Ratio Of Rb Research Articles

Comparison of chemical components and quality evaluation of Panax ginseng and its processed products from different habitats in Northeastern China

Ginseng (Panax ginseng C.A. Meyer) is a widely used dietary supplement in Traditional Chinese Medicine due to its numerous health-promoting properties. However, limited research is available on the distinctions in the chemical composition between different ginsengs. Hence, this study explores the chemical composition of different ginsengs obtained from different habitats in Northeastern China. The fresh, red, and white ginsengs were collected from different places in the Jilin province, China. Ginsenoside and non-ginsenoside contents in the ginseng extracts were analyzed by an Ultra-high performance liquid chromatography system & VION® ion mobility hybrid Quadrupole Time-of-Flight. The results show a notable difference in the ginsenoside content among the samples. The qualification ratio of ginsenoside Re, Rg1, and Rb was 46.2%, with Re being the most abundant, followed by Rg1 and Rb1 in all the ginseng analyzed. Furthermore, the study revealed that white and red ginseng had higher total ginsenosides (8.18 ± 0.04 mg/kg) and total polysaccharides (17.4%) content, respectively. The fresh ginseng samples exhibited higher protein content (20.02 ± 0.2 g/100g) and lower fat content (2.0 g/100g) than others. Further, the ginseng samples analyzed in this study met the requirements specified in the Chinese Pharmacopoeia for total ash, heavy metals, and organochlorine pesticide residues. This study offers a comprehensive comparative analysis of the chemical composition of P. ginseng sourced from various habitats in Northeastern China. It underscores the significance of making informed choices when selecting ginseng types for scientific evaluation.

Infinite spherical well as model of quantum carnot engine

The potential well is a simple example that generally used to present an understanding of quantum mechanics. In this article, we used infinite spherical well model to evaluate the thermodynamic processes in a quantum Carnot engine. The energy of the particles depended on the value of n and l lead to complex calculations. For simplicity we used the φ100 and φ200 quantum states to determine work and efficiency of a quantum Carnot machine. The results obtained show that efficiency depends on the value of which is the ratio of RC and RB.

Rose bengal-decorated rice husk-derived silica nanoparticles enhanced singlet oxygen generation for antimicrobial photodynamic inactivation.

The online version contains supplementary material available at 10.1007/s10853-023-08194-z.

Stable Yellow Light-Emitting Diodes Based on Quasi-Two-Dimensional Perovskites.

Perovskite light-emitting diodes (PeLEDs) show great potential in display and lighting because of their tunable wavelength, narrow emission bandwidths, and high color purity. Currently, the external quantum efficiency (EQE) of red and green PeLEDs has reached >23%. However, yellow PeLEDs are still rarely reported because of phase separation in mixed-halide perovskites and the coexistence of multiple phases in quasi-two-dimensional (quasi-2D) perovskites L2An-1BnX3n+1 (n = 1, 2, 3, ...), where L is a bulky organoammonium ligand. Here, we fabricate stable yellow PeLEDs by manipulating the phase distribution and incorporating rubidium cations (Rb+) in quasi-2D perovskites. The transient absorption results confirm that alkylammonium ligand butyl ammonium (BA) has a narrower phase distribution than phenylethyl ammonium (PEA) in the quasi-2D perovskites, resulting in a more blue-shifted emission peak. We further incorporate a proper molar ratio of Rb+ in the (BA)2CsPb2I7 perovskite to blue-shift the emission peak to the yellow range. Finally, the yellow PeLEDs exhibit an EQE of 3.5%, and the stable emission peak is located at 595 nm. Our work provides a useful approach for the fabrication of highly efficient and stable yellow PeLEDs.

