Potassium Calcium Research Articles

Effects of different dialysate calcium concentrations on intradialysis hemodynamic stability

The interplay of correct solute mass balances, such as those of sodium (Na+), potassium (K+) and total calcium (tCa) (Na+MB, K+MB and tCaMB, respectively) with adequate ultrafiltration volumes (VUF) is crucial to achieving hemodynamic stability during hemodialysis (HD). Twenty-two stable anuric uremic patients underwent three 4-hour bicarbonate HD sessions, each with a different dialysate tCa concentration (1.25, 1.375 and 1.50 mmol/L). The GENIUS dialysis system (Fresenius Medical Care, Germany) was used. Volumes of blood and dialysate processed, VUF and dialysate Na+ and K+ concentrations were prescribed to be the same. Hourly measurements of plasma water ionized Ca (Ca++), Na+ and K+ were made, and their trends analyzed. tCaMBs, Na+MBs and K+MBs were determined. Systolic (SBP), diastolic (DBP) blood pressure, mean arterial pressure (MAP) and heart rate (HR) trends during dialysis were analyzed. Mean hourly plasma water Ca++ concentrations were statistically significantly higher with a dialysate tCa concentration of 1.50 mmol/L. Mean tCaMBs were positive (diffusion gradient from the dialysate to the patient), increasing with increasing dialysate tCa concentrations (+75 ± 122 mg, +182 ± 125 mg, +293 ± 228 mg, respectively). Their difference was statistically significant (p<0.0005). Mean Na+MBs and K+MBs were not statistically significantly different. SBP, DBP, MAP and HR were not statistically significantly different among the 3 treatments. These highly controlled experiments showed that hemodynamic stability does not appear to be statistically significantly influenced by any specific dialysate tCa concentration in this peculiar subset of patients.

A novel model of an identified Drosophila crawl motoneuron for investigating functional effects of ion channel type across larval developmental stages

Drosophila is a powerful genetic model system for investigating neuronal function. Most of the important membrane ion channel genes, such as voltage-gated sodium and potassium channels, were first identified and isolated in the fruit fly. Technical advances have now made possible direct electrophysiological recording of channels in central neurons, allowing the genetic advantages of this system to be applied to analysis of cellular and circuit function and homeostasis. An important open question is the functional effect of channel splice variants that has recently been found in Drosophila neurons. Because of the experimental difficulties in the isolated expression of these splice variants, computational modeling becomes essential. In this work, we aim at assessing effects of Na channel splice variants [1] on neuronal activity by first building a full model neuron. For this full model neuron, parameters for individual ion channels are required. Previous literature on Drosophila ion channel parameters are highly variable. Taking an average of such disparate neuronal parameter values have been shown to be unideal [2]. Furthermore in our case, these data were collected from different neuronal types and preparations. We are thus focusing on identified larval aCC and RP2 abdominal dorsomedial motoneurons, which innervate the dorsal muscles [3], for building a novel full motoneuron model. We obtain their channel parameters by fitting models to experimental voltage-clamp data. We first present a minimal, isopotential spiking model neuron with transient and persistent sodium, delayed-rectifier, and A-type potassium channels. This model allows us to investigate the contributions of the two major types of A-type currents Shal and Shaker that are different in spatial expression over the neuron and in terms of electrophysiological and activity-related characteristics. We show how the Shal channel properties change between the larval stages of 1st and 3rd instar, and we show the effect of this change on neuronal activity characteristics. We then aim to add the calcium channel and potassium channels that are dependent on it. Overall, this neuron model will enable us to investigate the effect Na channel splice variants by varying half-activation and inactivation voltages and ratio of a persistent component.

