caffeine on addition of NaCl.« less

Influence of biomass acclimation on the performance of a partial nitritation-anammox reactor treating industrial saline effluents.

PubMed

Giustinianovich, Elisa A; Campos, José-Luis; Roeckel, Marlene D; Estrada, Alejandro J; Mosquera-Corral, Anuska; Val Del Río, Ángeles

2018-03-01

The performance of the partial nitritation/anammox processes was evaluated for the treatment of fish canning effluents. A sequencing batch reactor (SBR) was fed with industrial wastewater, with variable salt and total ammonium nitrogen (TAN) concentrations in the range of 1.75-18.00 g-NaCl L -1 and 112 - 267 mg-TAN L -1 . The SBR operation was divided into two experiments: (A) progressive increase of salt concentrations from 1.75 to 18.33 g-NaCl L -1 ; (B) direct application of high salt concentration (18 g-NaCl L -1 ). The progressive increase of NaCl concentration provoked the inhibition of the anammox biomass by up to 94% when 18 g-NaCl L -1 were added. The stable operation of the processes was achieved after 154 days when the nitrogen removal rate was 0.021 ± 0.007 g N/L·d (corresponding to 30% of removal efficiency). To avoid the development of NOB activity at low salt concentrations and to stabilize the performance of the processes dissolved oxygen was supplied by intermittent aeration. A greater removal rate of 0.029 ± 0.017 g-N L -1 d -1 was obtained with direct exposure of the inoculum to 18 g-NaCl L -1 in less than 40 days. Also, higher specific activities than those from the inoculum were achieved for salt concentrations of 15 and 20 g-NaCl L -1 after 39 days of operation. This first study of the performance of the partial nitritation/anammox processes, to treat saline wastewaters, indicates that the acclimation period can be avoided to shorten the start-up period for industrial application purposes. Nevertheless, further experiments are needed in order to improve the efficiency of the processes. Copyright © 2017 Elsevier Ltd. All rights reserved.

Norandrosterone and noretiocholanolone concentration before and after submaximal standardized exercise.

PubMed

de Geus, B; Delbeke, F; Meeusen, R; Van Eenoo, P; De Meirleir, K; Busschaert, B

2004-10-01

19-Norandrosterone (19-NA) and 19-noretiocholanolone (19-NE) are the two main urinary indicators used to detect illegal use of nandrolone. Recent studies showed that 19-NA and 19-NE can be endogenously produced in non-treated humans. The concentrations were close to the threshold of the International Olympic Committee (IOC), i.e. 2 ng/ml for men and seem to increase after prolonged intense effort. Androgens are involved in the biosynthesis of estrogens and estrogen has a protective effect against skeletal muscle damage following eccentric exercise. Furthermore, the testicular tissue can synthesize 19-norandrogens from androgens, we hypothetisize that the 19-norandrogen production might be influenced by muscle damage following eccentric exercise. Therefore the purpose of this study is to examine if three different exercise methods will influence the urinary concentration of 19-NA and 19-NE in healthy young subjects. Fifteen amateur hockey players undertook a 30 min submaximal standardized exercise protocol. They were randomised for three different types of exercise, namely a cycle ergometer test (cyclic muscle activity), a treadmill test (concentric muscle activity), or a bench-steptest (eccentric muscle activity) at a target heart rate corresponding to 65 % (+/- 5 %) of Karvonen heart rate. Urine samples were obtained before the test and 60 min and 120 min after the end of exercise. Subjects completed a Likert scale of muscle soreness before and 12 h after exercise. 19-NA and 19-NE were determined by gas chromatography-tandem mass spectrometry (GC-MS-MS). Baseline urinary 19-NA and 19-NE concentrations were under limit of detection of 0.05 ng/ml, except for one sample (0.13 ng/ml). No 19-NA or 19-NE could be detected post exercise. In our experimental conditions, the exercise mode (eccentric or concentric) had no impact on 19-NA or 19-NE excretion. Our findings confirm that the current International Olympic Committee threshold level for nandrolone metabolites is sufficiently high to avoid false positive cases.

Quinoa Seed Quality Response to Sodium Chloride and Sodium Sulfate Salinity

PubMed Central

Wu, Geyang; Peterson, Adam J.; Morris, Craig F.; Murphy, Kevin M.

2016-01-01

Quinoa (Chenopodium quinoa Willd.) is an Andean crop with an edible seed that both contains high protein content and provides high quality protein with a balanced amino acid profile in embryonic tissues. Quinoa is a halophyte adapted to harsh environments with highly saline soil. In this study, four quinoa varieties were grown under six salinity treatments and two levels of fertilization, and then evaluated for quinoa seed quality characteristics, including protein content, seed hardness, and seed density. Concentrations of 8, 16, and 32 dS m-1 of NaCl and Na2SO4, were applied to the soil medium across low (1 g N, 0.29 g P, 0.29 g K per pot) and high (3 g N, 0.85 g P, 0.86 g K per pot) fertilizer treatments. Seed protein content differed across soil salinity treatments, varieties, and fertilization levels. Protein content of quinoa grown under salinized soil ranged from 13.0 to 16.7%, comparable to that from non-saline conditions. NaCl and Na2SO4 exhibited different impacts on protein content. Whereas the different concentrations of NaCl did not show differential effects on protein content, the seed from 32 dS m-1 Na2SO4 contained the highest protein content. Seed hardness differed among varieties, and was moderately influenced by salinity level (P = 0.09). Seed density was affected significantly by variety and Na2SO4 concentration, but was unaffected by NaCl concentration. The samples from 8 dS m-1 Na2SO4 soil had lower density (0.66 g/cm3) than those from 16 dS m-1 and 32 dS m-1 Na2SO4, 0.74 and 0.72g/cm3, respectively. This paper identifies changes in critical seed quality traits of quinoa as influenced by soil salinity and fertility, and offers insights into variety response and choice across different abiotic stresses in the field environment. PMID:27375648

Electrogenic properties of the Na+/K+ ATPase control transitions between normal and pathological brain states

PubMed Central

Krishnan, Giri P.; Filatov, Gregory; Shilnikov, Andrey

2015-01-01

Ionic concentrations fluctuate significantly during epileptic seizures. In this study, using a combination of in vitro electrophysiology, computer modeling, and dynamical systems analysis, we demonstrate that changes in the potassium and sodium intra- and extracellular ion concentrations ([K+] and [Na+], respectively) during seizure affect the neuron dynamics by modulating the outward Na+/K+ pump current. First, we show that an increase of the outward Na+/K+ pump current mediates termination of seizures when there is a progressive increase in the intracellular [Na+]. Second, we show that the Na+/K+ pump current is crucial in maintaining the stability of the physiological network state; a reduction of this current leads to the onset of seizures via a positive-feedback loop. We then present a novel dynamical mechanism for bursting in neurons with a reduced Na+/K+ pump. Overall, our study demonstrates the profound role of the current mediated by Na+/K+ ATPase on the stability of neuronal dynamics that was previously unknown. PMID:25589588

[Effect of nano-selenium on the activities of glutathione peroxidase and type-I deiodinase in the liver of weanling pigs].

PubMed

Zhang, Hongmei; Xia, Meisheng; Hu, Caihong

2007-02-01

To study the effects of nano elemental selenium (Nano-Se) or sodium selenite (Na2SeO3) on the activities of glutathione peroxidase (GSH-Px) and Type-I deiodinase in the liver. A total of 234 weanling pigs (Duroc x Landrace x Yorkshire) at an average initial body weight of 8.3 kg were allocated to 13 treatments. The thirteen dietary treatments were basal diet only (containing 0.04 mg/kg Se), basal diet + 0.1, 0.2, 0.3, 0.4, 0.5, 1.0 mg/kg Se as Na2SeO3 or Nano-Se, respectively. The results were as follows: Supplementation with 1.0 mg/ kg Se as Na2SeO3 reduced (P < 0.05) growth performance and GSH-Px activities as compared with the addition of a concentration range of 0.20-0.40 mg/kg Se. When Nano-Se was added to the diet, the growth and GSH-Px activities remained steady at the peak value as at a concentration of 1.0 mg/kg Se; There were no difference in the activities of GSH-Px between the treatments of Nano-Se and Na2SeO3 when added concentration of Se was 0.10-0.40 mg/kg. The pigs had higher (P < 0.05) activities of GSH-Px at a concentration range of 0.50 and 1.0 mg/kg as Nano-Se than Na2SeO3; Supplentation with Se increased the activity of Type- I deiodinase in liver, however, the increased extent was affected by neither Se sources nor added concentration of Se. The results implicated that for the best concentration range of Weinberg curve, Nano-Se is wider than Na2SeO3.

Skin Tattoos Alter Sweat Rate and Na+ Concentration.

PubMed

Luetkemeier, Maurie Joe; Hanisko, Joseph Michael; Aho, Kyle Mathiew

2017-07-01

The popularity of tattoos has increased tremendously in the last 10 yr particularly among athletes and military personnel. The tattooing process involves permanently depositing ink under the skin at a similar depth as eccrine sweat glands (3-5 mm). The purpose of this study was to compare the sweat rate and sweat Na concentration of tattooed versus nontattooed skin. The participants were 10 healthy men (age = 21 ± 1 yr), all with a unilateral tattoo covering a circular area at least 5.2 cm. Sweat was stimulated by iontophoresis using agar gel disks impregnated with 0.5% pilocarpine nitrate. The nontattooed skin was located contralateral to the position of the tattooed skin. The disks used to collect sweat were composed of Tygon® tubing wound into a spiral so that the sweat was pulled into the tubing by capillary action. The sweat rate was determined by weighing the disk before and after sweat collection. The sweat Na concentration was determined by flame photometry. The mean sweat rate from tattooed skin was significantly less than nontattooed skin (0.18 ± 0.15 vs 0.35 ± 0.25 mg·cm·min; P = 0.001). All 10 participants generated less sweat from tattooed skin than nontattooed skin and the effect size was -0.79. The mean sweat Na concentration from tattooed skin was significantly higher than nontattooed skin (69.1 ± 28.9 vs 42.6 ± 15.2 mmol·L; P = 0.02). Nine of 10 participants had higher sweat Na concentration from tattooed skin than nontattooed skin, and the effect size was 1.01. Tattooed skin generated less sweat and a higher Na concentration than nontattooed skin when stimulated by pilocarpine iontophoresis.

Cyclic lipopeptide signature as fingerprinting for the screening of halotolerant Bacillus strains towards microbial enhanced oil recovery.

PubMed

Farias, Bárbara C S; Hissa, Denise C; do Nascimento, Camila T M; Oliveira, Samuel A; Zampieri, Davila; Eberlin, Marcos N; Migueleti, Deivid L S; Martins, Luiz F; Sousa, Maíra P; Moyses, Danuza N; Melo, Vânia M M

2018-02-01

Cyclic lipopeptides (CLPs) are non-ribosomal biosurfactants produced by Bacillus species that exhibit outstanding interfacial activity. The synthesis of CLPs is under genetic and environmental influence, and representatives from different families are generally co-produced, generating isoforms that differ in chemical structure and biological activities. This study to evaluate the effect of low and high NaCl concentrations on the composition and surface activity of CLPs produced by Bacillus strains TIM27, TIM49, TIM68, and ICA13 towards microbial enhanced oil recovery (MEOR). The strains were evaluated in mineral medium containing NaCl 2.7, 66, or 100 g L -1 and growth, surface tension and emulsification activity were monitored. Based on the analysis of 16S rDNA, gyrB and rpoB sequences TIM27 and TIM49 were assigned to Bacillus subtilis, TIM68 to Bacillus vallismortis, and ICA13 to Bacillus amyloliquefaciens. All strains tolerated up to 100-g L -1 NaCl, but only TIM49 and TIM68 were able to reduce surface tension at this concentration. TIM49 also showed emulsification activity at concentrations up to 66-g L -1 NaCl. ESI-MS analysis showed that the strains produced a mixture of CLPs, which presented distinct CLP profiles at low and high NaCl concentrations. High NaCl concentration favored the synthesis of surfactins and/or fengycins that correlated with the surface activities of TIM49 and TIM68, whereas low concentration favored the synthesis of iturins. Taken together, these findings suggest that the determination of CLP signatures under the expected condition of oil reservoirs can be useful in the guidance for choosing well-suited strains to MEOR.

Chemical composition of modern and fossil Hippopotamid teeth and implications for paleoenvironmental reconstructions and enamel formation: 1. major and minor element variation

NASA Astrophysics Data System (ADS)

Brügmann, G.; Krause, J.; Brachert, T. C.; Kullmer, O.; Schrenk, F.; Ssemmanda, I.; Mertz, D. F.

2011-05-01

Bioapatite in mammalian teeth is readily preserved in continental sediments and represents a very important archive for reconstructions of environment and climate evolution. This project intends to provide a detailed data base of major, minor and trace element and isotope tracers for tooth apatite using a variety of microanalytical techniques. The aim is to identify specific sedimentary environments and to improve our understanding on the interaction between internal metabolic processes during tooth formation and external nutritional control and secondary alteration effects. Here, we use the electron microprobe, to determine the major and minor element contents of fossil and modern molar enamel, cement and dentin from hippopotamids. Most of the studied specimens are from different ecosystems in Eastern Africa, representing modern and fossil lakustrine (Lake Kikorongo, Lake Albert, and Lake Malawi) and modern fluvial environments of the Nile River system. Secondary alteration effects in particular FeO, MnO, SO3 and F concentrations, which are 2 to 10 times higher in fossil than in modern enamel; secondary enrichments in fossil dentin and cement are even higher. In modern and fossil enamel, along sections perpendicular to the enamel-dentin junction (EDJ) or along cervix-apex profiles, P2O5 and CaO contents and the CaO/P2O5 ratios are very constant (StdDev ~1 %). Linear regression analysis reveals very tight control of the MgO (R2∼0.6), Na2O and Cl variation (for both R2>0.84) along EDJ-outer enamel rim profiles, despite large concentration variations (40 % to 300 %) across the enamel. These minor elements show well defined distribution patterns in enamel, similar in all specimens regardless of their age and origin, as the concentration of MgO and Na2O decrease from the enamel-dentin junction (EDJ) towards the outer rim, whereas Cl displays the opposite variation. Fossil enamel from hippopotamids which lived in the saline Lake Kikorongo have a much higher MgO/Na2O ratio (∼1.11) than those from the Neogene fossils of Lake Albert (MgO/Na2O∼0.4), which was a large fresh water lake like those in the western Branch of the East African Rift System today. Similarly, the MgO/Na2O ratio in modern enamel from the White Nile River (∼0.36), which has a Precambrian catchment of dominantly granite and gneisses and passes through several saline zones, is higher than that from the Blue Nile River, whose catchment is the Neogene volcanic Ethiopian Highland (MgO/Na2O∼0.22). Thus, particularly MgO/Na2O might be a sensitive fingerprint for environments where river and lake water have suffered strong evaporation. Enamel formation in mammals takes place at successive mineralization fronts within a confined chamber where ion and molecule transport is controlled by the surrounding enamel organ. During the secretion and maturation phases the epithelium generates different fluid composition, which in principle, should determine the final composition of enamel apatite. This is supported by co-linear relationships between MgO, Cl and Na2O which can be interpreted as binary mixing lines. However, if maturation starts after secretion is completed the observed element distribution can only be explained by recrystallization of existing and addition of new apatite during maturation. Perhaps the initial enamel crystallites precipitating during secretion and the newly formed bioapatite crystals during maturation equilibrate with a continuously evolving fluid. During crystallization of bioapatite the enamel fluid becomes continuously depleted in MgO and Na2O, but enriched in Cl which results in the formation of MgO, and Na2O-rich, but Cl-poor bioapatite near the EDJ and MgO- and Na2O-poor, but Cl-rich bioapatite at the outer enamel rim. The linkage between lake and river water composition, bioavailability of elements for plants, animal nutrition and tooth formation is complex and multifaceted. The quality and limits of the MgO/Na2O and other proxies have to be established with systematic investigations relating chemical distribution patterns to sedimentary environment and to growth structures developing as secretion and maturation proceed during tooth formation.

Chemical composition of modern and fossil Hippopotamid teeth and implications for paleoenvironmental reconstructions and enamel formation - Part 1: Major and minor element variation

NASA Astrophysics Data System (ADS)

Brügmann, G.; Krause, J.; Brachert, T. C.; Kullmer, O.; Schrenk, F.; Ssemmanda, I.; Mertz, D. F.

2012-01-01

Bioapatite in mammalian teeth is readily preserved in continental sediments and represents a very important archive for reconstructions of environment and climate evolution. This project provides a comprehensive data base of major, minor and trace element and isotope tracers for tooth apatite using a variety of microanalytical techniques. The aim is to identify specific sedimentary environments and to improve our understanding on the interaction between internal metabolic processes during tooth formation and external nutritional control and secondary alteration effects. Here, we use the electron microprobe to determine the major and minor element contents of fossil and modern molar enamel, cement and dentin from Hippopotamids. Most of the studied specimens are from different ecosystems in Eastern Africa, representing modern and fossil lacustrine (Lake Kikorongo, Lake Albert, and Lake Malawi) and modern fluvial environments of the Nile River system. Secondary alteration effects - in particular FeO, MnO, SO3 and F concentrations - are 2 to 10 times higher in fossil than in modern enamel; the secondary enrichment of these components in fossil dentin and cement is even higher. In modern and fossil enamel, along sections perpendicular to the enamel-dentin junction (EDJ) or along cervix-apex profiles, P2O5 and CaO contents and the CaO/P2O5 ratios are very constant (StdDev ∼1%). Linear regression analysis reveals tight control of the MgO (R2∼0.6), Na2O and Cl variation (for both R2>0.84) along EDJ-outer enamel rim profiles, despite large concentration variations (40% to 300%) across the enamel. These minor elements show well defined distribution patterns in enamel, similar in all specimens regardless of their age and origin, as the concentration of MgO and Na2O decrease from the enamel-dentin junction (EDJ) towards the outer rim, whereas Cl displays the opposite trend. Fossil enamel from Hippopotamids which lived in the saline Lake Kikorongo have a much higher MgO/Na2O ratio (∼1.11) than those from the Neogene fossils of Lake Albert (MgO/Na2O∼0.4), which was a large fresh water lake like those in the western Branch of the East African Rift System today. Similarly, the MgO/Na2O ratio in modern enamel from the White Nile River (∼0.36), which has a Precambrian catchment of dominantly granites and gneisses and passes through several saline zones, is higher than that from the Blue Nile River, whose catchment is the Neogene volcanic Ethiopian Highland (MgO/Na2O∼0.22). Thus, particularly MgO/Na2O might be a sensitive fingerprint for environments where river and lake water have suffered strong evaporation. Enamel formation in mammals takes place at successive mineralization fronts within a confined chamber where ion and molecule transport is controlled by the surrounding enamel organ. During the secretion and maturation phases the epithelium generates different fluid composition, which in principle, should determine the final composition of enamel apatite. This is supported by co-linear relationships between MgO, Cl and Na2O which can be interpreted as binary mixing lines. However, if maturation starts after secretion is completed, the observed element distribution can only be explained by equilibration of existing and addition of new apatite during maturation. It appears the initial enamel crystallites precipitating during secretion and the newly formed bioapatite crystals during maturation equilibrate with a continuously evolving fluid. During crystallization of bioapatite the enamel fluid becomes continuously depleted in MgO and Na2O, but enriched in Cl which results in the formation of MgO, and Na2O-rich, but Cl-poor bioapatite near the EDJ and MgO- and Na2O-poor, but Cl-rich bioapatite at the outer enamel rim. The linkage between lake and river water compositions, bioavailability of elements for plants, animal nutrition and tooth formation is complex and multifaceted. The quality and limits of the MgO/Na2O and other proxies have to be established with systematic investigations relating chemical distribution patterns to sedimentary environment and to growth structures developing as secretion and maturation proceed during tooth formation.

