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Molecules (Basel, Switzerland) Jun 2022This novel work reports nimorazole (NIMO) radiosensitizer reduction upon electron transfer in collisions with neutral potassium (K) atoms in the lab frame energy range...
This novel work reports nimorazole (NIMO) radiosensitizer reduction upon electron transfer in collisions with neutral potassium (K) atoms in the lab frame energy range of 10-400 eV. The negative ions formed in this energy range were time-of-flight mass analyzed and branching ratios were obtained. Assignment of different anions showed that more than 80% was due to the formation of the non-dissociated parent anion NIMO at 226 u and nitrogen dioxide anion NO at 46 u. The rich fragmentation pattern revealed that significant collision induced the decomposition of the 4-nitroimidazole ring, as well as other complex internal reactions within the temporary negative ion formed after electron transfer to neutral NIMO. Other fragment anions were only responsible for less than 20% of the total ion yield. Additional information on the electronic state spectroscopy of nimorazole was obtained by recording a K energy loss spectrum in the forward scattering direction ( ≈ 0°), allowing us to determine the most accessible electronic states within the temporary negative ion. Quantum chemical calculations on the electronic structure of NIMO in the presence of a potassium atom were performed to help assign the most significant lowest unoccupied molecular orbitals participating in the collision process. Electron transfer was shown to be a relevant process for nimorazole radiosensitisation through efficient and prevalent non-dissociated parent anion formation.
Topics: Anions; Electron Transport; Electrons; Ions; Nimorazole; Potassium
PubMed: 35807379
DOI: 10.3390/molecules27134134 -
Biosensors Apr 2021This study aimed to develop simple electrochemical electrodes for the fast detection of chloride, sodium and potassium ions in human serum. A flat thin-film gold...
This study aimed to develop simple electrochemical electrodes for the fast detection of chloride, sodium and potassium ions in human serum. A flat thin-film gold electrode was used as the detection electrode for chloride ions; a single-piece type membrane based solid-state ion-selective electrode (ISE), which was formed by covering a flat thin-film gold electrode with a mixture of 7,7,8,8-tetracyanoquinodimethane (TCNQ) and ion-selective membrane (ISM), was developed for sodium and potassium ions detection. Through cyclic voltammetry (CV) and square-wave voltammetry (SWV), the detection data can be obtained within two minutes. The linear detection ranges in the standard samples of chloride, sodium, and potassium ions were 25-200 mM, 50-200 mM, and 2-10 mM, with the average relative standard deviation (RSD) of 0.79%, 1.65%, and 0.47% and the average recovery rates of 101%, 100% and 96%, respectively. Interference experiments with Na, K, Cl, Ca, and Mg ions demonstrated that the proposed detection electrodes have good selectivity. Moreover, the proposed detection electrodes have characteristics such as the ability to be prepared under relatively simple process conditions, excellent detection sensitivity, and low RSD, and the detection linear range is suitable for the Cl, Na and K concentrations in human serum.
Topics: Electrochemical Techniques; Electrodes; Electrolytes; Gold; Humans; Ion-Selective Electrodes; Ions; Potassium
PubMed: 33917075
DOI: 10.3390/bios11040109 -
Nature Communications Jul 2020Ions are ubiquitous biological regulators playing a key role for vital processes in animals and plants. The combined detection of ion concentration and real-time...
Ions are ubiquitous biological regulators playing a key role for vital processes in animals and plants. The combined detection of ion concentration and real-time monitoring of small variations with respect to the resting conditions is a multiscale functionality providing important information on health states. This multiscale functionality is still an open challenge for current ion sensing approaches. Here we show multiscale real-time and high-sensitivity ion detection with complementary organic electrochemical transistors amplifiers. The ion-sensing amplifier integrates in the same device both selective ion-to-electron transduction and local signal amplification demonstrating a sensitivity larger than 2300 mV V dec, which overcomes the fundamental limit. It provides both ion detection over a range of five orders of magnitude and real-time monitoring of variations two orders of magnitude lower than the detected concentration, viz. multiscale ion detection. The approach is generally applicable to several transistor technologies and opens opportunities for multifunctional enhanced bioelectronics.
Topics: Amplifiers, Electronic; Computer Systems; Electricity; Electrochemical Techniques; Humans; Ions; Organic Chemicals; Potassium; Transistors, Electronic
PubMed: 32719350
DOI: 10.1038/s41467-020-17547-0 -
Journal of Dairy Science Feb 1987Twenty-four lactating Holstein cows were offered diets containing .93, 1.29, and 1.53% potassium during hot weather. Cows fed 1.53% potassium consumed more dry matter...