Separation and enrichment of Rb(I) in dicyclohexano 18 crown 6(DCH18C6)/PVC polymer inclusion membrane assisted by electric field

The effective extraction of liquid rubidium resources such as salt lake brine and seawater and the recovery of rubidium(I) at the end of the extraction process of lithium resources have always been a challenge in the industry. Two series of polymer inclusion membranes(PDA-PIM and PDT-PIM) were prepared to study the separation and enrichment of Rb(I). PDA-PIM and PDT-PIM used polyvinyl chloride (PVC) and dicyclohexano 18 crown 6(DCH18C6) as carriers, and tricaprylmethylammonium chloride (Aliquat 336) and trioctylphosphine oxide (TOPO) as a plasticizer, respectively. The optimal mass ratio (W/W) of PDA-PIM and PDT-PIM were P25D3.5A25 and P25D3.5T1, respectively. The applied electric field is a core condition for the mass transfer and separation of Rb(I). With the increase of voltage, the permeability coefficient P of Rb(I) and the separation factor (S) relative to Na(I) and K(I) increases. At 180 V, the PRb of PDA-PIM and PDT-PIM were 12.08 and 2.39 µm/s, and the SRB/NA were 11.21 and 14.44. After four mass transfer cycles of PDT-PIM, PRb only decreased by 4.6%. In addition, after 81.5 h of mass transfer, the enrichment ratio of Rb(I) was 3.02 times. These results show the excellent stability and mass transfer performance of PDT-PIM. It's of great significance for low concentration Rb(I) extraction.

Petrogenesis of coeval shoshonitic and high-K calc-alkaline igneous suites in the Eopyeong granitoids, Taebaeksan Basin, South Korea: Lithospheric thinning-related Early Cretaceous magmatism in the Korean Peninsula

The Early Cretaceous was the initial period of prolonged Cretaceous-Tertiary magmatic episode in the Korean Peninsula, during which a tectonic transition from compression to extension occurred. The Early Cretaceous Eopyeong granitoids in the Taebaeksan Basin consist of two distinct series of magmas: shoshonitic and high-K calc-alkaline series. We investigated the petrology, whole-rock major and trace element geochemistry, and Sr-Nd-Pb isotope compositions of the Eopyeong granitoids to understand their magma evolution processes and source characteristics. Sensitive high-resolution ion microprobe zircon U-Pb analysis was performed on the Eopyeong granitoids to constrain their intrusion ages. Zircon U-Pb ages of the shoshonitic and high-K calc-alkaline series are 110.63 ± 0.52 and 110.65 ± 0.66 Ma, respectively, indicating that the two series formed during the same magmatic event. The mafic mineral assemblages of the shoshonitic series change from two-pyroxene+biotite to clinopyroxene+amphibole+biotite through magma evolution, whereas those of the high-K calc-alkaline series consist of more hydrous assemblages of amphibole+biotite. The shoshonitic series is also distinguished from the high-K calc-alkaline series by its higher La/Yb ratio and negative anomalies of Rb, Ba, and Eu. Mineral geothermobarometry and hygrometry data and geochemical mass balance modeling results show that the two series evolved mainly by fractional crystallization from two distinct parental magmas containing different water contents. Primitive rocks from each series have high compatible element contents such as MgO, Cr, and Ni with high Mg# compared to crustal melts in a similar range of SiO2, suggesting their mantle origin. They also have abundant incompatible elements and ‘crust-like’ isotopic compositions [(87Sr/86Sr)i = 0.7093–0.7098; εNd(t) = −7.1 to −8.8; (206Pb/204Pb)i = 18.133–18.327; (207Pb/204Pb)i = 15.621–15.665; (208Pb/204Pb)i = 38.691–38.862] with negative Nb-Ta anomalies in the primitive mantle-normalized patterns. The enrichment in both compatible and incompatible elements can be best explained by partial melting of phlogopite-bearing lithospheric mantle metasomatized by isotopically enriched upper crustal sediment-derived melt or fluid. The two magma series may have been generated by different degrees of partial melting of the mantle sources with varying water contents. Changes in subduction angle and direction of the paleo-Pacific plate during the Early Cretaceous may have led to lithospheric thinning and upwelling of asthenospheric mantle, which triggered the partial melting of fusible domains of metasomatized lithospheric mantle. The small igneous bodies of the Early Cretaceous shoshonitic to alkaline mafic rocks occur sporadically throughout the southern part of the Korean Peninsula in close spatial association with the Cretaceous basins. They also show crust-like geochemistry and isotopic compositions, similar to the Eopyeong granitoids, implying that the lithospheric thinning-related melting of the metasomatized lithospheric mantle may have been widespread in the southern part of the Korean Peninsula.