Phototrophic cultivation of NaCl-tolerant mutant of Spirulina platensis for enhanced C-phycocyanin production under optimized culture conditions and its dynamic modeling.

PubMed

Gupta, Apurva; Mohan, Devendra; Saxena, Rishi Kumar; Singh, Surendra

2018-02-01

Commercial cultivation of Spirulina sp. is highly popular due to the presence of high amount of C-phycocyanin (C-PC) and other valuable chemicals like carotenoids and γ-linolenic acid. In this study, the pH and the concentrations of nitrogen and carbon source were manipulated to achieve improved cell growth and C-PC production in NaCl-tolerant mutant of Spirulina platensis. In this study, highest C-PC (147 mg · L -1 ) and biomass (2.83 g · L -1 ) production was achieved when a NaCl-tolerant mutant of S. platensis was cultivated in a nitrate and bicarbonate sufficient medium (40 and 60 mM, respectively) at pH 9.0 under phototrophic conditions. Kinetic study of wildtype S. platensis and its NaCl-tolerant mutant was also done to determine optimum nitrate concentrations for maximum growth and C-PC production. Kinetic parameter of inhibition (Haldane model) was fitted to the relationship between specific growth rate and substrate concentration obtained from the growth curves. Results showed that the maximum specific growth rate (μ max ) for NaCl-tolerant mutant increased by 17.94% as compared to its wildtype counterpart, with a slight increase in half-saturation constant (K s ), indicating that this strain could grow well at high concentration of NaNO 3 . C-PC production rate (C max ) in mutant cells increased by 12.2% at almost half the value of K s as compared to its wildtype counterpart. Moreover, the inhibition constant (K i ) value was 207.85% higher in NaCl-tolerant mutant as compared to its wildtype strain, suggesting its ability to produce C-PC even at high concentrations of NaNO 3 . © 2017 Phycological Society of America.

[Effects of hot-NaOH pretreatment on Jerusalem artichoke stalk composition and subsequent enzymatic hydrolysis].

PubMed

Wang, Qing; Qiu, Jingwen; Li, Yang; Shen, Fei

2015-10-01

In order to explore the possibility of Jerusalem artichoke stalk for bioenergy conversion, we analyzed the main composition of whole stalk, pitch, and core of the stalk. Meanwhile, these parts were pretreated with different NaOH concentrations at 121 degrees C. Afterwards, enzymatic hydrolysis was performed to evaluate the pretreatment efficiency. Jerusalem artichoke stalk was characterized by relatively high lignin content (32.0%) compared with traditional crop stalks. The total carbohydrate content was close to that of crop stalks, but with higher cellulose content (40.5%) and lower hemicellulose (19.6%) than those of traditional crop stalks. After pretreatment, the lignin content in the whole stalk, pitch, and core decreased by 13.1%-13.4%, 8.3%-13.5%, and 19.9%-27.2%, respectively, compared with the unpretreated substrates. The hemicellulose content in the whole stalk, pitch, and core decreased 87.8%-96.9%, 87.6%-95.0%, and 74.0%-90.2%, respectively. Correspondingly, the cellulose content in the pretreated whole stalk, pitch, and core increased by 56.5%-60.2%, 52.2%-55.4%, and 62.7%-73.2%, respectively. Moreover, increase of NaOH concentration for pretreatment could improve the enzymatic hydrolysis of the whole stalk and pitch by 2.3-2.6 folds and 10.3-18.5 folds, respectively. The hydrolysis of pretreated stalk core decreased significantly as 2.0 mol/L NaOH was employed, although the increased NaOH concentration can also improve its hydrolysis performance. Based on these results, hot-NaOH can be regarded as an option for Jerusalem artichoke stalk pretreatment. Increasing NaOH concentration was beneficial to hemicellulose and lignin removal, and consequently improved sugar conversion. However, the potential decrease of sugar conversion of the pretreated core by higher NaOH concentration suggested further optimization on the pretreatment conditions should be performed.

Preparation of sodium fluoride-loaded gelatin microspheres, characterization and cariostatic studies.

PubMed

Wu, H; Zhang, Z X; Zhao, H P; Wu, D C; Wu, B L; Cong, R

2004-12-01

Sodium fluoride-loaded gelatin microspheres (NaF-GMS) were prepared using double-phase emulsified condensation polymerization. The average diameter of microspheres was (11.33+/-5.56) microm. The drug content and encapsulation efficiency were 8.80% and 76.73%, respectively. The fluoride releasing profiles of NaF-GMS in physiological saline and artificial saliva (pH 4.5, pH 6.8) showed that NaF-GMS had a sustained-release property and fluoride release rate was increased in pH 4.5 artificial saliva. Experiments conducted in rabbits' oral cavity using NaF-GMS and NaF solution as control revealed NaF-GMS could maintain oral fluoride retention longer than NaF solution. Cariostatic abilities of NaF-GMS including demineralization prohibition in vitro, fluoride deposition in artificial dental plaque and the ability of targeting to cariogenic bacteria were investigated in artificial dental plaque. The results indicated NaF-GMS with lower fluoride concentrations could achieve equivalent cariostatic effect to the concentrated NaF solution, at the same time, could prolong fluoride retention in dental plaque. Microscopic observation showed that NaF-GMS carrying fusion protein of glucan-binding domain could adhere more bacteria than NaF-GMS and this might indicate the possibility of targeting to cariogenic bacteria when NaF-GMS were properly modified.

Characterization of Two HKT1;4 Transporters from Triticum monococcum to Elucidate the Determinants of the Wheat Salt Tolerance Nax1 QTL.

PubMed

Tounsi, Sana; Ben Amar, Siwar; Masmoudi, Khaled; Sentenac, Hervé; Brini, Faiçal; Véry, Anne-Aliénor

2016-10-01

TmHKT1;4-A1 and TmHKT1;4-A2 are two Na + transporter genes that have been identified as associated with the salt tolerance Nax1 locus found in a durum wheat (Triticum turgidum L. subsp. durum) line issued from a cross with T. monococcum. In the present study, we were interested in getting clues on the molecular mechanisms underpinning this salt tolerance quantitative trait locus (QTL). By analyzing the phylogenetic relationships between wheat and T. monococcum HKT1;4-type genes, we found that durum and bread wheat genomes possess a close homolog of TmHKT1;4-A1, but no functional close homolog of TmHKT1;4-A2. Furthermore, performing real-time reverse transcription-PCR experiments, we showed that TmHKT1;4-A1 and TmHKT1;4-A2 are similarly expressed in the leaves but that TmHKT1;4-A2 is more strongly expressed in the roots, which would enable it to contribute more to the prevention of Na + transfer to the shoots upon salt stress. We also functionally characterized the TmHKT1;4-A1 and TmHKT1;4-A2 transporters by expressing them in Xenopus oocytes. The two transporters displayed close functional properties (high Na + /K + selectivity, low affinity for Na + , stimulation by external K + of Na + transport), but differed in some quantitative parameters: Na + affinity was 3-fold lower and the maximal inward conductance was 3-fold higher in TmHKT1;4-A2 than in TmHKT1;4-A1. The conductance of TmHKT1;4-A2 at high Na + concentration (>10 mM) was also shown to be higher than that of the two durum wheat HKT1;4-type transporters so far characterized. Altogether, these data support the hypothesis that TmHKT1;4-A2 is responsible for the Nax1 trait and provide new insight into the understanding of this QTL. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Effect of Sodium Fluoride Ingestion on Malondialdehyde Concentration and the Activity of Antioxidant Enzymes in Rat Erythrocytes

PubMed Central

Morales-González, José A.; Gutiérrez-Salinas, José; García-Ortiz, Liliana; del Carmen Chima-Galán, María; Madrigal-Santillán, Eduardo; Esquivel-Soto, Jaime; Esquivel-Chirino, César; González-Rubio, Manuel García-Luna y

2010-01-01

Fluoride intoxication has been shown to produce diverse deleterious metabolic alterations within the cell. To determine the effects of sodium fluoride (NaF) treatment on malondialdehyde (MDA) levels and on the activity of antioxidant enzymes in rat erythrocytes, Male Wistar rats were treated with 50 ppm of NaF or were untreated as controls. Erythrocytes were obtained from rats sacrificed weekly for up to eight weeks and the concentration of MDA in erythrocyte membrane was determined. In addition, the activity of the enzymes superoxide, dismutase, catalase, and glutathione peroxidase were determined. Treatment with NaF produces an increase in the concentration of malondialdehyde in the erythrocyte membrane only after the eight weeks of treatment. On the other hand, antioxidant enzyme activity was observed to increase after the fourth week of NaF treatment. In conclusion, intake of NaF produces alterations in the erythrocyte of the male rat, which indicates induction of oxidative stress. PMID:20640162

Representation of sweet and salty taste intensity in the brain.

PubMed

Spetter, M S; Smeets, P A M; de Graaf, C; Viergever, M A

2010-11-01

The intensity of the taste of a food is affected mostly by the amount of sugars (mono- and disaccharides) or salt it contains. To season savory-tasting foods mainly table salt (NaCl) is used and to sweeten foods, sugars like sucrose are used. Foods with highly intense tastes are consumed in smaller amounts. The optimal taste intensity of a food is the intensity at which it is perceived as most pleasant. When taste intensity decreases or increases from optimal, the pleasantness of a food decreases. Here, we investigated the brain representation of sweet and salty taste intensity using functional magnetic resonance imaging. Fifteen subjects visited twice and tasted a range of 4 watery solutions (0-1 M) of either sucrose or NaCl in water. Middle insula activation increased with increasing concentration for both NaCl and sucrose. Despite similar subjective intensity ratings, anterior insula activation by NaCl increased more with concentration than that by sucrose. Amygdala activation increased with increasing NaCl concentration but not sucrose concentration. In conclusion, sweet and salty taste intensity are represented in the middle insula. Amygdala activation is only modulated by saltiness. Further research will need to extrapolate these results from simple solutions to real foods.

Do freshwater mussel shells record road-salt pollution?

NASA Astrophysics Data System (ADS)

O'Neil, Dane D.; Gillikin, David P.

2014-11-01

Road-salt pollution in streams in the Northeastern United States has become a major concern, but historical data are scarce. Freshwater bivalve shells have the ability to record past environmental information, and may act as archives of road-salt pollution. We sampled Elliptio complanata shells from four streams, as well as specimens collected in 1877. Average [Na/Ca]shell was highest in modern shells from the stream with the highest sodium concentrations, and low in shells collected from this same stream in 1877 as well as in the shells from other streams, suggesting that [Na/Ca]shell serves as a proxy for road-salt pollution. We expected higher [Na/Ca]shell in winter and spring. However, high-resolution [Na/Ca]shell analyses along the growth axis of one shell did not reveal any clear subannual patterns, which could be the result of shell growth cessation in winter and/or during periods of high stream sodium concentrations. Therefore, bulk [Na/Ca]shell analysis from multiple shells can be used as a proxy of large changes in stream sodium concentrations, but high-resolution variations in stream sodium concentrations do not seem to be recorded in the shells.

Do freshwater mussel shells record road-salt pollution?

PubMed Central

O'Neil, Dane D.; Gillikin, David P.

2014-01-01

Road-salt pollution in streams in the Northeastern United States has become a major concern, but historical data are scarce. Freshwater bivalve shells have the ability to record past environmental information, and may act as archives of road-salt pollution. We sampled Elliptio complanata shells from four streams, as well as specimens collected in 1877. Average [Na/Ca]shell was highest in modern shells from the stream with the highest sodium concentrations, and low in shells collected from this same stream in 1877 as well as in the shells from other streams, suggesting that [Na/Ca]shell serves as a proxy for road-salt pollution. We expected higher [Na/Ca]shell in winter and spring. However, high-resolution [Na/Ca]shell analyses along the growth axis of one shell did not reveal any clear subannual patterns, which could be the result of shell growth cessation in winter and/or during periods of high stream sodium concentrations. Therefore, bulk [Na/Ca]shell analysis from multiple shells can be used as a proxy of large changes in stream sodium concentrations, but high-resolution variations in stream sodium concentrations do not seem to be recorded in the shells. PMID:25418687

Raman microspectroscopic study of effects of Na(I) and Mg(II) ions on low pH induced DNA structural changes.

PubMed

Muntean, C M; Segers-Nolten, G M J

2003-01-01

In this work a confocal Raman microspectrometer is used to investigate the influence of Na(+) and Mg(2+) ions on the DNA structural changes induced by low pH. Measurements are carried out on calf thymus DNA at neutral pH (7) and pH 3 in the presence of low and high concentrations of Na(+) and Mg(2+) ions, respectively. It is found that low concentrations of Na(+) ions do not protect DNA against binding of H(+). High concentrations of monovalent ions can prevent protonation of the DNA double helix. Our Raman spectra show that low concentrations of Mg(2+) ions partly protect DNA against protonation of cytosine (line at 1262 cm(-1)) but do not protect adenine and guanine N(7) against binding of H(+) (characteristic lines at 1304 and 1488 cm(-1), respectively). High concentrations of Mg(2+) can prevent protonation of cytosine and protonation of adenine (disruption of AT pairs). By analyzing the line at 1488 cm(-1), which obtains most of its intensity from a guanine vibration, high magnesium salt protect the N(7) of guanine against protonation. A high salt concentration can prevent protonation of guanine, cytosine, and adenine in DNA. Higher salt concentrations cause less DNA protonation than lower salt concentrations. Magnesium ions are found to be more effective in protecting DNA against binding of H(+) as compared with calcium ions presented in a previous study. Divalent metal cations (Mg(2+), Ca(2+)) are more effective in protecting DNA against protonation than monovalent ions (Na(+)). Copyright 2003 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 72: 000-000, 2003

Isolation of fish skin and bone gelatin from tilapia (Oreochromis niloticus): Response surface approach

NASA Astrophysics Data System (ADS)

Arpi, N.; Fahrizal; Novita, M.

2018-03-01

In this study, gelatin from fish collagen, as one of halal sources, was extracted from tilapia (Oreochromis niloticus) skin and bone, by using Response Surface Methodology to optimize gelatin extraction conditions. Concentrations of alkaline NaOH and acid HCl, in the pretreatment process, and temperatures in extraction process were chosen as independent variables, while dependent variables were yield, gel strength, and emulsion activity index (EAI). The result of investigation showed that lower NaOH pretreatment concentrations provided proper pH extraction conditions which combine with higher extraction temperatures resulted in high gelatin yield. However, gelatin emulsion activity index increased proportionally to the decreased in NaOH concentrations and extraction temperatures. No significant effect of the three independent variables on the gelatin gel strength. RSM optimization process resulted in optimum gelatin extraction process conditions using alkaline NaOH concentration of 0.77 N, acid HCl of 0.59 N, and extraction temperature of 66.80 °C. The optimal solution formula had optimization targets of 94.38%.

ANTICARIOGENIC POTENCIAL OF ACIDULATE SOLUTIONS WITH LOW FLUORIDE CONCENTRATION

PubMed Central

Delbem, Alberto Carlos Botazzo; Tiano, Gilberto Carlos; Alves, Karina Mirela Ribeiro Pinto; Cunha, Robson Frederico

2006-01-01

Objectives: The aim of this study was to verify the anticariogenic effect of acidulate solutions with low NaF concentration, using pH-cycling model and bovine enamel. Material and methods: Enamel blocks were submitted to the surface microhardness (SMH) test and randomly divided in 12 experimental and one placebo groups. The blocks were submitted to pH cycling for 7 days, with daily applications once/day of 0.05% NaF and 0.1% NaF and twice/day of 0.02% NaF solutions. Four different pH: 4.0, 5.0, 6.0 and 7.0 were used. Next, SMH test was again used to determine the surface microhardness percentage change (%SMH). Data obtained for %SMH were homogeneous and passed through variance analyses and Tukey's test (5%) as far as fluoride concentrations and pH. Results: The results showed that pH influenced %SMH in 0.02% NaF and 0.05% NaF solutions with pH 4.0, which had less mineral loss compared to pH 7.0 (p<0.05). The 0.02% NaF - pH 4.0, and 0.05% NaF – pH 7.0 groups showed similar results (p>0.05). A dose-response relationship was observed among the tested solutions, with better anticariogenic effect for the 0.1% NaF solution. Conclusion: The results suggest that the addition of citric acid to acidulate mouth rinses reduce mineral loss. PMID:19089268

Fluid intake and changes in limb volumes in male ultra-marathoners: does fluid overload lead to peripheral oedema?

PubMed

Bracher, Alexia; Knechtle, Beat; Gnädinger, Markus; Bürge, Jolanda; Rüst, Christoph Alexander; Knechtle, Patrizia; Rosemann, Thomas

2012-03-01

An increase in body mass due to oedema has been previously described. The aim of this study was to investigate a potential association between both fluid and electrolyte intake and the formation of peripheral oedemas. Fluid and electrolyte intakes and the changes in limb volumes in 50 male 100-km ultra-marathoners were measured. Pre- and post-race serum sodium concentration ([Na(+)]), serum aldosterone concentration, serum copeptin concentration, serum and urine osmolality and body mass were determined. Fluid intake, renal function parameters and urinary output, as well as the changes of volume in the extremities, were measured. The changes of volume in the limbs were measured using plethysmography. Serum [Na(+)] increased by 1.6%; body mass decreased by 1.9 kg. Serum copeptin and aldosterone concentrations were increased. The change in serum copeptin concentration and the change in serum [Na(+)] correlated positively; the change in serum [Na(+)] and body mass correlated negatively. A mean fluid intake of 0.58 L/h was positively related to running speed and negatively to post-race serum [Na(+)]. Total fluid intake was positively related to the changes in both arm and lower leg volumes. Running speed was positively associated with the changes in arm and lower leg volumes; race time was related to the changes in serum copeptin or aldosterone concentrations. To conclude, fluid intake was related to the changes in limb volumes, where athletes with an increased fluid intake developed an increase in limb volumes.

Urea inhibits NaK2Cl cotransport in human erythrocytes.

PubMed Central

Lim, J; Gasson, C; Kaji, D M

1995-01-01

We examined the effect of urea on NaK2Cl cotransport in human erythrocytes. In erythrocytes from nine normal subjects, the addition of 45 mM urea, a concentration commonly encountered in uremic subjects, inhibited NaK2Cl cotransport by 33 +/- 7%. Urea inhibited NaK2Cl cotransport reversibly, and in a concentration-dependent fashion with half-maximal inhibition at 63 +/- 10 mM. Acute cell shrinkage increased, and acute cell swelling decreased NaK2Cl cotransport in human erythrocytes. Okadaic acid (OA), a specific inhibitor of protein phosphatase 1 and 2A, increased NaK2Cl cotransport by nearly 80%, suggesting an important role for these phosphatases in the regulation of NaK2Cl cotransport. Urea inhibited bumetanide-sensitive K influx even when protein phosphatases were inhibited with OA, suggesting that urea acted by inhibiting a kinase. In cells subjected to shrinking and OA pretreatment, maneuvers expected to increase the net phosphorylation, urea inhibited cotransport only minimally, suggesting that urea acted by causing a net dephosphorylation of the cotransport protein, or some key regulatory protein. The finding that concentrations of urea found in uremic subjects inhibited NaK2Cl cotransport, a widespread transport pathway with important physiological functions, suggests that urea is not only a marker for accumulation of other uremic toxins, but may be a significant uremic toxin itself. PMID:7593597

Two cation exchange models for direct and inverse modelling of solution major cation composition in equilibrium with illite surfaces

NASA Astrophysics Data System (ADS)

Tournassat, Christophe; Gailhanou, Hélène; Crouzet, Catherine; Braibant, Gilles; Gautier, Anne; Lassin, Arnault; Blanc, Philippe; Gaucher, Eric C.