Twenty-four lactating Holstein cows were offered diets containing .93, 1.29, and 1.53% potassium during hot weather. Cows fed 1.53% potassium consumed more dry matter than cows fed either .93 or 1.29% potassium. Milk production and composition were not different. Potassium intake and fractional excretion increased, and fecal output as a percentage of intake declined with diets containing 1.29 and 1.53% potassium. Magnesium fractional excretion was least and fecal output greatest in cows fed 1.29% potassium. Fecal sodium output and fecal output as a percentage of intake was reduced by 1.53% dietary potassium. During comparison period 2, potassium carbonate at 0, .5, or 1.0% had no effect on feed consumption or milk yield, but buffered diets increased milk fat percentage and depressed milk protein percentage. No effects of buffers on ruminal pH, volatile fatty acids, or digestibility of dry matter or fiber were noted. Cows responded favorably during hot weather to potassium supplementation at 1.53% of the diet, but with high dietary potassium, effects on other minerals must be considered. Chloride, although present above requirements in all diets, was greater in the highest potassium diet.
Topics: Animal Feed; Animals; Buffers; Carbonates; Cattle; Female; Hot Temperature; Lactation; Potassium; Pregnancy
PubMed: 3571637
DOI: 10.3168/jds.S0022-0302(87)80012-7 -
Cell Metabolism Jan 2015Dietary potassium deficiency, common in modern diets, raises blood pressure and enhances salt sensitivity. Potassium homeostasis requires a molecular switch in the...
Dietary potassium deficiency, common in modern diets, raises blood pressure and enhances salt sensitivity. Potassium homeostasis requires a molecular switch in the distal convoluted tubule (DCT), which fails in familial hyperkalemic hypertension (pseudohypoaldosteronism type 2), activating the thiazide-sensitive NaCl cotransporter, NCC. Here, we show that dietary potassium deficiency activates NCC, even in the setting of high salt intake, thereby causing sodium retention and a rise in blood pressure. The effect is dependent on plasma potassium, which modulates DCT cell membrane voltage and, in turn, intracellular chloride. Low intracellular chloride stimulates WNK kinases to activate NCC, limiting potassium losses, even at the expense of increased blood pressure. These data show that DCT cells, like adrenal cells, sense potassium via membrane voltage. In the DCT, hyperpolarization activates NCC via WNK kinases, whereas in the adrenal gland, it inhibits aldosterone secretion. These effects work in concert to maintain potassium homeostasis.
Topics: Animals; Blood Pressure; Cell Line; Chlorides; Electrolytes; Humans; Kidney Tubules, Distal; Membrane Potentials; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Mice, Knockout; Minor Histocompatibility Antigens; Potassium; Potassium Channels, Inwardly Rectifying; Potassium, Dietary; Protein Serine-Threonine Kinases; Pseudohypoaldosteronism; Sodium Chloride, Dietary; Solute Carrier Family 12, Member 3; WNK Lysine-Deficient Protein Kinase 1
PubMed: 25565204
DOI: 10.1016/j.cmet.2014.12.006 -
Sensors (Basel, Switzerland) Apr 2019Cystic Fibrosis (CF) is the most common fatal human genetic disease, which is caused by a defect in an anion channel protein (CFTR) that affects ion and water transport...
New ISE-Based Apparatus for Na, K, Cl, pH and Transepithelial Potential Difference Real-Time Simultaneous Measurements of Ion Transport across Epithelial Cells Monolayer⁻Advantages and Pitfalls.
Cystic Fibrosis (CF) is the most common fatal human genetic disease, which is caused by a defect in an anion channel protein (CFTR) that affects ion and water transport across the epithelium. We devised an apparatus to enable the measurement of concentration changes of sodium, potassium, chloride, pH, and transepithelial potential difference by means of ion-selective electrodes that were placed on both sides of a 16HBE14σ human bronchial epithelial cell line that was grown on a porous support. Using flat miniaturized ISE electrodes allows for reducing the medium volume adjacent to cells to approximately 20 μL and detecting changes in ion concentrations that are caused by transport through the cell layer. In contrast to classic electrochemical measurements, in our experiments neither the calibration of electrodes nor the interpretation of results is simple. The calibration solutions might affect cell physiology, the medium composition might change the direction of actions of the membrane channels and transporters, and water flow that might trigger or cut off the transport pathways accompanies the transport of ions. We found that there is an electroneutral transport of sodium chloride in both directions of the cell monolayer in the isosmotic transepithelial concentration gradient of sodium or chloride ions. The ions and water are transported as an isosmotic solution of 145 mM of NaCl.