RbCs(MAFA)PbI3 perovskite solar cell with 22.81% efficiency using the precise ions cascade regulation

By controlling the doping ratio of Rb+ and Cs+ ions in the perovskite precursor solution, the morphology of the perovskite film is effectively improved, and the δ phase (non perovskite phase) and PbI2 phase in the rod-shaped structure of the film are transformed into α phase (perovskite phase), and the formation of impurity phase is inhibited. At the same time, the addition of mixed Rb+ and Cs+ ions can be embedded in the “ion cascade” of (MA0.5FA0.5) PbI3 films, and a gradient potential is formed. Rb+ and Cs+ ions can effectively reduce the non radiation recombination and trap density of RbxCsx(MA(1-2x)/2 FA(1-2x)/2) PbI3 films, and form larger grains and smaller surface roughness in the perovskite films, which are conducive to the formation of better contact between the perovskite film and the electron transport layer, and result in larger open circuit voltage, short circuit current density and filling factor. Compared with the PCE of undoped (MA0.5FA0.5) PbI3 perovskite solar cells (PCE = 17.15%,VOC = 1.22 V, JSC = 18.75 mA/cm2, FF = 75), the open circuit voltage of Rb0.2Cs0.2(MA0.3FA0.3)PbI3 perovskite solar cells with doping concentration of 20% is increased to 1.25 V, the short circuit current density is increased to 23.70 mA/cm2 and the filling factor is 77%, the power conversion efficiency is 22.81%, and the increase of PCE is nearly 33%, which is the highest reported efficiency of a four component RbxCsx(MA(1-2x)/2 FA(1-2x)/2) PbI3 perovskite solar cell so far.

Clean and efficient process for the extraction of rubidium from granitic rubidium ore

Abstract The extraction of rubidium from natural resources has attracted much attention due to its growing application in many fields. This paper presents a novel clean process for extracting rubidium from granitic rubidium ore. The process consists of alkaline leaching, desilication, and solvent extraction. The experiment results show that the leaching ratio of Rb can be greater than 95% at a leaching temperature of 230 °C, NaOH concentration of 200 g/L, particle size of 100 mesh, liquid/solid ratio of 10:1, leaching time of 1 h, and stirring rate of 500 rpm. The optimum conditions for the desilication were determined to be the temperature of 95 °C, mass ratio of CaO to SiO2 of 1.2, and reaction time of 1 h. The SiO2 precipitation under optimum conditions was up to 96.2%. Approximately 98% of Rb in desilication liquor was extracted using 1 mol/L 4-tert-butyl-2-(α-methylbenzyl) phenol (in xylene) in three stages at a phase ratio (O/A) of 3:1 for 1.5 min and more than 99% of Rb in loaded organic phase was stripped using 1 mol/L HCl in two stages at a phase ratio of 10:1. The raffinate of Rb can be sent to the leaching step again after the extraction of potassium to close the loop. The results of mineralogy research suggest that the rubidium-bearing micas and feldspar were altered to zeolite and cancrinite during the hydrothermal alkaline leaching, which contributed to the release of rubidium from ore. Compared with the existing processes, this process has the advantages of lower energy consumption and no wastewater/emission gas disposals. In addition, the solid wastes can be utilized as the value-added products.