2007-03-01

Na/K, Na/Ca and Na/Mg exchange isotherms were performed on the fine fraction (<2 μm) of Imt-2 illite samples at a total normality of about 0.005 mol/L in anionic chloride medium. The derived selectivity coefficients for Na/K, Na/Ca and Na/Mg were found to vary as a function of the exchanger composition and compared well with the data collected in the literature for similar experimental conditions. Two models were built to reproduce the data: the first was a multi(2)-site model with constant Gaines and Thomas selectivity coefficients; the second was a one-site model taking into account surface species activity coefficients. The results of the models were in rather good agreement with both our data and literature data. The multi-site model proved to be efficient in predicting the exchanger composition as a function of the Na/Ca/Mg/K concentrations in solution, whereas the one-site model proved to be a better approach to derive the Na/Ca/Mg/K concentrations in solution based on the knowledge of the exchanger composition and the total normality of the solution. The interest of this approach is illustrated by the need for major cation solute concentration predictions in compacted clay for the characterization of nuclear deep disposal host rock repositories.

The detailed chemistry and thermodynamics of sodium in oxygen-rich flames

NASA Technical Reports Server (NTRS)

Hynes, A. J.; Steinberg, M.; Schofield, K.

1982-01-01

Measurement of sodium and OH concentrations in ten oxygen-rich H2/O2/N2 flames by respective saturated and low-power laser induced fluorescence techniques have permitted a detailed examination of the pronounced flame chemistry of sodium in such oxygen rich media. Previous interpretations have been shown to be largely incomplete or in error. The flame downstream profiles indicate that the amount of free sodium tracks the decay of H-atom and as the flame radicals decay sodium becomes increasingly bound in a molecular form. A detailed kinetic model indicates that the sodium is distributed between NaOH and NaO2 species. Concentrations of NaO are very small and NaH negligible. The actual distribution is controlled by the state of equilibrium of the flames' basic free radicals. Na, NaO2 and NaOH are all coupled to one another by fast reactions which can rapidly interconvert one to another as flame conditions vary. Above about 2000K, NaOH becomes dominant whereas NaO2 plays an increasingly important contribution at lower temperatures.

A possible molecular mechanism of the action of digitalis: ouabain action on calcium binding to sites associated with a purified sodium-potassium-activated adenosine triphosphatase from kidney.

PubMed

Gervais, A; Lane, L K; Anner, B M; Lindenmayer, G E; Schwartz, A

1977-01-01

Calcium binding at 0 degrees C to a purified sheep kidney Na+,K+-ATPase was described by linear Scatchard plots. Binding at saturating free calcium was 65-80 nmol/mg of protein, or 30-40 mol of calcium/mol of enzyme. Aqueous emulsions of lipids extracted from Na+,K+-ATPase yielded dissociation constants and maximum calcium-binding values that were similar to those for native Na+,K+-ATPase. Phospholipase A treatment markedly reduced calcium binding. Pretreatment of native Na+,K+-ATPase with ouabain increased the dissociation constant for calcium binding from 131 +/- 7 to 192 +/- 7 muM without altering maximum calcium binding. Ouabain pretreatment did not affect calcium binding to extracted phospholipids, ouabain-insensitive ATPases, or heat denatured Na+,K+-ATPase, Na+ and K+ (5-20 mM) increased the dissociation constants for calcium, which suggests competition between the monovalent cations and calcium for the binding sites. At higher concentrations of monovalent cations, ouabain increased the apparent affinity of binding sites for calcium. Extrapolation to physiological cation concentrations revealed that the ouabain-induced increase in apparent affinity for calcium may be as much as 2- to 3-fold. These results suggest: (1) calcium binds to phospholipids associated with Na+,K+-ATPase; (2) ouabain interaction with Na+,K+-ATPase induces a perturbation that is transmitted to adjacent phospholipids, altering their affinity for calcium; and (3) at physiological concentrations of Na+ or K+, or both, ouabain interaction with Na+,K+-ATPase may lead to an increased pool of membrane-bound calcium.

Effect of salts (NaCl and Na2CO3) on callus and suspension culture of Stevia rebaudiana for Steviol glycoside production.

PubMed

Gupta, Pratibha; Sharma, Satyawati; Saxena, Sanjay

2014-03-01

Steviol glycosides are natural non-caloric sweeteners which are extracted from the leaves of Stevia rebaudiana plant. Present study deals the effect of salts (NaCl and Na2CO3) on callus and suspension culture of Stevia plant for steviol glycoside (SGs) production. Yellow-green and compact calli obtained from in vitro raised Stevia leaves sub-cultured on MS medium supplemented with 2.0 mg l(-1) NAA and different concentrations of NaCl (0.05-0.20%) and Na2CO3 (0.0125-0.10%) for 2 weeks, and incubated at 24 ± 1 °C and 22.4 μmol m(-2) s(-1) light intensity provided by white fluorescent tubes for 16 h. Callus and suspension biomass cultured on salts showed less growth as well as browning of medium when compared with control. Quantification of SGs content in callus culture (collected on 15th day) and suspension cultures (collected at 10th and 15th days) treated with and without salts were analyzed by HPLC. It was found that abiotic stress induced by the salts increased the concentration of SGs significantly. In callus, the quantity of SGs got increased from 0.27 (control) to 1.43 and 1.57% with 0.10% NaCl, and 0.025% Na2CO3, respectively. However, in case of suspension culture, the same concentrations of NaCl and Na2CO3 enhanced the SGs content from 1.36 (control) to 2.61 and 5.14%, respectively, on the 10th day.

Na+-dependent and Na+-independent betaine transport across the apical membrane of rat renal epithelium.

PubMed

Cano, Mercedes; Calonge, María L; Ilundáin, Anunciación A

2015-10-01

The low renal excretion of betaine indicates that the kidney efficiently reabsorbs the betaine filtered by the glomeruli but the mechanisms involved in such a process have been scarcely investigated. We have detected concentrative and non-concentrative betaine transport activity in brush-border membrane vesicles (BBMV) from rat renal cortex and medulla. The concentrative system is the Sodium/Imino-acid Transporter 1 (SIT1) because it is Na+- and Cl--dependent, electrogenic and is inhibited by an anti-SIT1 antibody. Its apparent affinity constant for betaine, Kt, is 1.1±0.5 mM and its maximal transport velocity, Vmax, 0.5±0.1 nmol betaine/mg protein/s. Inhibitors of the Na+/Cl-/betaine uptake are L-proline (75%) and cold betaine, L-carnitine and choline (40-60%). Neither creatine, TEA, taurine, β-alanine, GABA nor glycine significantly inhibited Na+/Cl-/betaine uptake. The non-concentrative betaine transport system is Na+- and H+-independent, electroneutral, with a Kt for betaine of 47±7 μM and a Vmax of 7.8±1 pmol betaine/mg protein/s. Its transport activity is nearly abolished by betaine, followed by L-carnitine (70-80%) and proline (40-50%), but a difference from the Na+/Cl-/betaine transport is that it is inhibited by TEA (approx. 50%) and unaffected by choline. The underlying carrier functions as an antiporter linking betaine entry into the BBMV with the efflux of either L-carnitine or betaine, an exchange unaffected by the anti-SIT1 antibody. As far as we know this is the first work reporting that betaine crosses the apical membrane of rat renal epithelium by SIT1 and by a Na+- and H+-independent transport system. Copyright © 2015 Elsevier B.V. All rights reserved.

Mammography film processor replenishment rate: bromide level monitoring.

PubMed

Kimme-Smith, C; Wuelfing, P; Kitts, E L; Cagnon, C; Basic, M; Bassett, L

1997-03-01

The effects of the mammography film processing replenishment rate on contrast and speed are studied sensitometrically. Two experiments studied decreasing replenishment rates in the Kodak RP developer and quantified changes in the developer by measuring bromide ion concentrations. First, values of NaBr concentration from 1.7 to 8.4 g/L, achieved by reducing the replenishment rate, were tested with sensitometry strips. Second, the developer replenishment rate of a high volume dedicated mammography processor was reduced by one-third, to 20 cm3/1560 cm2, so that the NaBr concentration rose from 2.0 to 12.36. Sensitometric results for four film types and patient films were tested for changes from standard values as NaBr concentration was restored to 3.31 g/L. Fifty-five clinical images obtained at 7.3-9.3 NaBr g/L were compared to their matching previous films, with NaBr levels of 2-3 g/L, for contrast and visibility of the skin line. For the range of the NaBr ion from 1.7 to 7 g/L, no significant sensitometric differences were found. Above 7 g/L, different film types had different sensitometric results. From 7.3 to 9.3 NaBr g/L, 47.5% of the clinical films reviewed by four radiologists had less contrast compared to previous films. Dedicated mammography processors with high film volume (i.e., those that do not have excessive oxidation or foreign dye problems) can operate at lower replenishment rates than are currently employed. All common mammography film types are stable at these lower replenishment rates up to 7.0 NaBr g/L.

Effects of thyroid hormone on Na sup + -K sup + transport in resting and stimulated rat skeletal muscle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Everts, M.E.; Clausen, T.

1988-11-01

The effects of hypothyroidism and 3,5,3{prime}-triiodothyronine (T{sub 3}) treatment on passive Na{sup +}-K{sup +} fluxes and Na{sup +}-K{sup +} pump concentration were investigated in isolated rat muscle. Within 12 h after a single dose of T{sub 3} (20 {mu}g/100 g body wt), K{sup +} efflux had increased by 21% in soleus and by 20% in extensor digitorum longus muscle. In the presence of ouabain, even larger effects were observed. These changes were associated with a 12% rise in amiloride-suppressible Na{sup +} influx but no significant increase in ({sup 3}H)ouabain binding site concentration. After 3 days of T{sub 3} treatment, themore » stimulating effect on K{sup +} efflux and Na{sup +} influx in soleus reached a plateau {approximately}80 and 40% above control levels, respectively, whereas the maximum increase in ({sup 3}H)ouabain binding site concentration (103%) was only fully developed after 8 days. Hypothyroidism decreased {sup 86}Rb efflux by 30%. The efflux of K{sup +} and the influx of Na{sup +} per contraction (both {approximately}7 nmol/g wet wt) as well as the net loss of K{sup +} induced by electrical stimulation were unaffected by T{sub 3} treatment. The rise in resting K{sup +} efflux after 12-24 h of T{sub 3} treatment could be partly blocked by dantrolene or trifluoroperazine, indicating that an increase in the cytoplasmic Ca{sup 2+} concentration may contribute to the early rise in K{sup +} efflux. It is concluded that the early rise in the resting passive leaks of Na{sup +} and K{sup +} induced by T{sub 3} is a major driving force for Na{sup +}-K{sup +} pump synthesis.« less

n/a

NASA Image and Video Library

1977-09-09

The first Space Shuttle External Tank, the Main Propulsion Test Article (MPTA), rolls off the assembly line September 9, 1977 at the Michoud Assembly Facility in New Orleans. The MPTA was then transported to the National Space Technology Laboratories in southern Mississippi where it was used in the first static firing of the three main engines. Marshall Space Flight Center had management responsibility for Space Shuttle propulsion elements, including the External Tank. Martin Marietta was the prime contractor who designed and assembled the tanks at Michoud.

Evolution of ferromagnetism in charge ordered manganite: An effect of external pressure

NASA Astrophysics Data System (ADS)

Dash, S.; Pradhan, M. K.; Rao, T. Lakshmana

2018-05-01

Detailed magnetic measurements of the Pr0.75Na0.25MnO3 polycrystalline sample have been carried out under external hydrostatic pressure upto 10kbar. Pressure strongly suppresses the first order magnetic transition, while thermal hysteresis narrows down progressively and then disappears with increase in pressure. The significant enhancement of the field cooled magnetization value at different pressures is due to the antiferromagnetic to ferromagnetic transformation, while ruling out any contribution from the domain alignment within the ferromagnetic phase.

Decreased Urinary Sodium-to-urinary Creatinine Ratio Identifies Sodium Depletion in Pediatric Acute Gastroenteritis.

PubMed

Heinz-Erian, P; Akdar, Z; Haerter, B; Waldegger, S; Giner, T; Scholl-Bürgi, S; Mueller, T

2016-01-01

In acute gastroenteritis (AG) fecal losses may cause depletion of sodium (NaD) which may not be recognized because of normal plasma Na (pNa) concentrations. We studied the incidence of this state of normonatremic sodium depletion (NNaD) and the suitability of the urinary Na/urinary creatinine ratio (uNa/uCr) for diagnosing NNaD. 16 AG- and 16 healthy control children aged 0.8-15.0 years. Prospective cross sectional pilot study. Measurements of Na, K and creatinine in plasma (p) and urine (u). Calculation of uNa/uCr Ratio, fractional excretion of Na (FENa) and uNa/uK ratio as the hitherto best known parameters of prerenal Na depletion, respectively. pNa concentrations were normal in 15/16 AG patients (93.8%) with only one subnormal value of 133 mmol/L, and a mean value of 137.9±2.3 mmol/L not different from the normal control group (139.4±2.2 mmol/L). Also, mean uNa concentrations and uNa/uK ratios did not differ between both groups. However, uNa/uCr ratios were below normal in 13/16 AG children (81.3%) but normal in all healthy controls with a significantly lower mean value in the AG group (12.6±8.8 vs. 31.2±8.3 mmol/mmol; p<0.0001). Similarly, 14/16 AG patients (87.5%) had a decreased FENa<0.5% with a mean FENa value significantly lower than in controls (0.36±0.28% vs. 0.95±0.26%, p<0.0001). The good agreement between FENa and uNa/uCr results was also reflected by a high correlation coefficient of r=0.9333. The majority of AG patients was found to have NNaD as determined by uNa/uCr and FENa. Calculation of uNa/uCr may be useful for diagnosing NNaD in AG. © Georg Thieme Verlag KG Stuttgart · New York.

Examination of the Behavior of Bismuth in Shallow-Level Hydrothermal Ore Systems: Constraints Based on Hydrothermal Experiments at 800°C and 100 MPa

NASA Astrophysics Data System (ADS)

Wilmot, M. S.; Candela, P. A.; Piccoli, P. M.; Simon, A. C.; McDonough, W. F.

2006-05-01

The partitioning of ore metals between melt and crystals affects the concentrations of these metals in an evolving ore fluid, and therefore the efficiency of their removal from the magma by hydrothermal processes. Some porphyry-type W-Mo deposits contain recoverable amounts of Bi, whereas others contain only trace amounts. In order to determine the magmatic controls on the ratio of Bi to other commodities in these and other deposits, we examined the partitioning behavior of bismuth between melt, minerals and aqueous phases. Hydrothermal experiments were performed by using externally heated cold seal vessels and employing a double capsule technique. Experiments contained 40 mg of Bishop Tuff glass (SiO2 = 74% ) and 40 mg of either magnetite or pyrrhotite. Bi was added as elemental Bi (< 1 mg). Two different aqueous solutions were used. Initially, the added aqueous phase comprised the solutes HCl, KCl and NaCl in a molar1:1:1 ratio, with a bulk salinity of 10 wt % NaCl eq. The aqueous phase for later experiments contained only the solutes KCl and NaCl in a 1:1 molar ratio. Pre-fractured quartz was added to the experiments to trap fluid inclusions at run PTX conditions. Experiments were performed in Au or Pt capsules held inside Rene 41 cold-seal vessels at 800°C and 100 MPa for durations of up to 36 hours. Analytical data have been collected from the run product solids by using an electron probe microanalyzer (major and trace elements) and laser ablation inductively coupled plasma mass spectrometry (trace elements). Bi in Mt is found in concentrations up to 100 ppm, with higher concentrations in runs where Po decomposed to form magnetite. The Bi concentration in the glass ranges up to 100 ppm. In the Po-bearing runs, data were only collected from Po grains in the experiments containing the HCl-free aqueous solution (the Po grains in the other experiments were too small to analyze). Pyrrhotite contained 10-20 ppm Bi, whereas the glass contained 5-10 ppm. Preliminary Nernst- type partition coefficients for Bi between Mt and melt and Po and melt are approximately 5 and 2, respectively. These data reveal that Bi is only slightly compatible in Mt and Po, and that the Po/melt partition coefficient for Bi is much lower than for Cu, Ag and Au, and is comparable to Mn and Zn. Additional experiments are in progress to more compare the partitioning of Bi with that of W and Mo.

[Characterization and optimization of the NaOH-EDTA extracts for solution 31P-NMR analysis of organic phosphorus in river sediments].

PubMed

Zhang, Wen-Qiang; Shan, Bao-Qing; Zhang, Hong; Tang, Wen-Zhong

2014-01-01

Optimization and mechanism of NaOH-EDTA extraction solutions were studied in phosphorus (P) pollution river sediments, which were Fe, Al-rich sediment, by solution 31P nuclear magnetic resonance spectroscopy (31P-NMR). Different proportions of NaOH and EDTA showed different extraction efficiency on total P (TP) and organic P (Po) in the sediment. The concentration of Po in NaOH + EDTA extract was higher than that in NaOH extract. The mechanism was that the TP and Po were released under the conditions of EDTA chelating with Fe and Al. The concentration of TP and Po were the highest in 1.00 mol x L(-1) NaOH +75 mmol x L(-1) EDTA extract and 0.25 mol x L(-1) NaOH + 50 mmol x L(-1) EDTA extract, which were 3.88 mg x g(-1) and 0.24 mg x g(-1), respectively. The extractions of Fe, Mn, Ca, Mg, Al were increasing as the EDTA increased under the same NaOH concentration. Extraction efficiency of Fe, Mn, Ca showed negative correlation with the pH of the extracting solution (P < 0.01). Exponential relationship was found between the extraction of Al and the pH of the extraction solution (P < 0.01) because of the AlO2- and EDTA-Al complex. The quality of spectra of NaOH-EDTA extract was better than that of NaOH extract. Six P species were detected in different extractions, including phosphonates, orthophosphate, pyrophosphate, orthophosphate monoesters, phospholipids and deoxyribonucleic acids. Therefore, 0. 25 mol x L(-1) NaOH + 50 mmol x L(-1) EDTA was the optimization extraction solution for Po analysis in Fe and Al-rich river sediment by 31P-NMR.

Intracellular sodium modulates the state of protein kinase C phosphorylation of rat proximal tubule Na+,K+-ATPase.