Lymphocyte calcium influx characteristics and its modulation by Kv1.3 and IKCa1 potassium channel inhibitors in multiple sclerosis

Lymphocyte calcium influx characteristics and its modulation by Kv1.3 and IKCa1 potassium channel inhibitors in multiple sclerosis

Na, K, Ca and Mg concentrations in effluent water drained from agricultural catchment basins in Lower Silesia

This paper contains the results of research of the content Na, K, Ca and Mg in waters drained from three agricultural river basins in Lower Silesia. The investigations covered two objects situated close to Wroc³aw and one in the border region between the Bolkow-Wa³brzych Plateau and the Wa³brzych Mountains. The effect of the agricultural use of the land on changes in the concentrations of the analyzed macroelements in the water flowing from the river basins has been assessed. Between 58 and 91 samples of waters for chemical analyses were taken once a month. Our analysis has shown that the concentrations of the analyzed elements were considerably different, both in the water flowing into and from the basins. The effluent water from the river basins was characterized by an elevated content of calcium and low concentrations of potassium. However, the content of magnesium was typical for the conditions in Poland. The content of magnesium in waters drained from all the river basins was higher than in the water flowing into the basins and the correlation coefficients for the concentrations in both of these cross-sections ranged from 0.7846 to 0.8603. Likewise, for sodium, calcium and potassium, dependences were found between the concentrations of these elements above and below the analyzed objects but the correlation coefficients were lower. Distinctly lower values of the correlation coefficients were obtained for the village of Samotwor. The agricultural use of the river basin area contributed to a higher magnesium and calcium content in waters and an insignificantly raised content of sodium. These changes were accompanied by a decrease in the concentration of potassium.

Effect of ion irradiation on the thermoluminescence properties of K2Ca2(SO4)3 phosphor

This paper presents the thermoluminescence (TL) studies of ion-irradiated potassium–calcium mixed sulfate phosphor. The sample was prepared by the solid-state diffusion method. The X-ray diffraction study of the prepared sample suggests an orthorhombic structure with an average particle size of 0.16 μ m. The samples were irradiated with 1.2 MeV argon ions at fluences varying between 1011 and 1015 ions/cm2. The argon ions penetrate to a depth of 1.93 μ m and lose their energy mainly via electronic stopping. Due to ion irradiation, a large number of defects such as oxygen vacancies, radicals and color centers are formed in the sample. TL glow curves were recorded for each of the ion fluences. A linear increase in the intensity of TL glow peaks was found with an increase in the ion dose from 72 kGy to 720 MGy. The kinetic parameters associated with the prominent glow peaks were calculated using glow curve deconvolution, different glow curve shapes and sample heating rate methods.

Biochemical control of bone loss and stone-forming propensity by potassium-calcium citrate after bariatric surgery

Background Patients undergoing Roux-en- Y gastric bypass (RYGB) surgery are prone to developing bone loss and kidney stones. The goal of the present study was to test the hypothesis that an effervescent formulation of potassium calcium citrate (PCC) would avert metabolic complications by providing bioavailable calcium and alkali. Methods A total of 24 patients with RYGB underwent a 2-phase crossover randomized trial comparing PCC and placebo. During the last 2 days of each 2-week phase, the serum and 24-hour urine samples were analyzed for calcium and bone turnover markers, acid base status, and urinary stone risk factors. Results Compared with placebo, PCC marginally reduced the serum parathyroid hormone level and significantly decreased urinary deoxypyridinoline by 12% ( P <.001) and serum type 1 collagen C-telopeptide by 22% ( P <.01). PCC significantly increased the net gastrointestinal alkali absorption, citrate, and pH and significantly lowered the urinary net acid excretion ( P <.001). The urinary saturation of uric acid decreased significantly ( P <.001). The supersaturation of calcium oxalate and brushite did not change despite an increase in calcium and pH. In untreated urine samples with citrate concentrations altered to mimic those of placebo and PCC, calcium oxalate agglomeration was significantly inhibited by PCC. Conclusion In RYGB patients, PCC supplementation inhibited bone resorption by providing bioavailable calcium, reduced the urinary saturation of uric acid, and increased the inhibitor activity against calcium oxalate agglomeration by providing alkali that increased urinary pH and citrate.