Topics: Anions; Chlorides; Epithelial Cells; Humans; Hydrogen-Ion Concentration; Ion Transport; Ion-Selective Electrodes; Potassium; Sodium; Transendothelial and Transepithelial Migration
PubMed: 31009998
DOI: 10.3390/s19081881 -
The Journal of Nutrition Jan 2008Public health nutrition strategies to develop and maintain bone health throughout the lifecycle as well as to prevent osteoporosis in later life are urgently needed. In... (Review)
Review
Public health nutrition strategies to develop and maintain bone health throughout the lifecycle as well as to prevent osteoporosis in later life are urgently needed. In the United States, approximately 10 million Americans have osteoporosis, with costs estimated at $17.9 billion per year and costs in Europe well in excess of 13.9 billion euros. This review article outlines the current evidence available in the literature linking potassium-rich, bicarbonate-rich foods to osteoporosis prevention. The health-related benefits of a high intake of potassium-rich, bicarbonate-rich foods (e.g., fruits and vegetables) on disease prevention (e.g., cancer, heart disease) have been gaining increasing attention in the literature, and there is growing belief, from a variety of observational, experimental, clinical, and intervention studies, that a positive link exists between potassium-rich, bicarbonate-rich foods and indices of bone health. However, observational studies are not hypothesis proving and can only suggest the potential mechanisms of action. We now urgently need data from randomized controlled trials to determine for certain whether a potassium-rich, bicarbonate-rich diet or supplement is important to the skeleton. A 1-mo dietary intervention study involving 23- to 76-y-old men and women has shown that a diet high in bicarbonate (high fruits and vegetables) and potassium (high in milk and dairy products) (Dietary Approaches to Stopping Hypertension) significantly reduces bone turnover. Longer-term dietary studies are critical. In addition, the mechanisms underlying a positive effect of a potassium-rich, bicarbonate-rich diet on bone need to be fully determined. These currently include, but are not limited to, 1) the potential role of the skeleton in acid-base homeostasis; 2) other nutrient or dietary components found in abundance in fruits and vegetables such as vitamin K, beta-carotene, and vitamin C; and 3) other as yet "unidentified" dietary components. The road ahead is a challenging one.
Topics: Bicarbonates; Bone and Bones; Diet; Humans; Osteoporosis; Potassium
PubMed: 18156420
DOI: 10.1093/jn/138.1.172S -
PloS One 2020Several hemipteran species feed on the phloem sap of plants and produce large amounts of honeydew that is collected by bees to produce honeydew honey. Therefore, it is...
Several hemipteran species feed on the phloem sap of plants and produce large amounts of honeydew that is collected by bees to produce honeydew honey. Therefore, it is important to know whether it is predominantly the hemipteran species or the host plant to influence the honeydew composition. This is particularly relevant for those botanical and zoological species from which the majority of honeydew honey originates. To investigate this issue, honeydew from two Cinara species located on Abies alba as well as from two Cinara and two Physokermes species located on Picea abies were collected. Phloem exudates of the host plants were also analyzed. Honeydew of all species contained different proportions of hexoses, sucrose, melezitose, erlose, and further di- and trisaccharides, whereas the phloem exudates of the host trees contained no trisaccharides. Moreover, the proportions of sugars differed significantly between hemipteran species feeding on the same tree species. Sucrose hydrolysis and oligosaccharide formation was shown in whole-body homogenates of aphids. The type of the produced oligosaccharides in the aphid-extracts correlated with the oligosaccharide composition in the honeydew of the different aphid species. The total contents of amino acids and inorganic ions in the honeydew were much lower than the sugar content. Glutamine and glutamate were predominant amino acids in the honeydew of all six hemipteran species and also in the phloem exudates of both tree species. Potassium was the dominant inorganic ion in all honeydew samples and also in the phloem exudate. Statistical analyses reveal that the sugar composition of honeydew is determined more by the hemipteran species than by the host plant. Consequently, it can be assumed that the sugar composition of honeydew honey is also more influenced by the hemipteran species than by the host tree.