PubMed

Ibarra, F R; Cheng, S X Jun; Agrén, M; Svensson, L-B; Aizman, O; Aperia, A

2002-06-01

The natriuretic hormone dopamine and the antinatriuretic hormone noradrenaline, acting on alpha-adrenergic receptors, have been shown to bidirectionally modulate the activity of renal tubular Na+,K+-adenosine triphosphate (ATPase). Here we have examined whether intracellular sodium concentration influences the effects of these bidirectional forces on the state of phosphorylation of Na+,K+-ATPase. Proximal tubules dissected from rat kidney were incubated with dopamine or the alpha-adrenergic agonist, oxymetazoline, and transiently permeabilized in a medium where sodium concentration ranged between 5 and 70 mM. The variations of sodium concentration in the medium had a proportional effect on intracellular sodium. Dopamine and protein kinase C (PKC) phosphorylate the catalytic subunit of rat Na+,K+-ATPase on the Ser23 residue. The level of PKC induced Na+,K+-ATPase phosphorylation was determined using an antibody that only recognizes Na+,K+-ATPase, which is not phosphorylated on its PKC site. Under basal conditions Na+,K+-ATPase was predominantly in its phosphorylated state. When intracellular sodium was increased, Na+,K+-ATPase was predominantly in its dephosphorylated state. Phosphorylation of Na+,K+-ATPase by dopamine was most pronounced when intracellular sodium was high, and dephosphorylation by oxymetazoline was most pronounced when intracellular sodium was low. The oxymetazoline effect was mimicked by the calcium ionophore A23187. An inhibitor of the calcium-dependent protein phosphatase, calcineurin, increased the state of Na+,K+-ATPase phosphorylation. The results imply that phosphorylation of renal Na+,K+-ATPase activity is modulated by the level of intracellular sodium and that this effect involves PKC and calcium signalling pathways. The findings may have implication for the regulation of salt excretion and sodium homeostasis.

Osmotic adjustment, gas exchanges and chlorophyll fluorescence of a hexaploid triticale and its parental species under salt stress.

PubMed

Morant-Manceau, Annick; Pradier, Elisabeth; Tremblin, Gérard

2004-01-01

The effect of salt stress (NaCl 85.7 or 110 mmol/L) was investigated in the triticale T300 and its parental species, Triticum dicoccum farrum (Triticum df) and Secale cereale cv. Petkus. Triticum df and T300 were more salt-tolerant than the rye (110 mmol/L NaCl was the highest concentration allowing rye growth to the three-leaf stage). Na+, K+ and Cl- ions accounted for almost half of the osmotic adjustment in Triticum df and T300, and up to 90% in rye. Salinity decreased the net photosynthesis and transpiration rates of the three cereals as compared to control plants, but induced no significant change in chlorophyll a fluorescence parameters. Water-use efficiency (WUE) increased with salinity. In the presence of 110 mmol/L NaCl, the K+/Na+ ratio decreased markedly in rye as compared to the other two cereals. Proline concentration, which increased in Triticum df and T300, could have protected membrane selectivity in favour of K+. Proline content remained low in rye, and increasing soluble sugar content did not appear to prevent competition between Na+ and K+. The salt sensitivity of rye could be due to low K+ uptake in the presence of a high NaCl concentration.

Feedforward activation of endothelial ENaC by high sodium

PubMed Central

Korte, Stefanie; Sträter, Alexandra S.; Drüppel, Verena; Oberleithner, Hans; Jeggle, Pia; Grossmann, Claudia; Fobker, Manfred; Nofer, Jerzy-Roch; Brand, Eva; Kusche-Vihrog, Kristina

2014-01-01

Kidney epithelial sodium channels (ENaCs) are known to be inactivated by high sodium concentrations (feedback inhibition). Recently, the endothelial sodium channel (EnNaC) was identified to control the nanomechanical properties of the endothelium. EnNaC-dependent endothelial stiffening reduces the release of nitric oxide, the hallmark of endothelial dysfunction. To study the regulatory impact of sodium on EnNaC, endothelial cells (EA.hy926 and ex vivo mouse endothelium) were incubated in aldosterone-free solutions containing either low (130 mM) or high (150 mM) sodium concentrations. By applying atomic force microscopy-based nanoindentation, an unexpected positive correlation between increasing sodium concentrations and cortical endothelial stiffness was observed, which can be attributed to functional EnNaC. In particular, an acute rise in sodium concentration (+20 mM) was sufficient to increase EnNaC membrane abundance by 90% and stiffening of the endothelial cortex by 18%. Despite the absence of exogenous aldosterone, these effects were prevented by the aldosterone synthase inhibitor FAD286 (100 nM) or the mineralocorticoid receptor (MR)-antagonist spironolactone (100 nM), indicating endogenous aldosterone synthesis and MR-dependent signaling. Interestingly, in the presence of high-sodium concentrations, FAD286 increased the transcription of the MR by 69%. Taken together, a novel feedforward activation of EnNaC by sodium is proposed that contrasts ENaC feedback inhibition in kidney.—Korte, S., Sträter, A. S., Drüppel, V., Oberleithner, H., Jeggle, P., Grossmann, C., Fobker, M., Nofer, J.-R., Brand, E., Kusche-Vihrog, K. Feedforward activation of endothelial ENaC by high sodium. PMID:24868010

Genotypic differences in physiological and biochemical responses to salinity stress in melon (Cucumis melo L.) plants: Prospects for selection of salt tolerant landraces.

PubMed

Sarabi, Behrooz; Bolandnazar, Sahebali; Ghaderi, Nasser; Ghashghaie, Jaleh

2017-10-01

Melon (Cucumis melo L.) is one of the most important horticultural crops in Iran often cultivated in arid and semiarid regions of the country with salinity problems. The objective of this work was to better understand the mechanisms of physiological and biochemical responses to salinity stress of five Iranian melon landraces "Samsuri", "Kashan", "Khatouni", "Suski-e-Sabz", and "Ghobadlu" from different geographical origins, and "Galia" F1 cultivar. Plants were grown under greenhouse conditions and irrigated with half-strength Hoagland solution containing 0, 30, 60, or 90 mM NaCl for 60 days. Increase in the external salt concentration was accompanied by an obvious depression in leaf relative water content, membrane stability index, chlorophyll a and b and carotenoid contents, stomata and trichome density, leaf area, specific leaf area, biomass, leaf and stem K + concentrations as well as leaf and stem K + /Na + ratios in all landraces studied. In contrast, hydrogen peroxide, lipid peroxidation, proline and soluble carbohydrate contents, activity of antioxidant enzymes as well as leaf and stem Na + and Cl - concentrations, all increased significantly with increasing stress over all plants. Moreover, carbon isotope discrimination (Δ 13 C), determined on leaf organic matter, was found to be associated with evaluated traits. For example, a highly positive correlation between Δ 13 C and both biomass production and salt tolerance index was notable when all saline treatments were averaged (r = 0.998 and 0.998, respectively). Also, scatter plot and clustering analysis showed that "Suski-e-Sabz" and "Ghobadlu" were placed close to "Galia" F1, a salt tolerant cultivar, indicating that their similar behavior under salinity. Overall, the present results indicated a significant genetic variability for most of the traits studied, suggesting that "Suski-e-Sabz" and "Ghobadlu" could be introduced as the superior landraces and the most promising tolerant parents in the future melon breeding programs due to their suitable performance, in terms of responses to salt stress as compared with other landraces. Also, Δ 13 C can be used as a powerful criterion in melon breeding programs aimed at selection of salt tolerant landraces. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Fluid dilution and efficiency of Na(+) transport in a mathematical model of a thick ascending limb cell.

PubMed

Nieves-González, Aniel; Clausen, Chris; Marcano, Mariano; Layton, Anita T; Layton, Harold E; Moore, Leon C

2013-03-15

Thick ascending limb (TAL) cells are capable of reducing tubular fluid Na(+) concentration to as low as ~25 mM, and yet they are thought to transport Na(+) efficiently owing to passive paracellular Na(+) absorption. Transport efficiency in the TAL is of particular importance in the outer medulla where O(2) availability is limited by low blood flow. We used a mathematical model of a TAL cell to estimate the efficiency of Na(+) transport and to examine how tubular dilution and cell volume regulation influence transport efficiency. The TAL cell model represents 13 major solutes and the associated transporters and channels; model equations are based on mass conservation and electroneutrality constraints. We analyzed TAL transport in cells with conditions relevant to the inner stripe of the outer medulla, the cortico-medullary junction, and the distal cortical TAL. At each location Na(+) transport efficiency was computed as functions of changes in luminal NaCl concentration ([NaCl]), [K(+)], [NH(4)(+)], junctional Na(+) permeability, and apical K(+) permeability. Na(+) transport efficiency was calculated as the ratio of total net Na(+) transport to transcellular Na(+) transport. Transport efficiency is predicted to be highest at the cortico-medullary boundary where the transepithelial Na(+) gradient is the smallest. Transport efficiency is lowest in the cortex where luminal [NaCl] approaches static head.

Concentrated aqueous sodium chloride solution in clays at thermodynamic conditions of hydraulic fracturing: Insight from molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Svoboda, Martin; Lísal, Martin

2018-06-01

To address a high salinity of flow-back water during hydraulic fracturing, we use molecular dynamics (MD) simulations and study the thermodynamics, structure, and diffusion of concentrated aqueous salt solution in clay nanopores. The concentrated solution results from the dissolution of a cubic NaCl nanocrystal, immersed in an aqueous NaCl solution of varying salt concentration and confined in clay pores of a width comparable to the crystal size. The size of the nanocrystal equals to about 18 Å which is above a critical nucleus size. We consider a typical shale gas reservoir condition of 365 K and 275 bar, and we represent the clay pores as pyrophyllite and Na-montmorillonite (Na-MMT) slits. We employ the Extended Simple Point Charge (SPC/E) model for water, Joung-Cheatham model for ions, and CLAYFF for the slit walls. We impose the pressure in the normal direction and the resulting slit width varies from about 20 to 25 Å when the salt concentration in the surrounding solution increased from zero to an oversaturated value. By varying the salt concentration, we observe two scenarios. First, the crystal dissolves and its dissolution time increases with increasing salt concentration. We describe the dissolution process in terms of the number of ions in the crystal, and the crystal size and shape. Second, when the salt concentration reaches a system solubility limit, the crystal grows and attains a new equilibrium size; the crystal comes into equilibrium with the surrounding saturated solution. After crystal dissolution, we carry out canonical MD simulations for the concentrated solution. We evaluate the hydration energy, density profiles, orientation distributions, hydrogen-bond network, radial distribution functions, and in-plane diffusion of water and ions to provide insight into the microscopic behaviour of the concentrated aqueous sodium chloride solution in interlayer galleries of the slightly hydrophobic pyrophyllite and hydrophilic Na-MMT pores.

Concentrated aqueous sodium chloride solution in clays at thermodynamic conditions of hydraulic fracturing: Insight from molecular dynamics simulations.

PubMed

Svoboda, Martin; Lísal, Martin

2018-06-14

To address a high salinity of flow-back water during hydraulic fracturing, we use molecular dynamics (MD) simulations and study the thermodynamics, structure, and diffusion of concentrated aqueous salt solution in clay nanopores. The concentrated solution results from the dissolution of a cubic NaCl nanocrystal, immersed in an aqueous NaCl solution of varying salt concentration and confined in clay pores of a width comparable to the crystal size. The size of the nanocrystal equals to about 18 Å which is above a critical nucleus size. We consider a typical shale gas reservoir condition of 365 K and 275 bar, and we represent the clay pores as pyrophyllite and Na-montmorillonite (Na-MMT) slits. We employ the Extended Simple Point Charge (SPC/E) model for water, Joung-Cheatham model for ions, and CLAYFF for the slit walls. We impose the pressure in the normal direction and the resulting slit width varies from about 20 to 25 Å when the salt concentration in the surrounding solution increased from zero to an oversaturated value. By varying the salt concentration, we observe two scenarios. First, the crystal dissolves and its dissolution time increases with increasing salt concentration. We describe the dissolution process in terms of the number of ions in the crystal, and the crystal size and shape. Second, when the salt concentration reaches a system solubility limit, the crystal grows and attains a new equilibrium size; the crystal comes into equilibrium with the surrounding saturated solution. After crystal dissolution, we carry out canonical MD simulations for the concentrated solution. We evaluate the hydration energy, density profiles, orientation distributions, hydrogen-bond network, radial distribution functions, and in-plane diffusion of water and ions to provide insight into the microscopic behaviour of the concentrated aqueous sodium chloride solution in interlayer galleries of the slightly hydrophobic pyrophyllite and hydrophilic Na-MMT pores.

Densities and apparent molar volumes of atmospherically important electrolyte solutions. 1. The solutes H2SO4, HNO3, HCl, Na2SO4, NaNO3, NaCl, (NH4)2SO4, NH4NO3, and NH4Cl from 0 to 50 °C, including extrapolations to very low temperature and to the pure liquid state, and NaHSO4, NaOH, and NH3 at 25 °C.

PubMed

Clegg, S L; Wexler, A S

2011-04-21

Calculations of the size and density of atmospheric aerosols are complicated by the fact that they can exist at concentrations highly supersaturated with respect to dissolved salts and supercooled with respect to ice. Densities and apparent molar volumes of solutes in aqueous solutions containing the solutes H(2)SO(4), HNO(3), HCl, Na(2)SO(4), NaNO(3), NaCl, (NH(4))(2)SO(4), NH(4)NO(3), and NH(4)Cl have been critically evaluated and represented using fitted equations from 0 to 50 °C or greater and from infinite dilution to concentrations saturated or supersaturated with respect to the dissolved salts. Using extrapolated densities of high-temperature solutions and melts, the relationship between density and concentration is extended to the hypothetical pure liquid solutes. Above a given reference concentration of a few mol kg(-1), it is observed that density increases almost linearly with decreasing temperature, and comparisons with available data below 0 °C suggest that the fitted equations for density can be extrapolated to very low temperatures. As concentration is decreased below the reference concentration, the variation of density with temperature tends to that of water (which decreases as temperature is reduced below 3.98 °C). In this region below the reference concentration, and below 0 °C, densities are calculated using extrapolated apparent molar volumes which are constrained to agree at the reference concentrations with an equation for the directly fitted density. Calculated volume properties agree well with available data at low temperatures, for both concentrated and dilute solutions. Comparisons are made with literature data for temperatures of maximum density. Apparent molar volumes at infinite dilution are consistent, on a single ion basis, to better than ±0.1 cm(3) mol(-1) from 0 to 50 °C. Volume properties of aqueous NaHSO(4), NaOH, and NH(3) have also been evaluated, at 25 °C only. In part 2 of this work (ref 1 ) an ion interaction (Pitzer) model has been used to calculate apparent molar volumes of H(2)SO(4) in 0-3 mol kg(-1) aqueous solutions of the pure acid and to represent directly the effect of the HSO(4)(-) ↔ H(+) + SO(4)(2-) reaction. The results are incorporated into the treatment of aqueous H(2)SO(4) density described here. Densities and apparent molar volumes from -20 to 50 °C, and from 0 to 100 wt % of solute, are tabulated for the electrolytes listed in the title and have also been incorporated into the extended aerosol inorganics model (E-AIM, http://www.aim.env.uea.ac.uk/aim/aim.php) together with densities of the solid salts and hydrates.

Effects of Different Oral Doses of Sodium Chloride on the Basal Acid-Base and Mineral Status of Exercising Horses Fed Low Amounts of Hay.

PubMed

Zeyner, Annette; Romanowski, Kristin; Vernunft, Andreas; Harris, Patricia; Müller, Ann-Marie; Wolf, Carola; Kienzle, Ellen

2017-01-01

The provision of NaCl, according to current recommendations, to horses in moderate work has been shown to induce immediate postprandial acidosis. The present study aimed to clarify whether this NaCl induced acidosis i) persists beyond the immediate postprandial period, and ii) is still present after a 2 week adaptation period. Six adult warmblood mares in moderate work received daily 1.00 kg hay per 100 kg body weight (bwt) only together with 0.64 kg unprocessed cereal grains/100 kg bwt.d as fed basis. Using a 3x3 Latin Square, either 0 (NaCl-0), 50 (NaCl-50) or 100 (NaCl-100) g NaCl/d were fed together with the concentrates in two equal doses for 3 weeks. During the final week, a mineral digestibility trial was undertaken. The middle sodium and chloride intake (NaCl-50) at least met the most common recommendations for moderate work. Morning (7:00 AM) urine and venous blood samples were collected on days 0, 1-4, 8, and 15, and analysed for pH, acid-base status, creatinine and electrolyte concentrations. Fractional electrolyte clearances (FC) were determined. Mean apparent sodium digestibility ranged between 60-62% whereas chloride digestibility was consistently above 94%. Supplementing 100 g but not 50 g of NaCl resulted in significant reduction of blood pH and base excess as well as urinary pH and urine acid excretion. Both 50 g and 100 g NaCl supplementation caused a significant reduction in base and net acid-base excretion, urine density and potassium concentration, but increased urine sodium concentration and the FC of sodium and chloride (P < 0.05). This suggests that a high proportion of the recommended salt doses is excreted renally. The above effects of NaCl supplementation persisted over the 2 week measurement period. Results suggest that feeding 100 g NaCl to moderately exercising horses results in mild metabolic acidosis, whereas feeding 50 g according to current recommendations resulted in compensated acidosis.

Effects of Different Oral Doses of Sodium Chloride on the Basal Acid-Base and Mineral Status of Exercising Horses Fed Low Amounts of Hay

PubMed Central

Zeyner, Annette; Romanowski, Kristin; Vernunft, Andreas; Harris, Patricia; Müller, Ann-Marie; Wolf, Carola; Kienzle, Ellen

2017-01-01

The provision of NaCl, according to current recommendations, to horses in moderate work has been shown to induce immediate postprandial acidosis. The present study aimed to clarify whether this NaCl induced acidosis i) persists beyond the immediate postprandial period, and ii) is still present after a 2 week adaptation period. Six adult warmblood mares in moderate work received daily 1.00 kg hay per 100 kg body weight (bwt) only together with 0.64 kg unprocessed cereal grains/100 kg bwt.d as fed basis. Using a 3x3 Latin Square, either 0 (NaCl-0), 50 (NaCl-50) or 100 (NaCl-100) g NaCl/d were fed together with the concentrates in two equal doses for 3 weeks. During the final week, a mineral digestibility trial was undertaken. The middle sodium and chloride intake (NaCl-50) at least met the most common recommendations for moderate work. Morning (7:00 AM) urine and venous blood samples were collected on days 0, 1–4, 8, and 15, and analysed for pH, acid-base status, creatinine and electrolyte concentrations. Fractional electrolyte clearances (FC) were determined. Mean apparent sodium digestibility ranged between 60–62% whereas chloride digestibility was consistently above 94%. Supplementing 100 g but not 50 g of NaCl resulted in significant reduction of blood pH and base excess as well as urinary pH and urine acid excretion. Both 50 g and 100 g NaCl supplementation caused a significant reduction in base and net acid-base excretion, urine density and potassium concentration, but increased urine sodium concentration and the FC of sodium and chloride (P < 0.05). This suggests that a high proportion of the recommended salt doses is excreted renally. The above effects of NaCl supplementation persisted over the 2 week measurement period. Results suggest that feeding 100 g NaCl to moderately exercising horses results in mild metabolic acidosis, whereas feeding 50 g according to current recommendations resulted in compensated acidosis. PMID:28045916

K+ transport and membrane potentials in isolated rat parotid acini

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nauntofte, B.; Dissing, S.