Characterization of Particulate Matter in the Hot Product Gas from Indirect Steam Bubbling Fluidized Bed Gasification of Wood Pellets

This study characterized the particulate matter (PM) formed during indirect steam bubbling fluidized bed gasification of wood pellets at atmospheric pressure. A system including a dilution probe, a bed of granular activated carbon, and a thermodenuder was used to sample the PM at high temperature with the aim of separating it from condensing inorganic vapors and tars. The particle mass size distribution was bimodal with a fine mode in the <0.5-μm size range and a dominating coarse mode in the >0.5-μm size range. The coarse mode was representatively characterized, but condensing inorganic vapors and tars complicated the evaluation of the results for the fine-mode PM. Morphological analysis of the PM indicated that the char content was low. The inorganic fraction was dominated by potassium and chlorine for fine-mode PM and calcium and silicon for coarse-mode PM.

Does K2CaSiO4 Exist? A Phase-Analytical Study in the System K2O-CaO-SiO2 with Implications for the Characterization of Residual Materials

K2CaSiO4 or K2O × CaO × SiO2 has been reported to be a major constituent of residual materials that are of interest for the field of applied mineralogy, including ashes from biomass combustion as well as fertilizers produced from the residues of oil-shale industry or from steelmaking slags. Unfortunately, contradictory results concerning basic crystallographic and physicochemical data of this compound have been described in the literature. In a series of solid-state reactions we tried to prepare this material for a more detailed investigation. The temperature regime for the subsolidus synthesis experiments was selected according to previous studies where the occurrence of this so-called “1:1:1” phase had been reported. The samples were characterized by thermal and X-ray fluorescence analysis as well as X-ray powder diffraction. Our results indicate that “K2CaSiO4” does not exist as a crystalline phase in the ternary system K2O–CaO–SiO2 and that the 1:1:1 compound, mentioned in earlier studies is actually misinterpreted K2Ca2Si2O7. Furthermore, the start of melt formation of an oxide mixture with composition K2O × CaO × SiO2 has been determined to be 1170°C, which is dramatically lower than the value of 1630°C mentioned in the only available comprehensive but more than 80 years old phase analytical study on potassium calcium silicates.

Induction-dependent neural marker expression and electrophysiological characteristics of bone marrow mesenchymal stem cells that naturally express high levels of nestin

Under certain experimental conditions, bone marrow mesenchymal stem cells (MSCs) express neuronal phenotypes and neuronal markers, which suggests that they could be used to treat various neurological diseases. In the present study, MSCs were isolated from adult rat bone marrow, cultivated, and evaluated for neurotrophin expression profiles, as well as the potential to differentiate into functional neuronal-like cells in vitro. MSCs from passage 5 were pre-induced with DMEM/F12 medium containing 10% fetal bovine serum (FBS) and 10 ng/mL bFGF (fibroblast growth factor-2). Subsequently, a chemical inductor containing Dimethyl Sulphoxide (DMSO), Butylated Hydroxyanisole (BHA) and forskolin were used to induce neural expression of MSCs. Expression patterns of nestin, NF-200, and GFAP at time points before and after induction were detected by immunofluorescence. Nerve Growth Factor (NGF), brain-derived neurotrophic factor (BDNF) expressions in MSCs were evaluated by RT-PCR. The whole-cell patch clamp technique was utilized to elucidate the electrical behavior of MSC before and after 24-h differentiation induction. Immunofluorescence analysis revealed that MSCs expressed nestin (57.1% ± 6.9%), but not NF-200 or GFAP. Following neural induction, the cells exhibited a neuronal-like appearance. Nestin and NF-200 expression was positive in the neuronal-like cells, but GFAP expression was negative. After 6-, 12- and 24-h induction, the ratio of nestin-positive cells was 96.5% ± 1.9%, 88.1% ± 5.4%, and 33.5% ± 5.4%. NF-200 positive cells were 90.1% ± 2.9%, 97.5% ± 1.3%, and 98.1% ± 1.6%, respectively. However, prior to induction, MSCs already expressed NGF and BDNF. With a stimulus impulse of 40 mV, the density of the transient outward K current was (9.95 ± 4.85) pA/pF (n = 9) and (328.50 ± 30.62) pA/pF (n = 9) before and after induction, and the density of transient calcium ion currents was (−0.059 ± 0.027) pA/pF (n = 7) and (−6.66 ± 0.50) pA/pF (n = 7), respectively. Transient outward potassium currents and calcium ions currents gradually increased following induction. In addition, MSCs isolated from bone marrow exhibited characteristics of neuronal progenitor cells and expressed neurotrophins. These cells exhibited the capacity to differentiate into functional neuronal-like cells in vitro. These results suggested that MSCs express high levels of nestin and could be utilized for therapeutic strategies to treat nervous system diseases.