Wear behavior of quenched iron with various shapes and unit processed through two-step laser alloying of C powder

The two-step laser treatment, including laser ablation and secondary laser carburization, is a biomimetic processing technology, well-suited for the surface wear resistance recovery of quenched gray iron parts. The microstructure and microhardness of the treated region (unit) could be effectively strengthened. In addition, three types of regions (Ra, Rb, Rc) with different microstructures and microhardness values were observed in a variety of shape units, whereas the area ratio of Ra, Rb and Rc in the treatment area of different morphological samples was given. Moreover, the biomimetic surfaces with a variety of morphologies could effectively increase the wear resistance of the original surface (untreated surface) in the oil lubrication environment. Also, the support capacity and the oil and debris storage capacity of each shape unit, as the two main factors that affected the wear properties of biomimetic samples during the wear mechanism analysis, were analyzed and discussed.

Aberrant promoter hypermethylation of p16, survivin, and retinoblastoma in gastric cancer.

Gastric cancer is common and can be found throughout the world. Notoriously like other cancers, gastric cancer is a consequence of cellular regulation disorder. Epigenetics, including many oncogenes or tumour suppressor genes, can provide some clues for this kind of disorder. DNA methylation, especially promoter methylation, which causes the silence/decrease of tumour related genes, has become a focus in various tumour types. The aim of this study was to investigate promoter methylation of certain genes: p16, survivin, retinoblastoma (Rb), all of which have been regarded as genes related to gastric cancer. To detect the promoter methylation of p16, survivin, and Rb genes, peripheral blood samples from 106 gastric cancer patients as well as 18 healthy individuals were collected for Methylation-Specific Polymerase Chain Reaction (MSP) analysis. According to the statistical analysis, positive methylation ratio of p16 was 72.6 % (77 cases), 6 % had methylated survivin (7 cases), and positive methylation ratio of Rb was only 17.9 % (19 cases). The differences of promoter methylation of these genes between the patients group and control group were observed: P (P16) = 5.097E-08, P (survivin) = 0.262, and P (Rb) = 0.187. In the control group, methylated p16 was found in only one case that also had a methylated Rb. However, Survivin could not be found methylated in control cases. In this study, promoter methylation was observed for the p16 gene, which was considered an early potential marker in gastric cancer. This data supports that further investigations should study Rb and survivin as candidate markers for gastric cancer (Tab. 2, Fig. 1, Ref. 35).

Preparation of Edible Zein Hybrid Particles and Its Controlled Release Behaviors

A kind of novel hybrid particles (ZCa: Zein/CaCO3) for delivering water-soluble drugs have been prepared by solvent-nonsolvent phase separation method. The obtained ZCa hybrid particles were characterized by DLS, FT-IR spectra and SEM. ZCa hybrid particles have favorable dispersibility. The particle size and shape could be controlled by Zein/CaCO3 mass ratio, with the average size of ZCa hybrid particles being close to 200 nm. Using RB as water-soluble model drug, drug loading and release behaviors of ZCa hybrid particles were investigated. Compared with the pure zein particles, the encapsulation efficiency of ZCa was enhanced obviously, which reached 75.7%. The release ratio of RB in RB@ZCa could be controlled by pH value and by the content of CaCO3. ZCa was also applied to carry and release Dox, anticancer drug, and the cumulative release ratio of Dox@ZCa was obviously enhanced. The cumulative release ratio of Dox@ZCa reached 89 %. ZCa hybrid particles are a promising candidate in nutraceuticals and drugs delivery system. Keywords: Biocompatible polymers, Zein-based hybrid particles, edible drug carrier, calcium carbonate, zein, controllable release.