1988-10-01

42K+ transport properties of isolated rat parotid acini were characterized concomitant with measurements of membrane potentials (Em) by means of the fluorescent dye diSC3-(5). In unstimulated acini suspended in a 5 mM K+ buffer, Em was governed by the K+ and Cl- gradients and amounted to about -59 mV, a value that remained unaffected on cholinergic stimulation. In unstimulated acini, 42K+ influx was largely mediated by the Na+-K+ pump, and the residual influxes were mediated by a bumetanide-sensitive component (cotransport system) and by K+ channels. Efflux of 42K+ was largely mediated by a bumetanide-sensitive component and by K+ channels. Inmore » the unstimulated state, the cotransport system was mediating K+-K+ exchange without contributing to the net uptake of K+. Within 10 s after stimulation, a approximately 10-fold increase in the acinar K+ conductance (gK) occurred, resulting in a rapid net efflux of K+ that amounted to approximately 3.8 mmol.l cells-1.s-1. Measurements of 42K+ fluxes as a function of the external K+ concentration revealed that in the stimulated state gK increases when external K+ is raised from 0.7 to 10 mM, consistent with an activation of acinar gK by the binding of external K+ to the channel. 42K+ flux ratios as well as the effect of the K+ channel inhibitor from scorpion venom (LQV) suggest that approximately 90% of K+ transport in the stimulated state is mediated by ''maxi'' K+ channels.« less

Transepithelial glucose transport and Na+/K+ homeostasis in enterocytes: an integrative model

PubMed Central

Drengstig, Tormod; Ruoff, Peter

2014-01-01

The uptake of glucose and the nutrient coupled transcellular sodium traffic across epithelial cells in the small intestine has been an ongoing topic in physiological research for over half a century. Driving the uptake of nutrients like glucose, enterocytes must have regulatory mechanisms that respond to the considerable changes in the inflow of sodium during absorption. The Na-K-ATPase membrane protein plays a major role in this regulation. We propose the hypothesis that the amount of active Na-K-ATPase in enterocytes is directly regulated by the concentration of intracellular Na+ and that this regulation together with a regulation of basolateral K permeability by intracellular ATP gives the enterocyte the ability to maintain ionic Na+/K+ homeostasis. To explore these regulatory mechanisms, we present a mathematical model of the sodium coupled uptake of glucose in epithelial enterocytes. Our model integrates knowledge about individual transporter proteins including apical SGLT1, basolateral Na-K-ATPase, and GLUT2, together with diffusion and membrane potentials. The intracellular concentrations of glucose, sodium, potassium, and chloride are modeled by nonlinear differential equations, and molecular flows are calculated based on experimental kinetic data from the literature, including substrate saturation, product inhibition, and modulation by membrane potential. Simulation results of the model without the addition of regulatory mechanisms fit well with published short-term observations, including cell depolarization and increased concentration of intracellular glucose and sodium during increased concentration of luminal glucose/sodium. Adding regulatory mechanisms for regulation of Na-K-ATPase and K permeability to the model show that our hypothesis predicts observed long-term ionic homeostasis. PMID:24898586

An isopiestic study of aqueous NaBr and KBr at 50 °C: Chemical equilibrium model of solution behavior and solubility in the NaBr-H 2O, KBr-H 2O and Na-K-Br-H 2O systems to high concentration and temperature

NASA Astrophysics Data System (ADS)

Christov, Christomir

2007-07-01

The isopiestic method has been used to determine the osmotic coefficients of the binary solutions NaBr-H 2O (from 0.745 to 5.953 mol kg -1) and KBr-H 2O (from 0.741 to 5.683 mol kg -1) at the temperature t = 50 °C. Sodium chloride solutions have been used as isopiestic reference standards. The isopiestic results obtained have been combined with all other experimental thermodynamic quantities available in literature (osmotic coefficients, water activities, bromide mineral's solubilities) to construct a chemical model that calculates solute and solvent activities and solid-liquid equilibria in the NaBr-H 2O, KBr-H 2O and Na-K-Br-H 2O systems from dilute to high solution concentration within the 0-300 °C temperature range. The Harvie and Weare [Harvie C., and Weare J. (1980) The prediction of mineral solubilities in naturalwaters: the Na-K-Mg-Ca-Cl-SO 4-H 2O system from zero to high concentration at 25 °C. Geochim. Cosmochim. Acta44, 981-997] solubility modeling approach, incorporating their implementation of the concentration-dependent specific interaction equations of Pitzer [Pitzer K. (1973) Thermodynamics of electrolytes. I. Theoretical basis and general equations. J. Phys. Chem.77, 268-277] is employed. The model for binary systems is validated by comparing activity coefficient predictions with those given in literature, and not used in the parameterization process. Limitations of the mixed solutions model due to data insufficiencies are discussed. This model expands the variable temperature sodium-potassium model of Greenberg and Moller [Greenberg J., and Moller N. (1989) The prediction of mineral solubilities in natural waters: a chemical equilibrium model for the Na-K-Ca-Cl-SO 4-H 2O system to high concentration from 0 to 250 °C. Geochim. Cosmochim. Acta53, 2503-2518] by evaluating Br - pure electrolyte and mixing solution parameters and the chemical potentials of three bromide solid phases: NaBr-2H 2O (cr), NaBr (cr) and KBr (cr).

Sodium relations in desert plants: 7. Effects of sodium chloride on Atriplex polycarpa and Atriplex canescens

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wallace, A.; Romney, E.M.; Mueller, R.T.

1982-07-01

Atriplex canescens (Pursh) Nutt. ssp. canescens (Caligonum c. Pursh.) and Atriplex polycarpa (Torr.) Wats. (Obione p. Torr.) plants were grown in Yolo loam soil in a glasshouse with different levels of sodium salts. Both species tolerated concentrations of salt equivalent to seawater, using either NaCl or Na/sub 2/SO/sub 4/. Vegetative yields were sightly higher with chloride, particularly with stems of A. polycarpa; SO/sub 4//sup 2 -/ decreased calcium and magnesium concentrations. Atriplex canescens leaves contained less Na, total cations, Cl, S, and Si, but more N than did those of A. polycarpa. The A. polycarpa would have high concentrations ormore » organic acids in leaves. Chloride decreased N concentrations in leaves of A. polycarpa.« less

Electron microprobe analysis of human labial gland secretory granules in cystic fibrosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Izutsu, K.; Johnson, D.; Schubert, M.

1985-06-01

X-ray microanalysis of freeze-dried labial gland cryosections revealed that Na concentration was doubled and the Ca/S concentration ratio was decreased in secretory granules of labial glands from patients with cystic fibrosis (CF) when compared with glands from normal subjects. Other results suggested that the decrease in the Ca/S concentration ratio resulted from an increase in S concentration. These findings imply that mucous granules in labial saliva showed a CF-related increase in Na and S content, and such changes would be expected to affect the rheology of the mucus after exocytosis. In contrast with a previous study in human parotid glands,more » no evidence was found for CF-related changes in cytoplasmic or nuclear Na, K, and Ca concentrations. Significant elemental differences were found between secretory granules and nuclei and cytoplasm of control cells.« less

High-Performance Na-O2 Batteries Enabled by Oriented NaO2 Nanowires as Discharge Products.

PubMed

Khajehbashi, S Mohammad B; Xu, Lin; Zhang, Guobin; Tan, Shuangshuang; Zhao, Yan; Wang, Lai-Sen; Li, Jiantao; Luo, Wen; Peng, Dong-Liang; Mai, Liqiang

2018-06-13

Na-O 2 batteries are emerging rechargeable batteries due to their high theoretical energy density and abundant resources, but they suffer from sluggish kinetics due to the formation of large-size discharge products with cubic or irregular particle shapes. Here, we report the unique growth of discharge products of NaO 2 nanowires inside Na-O 2 batteries that significantly boosts the performance of Na-O 2 batteries. For this purpose, a high-spin Co 3 O 4 electrocatalyst was synthesized via the high-temperature oxidation of pure cobalt nanoparticles in an external magnetic field. The discharge products of NaO 2 nanowires are 10-20 nm in diameter and ∼10 μm in length, characteristics that provide facile pathways for electron and ion transfer. With these nanowires, Na-O 2 batteries have surpassed 400 cycles with a fixed capacity of 1000 mA h g -1 , an ultra-low over-potential of ∼60 mV during charging, and near-zero over-potential during discharging. This strategy not only provides a unique way to control the morphology of discharge products to achieve high-performance Na-O 2 batteries but also opens up the opportunity to explore growing nanowires in novel conditions.

Control of binder viscosity and hygroscopicity on particle aggregation efficiency

NASA Astrophysics Data System (ADS)

Mueller, Sebastian B.; Kueppers, Ulrich; Ayris, Paul M.; Jacob, Michael; Delmelle, Pierre; Dingwell, Donald B.

2016-04-01

In the course of explosive volcanic eruptions, large amounts of ash are released into the atmosphere and may subsequently pose a threat to infrastructure, such as aviation industry. Ash plume forecasting is therefore a crucial tool for volcanic hazard mitigation but may be significantly affected by aggregation, altering the aerodynamic properties of particles. Models struggle with the implementation of aggregation since external conditions promoting aggregation have not been completely understood; in a previous study we have shown the rapid generation of ash aggregates through liquid bonding via the use of fluidization bed technology and further defined humidity and temperature ranges necessary to trigger aggregation. Salt (NaCl) was required for the recovery of stable aggregates, acting as a cementation agent and granting aggregate cohesion. A numerical model was used to explain the physics behind particle aggregation mechanisms and further predicted a dependency of aggregation efficiency on liquid binder viscosity. In this study we proof the effect of viscosity on particle aggregation. HCl and H2SO4 solutions were diluted to various concentrations resulting in viscosities between 1 and 2 mPas. Phonolitic and rhyolitic ash samples as well as soda-lime glass beads (serving as analogue material) were fluidized in the ProCell Lab® of Glatt Ingenieurtechnik GmbH and treated with the acids via a bottom-spray technique. Chemically driven interaction between acid liquids and surfaces of the three used materials led to crystal precipitation. Salt crystals (e.g. NaCl) have been confirmed through scanning electron microscopy (SEM) and leachate analysis. Both volcanic ash samples as well as the glass beads showed a clear dependency of aggregation efficiency on viscosity of the sprayed HCl solution. Spraying H2SO4 provoked a collapse of the fluidized bed and no aggregation has been observed. This is accounted by the high hygroscopicity of H2SO4. Dissolving CaCl2 (known to be a highly hygroscopic salt) in de-ionized water yielded comparable results without observable aggregation. In case of successful aggregation, concentration of salts has been found to be in the range of published values. We conclude that non-hygroscopic salt crystal precipitation from an aqueous liquid interacting with the glass phase in volcanic ash is a very efficient way to produce cohesive ash aggregates that can survive external forces acting during transport and sedimentation.

Optimization for zeolite regeneration and nitrogen removal performance of a hypochlorite-chloride regenerant.

PubMed

Zhang, Wei; Zhou, Zhen; An, Ying; Du, Silu; Ruan, Danian; Zhao, Chengyue; Ren, Ning; Tian, Xiaoce

2017-07-01

Simultaneous zeolites regeneration and nitrogen removal were investigated by using a mixed solution of NaClO and NaCl (NaClO-NaCl solution), and effects of the regenerant on ammonium removal performance and textural properties of zeolites were analyzed by long-term adsorption and regeneration operations. Mixed NaClO-NaCl solution removed more NH 4 + exchanged on zeolites and converted more of them to nitrogen than using NaClO or NaCl solution alone. Response surface methodological analysis indicated that molar ratio of hypochlorite and nitrogen (ClO - /N), NaCl concentration and pH value all had significant effects on zeolites regeneration and NH 4 + conversion to nitrogen, and the optimum condition was obtained at ClO - /N of 1.75, NaCl concentration of 20 g/L and pH of 10.0. Zeolites regenerated by mixed NaClO-NaCl solution showed higher ammonium adsorption rate and lower capacity than unused zeolites. Zeolites and the regeneration solution were both effective even after 20 cycles of use. Composition and morphological analysis revealed that the main mineral species and surface morphology of zeolites before and after NaClO-NaCl regeneration were unchanged. Textural analysis indicated that NaClO-NaCl regeneration leads to an increased surface area of zeolites, especially the microporosity. The results indicated that NaClO-NaCl regeneration is an attractive method to achieve sustainable removal of nitrogen from wastewater through zeolite. Copyright © 2017 Elsevier Ltd. All rights reserved.

Temperature responses to infusion of electrolytes during exercise

NASA Technical Reports Server (NTRS)

Greenleaf, J. E.; Kozlowski, S.; Kaciuba-Uscilko, H.; Nazar, K.; Brzezinska, Z.

1975-01-01

Past studies on the influence of various metal ions on heat regulation in mammals are reviewed, and results of a study on the effect of Na and citrate in isotonic and hypertonic concentrations on temperature elevation during exercise in dogs are presented. Hypertonic administration of Na before or during treadmill running and dosis of citrate during treadmill running significantly raised core temperature over controls and isotonic cases. Thus the higher the plasma Na-osmotic concentration, the greater the inhibition of heat dissipation.

Effect of Alkali Concentration on Fly Ash Geopolymers

NASA Astrophysics Data System (ADS)

Fatimah Azzahran Abdullah, Siti; Yun-Ming, Liew; Bakri, Mohd Mustafa Al; Cheng-Yong, Heah; Zulkifly, Khairunnisa; Hussin, Kamarudin

2018-03-01

This paper presents the effect of NaOH concentration on fly ash geopolymers with compressive up to 56 MPa at 12M. The physical and mechanical on fly ash geopolymer are investigated. Test results show that the compressive strength result complied with bulk density result whereby the higher the bulk density, the higher the strength. Thus, the lower water absorption and porosity due to the increasing of NaOH concentration.

Correlation of the Processing Parameters in the Formation of Granulated Ground Blast Furnace Slag Geopolymer

NASA Astrophysics Data System (ADS)

Aziz, I. H.; Abdullah, M. M. A. B.; Yong, H. C.; Ming, L. Y.; Panias, D.; Sakkas, K.

2017-06-01

Geopolymers are inorganic materials with huge potential applications including building material, fire resistant materials, and agricultural construction materials. Various parameters influenced the final properties of these geopolymer concretes. This study developed the effects of several factors such as solid-to-liquid ratio, NaOH concentration, and Na2SiO3/NaOH ratio on the compressive strength of granulated ground blast furnace slag (GGBFS) by statistical design of experiment (DOE) approach. Analysis of the experimental results through ANOVA exhibited that the specimen with NaOH concentration of 10M, Na2SiO3/NaOH ratio equals to 2.5, and solid-to-liquid ratio of 3.0 curing at room temperatures for 28 days was potential of highest strength (168.705 MPa) in the considered procedure. Besides, the relationship between compressive strength and influential factors could be suitably by fraction factorial design method.

H2O activity in concentrated NaCl solutions at high pressures and temperatures measured by the brucite-periclase equilibrium

NASA Astrophysics Data System (ADS)

Aranovich, L. Y.; Newton, R. C.

1996-10-01

H2O activities in concentrated NaCl solutions were measured in the ranges 600° 900° C and 2 15 kbar and at NaCl concentrations up to halite saturation by depression of the brucite (Mg(OH)2) periclase (MgO) dehydration equilibrium. Experiments were made in internally heated Ar pressure apparatus at 2 and 4.2 kbar and in 1.91-cm-diameter piston-cylinder apparatus with NaCl pressure medium at 4.2, 7, 10 and 15 kbar. Fluid compositions in equilibrium with brucite and periclase were reversed to closures of less than 2 mol% by measuring weight changes after drying of punctured Pt capsules. Brucite-periclase equilibrium in the binary system was redetermined using coarsely crystalline synthetic brucite and periclase to inhibit back-reaction in quenching. These data lead to a linear expression for the standard Gibbs free energy of the brucite dehydration reaction in the experimental temperature range: ΔG° (±120J)=73418 134.95 T(K). Using this function as a baseline, the experimental dehydration points in the system MgO-H2O-NaCl lead to a simple systematic relationship of high-temperature H2O activity in NaCl solution. At low pressure and low fluid densities near 2 kbar the H2O activity is closely approximated by its mole fraction. At pressures of 10 kbar and greater, with fluid densities approaching those of condensed H2O, the H2O activity becomes nearly equal to the square of its mole fraction. Isobaric halite saturation points terminating the univariant brucite-periclase curves were determined at each experimental pressure. The five temperature-composition points in the system NaCl-H2O are in close agreement with the halite saturation curves (liquidus curves) given by existing data from differential thermal analysis to 6 kbar. Solubility of MgO in the vapor phase near halite saturation is much less than one mole percent and could not have influenced our determinations. Activity concentration relations in the experimental P-T range may be retrieved for the binary system H2O-NaCl from our brucite-periclase data and from halite liquidus data with minor extrapolation. At two kbar, solutions closely approach an ideal gas mixture, whereas at 10 kbar and above the solutions closely approximate an ideal fused salt mixture, where the activities of H2O and NaCl correspond to an ideal activity formulation. This profound pressure-induced change of state may be characterized by the activity ( a) concentration ( X) expression: a H 2O= X H 2O/(1+α X NaCl), and a NaCl=(1+α)(1+α)[ X NaCl/(1+α X NaCl)](1+α). The parameter α is determined by regression of the brucite-periclase H2O activity data: α=exp[A B/ϱH 2O ]-C P/ T, where A=4.226, B=2.9605, C=164.984, and P is in kbar, T is in Kelvins, and ϱH 2O is the density of H2O at given P and T in g/cm3. These formulas reproduce both the H2O activity data and the NaCl activity data with a standard deviation of ±0.010. The thermodynamic behavior of concentrated NaCl solutions at high temperature and pressure is thus much simpler than portrayed by extended Debye-Hückel theory. The low H2O activity at high pressures in concentrated supercritical NaCl solutions (or hydrosaline melts) indicates that such solutions should be feasible as chemically active fluids capable of coexisting with solid rocks and silicate liquids (and a CO2-rich vapor) in many processes of deep crustal and upper mantle metamorphism and metasomatism.

Bactericidal activity of electrolyzed acid water from solution containing sodium chloride at low concentration, in comparison with that at high concentration.

PubMed

Kiura, Hiromasa; Sano, Kouichi; Morimatsu, Shinichi; Nakano, Takashi; Morita, Chizuko; Yamaguchi, Masaki; Maeda, Toyoyuki; Katsuoka, Yoji

2002-05-01

Electrolyzed strong acid water (ESW) containing free chlorine at various concentrations is becoming to be available in clinical settings as a disinfectant. ESW is prepared by electrolysis of a NaCl solution, and has a corrosive activity against medical instruments. Although lower concentrations of NaCl and free chlorine are desired to eliminate corrosion, the germicidal effect of ESW with low NaCl and free-chlorine concentrations (ESW-L) has not been fully clarified. In this study, we demonstrated that ESW-L possesses bactericidal activity against Mycobacteria and spores of Bacillus subtilis. The effect was slightly weaker than that of ESW containing higher NaCl and free-chlorine concentrations (ESW-H), but acceptable as a disinfectant. To clarify the mechanism of the bactericidal activity, we investigated ESW-L-treated Pseudomonas aeruginosa by transmission electron microscopy, a bacterial enzyme assay and restriction fragment length polymorphism pattern (RFLP) assay. Since the bacterium, whose growth was completely inhibited by ESW-L, revealed the inactivation of cytoplasmic enzyme, blebs and breaks in its outer membrane and remained complete RFLP of DNA, damage of the outer membrane and inactivation of cytoplasmic enzyme are the important determinants of the bactericidal activity.

Water structure and aqueous uranyl(VI) adsorption equilibria onto external surfaces of beidellite, montmorillonite, and pyrophyllite: results from molecular simulations.