Composites from mixtures of potassium polytitanate and biocompatible glasses

The possibility of synthesizing ceramic composites from mixtures of powders of two types of biocompatible glass and potassium polytitanate was investigated. It was shown that during the reaction of these composites with a solution simulating blood plasma, a porous structure reinforced with potassium hexatitanate or calcium titanate fibers formed on the surface of the material; the pores were filled with hydroxyapatite, which should cause intergrowth of bone tissue in the structure of the implants made from them.

Flammability of antifreeze agents for automatic sprinkler systems

This article evaluates several antifreeze agents for automatic sprinkler systems by focusing on the expected contribution of the combustion energy of such agents to a fire. Such an energy contribution could potentially result in an excessive number of sprinklers being activated and thereby overtax the capacity of the water supply. To investigate this, an analysis and experimental program were initiated involving several different antifreeze agents. The results of this study show that only two of the antifreeze solutions did not increase the intensity of the fire source compared to water only, namely calcium chloride and potassium acetate. The other antifreeze agent solutions that were tested resulted in a significant increase in fire heat release rate. In some cases, the energy released during the period of application was 1.5--2 times higher than that found when only water was used. These results correlated well with the analysis calculations.

Aluminium-induced alteration of ion homeostasis in root tip vacuoles of two maize varieties differing in Al tolerance

Root elongation is a primary target of Al toxicity in plants. The objective of this study was to see whether Al-induced disturbance of ion homeostasis is related to the inhibition of root elongation. For this purpose, root growth rate, free cytoplasmic calcium (Ca 2+) and vacuolar content of phosphate (P i), potassium (K +), nitrate (NO 3 −) and malate, as well as malate and citrate exudation and nitrate reductase activity were analysed in tips of two Zea mays L. varieties differing in Al resistance. Aluminium treatment affected root growth and cytoplasmic Ca 2+ in the Al sensitive variety Bakero, but not in the Al tolerant variety Sikuani. However, both varieties suffered Al-induced decrease of vacuolar K +, and phosphate concentrations. Vacuolar malate concentrations were more affected by Al in Bakero than in Sikuani. Vacuolar nitrate concentrations increased upon Al exposure in both varieties. Only in Sikuani rhizosphere, pH slightly increased upon Al exposure. Our data are consistent with the hypothesis that disturbance of Ca 2+ homeostasis is an early event in the Al toxicity syndrome. However, Al-induced alterations of the root tip homeostasis of major ions seem unrelated to Al-induced inhibition of root elongation.