Topics: Abies; Amino Acids; Animals; Aphids; Chromatography, High Pressure Liquid; Inorganic Chemicals; Ions; Oligosaccharides; Phloem; Picea; Plant Bark; Potassium; Sugars
PubMed: 31978201
DOI: 10.1371/journal.pone.0228171 -
American Journal of Physiology. Renal... May 2021Phosphorylation of the thiazide-sensitive NaCl cotransporter (NCC) in the distal convoluted tubule (DCT) is altered rapidly in response to changes in extracellular K...
Phosphorylation of the thiazide-sensitive NaCl cotransporter (NCC) in the distal convoluted tubule (DCT) is altered rapidly in response to changes in extracellular K concentration ([K]). High extracellular [K] is believed to activate specific phosphatases to dephosphorylate NCC, thereby reducing its activity. This process is defective in the human disease familial hyperkalemic hypertension, in which extracellular [K] fails to dephosphorylate NCC, suggesting an interplay between NCC-activating and NCC-inactivating switches. Here, we explored the role of STE20/SPS1-related proline-alanine-rich protein kinase (SPAK) and intracellular Cl concentration in the rapid effects of extracellular K on NCC phosphorylation. SPAK was found to be rapidly dephosphorylated in vitro in human embryonic kidney cells and ex vivo in kidney slices by high [K]. Acute high-K challenge resulted in DCT1-specific SPAK dephosphorylation in vivo and dissolution of SPAK puncta. In line with the postulate of interplay between activating and inactivating switches, we found that the "on" switch, represented by with no lysine kinase 4 (WNK4)-SPAK, must be turned off for rapid NCC dephosphorylation by high [K]. Longer-term WNK-SPAK-mediated stimulation, however, altered the sensitivity of the system, as it attenuated rapid NCC dephosphorylation due to acute K loading. Although blockade of protein phosphatase (PP)1 increased NCC phosphorylation at baseline, neither PP1 nor PP3, singly or in combination, was essential for NCC dephosphorylation. Overall, our data suggest that NCC phosphorylation is regulated by a dynamic equilibrium between activating kinases and inactivating phosphatases, with kinase inactivation playing a key role in the rapid NCC dephosphorylation by high extracellular K. Although a great deal is known about mechanisms by which thiazide-sensitive NaCl cotransporter is phosphorylated and activated, much less is known about dephosphorylation. Here, we show that rapid dephosphorylation by high K depends on the Cl sensitivity of with no lysine kinase 4 and the rapid dephosphorylation of STE20/SPS1-related proline-alanine-rich protein kinase, primarily along the early distal convoluted tubule.
Topics: Animals; Chlorides; HEK293 Cells; Humans; Kidney Tubules, Distal; Kinetics; Male; Mice, Inbred C57BL; Mice, Knockout; Phosphorylation; Potassium, Dietary; Protein Serine-Threonine Kinases; Protein Transport; Solute Carrier Family 12, Member 3; Mice
PubMed: 33719576
DOI: 10.1152/ajprenal.00459.2020 -
Scientific Reports Jan 2019Intracellular monovalent ions have been shown to be important for cell proliferation, however, mechanisms through which ions regulate cell proliferation is not well...
Intracellular monovalent ions have been shown to be important for cell proliferation, however, mechanisms through which ions regulate cell proliferation is not well understood. Ion transporters may be implicated in the intracellular signaling: Na and Cl participate in regulation of intracellular pH, transmembrane potential, Ca homeostasis. Recently, it is has been suggested that K may be involved in "the pluripotency signaling network". Our study has been focused on the relations between K transport and stem cell proliferation. We compared monovalent cation transport in human mesenchymal stem cells (hMSCs) at different passages and at low and high densities of culture as well as during stress-induced cell cycle arrest and revealed a decline in K content per cell protein which was associated with accumulation of G1 cells in population and accompanied cell proliferation slowing. It is suggested that cell K may be important for successful cell proliferation as the main intracellular ion that participates in regulation of cell volume during cell cycle progression. It is proposed that cell K content as related to cell protein is a physiological marker of stem cell proliferation and may be used as an informative test for assessing the functional status of stem cells in vitro.
Topics: Cations; Cell Proliferation; Cells, Cultured; Cytoplasm; Humans; Mesenchymal Stem Cells; Potassium
PubMed: 30674973
DOI: 10.1038/s41598-018-36922-y