PubMed

Greathouse, Jeffery A; Cygan, Randall T

2006-06-15

Molecular dynamics simulations were performed to provide a systematic study of aqueous uranyl adsorption onto the external surface of 2:1 dioctahedral clays. Our understanding of this key process is critical in predicting the fate of radioactive contaminants in natural groundwaters. These simulations provide atomistic detail to help explain experimental trends in uranyl adsorption onto natural media containing smectite clays. Aqueous uranyl concentrations ranged from 0.027 to 0.162 M. Sodium ions and carbonate ions (0.027-0.243 M) were also present in the aqueous regions to more faithfully model a stream of uranyl-containing groundwater contacting a mineral system comprised of Na-smectite. No adsorption occurred near the pyrophyllite surface, and there was little difference in uranyl adsorption onto the beidellite and montmorillonite, despite the difference in location of clay layer charge between the two. At low uranyl concentration, the pentaaquouranyl complex dominates in solution and readily adsorbs to the clay basal plane. At higher uranyl (and carbonate) concentrations, the mono(carbonato) complex forms in solution, and uranyl adsorption decreases. Sodium adsorption onto beidellite occurred both as inner- and outer-sphere surface complexes, again with little effect on uranyl adsorption. Uranyl surface complexes consisted primarily of the pentaaquo cation (85%) and to a lesser extent the mono(carbonato) species (15%). Speciation diagrams of the aqueous region indicate that the mono(carbonato)uranyl complex is abundant at high ionic strength. Oligomeric uranyl complexes are observed at high ionic strength, particularly near the pyrophyllite and montmorillonite surfaces. Atomic density profiles of water oxygen and hydrogen atoms are nearly identical near the beidellite and montmorillonite surfaces. Water structure therefore appears to be governed by the presence of adsorbed ions and not by the location of layer charge associated with the substrate. The water oxygen density near the pyrophyllite surface is similar to the other cases, but the hydrogen density profile indicates reduced hydrogen bonding between adsorbed water molecules and the surface.

[Effect of chloride ion on corrosion of two commonly used dental alloys].

PubMed

Chen, Lei; Zhang, Weidan; Zhang, Yuanyuan

2014-11-01

To investigate the eff ect of chloride concentration on the corrosion of Co-Cr alloy and pure Ti in a simulated oral environment. The electrochemical corrosion tests of pure Ti and Co-Cr alloy were carried out in neutral artificial saliva solutions with different NaCl concentrations (0.9%, 2.0%, and 3.0%). Th e morphologies of corroded surface for pure Ti and Co-Cr alloy were observed by scanning electron microscope (SEM). Th e changes in the self-corrosion potentials (Ecorr) for pure Ti and Co-Cr alloy in three kinds of artificial saliva solutions was not obvious. However, the self-corrosion current densities (Icorr) of pure Ti were much lower than those of Co-Cr. The Icorr of Co-Cr alloy increased in a concentration-dependent manner of NaCl, whereas the breakdown potential (Eb) of Co-Cr alloy decreased in a concentration-dependent manner. Th e potential ranged for the breakdown of oxide film (Ev) was shortened in a concentration-dependent manner of NaCl. There was no obvious difference in the Icorr of pure Ti with different concentrations of NaCl. The breakdown potential was not seen according to the polarization curves. In a certain range, the increase of the concentration of Cl- leads to accelerate the corrosion behavior of Co-Cr alloy, but it does not affect pure Ti.

Impact of Sodium Contamination in Tin Sulfide Thin-Film Solar Cells

DOE PAGES

Steinmann, Vera; Brandt, Riley E.; Chakraborty, Rupak; ...

2016-02-12

Empirical observations show that sodium(Na) is a benign contaminant in some thin-filmsolar cells. Here, we intentionally contaminate thermally evaporated tin sulfide (SnS)thin-films with sodium and measure the SnS absorber properties and solar cellcharacteristics. The carrier concentration increases from 2 × 10 16 cm -3 to 4.3 × 10 17 cm -3 in Na-doped SnSthin-films, when using a 13 nm NaCl seed layer, which is detrimental for SnS photovoltaic applications but could make Na-doped SnS an attractive candidate in thermoelectrics. We observed trends in carrier concentration and found that it is in good agreement with density functional theory calculations, which predictmore » an acceptor-type NaSn defect with low formation energy.« less

Photoelectron spectroscopy of aqueous solutions: Streaming potentials of NaX (X = Cl, Br, and I) solutions and electron binding energies of liquid water and X{sup −}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kurahashi, Naoya; Horio, Takuya; Suzuki, Toshinori, E-mail: suzuki@kuchem.kyoto-u.ac.jp

2014-05-07

The streaming potentials of liquid beams of aqueous NaCl, NaBr, and NaI solutions are measured using soft X-ray, He(I), and laser multiphoton ionization photoelectron spectroscopy. Gaseous molecules are ionized in the vicinity of liquid beams and the photoelectron energy shifts are measured as a function of the distance between the ionization point and the liquid beam. The streaming potentials change their polarity with concentration of electrolytes, from which the singular points of concentration eliminating the streaming potentials are determined. The streaming currents measured in air also vanish at these concentrations. The electron binding energies of liquid water and I{sup −},more » Br{sup −}, and Cl{sup −} anions are revisited and determined more accurately than in previous studies.« less

Molecular characterization and expression analysis of the Na+/H+ exchanger gene family in Medicago truncatula

USDA-ARS?s Scientific Manuscript database

One important mechanism plants use to cope with salinity is keeping the cytosolic Na+ concentration low by sequestering Na+ in vacuoles, a process facilitated by Na+/H+ exchangers (NHX). There are eight NHX genes (NHX1 through NHX8) identified and characterized in Arabidopsis. Bioinformatic analysis...

Molecular analysis of the Na+/H+ exchanger gene family and its role in salt stress in Medicago truncatula

USDA-ARS?s Scientific Manuscript database

High salinity in irrigation water is detrimental to plant growth and productivity. Plants develop various mechanisms and strategies to cope with salinity. One important mechanism is keeping the cytosolic Na+ concentration low by sequestering Na+ in vacuoles, a process facilitated by Na+/H+ exchanger...

Concentrations of macro- and micro-elements in the milk of pasture-fed thoroughbred mares.

PubMed

Grace, N D; Pearce, S G; Firth, E C; Fennessy, P F

1999-03-01

To determine the changes in Ca, P, Mg, Na, K, S, Cu, Fe and Zn concentrations of milk during the lactation in pasture-fed Thoroughbred mares and then calculate the dietary mineral requirements of the sucking foal and the lactating mare. Milk was sampled on days 1, 3, 7, 14, 21, 28 and at various times between 55 to 65, 85 to 95 and 135 to 150 days after parturition from 21 pasture-fed mares. The concentrations of macro- and micro-elements in the milk were determined by inductively coupled plasma emission spectrometry. Concentrations (mg/L) of these elements were highest in colostrum (Mg 302, Na 561, K 955, S 1035, Cu 0.76, Fe 0.79 and Zn 5.5) except for Ca (1245) and P (895), which where highest on day 7. The mean milk mineral element concentrations (mg/L) over days 55 to 150 were Ca 843, P 543, Mg 47, Na 120, K 590, S 219, Cu 0.19, Fe 0.34 and Zn 2.1. The mean plasma element concentrations (mg/L) over the same period were Ca 120, P 77.1, Mg 17.0, Na 3110, K 168, S 983, Cu 1.1, Fe 1.5 and Zn 0.49. Concentration gradients between plasma and milk were observed and, in the case of Ca, P, Mg, K and Zn, their concentrations in milk were greater than those in plasma, while a reverse situation was observed for Na, S, Cu and Fe. With the exception of Ca and P, the highest concentrations of mineral elements were observed in the colostrum. The nursing foal should have access to good pasture or creep feed, because the intakes of Ca, P and Cu from milk may be less than optimum to meet the daily mineral element requirements.

High Concentrations of Sodium Chloride Improve Microbicidal Activity of Ibuprofen against Common Cystic Fibrosis Pathogens.

PubMed

Muñoz, Adrián J; Alasino, Roxana V; Garro, Ariel G; Heredia, Valeria; García, Néstor H; Cremonezzi, David C; Beltramo, Dante M

2018-05-17

Ibuprofen (IBU-H), a widely used anti-inflammatory, also shows a marked antimicrobial effect against several bacterial species, including those involved in cystic fibrosis such as Pseudomona aeruginosa , methicillin resistant Staphylococcus aureus and Burkholderia cepacia complex. Additionally, our results show significant synergy between water soluble Na-ibuprofen (IBU-Na) and ionic strength. Salt concentrations above 0.5 M modify the zeta potential promoting the action of Na-IBU; thus, with 1 M sodium chloride, IBU-Na is ten times more efficient than in the absence of ionic strength, and the minimum effective contact time is reduced from hours to minutes. In short time periods, where neither IBU-Na nor controls with 1 M NaCl show activity, the combination of both leads to a reduction in the bacterial load. We also analyzed whether the changes caused by salt on the bacterial membrane also promoted the activity of other microbicide compounds used in cystic fibrosis like gentamicin, tobramycin and phosphomycin. The results show that the presence of ionic strength only enhanced the bactericidal activity of the amphipathic molecule of IBU-Na. In this respect, the effect of saline concentration was also reflected in the surface properties of IBU-Na, where, in addition to the clear differences observed between 145 mM and 1 M, singular behaviors were also found, different in each condition. The combination of anti-inflammatory activity and this improved bactericidal effect of Na-IBU in hypertonic solution provides a new alternative for the treatment of respiratory infections of fibrotic patients based on known and widely used compounds.

Additive effects of Na+ and Cl– ions on barley growth under salinity stress

PubMed Central

Tavakkoli, Ehsan; Fatehi, Foad; Coventry, Stewart; Rengasamy, Pichu; McDonald, Glenn K.

2011-01-01

Soil salinity affects large areas of the world's cultivated land, causing significant reductions in crop yield. Despite the fact that most plants accumulate both sodium (Na+) and chloride (Cl–) ions in high concentrations in their shoot tissues when grown in saline soils, most research on salt tolerance in annual plants has focused on the toxic effects of Na+ accumulation. It has previously been suggested that Cl– toxicity may also be an important cause of growth reduction in barley plants. Here, the extent to which specific ion toxicities of Na+ and Cl– reduce the growth of barley grown in saline soils is shown under varying salinity treatments using four barley genotypes differing in their salt tolerance in solution and soil-based systems. High Na+, Cl–, and NaCl separately reduced the growth of barley, however, the reductions in growth and photosynthesis were greatest under NaCl stress and were mainly additive of the effects of Na+ and Cl– stress. The results demonstrated that Na+ and Cl– exclusion among barley genotypes are independent mechanisms and different genotypes expressed different combinations of the two mechanisms. High concentrations of Na+ reduced K+ and Ca2+ uptake and reduced photosynthesis mainly by reducing stomatal conductance. By comparison, high Cl– concentration reduced photosynthetic capacity due to non-stomatal effects: there was chlorophyll degradation, and a reduction in the actual quantum yield of PSII electron transport which was associated with both photochemical quenching and the efficiency of excitation energy capture. The results also showed that there are fundamental differences in salinity responses between soil and solution culture, and that the importance of the different mechanisms of salt damage varies according to the system under which the plants were grown. PMID:21273334

Effect of sodium chloride gradients on water flux in rat descending vasa recta.

PubMed

Pallone, T L

1991-01-01

In the hydropenic kidney, volume efflux from descending vasa recta (DVR) occurs despite an intracapillary oncotic pressure that exceeds hydraulic pressure. That finding has been attributed to small solute gradients which may provide an additional osmotic driving force favoring water transport from DVR plasma to the papillary interstitium. To test this hypothesis, axial gradients of NaCl and urea in the papilla were eliminated by administration of furosemide and saline. DVR were then blocked with paraffin and microperfused at 10 nl/min with a buffer containing albumin, fluorescein isothiocyanate labeled dextran (FITC-Dx), 22Na, and NaCl in a concentration of 0 (hypotonic to the interstitium), 161 (isotonic) or 322 mM (hypertonic). Collectate was obtained from the perfused DVR by micropuncture and the collectate-to-perfusate ratios of FITC-Dx and 22Na were measured. A mathematical model was employed to determine DVR permeability (Ps) and reflection coefficient to NaCl (sigma NaCl). The rate of transport of water from the DVR lumen to the papillary interstitium was 2.8 +/- 0.3 (Nv = 22), -0.19 +/- 0.4 (Nv = 15), and -2.3 +/- 0.3 nl/min (Nv = 21) (mean +/- SE) when perfusate NaCl was 0, 161, or 322 mM, respectively (Nv = number of DVR perfused). The collectate-to-perfusate 22Na concentration ratios were 0.34 +/- 0.04, 0.36 +/- 0.04 and 0.37 +/- 0.03 for those groups, respectively. Based on these data, Ps is calculated to be 60.4 x 10(-5) +/- 4.0 x 10(-5) cm/s and sigma NaCl less than 0.05. The results of this study confirm that transcapillary NaCl concentrations gradients induce water movement across the wall of the DVR.

Molecular simulations of diffusion in electrolytes

NASA Astrophysics Data System (ADS)

Wheeler, Dean Richard

This work demonstrates new methodologies for simulating multicomponent diffusion in concentrated solutions using molecular dynamics (MD). Experimental diffusion data for concentrated multicomponent solutions are often lacking, as are accurate methods of predicting diffusion for nonideal solutions. MD can be a viable means of understanding and predicting multicomponent diffusion. While there have been several prior reports of MD simulations of mutual diffusion, no satisfactory expressions for simulating Stefan-Maxwell diffusivities for an arbitrary number of species exist. The approaches developed here allow for the computation of a full diffusion matrix for any number of species in both nonequilibrium and equilibrium MD ensembles. Our nonequilibrium approach is based on the application of constant external fields to drive species diffusion. Our equilibrium approach uses a newly developed Green-Kubo formula for Stefan-Maxwell diffusivities. In addition, as part of this work, we demonstrate a widely applicable means of increasing the computational efficiency of the Ewald sum, a technique for handling long-range Coulombic interactions in simulations. The theoretical development is applicable to any solution which can be simulated using MD; nevertheless, our primary interest is in electrochemical applications. To this end, the methods are tested by simulations of aqueous salt solutions and lithium-battery electrolytes. KCl and NaCl aqueous solutions were simulated over the concentration range 1 to 4 molal. Intermolecular-potential models were parameterized for these transport-based simulations. This work is the first to simulate all three independent diffusion coefficients for aqueous NaCl and KCl solutions. The results show that the nonequilibrium and equilibrium methods are consistent with each other, and in moderate agreement with experiment. We simulate lithium-battery electrolytes containing LiPF6 in propylene carbonate and mixed ethylene carbonate-dimethyl carbonate solvents. As with the aqueous-solution work, potential parameters were generated for these molecules. These nonaqueous electrolytes demonstrate rich transport behavior, which the simulations are able to reproduce qualitatively. In a mixed-solvent simulation we regress all six independent transport coefficients. The simulations show that strong ion pairing is responsible for the increase in viscosity and maximum in conductivity as ion concentrations are increased.

Mineral Ion Contents and Cell Transmembrane Electropotentials of Pea and Oat Seedling Tissue 1

PubMed Central

Higinbotham, N.; Etherton, Bud; Foster, R. J.

1967-01-01

The relationships of concentration gradients to electropotential gradients resulting from passive diffusion processes, after equilibration, are described by the Nernst equation. The primary criterion for the hypothesis that any given ion is actively transported is to establish that it is not diffusing passively. A test was made of how closely the Nernst equation describes the electrochemical equilibrium in seedling tissues. Segments of roots and epicotyl internodes of pea (Pisum sativum var. Alaska) and of roots and coleoptiles of oat (Avena sativa var. Victory) seedlings were immersed and shaken in defined nutrient solutions containing eight major nutrients (K+, Na+, Ca2+, Mg2+, Cl−, NO3−, H2PO4− and SO42−) at 1-fold and 10-fold concentrations. The tissue content of each ion was assayed at 0, 8, 24, and 48 hours. A near-equilibrium condition was approached by roots for most ions; however, the segments of shoot tissue generally continued to show a net accumulation of some ions, mainly K+ and NO3−. Only K+ approached a reasonable fit to the Nernst equation and this was true for the 1-fold concentration but not the 10-fold. The data suggest that for Na+, Mg2+, and Ca2+ the electrochemical gradient is from the external solution to the cell interior; thus passive diffusion should be in an inward direction. Consequently, some mechanism must exist in plant tissue either to exclude these cations or to extrude them (e.g., by an active efflux pump). For each of the anions the electrochemical gradient is from the tissue to the solution; thus an active influx pump for anions seems required. Root segments approach ionic equilibrium with the solution concentration in which the seedlings were grown. Segments of shoot tissue, however, are far removed from such equilibration. Thus in the intact seedling the extracellular (wall space) fluid must be very different from that of the nutrient solution bathing the segments; it would appear that the root is the site of regulation of ion uptake in the intact plant although other correlative mechanisms may be involved. PMID:16656483

Responses of Atriplex spongiosa and Suaeda monoica to Salinity

PubMed Central

Storey, Richard; Jones, R. Gareth Wyn

1979-01-01

The growth and tissue water, K+, Na+, Cl−, proline and glycinebetaine contents of the shoots and roots of two Chenopodiaceae, Atriplex spongiosa and Suaeda monoica have been measured over a range of external NaCl salinities. Both species showed some fresh weight response to low salinity mainly due to increased succulence. S. monoica showed both a greater increase in succulence (at low salinities) and tolerance of high salinities than A. spongiosa. Both species had high affinities for Na+ and maintained constant but low shoot K+ contents with increasing salinity. These trends were more marked with S. monoica in which Na+ stimulated the accumulation of K+ in roots. An association between high leaf Na+ accumulation, high osmotic pressure, succulence, and a positive growth response at low salinities was noted. Proline accumulation was observed in shoot tissues with suboptimal water contents. High glycinebetaine contents were found in the shoots of both species. These correlated closely with the sap osmotic pressure and it is suggested that glycinebetaine is the major cytoplasmic osmoticum (with K+ salts) in these species at high salinities. Na+ salts may be preferentially utilized as vacuolar osmotica. PMID:16660671

Inhibition of epithelial Na sup + transport by atriopeptin, protein kinase c, and pertussis toxin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mohrmann, M.; Cantiello, H.F.; Ausiello, D.A.

1987-08-01

The authors have recently shown the selective inhibition of an amiloride-sensitive, conductive pathway for Na{sup +} by atrial natriuretic peptide and 8-bromoguanosine 3{prime},5{prime}-cyclic monophosphate (8-BrcGMP) in the renal epithelial cell line, LLC-PK{sub i}. Using {sup 22}Na{sup +} fluxes, they further investigated the modulation of Na{sup +} transport by atrial natriuretic peptide and by agents that increase cGMP production, activate protein kinase c, or modulate guanine nucleotide regulatory protein function. Sodium nitroprusside increases intracellular cGMP concentrations without affecting cAMP concentrations and completely inhibits amiloride-sensitive Na{sup +} uptake in a time- and concentration-dependent manner. Oleoyl 2-acetylglycerol and phorbol 12-myristate 13-acetate, activators ofmore » protein kinase c, inhibit Na{sup +} uptake by 93 {plus minus} 13 and 51 {plus minus} 10%, respectively. Prolonged incubation with phorbol ester results in the downregulation of protein kinase c activity and reduces the inhibitory effect of atrial natriuretic peptide, suggesting that the action of this peptide involves stimulation of protein kinase c. Pertussis toxin, which induces the ADP-ribosylation of a 41-kDa guanine nucleotide regulatory protein in LLC-PK{sub i} cells, inhibits {sup 22}Na{sup +} influx to the same extent as amiloride. Thus, increasing cGMP, activating protein kinase c, and ADP-ribosylating a guanine nucleotide regulatory protein all inhibit Na{sup +} uptake. These events may be sequentially involved in the action of atrial natriuretic peptide.« less

Using iron fertilizer to control Cd accumulation in rice plants: a new promising technology.