Strong green upconversion emission from Er 3+–Yb 3+ co-doped KCaBO 3 phosphor

Potassium calcium mixed borate, KCaBO 3:Er 3+, phosphors with varied Yb 3+ concentrations were synthesized by solid-state reaction and studied for the first time. The obtained single monoclinic phased polycrystalline phosphor has the capability of accepting the Yb 3+ sensitizer up to 16 wt.%. Monotonically increasing green upconversion emission ( 2H 11/2, 4S 3/2 → 4I 15/2) of Er 3+ with the increase of Yb 3+ concentration is observed under 980 nm laser excitation. Upconversion mechanism is investigated in detail and attributed to the efficient resonant energy transfer from Yb 3+ to Er 3+ ions in such system. Our results suggest a potential material for green upconversion phosphor.

Fairchildite K 2Ca(CO 3) 2 in phoscorites from Phalaborwa, South Africa: the first occurrence in alkaline carbonatite complexes

The paper is devoted to monomineralic and multiphase (melt) inclusions in magnetites from the phoscorites of the Loolekop deposit, the Phalaborwa alkaline carbonatite complex, South Africa. Multiphase inclusions vary greatly in phase composition from essentially carbonate to carbonate–silicate–oxide. Their main components are dolomite, calcite, fluorapatite, picroilmenite, phlogopite, magnesite, and brucite. In one multiphase inclusion, a rare carbonate, fairchildite K 2Ca(CO 3) 2, was found in the central part of a large magnetite grain. It coexists with dolomite, picroilmenite, phlogopite, brucite, witherite, and halite. This is the first occurrence of fairchildite in carbonatite complexes and in igneous rocks in general. The composition of this mineral (38.54 wt.% K 2O, 23.15 wt.% CaO, 1.47 wt.% FeO, 0.63 wt.% Na 2O, n = 5) is close to the ideal K 2Ca(CO 3) 2. The phase relationships within the inclusion show that potassium–calcium carbonate crystallized after phlogopite and picroilmenite, but before dolomite. Temperature estimations from the pairs magnetite–ilmenite and dolomite–calcite indicate that phoscorites began to form at T > 630–750 °C and the phase K 2Ca(CO 3) 2 is a high-temperature modification (fairchildite) which crystallized directly from melt rather than by solid-phase reactions. However, it can be transformed into a low-temperature modification (bütschliite) with decreasing temperature at 547 °C. Apparently, the extremely low Na content and relatively high K content of the initial calciocarbonatite melt favored the formation of fairchildite in the Phalaborwa phoscorites. According to literature data, if Na 2O dominates over K 2O in the carbonatite melt, nyerereite Na 2Ca(CO 3) 2 is a favorable phase for crystallization and K incorporates into its structure as a minor component.

Enhanced dechlorination of chlorobenzene compounds on fly ash: effects of metals, solvents, and temperature

Dechlorination of di-chlorobenzene and tri-chlorobenzene on fly ash was optimized. Solutions of sulfur with alkaline solutions of potassium hydroxide, sodium hydroxide, and calcium hydroxide were applied for dechlorination of chlorobenzene compounds. Higher dechlorination (%) on surface of fly ash was achieved in sulfur and calcium hydroxide mixture, which further was enhanced with the addition of sodium hydroxide. Higher dechlorination (%) was obtained at 90°C, where metals in general, and copper and lead, in particular, enhance the catalytic potential of fly ash for dechlorination by hydrodechlorination and substitution reactions. But at high temperatures (120–170°C), dechlorination process was adversely affected by these metals. Moreover, the fly ash particles provided the surface to accomplish reduction and substitution reactions by adsorbing the chlorinated aromatic compound, hydrogen, hydroxyl, and thiol ions. The effects of water, organic solvents, and temperature were studied and reactions conditions were optimized to get maximum dechlorination.