PubMed

Shao, GuoSheng; Chen, MingXue; Wang, DanYing; Xu, ChunMei; Mou, RenXiang; Cao, ZhaoYun; Zhang, XiuFu

2008-03-01

Effects of two kinds of iron fertilizer, FeSO4 and EDTA.Na2Fe were studied on cadmium accumulation in rice plants with two rice genotypes, Zhongzao 22 and Zhongjiazao 02, with soil culture systems. The results showed that application of iron fertilizers could hardly make adverse effects on plant growth and rice grain yield. Soil application of EDTA.Na2Fe significantly reduced the Cd accumulation in rice roots, shoots and rice grain. Cd concentration in white rice of both rice genotypes in the treatment of soil application of EDTA.Na2Fe was much lower than 0.2 mg/kg, the maximal Cd permission concentration in cereal crop foods in State standard. However, soil application of FeSO4 or foliar application of FeSO4 or EDTA.Na2Fe resulted in the significant increase of Cd accumulation in rice plants including rice grain compared with the control. The results also showed iron fertilizers increased the concentration of iron, copper and manganese element in rice grain and also affected zinc concentration in plants. It may be a new promising way to regulate Cd accumulation in rice grain in rice production through soil application of EDTA.Na2Fe fertilizers to maintain higher content of available iron and ferrous iron in soils.

Passive transport and binding of lead by human red blood cells.

PubMed Central

Simons, T J

1986-01-01

The uptake of Pb into human red blood cells has been studied using Pb buffers. Passive Pb movements can be studied conveniently when the cells are depleted of adenosine 5'-triphosphate (ATP), to eliminate active transport, and of inorganic phosphate, to prevent precipitation of lead phosphate. Pb can cross the membrane passively in either direction. Influx and efflux show similar properties. Passive Pb transport is strongly stimulated by HCO3-, and is reduced by replacing Cl- with ClO4-. It is inhibited by low concentrations of 4-acetamido-4'-isothiocyanostilbene-2,2'-disulphonic acid (SITS) and 4,4'-diisothiocyanostilbene-2.2'-disulphonic acid (DIDS), characteristic inhibitors of anion transport. Pb uptake is unaffected by varying the external concentrations of Na+, K+ and Ca2+. When Pb enters the cell, it binds mainly to haemoglobin. The ratio of bound Pb:free Pb2+ in the cytosol is estimated to be 6000:1. Pb binding to haemoglobin is unaffected by oxygenation. Binding to albumin is quantitatively similar to binding to haemoglobin. The implications of these results for the transport and binding of Pb in the blood are discussed. PMID:3795106

Na/K pump inactivation, subsarcolemmal Na measurements, and cytoplasmic ion turnover kinetics contradict restricted Na spaces in murine cardiac myocytes

PubMed Central

Lu, Fang-Min

2017-01-01

Decades ago, it was proposed that Na transport in cardiac myocytes is modulated by large changes in cytoplasmic Na concentration within restricted subsarcolemmal spaces. Here, we probe this hypothesis for Na/K pumps by generating constitutive transsarcolemmal Na flux with the Na channel opener veratridine in whole-cell patch-clamp recordings. Using 25 mM Na in the patch pipette, pump currents decay strongly during continuous activation by extracellular K (τ, ∼2 s). In contradiction to depletion hypotheses, the decay becomes stronger when pump currents are decreased by hyperpolarization. Na channel currents are nearly unchanged by pump activity in these conditions, and conversely, continuous Na currents up to 0.5 nA in magnitude have negligible effects on pump currents. These outcomes are even more pronounced using 50 mM Li as a cytoplasmic Na congener. Thus, the Na/K pump current decay reflects mostly an inactivation mechanism that immobilizes Na/K pump charge movements, not cytoplasmic Na depletion. When channel currents are increased beyond 1 nA, models with unrestricted subsarcolemmal diffusion accurately predict current decay (τ ∼15 s) and reversal potential shifts observed for Na, Li, and K currents through Na channels opened by veratridine, as well as for Na, K, Cs, Li, and Cl currents recorded in nystatin-permeabilized myocytes. Ion concentrations in the pipette tip (i.e., access conductance) track without appreciable delay the current changes caused by sarcolemmal ion flux. Importantly, cytoplasmic mixing volumes, calculated from current decay kinetics, increase and decrease as expected with osmolarity changes (τ >30 s). Na/K pump current run-down over 20 min reflects a failure of pumps to recover from inactivation. Simulations reveal that pump inactivation coupled with Na-activated recovery enhances the rapidity and effectivity of Na homeostasis in cardiac myocytes. In conclusion, an autoregulatory mechanism enhances cardiac Na/K pump activity when cytoplasmic Na rises and suppresses pump activity when cytoplasmic Na declines. PMID:28606910

Thyroid thermogenesis. Relationships between Na+-dependent respiration and Na+ + K+-adenosine triphosphatase activity in rat skeletal muscle.

PubMed Central

Asano, Y; Liberman, U A; Edelman, I S

1976-01-01

The effect of thyroid status on QO2, QO2 (t) and NaK-ATPase activity was examined in rat skeletal muscle. QO2(t) (i.e. Na+-transport-dependent respiration) was estimated with ouabain or Na+-free media supplemented with K+. In contrast to the effects of ouabain on ion composition, intracellular K+ was maintained at about 125 meq/liter, and intracellular Na+ was almost nil in the Na+-free media. The estimates of QO2(t) were independent of the considerable differences in tissue ion concentrations. The increase in QO2(t) account for 47% of the increase in QO2 in the transition from the hypothyroid to the euthyroid state and 84% of the increase in the transition from the euthyroid to the hyperthyroid state. Surgical thyroidectomy lowered NaK-ATPase activity of the microsomal fraction (expressed per milligram protein) 32%; injections of triodothyronine (T3) increased this activity 75% in initially hypothyroid rats and 26% in initially euthyroid rats. Thyroidectomy was attended by significant falls in serum Ca and Pi concentrations. Administration of T3 resulted in further declines in serum Ca and marked increases in serum Ps concentrations. Similar effects were seen in 131I-treated rats, but the magnitude of the declines in serum Ca were less. The effects of T3 on QO2, QO2(t), and NaK-ATPase activity of skeletal muscle were indistinguishable in the 131I-ablated and surgically thyroidectomized rats. In thyroidectomized or euthyroid rats given repeated doses of T3, QO2(t) and NaA-ATPase activity increased proportionately. In thyroidectomized rats injected with single doses of T3, either 10, 50, or 250 mug/100 g body wt, QO2(t) increased linearly with NaK-ATPase activity. The kinetics of the NaK-ATPase activity was assessed with an ATP-generating system. T3 elicited a significant increase in Vmax with no change in Km for ATP. PMID:130385

Analysis of stress concentration in the Dutton groove regions of the Super Lightweight External Tank

NASA Astrophysics Data System (ADS)

Ahmed, R.

1995-05-01

Because the 2195 aluminum-lithium material of the super lightweight external tank (SLWT ET) has a lower toughness than the 2219 aluminum used in previous ET's, careful attention must be paid to stress concentrations. This report details the analysis performed on some of the stress concentrations in the orthogrid panels of the liquid hydrogen tank.

Intrarater reliability of the Humac NORM isokinetic dynamometer for strength measurements of the knee and shoulder muscles.

PubMed

Habets, Bas; Staal, J Bart; Tijssen, Marsha; van Cingel, Robert

2018-01-10

To determine the intrarater reliability of the Humac NORM isokinetic dynamometer for concentric and eccentric strength tests of knee and shoulder muscles. 54 participants (50% female, average age 20.9 ± 3.1 years) performed concentric and eccentric strength measures of the knee extensors and flexors, and the shoulder internal and external rotators on two different Humac NORM isokinetic dynamometers, which were situated at two different centers. The knee extensors and flexors were tested concentrically at 60° and 180°/s, and eccentrically at 60° s. Concentric strength of the shoulder internal and external rotators, and eccentric strength of the external rotators were measured at 60° and 120°/s. We calculated intraclass correlation coefficients (ICCs), standard error of measurement, standard error of measurement expressed as a %, and the smallest detectable change to determine reliability and measurement error. ICCs for the knee tests ranged from 0.74 to 0.89, whereas ICC values for the shoulder tests ranged from 0.72 to 0.94. Measurement error was highest for the concentric test of the knee extensors and lowest for the concentric test of shoulder external rotators.

Contextual amplification or attenuation of the impact of pubertal timing on Mexican-origin boys' mental health symptoms.

PubMed

White, Rebecca M B; Deardorff, Julianna; Liu, Yu; Gonzales, Nancy A

2013-12-01

To examine the role of neighborhood contextual variation in the putative association between pubertal timing and internalizing and externalizing symptoms among Mexican-origin boys. In a sample of seventh-grade Mexican-origin boys (N = 353; x¯age=12.8years) we assessed a range of secondary sexual characteristics, internalizing, and externalizing symptoms. Reports on all secondary sexual characteristics were collapsed and age-standardized to represent total pubertal timing. We also distinguished between the timing of physical changes driven by adrenal versus gonadal maturation. Boys' residential addresses were geocoded and American Community Survey data were used to describe neighborhoods along two dimensions: ethnic concentration and socioeconomic disadvantage. Three years later (in 10th grade) we re-assessed internalizing and externalizing symptoms. We examined the moderating influence of neighborhood ethnic concentration and neighborhood socioeconomic disadvantage on the prospective associations between puberty timing (total, gonadal, adrenal) and internalizing and externalizing symptoms. Earlier total pubertal timing predicted increases in externalizing symptoms, but only when Mexican-origin boys lived in neighborhoods low on ethnic concentration. Total timing results for externalizing symptoms were replicated for adrenal timing. Furthermore, early adrenal timing predicted increases in internalizing symptoms, but again, only when boys lived in neighborhoods low on ethnic concentration. No effects were observed for gonadal timing specifically. Early pubertal timing, especially advanced physical changes initiated and regulated by adrenal maturation, have important implications for Mexican-origin boys' internalizing and externalizing symptoms, but these implications depend on neighborhood characteristics. Ethnically concentrated neighborhoods are protective for early-maturing Mexican-origin boys. Copyright © 2013 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

Slow [Na+]i dynamics impacts arrhythmogenesis and spiral wave reentry in cardiac myocyte ionic model.

PubMed

Krogh-Madsen, Trine; Christini, David J

2017-09-01

Accumulation of intracellular Na + is gaining recognition as an important regulator of cardiac myocyte electrophysiology. The intracellular Na + concentration can be an important determinant of the cardiac action potential duration, can modulate the tissue-level conduction of excitation waves, and can alter vulnerability to arrhythmias. Mathematical models of cardiac electrophysiology often incorporate a dynamic intracellular Na + concentration, which changes much more slowly than the remaining variables. We investigated the dependence of several arrhythmogenesis-related factors on [Na + ] i in a mathematical model of the human atrial action potential. In cell simulations, we found that [Na + ] i accumulation stabilizes the action potential duration to variations in several conductances and that the slow dynamics of [Na + ] i impacts bifurcations to pro-arrhythmic afterdepolarizations, causing intermittency between different rhythms. In long-lasting tissue simulations of spiral wave reentry, [Na + ] i becomes spatially heterogeneous with a decreased area around the spiral wave rotation center. This heterogeneous region forms a functional anchor, resulting in diminished meandering of the spiral wave. Our findings suggest that slow, physiological, rate-dependent variations in [Na + ] i may play complex roles in cellular and tissue-level cardiac dynamics.

Slow [Na+]i dynamics impacts arrhythmogenesis and spiral wave reentry in cardiac myocyte ionic model

NASA Astrophysics Data System (ADS)

Krogh-Madsen, Trine; Christini, David J.

2017-09-01

Accumulation of intracellular Na+ is gaining recognition as an important regulator of cardiac myocyte electrophysiology. The intracellular Na+ concentration can be an important determinant of the cardiac action potential duration, can modulate the tissue-level conduction of excitation waves, and can alter vulnerability to arrhythmias. Mathematical models of cardiac electrophysiology often incorporate a dynamic intracellular Na+ concentration, which changes much more slowly than the remaining variables. We investigated the dependence of several arrhythmogenesis-related factors on [Na+]i in a mathematical model of the human atrial action potential. In cell simulations, we found that [Na+]i accumulation stabilizes the action potential duration to variations in several conductances and that the slow dynamics of [Na+]i impacts bifurcations to pro-arrhythmic afterdepolarizations, causing intermittency between different rhythms. In long-lasting tissue simulations of spiral wave reentry, [Na+]i becomes spatially heterogeneous with a decreased area around the spiral wave rotation center. This heterogeneous region forms a functional anchor, resulting in diminished meandering of the spiral wave. Our findings suggest that slow, physiological, rate-dependent variations in [Na+]i may play complex roles in cellular and tissue-level cardiac dynamics.

Effects of ions on the solubility transition and the phase-separation of N-isopropylacrylamide in water.

PubMed

Sasaki, Shigeo; Okabe, Satoshi

2011-11-10

The effects of NaCl, NaOH, and HCl on the solubility transition and the phase-separation of N-isopropylacrylamide (NIPA) were investigated for the purpose of clarifying the physicochemical mechanism of salting-out and salting-in phenomena. The discrete change in the solubility of NIPA in the salt-free water at the solubility transition (reported in J. Phys. Chem. B 2010, 114, 14995-15002) decreased with the addition of HCl and disappeared in the HCl solutions at concentrations higher than 2 M, while it increased with additions of NaOH and NaCl. A difference in NIPA concentration between the phase-separated solutions decreases with the addition of HCl and increases with additions of NaOH and NaCl. Partition coefficients of HCl in the phase-separated NIPA-rich solutions are higher than those in the NIPA poor solutions, while partition coefficients of NaCl and NaOH between the NIPA-rich and -poor solutions have trends opposite to those of HCl. The present results clearly indicate that the HCl favors the dehydrated NIPA and stabilizes the H(2)O-poor state of the NIPA molecule more than NaCl.

A novel process for recovery of iron, titanium, and vanadium from titanomagnetite concentrates: NaOH molten salt roasting and water leaching processes.

PubMed

Chen, Desheng; Zhao, Longsheng; Liu, Yahui; Qi, Tao; Wang, Jianchong; Wang, Lina

2013-01-15

A novel process for recovering iron, titanium, and vanadium from titanomagnetite concentrates has been developed. In the present paper, the treatment of rich titanium-vanadium slag by NaOH molten salt roasting and water leaching processes is investigated. In the NaOH molten salt roasting process, the metallic iron is oxidized into ferriferous oxide, MgTi(2)O(5) is converted to NaCl-type structure of Na(2)TiO(3), and M(3)O(5) (M=Ti, Mg, Fe) is converted to α-NaFeO(2)-type structure of NaMO(2), respectively. Roasting temperature and NaOH-slag mass ratio played a considerable role in the conversion of titanium in the rich titanium-vanadium slag during the NaOH molten salt roasting process. Roasting at 500 °C for 60 min and a 1:1 NaOH-slag mass ratio produces 96.3% titanium conversion. In the water leaching process, the Na(+) was exchanged with H(+), Na(2)TiO(3) is converted to undefined structure of H(2)TiO(3), and NaMO(2) is converted to α-NaFeO(2)-type structure of HMO(2). Under the optimal conditions, 87.3% of the sodium, 42.3% of the silicon, 43.2% of the aluminum, 22.8% of the manganese, and 96.6% of the vanadium are leached out. Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.

Multidrug resistance protein MdtM adds to the repertoire of antiporters involved in alkaline pH homeostasis in Escherichia coli

PubMed Central

2013-01-01

Background In neutralophilic bacteria, monovalent metal cation/H+ antiporters play a key role in pH homeostasis. In Escherichia coli, only four antiporters (NhaA, NhaB, MdfA and ChaA) are identified to function in maintenance of a stable cytoplasmic pH under conditions of alkaline stress. We hypothesised that the multidrug resistance protein MdtM, a recently characterised homologue of MdfA and a member of the major facilitator superfamily, also functions in alkaline pH homeostasis. Results Assays that compared the growth of an E. coli ΔmdtM deletion mutant transformed with a plasmid encoding wild-type MdtM or the dysfunctional MdtM D22A mutant at different external alkaline pH values (ranging from pH 8.5 to 10) revealed a potential contribution by MdtM to alkaline pH tolerance, but only when millimolar concentrations of sodium or potassium was present in the growth medium. Fluorescence-based activity assays using inverted vesicles generated from transformants of antiporter-deficient (ΔnhaA, ΔnhaB, ΔchaA) E. coli TO114 cells defined MdtM as a low-affinity antiporter that catalysed electrogenic exchange of Na+, K+, Rb+ or Li+ for H+. The K+/H+ antiport reaction had a pH optimum at 9.0, whereas the Na+/H+ exchange activity was optimum at pH 9.25. Measurement of internal cellular pH confirmed MdtM as contributing to maintenance of a stable cytoplasmic pH, acid relative to the external pH, under conditions of alkaline stress. Conclusions Taken together, the results support a role for MdtM in alkaline pH tolerance. MdtM can therefore be added to the currently limited list of antiporters known to function in pH homeostasis in the model organism E. coli. PMID:23701827

Multidrug resistance protein MdtM adds to the repertoire of antiporters involved in alkaline pH homeostasis in Escherichia coli.

PubMed

Holdsworth, Scarlett R; Law, Christopher J

2013-05-23

In neutralophilic bacteria, monovalent metal cation/H+ antiporters play a key role in pH homeostasis. In Escherichia coli, only four antiporters (NhaA, NhaB, MdfA and ChaA) are identified to function in maintenance of a stable cytoplasmic pH under conditions of alkaline stress. We hypothesised that the multidrug resistance protein MdtM, a recently characterised homologue of MdfA and a member of the major facilitator superfamily, also functions in alkaline pH homeostasis. Assays that compared the growth of an E. coli ΔmdtM deletion mutant transformed with a plasmid encoding wild-type MdtM or the dysfunctional MdtM D22A mutant at different external alkaline pH values (ranging from pH 8.5 to 10) revealed a potential contribution by MdtM to alkaline pH tolerance, but only when millimolar concentrations of sodium or potassium was present in the growth medium. Fluorescence-based activity assays using inverted vesicles generated from transformants of antiporter-deficient (ΔnhaA, ΔnhaB, ΔchaA) E. coli TO114 cells defined MdtM as a low-affinity antiporter that catalysed electrogenic exchange of Na+, K+, Rb+ or Li+ for H+. The K+/H+ antiport reaction had a pH optimum at 9.0, whereas the Na+/H+ exchange activity was optimum at pH 9.25. Measurement of internal cellular pH confirmed MdtM as contributing to maintenance of a stable cytoplasmic pH, acid relative to the external pH, under conditions of alkaline stress. Taken together, the results support a role for MdtM in alkaline pH tolerance. MdtM can therefore be added to the currently limited list of antiporters known to function in pH homeostasis in the model organism E. coli.

Metabolic Shift of Escherichia coli under Salt Stress in the Presence of Glycine Betaine

PubMed Central

Metris, A.; George, S. M.; Mulholland, F.; Carter, A. T.

2014-01-01

An important area of food safety focuses on bacterial survival and growth in unfavorable environments. In order to understand how bacteria adapt to stresses other than nutrient limitation in batch cultures, we need to develop mechanistic models of intracellular regulation and metabolism under stress. We studied the growth of Escherichia coli in minimal medium with added salt and different osmoprotectants. To characterize the metabolic efficiency with a robust parameter, we identified the optical density (OD) values at the inflection points of measured “OD versus time” growth curves and described them as a function of glucose concentration. We found that the metabolic efficiency parameter did not necessarily follow the trend of decreasing specific growth rate as the salt concentration increased. In the absence of osmoprotectant, or in the presence of proline, the metabolic efficiency decreased with increasing NaCl concentration. However, in the presence of choline or glycine betaine, it increased between 2 and 4.5% NaCl before declining at 5% NaCl and above. Microarray analysis of the transcriptional network and proteomics analysis with glycine betaine in the medium indicated that between 4.5 and 5% NaCl, the metabolism switched from aerobic to fermentative pathways and that the response to osmotic stress is similar to that for oxidative stress. We conclude that, although the growth rate appeared to decrease smoothly with increasing NaCl, the metabolic strategy of cells changed abruptly at a threshold concentration of NaCl. PMID:24858086

Dietary Fructose Enhances the Ability of Low Concentrations of Angiotensin II to Stimulate Proximal Tubule Na+ Reabsorption

PubMed Central

Gonzalez-Vicente, Agustin; Cabral, Pablo D.; Hong, Nancy J.; Asirwatham, Jessica; Yang, Nianxin; Berthiaume, Jessica M.; Dominici, Fernando P.; Garvin, Jeffrey L.

2017-01-01

Fructose-enriched diets cause salt-sensitive hypertension. Proximal tubules (PTs) reabsorb 70% of the water and salt filtered through the glomerulus. Angiotensin II (Ang II) regulates this process. Normally, dietary salt reduces Ang II allowing the kidney to excrete more salt, thereby preventing hypertension. We hypothesized that fructose-enriched diets enhance the ability of low concentrations of Ang II to stimulate PT transport. We measured the effects of a low concentration of Ang II (10−12 mol/L) on transport-related oxygen consumption (QO2), and Na/K-ATPase and Na/H-exchange (NHE) activities and expression in PTs from rats consuming tap water (Control) or 20% fructose (FRUC). In FRUC-treated PTs, Ang II increased QO2 by 14.9 ± 1.3 nmol/mg/min (p < 0.01) but had no effect in Controls. FRUC elevated NHE3 expression by 19 ± 3% (p < 0.004) but not Na/K-ATPase expression. Ang II stimulated NHE activity in FRUC PT (Δ + 0.7 ± 0.1 Arbitrary Fluorescent units (AFU)/s, p < 0.01) but not in Controls. Na/K-ATPase activity was not affected. The PKC inhibitor Gö6976 blocked the ability of FRUC to augment the actions of Ang II. FRUC did not alter the inhibitory effect of dopamine on NHE activity. We conclude that dietary fructose increases the ability of low concentrations of Ang II to stimulate PT Na reabsorption via effects on NHE. PMID:28813008

A clear effect of charge compensation through Na+ co-doping on the luminescence spectra and decay kinetics of Nd3+-doped CaAl4O7

NASA Astrophysics Data System (ADS)

Puchalska, M.; Watras, A.

2016-06-01

We present a detailed analysis of luminescence behavior of singly Nd3+ doped and Nd3+, Na+ co-doped calcium aluminates powders: Ca1-xNdxAl4O7 and Ca1-2xNdxNaxAl4O7 (x=0.001-0.1). Relatively intense Nd3+ luminescence in IR region corresponding to typical 4F3/2→4IJ (J=9/2-13/2) transitions with maximum located at about 1079 nm was obtained in all samples on direct excitation into f-f levels. The effect of dopant concentration and charge compensation by co-doping with Na+ ions on morphology and optical properties were studied. The results show that both, the Nd3+ concentration and the alkali metal co-doping affected the optical properties but had no influence on the powders morphology. The studies of luminescence spectra (298 and 77 K) in a function of dopant concentration showed an increasing distortion of the local symmetry of Nd3+with raising activator content due to certain defects created in the crystal lattice. On the other hand Na+ addition led to significant narrowing of absorption and luminescence bands and also a reduction of the number of their components, showing smaller disturbance of Nd3+ ions local symmetries. Consequently, charge compensated by Na+ co-doping materials showed significantly enhanced Nd3+ luminescence. The decrease of emission intensity and luminescence lifetimes with increase of activator concentration was attributed mainly to phonon-assisted cross-relaxation processes between Nd3+ ions. Analysis with Inokuti-Hirayama model indicated dipole-dipole mechanism of ion-ion interaction. Na+ addition led to much smaller concentration quenching due to smaller clustering of dopant ions in CaAl4O7 lattice.

Salinity effects on plasma ion levels, cortisol, and osmolality in Chinook salmon following lethal sampling

USGS Publications Warehouse

Stewart, Heather; Noakes, David L. G.; Cogliati, Karen M.; Peterson, James T.; Iversen, Martin H.; Schreck, Carl B.

2016-01-01

Studies on hydromineral balance in fishes frequently employ measurements of electrolytes following euthanasia. We tested the effects of fresh- or salt-water euthanasia baths of tricaine mesylate (MS-222) on plasma magnesium (Mg2+) and sodium (Na+) ions, cortisoland osmolality in fish exposed to saltwater challenges, and the ion and steroid hormone fluctuations over time following euthanasia in juvenile spring Chinook salmon (Oncorhynchus tshawytscha). Salinity of the euthanasia bath affected plasma Mg2+ and Na+concentrations as well as osmolality, with higher concentrations in fish euthanized in saltwater. Time spent in the bath positively affected plasma Mg2+ and osmolality, negatively affected cortisol, and had no effect on Na+ concentrations. The difference of temporal trends in plasma Mg2+ and Na+ suggests that Mg2+ may be more sensitive to physiological changes and responds more rapidly than Na+. When electrolytes and cortisol are measured as endpoints after euthanasia, care needs to be taken relative to time after death and the salinity of the euthanasia bath.

Salinity effects on plasma ion levels, cortisol, and osmolality in Chinook salmon following lethal sampling.

PubMed

Stewart, Heather A; Noakes, David L G; Cogliati, Karen M; Peterson, James T; Iversen, Martin H; Schreck, Carl B

2016-02-01

Studies on hydromineral balance in fishes frequently employ measurements of electrolytes following euthanasia. We tested the effects of fresh- or salt-water euthanasia baths of tricaine mesylate (MS-222) on plasma magnesium (Mg(2+)) and sodium (Na(+)) ions, cortisol and osmolality in fish exposed to saltwater challenges, and the ion and steroid hormone fluctuations over time following euthanasia in juvenile spring Chinook salmon (Oncorhynchus tshawytscha). Salinity of the euthanasia bath affected plasma Mg(2+) and Na(+) concentrations as well as osmolality, with higher concentrations in fish euthanized in saltwater. Time spent in the bath positively affected plasma Mg(2+) and osmolality, negatively affected cortisol, and had no effect on Na(+) concentrations. The difference of temporal trends in plasma Mg(2+) and Na(+) suggests that Mg(2+) may be more sensitive to physiological changes and responds more rapidly than Na(+). When electrolytes and cortisol are measured as endpoints after euthanasia, care needs to be taken relative to time after death and the salinity of the euthanasia bath. Copyright © 2015 Elsevier Inc. All rights reserved.

Chlorophylls, proteins and fatty acids amounts of arthrospira platensis growing under saline conditions.

PubMed

Ayachi, Samah; El Abed, Amor; Dhifi, Wissal; Marzouk, Brahim

2007-07-15

Spirulina platensis (Arthrospira platensis) is a Tunisian strain isolated for the first time, in Tunisia, in Oued Essed (Sidi Bou Ali, in Sousse region). Evolution of biomass, proteins, chlorophylls and fatty acids (FA) has been followed during Spirulina growth. Experiments were carried out by varying sodium chloride concentrations in the culture medium in a range from 1 g L(-1) (natural environment) to 60 g L(-1). Results analysis showed an increase in chlorophyll amounts at 15 g L(-1) NaCl in 10 days old cultures but a decrease at high NaCl concentrations. Optimal proteins amounts was observed at 15 g L(-1) NaCl in young cultures (5 and 10 days). FA composition was modified by NaCl and depended on culture age. Cultures exposed to high salinity concentrations showed not only a decrease in growth rate but also a loss in total fatty acids TFA quantities. Samples cultured over 15 days at 30 g L(-1) NaCl rendered optimal quantities of lipids and gamma-linolenic acid.

Effect of sodium bicarbonate and varying concentrations of sodium chloride in brine on the liquid retention of fish (Pollachius virens L.) muscle.

PubMed

Åsli, Magnus; Ofstad, Ragni; Böcker, Ulrike; Jessen, Flemming; Einen, Olai; Mørkøre, Turid

2016-03-15

Negative health effects associated with excessive sodium (Na) intake have increased the demand for tasty low-Na products (<2% NaCl) rather than traditional heavily salted fish products (∼20% NaCl). This study investigates the causes of improved yield and liquid retention of fish muscle brined with a combination of salt (NaCl) and sodium bicarbonate (NaHCO3 ). Water characteristics and microstructure of saithe (Pollachius virens L.) muscle brined in solutions of NaCl and NaHCO3 or NaCl alone were compared using low-field nuclear magnetic resonance (LF-NMR) T2 relaxometry, microscopy, salt content, liquid retention and colorimetric measurements. Saithe muscle was brined for 92 h in 0, 30, 60, 120 or 240 g kg(-1) NaCl or the respective solutions with added 7.5 g kg(-1) NaHCO3 . NaHCO3 inclusion improved the yield in solutions ranging from 0 to 120 g kg(-1) NaCl, with the most pronounced effect being observed at 30 g kg(-1) NaCl. The changes in yield were reflected in water mobility, with significantly shorter T2 relaxation times in all corresponding brine concentrations. Salt-dependent microstructural changes were revealed by light microscopy, where NaHCO3 supplementation resulted in greater intracellular space at 30 and 60 g kg(-1) NaCl. Sodium bicarbonate addition to low-salt solutions can improve yield and flesh quality of fish muscle owing to altered water mobility and wider space between the muscle cells. © 2015 Society of Chemical Industry.

Sodium Chloride Diffusion in Low-Acid Foods during Thermal Processing and Storage.

PubMed

Bornhorst, Ellen R; Tang, Juming; Sablani, Shyam S

2016-05-01

This study aimed at modeling sodium chloride (NaCl) diffusion in foods during thermal processing using analytical and numerical solutions and at investigating the changes in NaCl concentrations during storage after processing. Potato, radish, and salmon samples in 1% or 3% NaCl solutions were heated at 90, 105, or 121 °C for 5 to 240 min to simulate pasteurization and sterilization. Selected samples were stored at 4 or 22 °C for up to 28 d. Radish had the largest equilibrium NaCl concentrations and equilibrium distribution coefficients, but smallest effective diffusion coefficients, indicating that a greater amount of NaCl diffused into the radish at a slower rate. Effective diffusion coefficients determined using the analytical solution ranged from 0.2 × 10(-8) to 2.6 × 10(-8) m²/s. Numerical and analytical solutions showed good agreement with experimental data, with average coefficients of determination for samples in 1% NaCl at 121 °C of 0.98 and 0.95, respectively. During storage, food samples equilibrated to a similar NaCl concentration regardless of the thermal processing severity. The results suggest that sensory evaluation of multiphase (solid and liquid) products should occur at least 14 d after processing to allow enough time for the salt to equilibrate within the product. © 2016 Institute of Food Technologists®

Low concentration of sodium bicarbonate improves the bioactive compound levels and antioxidant and α-glucosidase inhibitory activities of tartary buckwheat sprouts.

PubMed

Qin, Peiyou; Wei, Aichun; Zhao, Degang; Yao, Yang; Yang, Xiushi; Dun, Baoqing; Ren, Guixing

2017-06-01

This study aimed to investigate the effects of different concentrations of sodium bicarbonate (NaHCO 3 ) on the accumulation of flavonoids, total phenolics and d-chiro-inositol (DCI), as well as the antioxidant and α-glucosidase inhibitory activities, in tartary buckwheat sprouts. Treatment with low concentrations of NaHCO 3 (0.05, 0.1, and 0.2%) resulted in an increase in flavonoids, total phenolic compounds and DCI concentrations, and improved DPPH radical-scavenging and α-glucosidase inhibition activities compared with the control (0%). The highest levels of total flavonoids (26.69mg/g DW), individual flavonoids (rutin, isoquercitrin, quercetin, and kaempferol), total phenolic compounds (29.31mg/g DW), DCI (12.56mg/g DW), as well as antioxidant and α-glucosidase inhibition activities, were observed in tartary buckwheat sprouts treated with 0.05% NaHCO 3 for 96h. These results indicated that appropriate treatment with NaHCO 3 could improve the healthy benefits of tartary buckwheat sprouts. Copyright © 2016 Elsevier Ltd. All rights reserved.

Trace elements and electrolytes in human resting mixed saliva after exercise

PubMed Central

Chicharro, J. L.; Serrano, V.; Urena, R.; Gutierrez, A. M.; Carvajal, A.; Fernandez-, H; Lucia, A.

1999-01-01

OBJECTIVES: Exercise is known to cause changes in the concentration of salivary components such as amylase, Na, and Cl. The aim of this investigation was to evaluate the effect of physical exercise on the levels of trace elements and electrolytes in whole (mixed) saliva. METHODS: Forty subjects performed a maximal exercise test on a cycle ergometer. Samples of saliva were obtained before and immediately after the exercise test. Sample concentrations of Fe, Mg, Sc, Cr, Mn, Co, Cu, Zn, Se, Sr, Ag, Sb, Cs, and Hg were determined by inductively coupled plasma mass spectrometry and concentrations of Ca and Na by atomic absorption spectrometry. RESULTS: After exercise, Mg and Na levels showed a significant increase (p < 0.05) while Mn levels fell (p < 0.05). Zn/Cu molar ratios were unaffected by exercise. CONCLUSIONS: Intense physical exercise induced changes in the concentrations of only three (Na, Mg, and Mn) of the 16 elements analysed in the saliva samples. Further research is needed to assess the clinical implications of these findings. 


 PMID:10378074

Supercooling of aqueous NaCl and KCl solutions under acoustic levitation.

PubMed

Lü, Y J; Wei, B

2006-10-14

The supercooling capability of aqueous NaCl and KCl solutions is investigated at containerless state by using acoustic levitation method. The supercooling of water is obviously enhanced by the alkali metal ions and increases linearly with the augmentation of concentrations. Furthermore, the supercooling depends on the nature of ions and is 2-3 K larger for NaCl solution than that for KCl solution in the present concentration range: Molecular dynamics simulations are performed to reveal the intrinsic correlation between supercoolability and microstructure. The translational and orientational order parameters are applied to quantitatively demonstrate the effect of ionic concentration on the hydrogen-bond network and ice melting point. The disrupted hydrogen-bond structure determines essentially the concentration dependence of supercooling. On the other hand, the introduced acoustic pressure suppresses the increase of supercooling by promoting the growth and coalescence of microbubbles, the effective nucleation catalysts, in water. However, the dissolved ions can weaken this effect, and moreover the degree varies with the ion type. This results in the different supercoolability for NaCl and KCl solutions under the acoustic levitation conditions.

Cooperative down-conversion of UV light in disordered scheelitelike Yb-doped NaGd(MoO4)2 and NaLa(MoO4)2 crystals

NASA Astrophysics Data System (ADS)

Subbotin, K. A.; Osipova, Yu. N.; Lis, D. A.; Smirnov, V. A.; Zharikov, E. V.; Shcherbakov, I. A.

2017-07-01

Concentration series of disordered scheelitelike Yb:NaGd(MoO4)2 and Yb:NaLa(MoO4)2 single crystals are grown by the Czochralski method. The actual concentrations of Yb3+ ions in the crystals are determined by optical-absorption spectroscopy. The luminescence of Yb3+ ions in these crystals in the region of 1 μm is studied under UV and IR excitation. In the case of UV excitation, this luminescence appears as a result of nonradiative excited state energy transfer from donor centers of unknown nature to ytterbium. The character of the concentration dependence of Yb3+ luminescence indicates that the energy transfer at high Yb concentrations occurs with active participation of a cooperative mechanism, according to which the excitation energy of one donor center is transferred simultaneously to two Yb3+ ions. In other words, the quantum yield of this transfer exceeds unity, which can be used to increase the efficiency of crystalline silicon (c-Si) solar cells.

Insights into metabolism and sodium chloride adaptability of carbaryl degrading halotolerant Pseudomonas sp. strain C7.

PubMed

Trivedi, Vikas D; Bharadwaj, Anahita; Varunjikar, Madhushri S; Singha, Arminder K; Upadhyay, Priya; Gautam, Kamini; Phale, Prashant S

2017-08-01

Pseudomonas sp. strain C7 isolated from sediment of Thane creek near Mumbai, India, showed the ability to grow on glucose and carbaryl in the presence of 7.5 and 3.5% of NaCl, respectively. It also showed good growth in the absence of NaCl indicating the strain to be halotolerant. Increasing salt concentration impacted the growth on carbaryl; however, the specific activity of various enzymes involved in the metabolism remained unaffected. Among various enzymes, 1-naphthol 2-hydroxylase was found to be sensitive to chloride as compared to carbaryl hydrolase and gentisate 1,2-dioxygenase. The intracellular concentration of Cl - ions remained constant (6-8 mM) for cells grown on carbaryl either in the presence or absence of NaCl. Thus the ability to adapt to the increasing concentration of NaCl is probably by employing chloride efflux pump and/or increase in the concentration of osmolytes as mechanism for halotolerance. The halotolerant nature of the strain will be beneficial to remediate carbaryl from saline agriculture fields, ecosystems and wastewaters.

A critical analysis of climatic influences on indoor radon concentrations: Implications for seasonal correction.

PubMed

Groves-Kirkby, Christopher J; Crockett, Robin G M; Denman, Antony R; Phillips, Paul S

2015-10-01

Although statistically-derived national Seasonal Correction Factors (SCFs) are conventionally used to convert sub-year radon concentration measurements to an annual mean, it has recently been suggested that external temperature could be used to derive local SCFs for short-term domestic measurements. To validate this approach, hitherto unanalysed radon and temperature data from an environmentally-stable location were analysed. Radon concentration and internal temperature were measured over periods totalling 1025 days during an overall period of 1762 days, the greatest continuous sampling period being 334 days, with corresponding meteorological data collected at a weather station 10 km distant. Mean daily, monthly and annual radon concentrations and internal temperatures were calculated. SCFs derived using monthly mean radon concentration, external temperature and internal-external temperature-difference were cross-correlated with each other and with published UK domestic SCF sets. Relatively good correlation exists between SCFs derived from radon concentration and internal-external temperature difference but correlation with external temperature, was markedly poorer. SCFs derived from external temperature correlate very well with published SCF tabulations, confirming that the complexity of deriving SCFs from temperature data may be outweighed by the convenience of using either of the existing domestic SCF tabulations. Mean monthly radon data fitted to a 12-month sinusoid showed reasonable correlation with many of the annual climatic parameter profiles, exceptions being atmospheric pressure, rainfall and internal temperature. Introducing an additional 6-month sinusoid enhanced correlation with these three parameters, the other correlations remaining essentially unchanged. Radon latency of the order of months in moisture-related parameters suggests that the principal driver for radon is total atmospheric moisture content rather than relative humidity. Copyright © 2015 Elsevier Ltd. All rights reserved.