Slagging Characteristics on the Superheaters of a 12 MW Biomass-Fired Boiler

In an attempt to understand the problem of severe slagging in biomass-fired boilers, slags formed on the fourth-, second-, and first-stage superheaters in a 12 MW biomass-fired grate furnace have been collected, sampled, and analyzed using X-ray fluorescence (XRF) and X-ray diffraction (XRD) techniques. The slag collected on each superheater has a unique morphology and structure. The slag on the fourth-stage superheater is loose and porous, while on the secondary and the primary superheaters, the slag shows a clear layered structure of different colors and levels of hardness. Aluminosilicate is the major component in the slag on the fourth-stage superheater, which is formed by Si, Al, and alkali species. On both the secondary and primary superheaters, the sticky sylvine, potassium calcium sulfate, and aphthitalite in the bottom layer trap coarse, large particles, resulting in further slagging. In the alternating layers, the particles containing high concentrations of K, Na, and Cl form the initial deposit...

Effect of methamphetamine on potassium and L-type calcium currents in rat ventricular myocytes

The mechanisms of cardiac toxicity caused by methamphetamine (MA) are poorly understood at present. This study was designed to investigate the effects of MA on ionic currents in myocardial cells. The effects of MA on transient outward potassium current (Ito), inward rectifying potassium current (IK1), and L-type calcium current (ICa-L) in isolated rat ventricular myocytes were studied using the whole-cell patch clamp technique. It was demonstrated that MA inhibited the Ito, IK1, and ICa-L in the rat ventricular myocytes concentration-dependently. MA shifted left the Ito steady-state inactivation curve and shifted down the recovery curve, but had no influence on the steady-state activation curve. MA did not affect the ICa-L steady-state activation curve or steady-state inactivation curve, but shifted down the recovery curve. We concluded that MA had inhibitory effects on the Ito, IK1, and ICa-L in ventricular myocytes, which might be one of the possible electrophysiological mechanisms of cardiac damage caused by MA.

Biphasic effects of H2O2 on BKCa channels

The inhibitory or activating effect of H2O2 on large conductance calcium and voltage-dependent potassium (BKCa) channels has been reported. However, the mechanism by which this occurs is unclear. In this paper, BKCa channels encoded by mouse Slo were expressed in HEK 293 cells and BKCa channel activity was measured by electrophysiology. The results showed that H2O2 inhibited BKCa channel activity in inside-out patches but enhanced BKCa channel activity in cell-attached patches. The inhibition by H2O2 in inside-out patches may be due to oxidative modification of cysteine residues in BKCa channels or other membrane proteins that regulate BKCa channel function. PI3K/AKT signaling modulates the H2O2-induced BKCa channel activation in cell-attached patches. BKCa channels and PI3K signaling pathway were involved in H2O2-induced vasodilation and H2O2-induced vasodilation by PI3K pathway was mainly due to modulation of BKCa channel activity.

Low solubility of He and Ar in carbonatitic liquids: Implications for decoupling noble gas and lithophile isotope systems

In order to asses the importance of carbonatitic liquids in transporting noble gases in the mantle, the solubilities of He and Ar in carbonatitic liquids were estimated from analyses of calcium–potassium carbonate glasses that had been synthesized at 1 bar and temperatures between 850 and 950 °C under He or Ar enriched atmospheres. Despite poor reproducibility related to difficulties synthesizing carbonatite glass, we have been able to estimate He and Ar solubilities in carbonatite liquids to be 1 × 10 −8 and 2 × 10 −9 mol g −1 at 1 bar respectively (with ⩾50% uncertainty). Despite the significant uncertainties on these estimates, it is clear that the noble gases are not massively soluble in carbonatite liquids (within error, these solubilities are identical to their equivalent solubilities in tholeiitic melts). Assuming the results of these low pressure experiments can be applied to mantle conditions, it seems unlikely that carbonatite metasomatism per se transports noble gases within the mantle. It is nevertheless possible that partitioning of lithophile trace elements (including the important radioelements, U, K and Th) and noble gases between a carbonatitic melt and a silicate melt could effectively decouple lithophile and noble gas isotope systematics because the carbonatitic melt expressedly does not transport noble gases, yet is known to efficiently transport incompatible trace elements.

Examining the neglected side of calcium regulation in taste cells

Examining the neglected side of calcium regulation in taste cells