Diffusion and Ion Conduction in Cation-Conducting Oxide Glasses

In this Chapter we review knowledge about diffusion and cation conduction in oxide glasses. We first remind the reader in Section 1 of major aspects of the glassy state and recall in Section 2 the more common glass families. The diffusive motion in ion-conducting oxide glasses can be studied by several techniques – measurements of radiotracer diffusion, studies of the ionic conductivity by impedance spectroscopy, viscosity studies and pressure dependent studies of tracer diffusion and ion conduction. These methods are briefly reviewed in Section 3. Radiotracer diffusion is element-specific, whereas ionic conduction is not. A comparison of both types of experiments can throw considerable light on the question which type of ions are carriers of ionic conduction. For ionic conductors Haven ratios can be obtained from the tracer diffusivity and the ionic conductivity for those ions which dominate the conductivity.In the following sections we review the diffusive motion of cations in soda-lime silicate glass and in several alkali-oxide glasses based mainly on results from our laboratory published in detail elsewhere, but we also take into account literature data.Section 4 is devoted to two soda-lime silicate glasses, materials which are commonly used for window glass and glass containers. A comparison between ionic conductivity and tracer diffusion of Na and Ca isotopes, using the Nernst-Einstein relation to deduce charge diffusivities, reveals that sodium ions are the carriers of ionic conduction in soda-lime glasses. A comparison with viscosity data on the basis of the Stokes-Einstein relation shows that the SiO2 network is many orders of magnitude less mobile than the relatively fast diffusing modifier cations Na. The Ca ions are less mobile than the Na ions but nevertheless Ca is considerably more mobile than the network.Section 5 summarizes results of ion conduction and tracer diffusion for single Na and single Rb borate glasses. Tracer diffusion and ionic conduction have been studied in single alkali-borate glasses as functions of temperature and pressure. The smaller ion is the faster diffusing species in its own glass. This is a common feature of all alkali oxide glasses. The Haven ratio of Na in Na borate glass is temperature independent whereas the Haven ratio of Rb diffusion in Rb borate glass decreases with decreasing temperature.Section 6 reviews major facts of alkali-oxide glasses with two different alkali ions. Such glasses reveal the so-called mixed-alkali effect. Its major feature is a deep minimum of the conductivity near some middle composition for the ratio of the two alkali ions. Tracer diffusion shows a crossover of the two tracer diffusivities as functions of the relative alkali content near the conductivity minimum. The values of the tracer diffusivities also reveal in which composition range which ions dominate ionic conduction. Tracer diffusion is faster for those alkali ions which dominate the composition of the mixed glass.Section 7 considers the pressure dependence of tracer diffusion and ionic conduction. Activation volumes of tracer diffusion and of charge diffusion are reviewed. By comparison of tracer and charge diffusion the so-called Haven ratios are obtained as functions of temperature, pressure and composition. The Haven ratio of Rb in Rb borate glass decreases with temperature and pressure whereas that of Na in Na borate glass is almost constant.Section 8 summarizes additional common features of alkali-oxide glasses. Activation enthalpies of charge diffusion decrease with decreasing average ion-ion distance. The Haven ratio is unity for large ion-ion distances and decreases with increasing alkali content and hence with decreasing ion-ion distance.Conclusions about the mechanism of diffusion are discussed in Section 9. The Haven ratio near unity at low alkali concentrations can be attributed to interstitial-like diffusion similar to interstitial diffusion in crystals. At higher alkali contents collective, chain-like motions of several ions prevail and lead to a decrease of the Haven ratio. The tracer diffusivities have a pressure dependence which is stronger than that of ionic conductivity. This entails a pressure-dependent Haven ratio, which can be attributed to an increasing degree of collectivity of the ionic jump process with increasing pressure. Monte Carlo simulations showed that the number of ions which participate in collective jump events increases with increasing ion content – i.e. with decreasing average ion-ion distance. For the highest alkali contents up to four ions can be involved in collective motion. Common aspects of the motion process of ions in glasses and of atoms in glassy metals are pointed out. Diffusion in glassy metals also occurs by collective motion of several atoms.Section 10 summarizes the major features of ionic conduction and tracer diffusion and its temperature and pressure dependence of oxide glasses.

Specific ion adsorption on alkyl carboxylate surfactant layers

Mixtures of dodecyl carboxylate, CsOH, RbOH and octanol in D2O were investigated to determine the relative ion specificity of Cs+ and Rb+ in their interactions with dodecyl carboxylate in a liquid crystalline phase. Octanol as cosurfactant was necessary to obtain the lamellar liquid crystalline phase. The technique used was the measurement of the NMR quadrupole splitting of 137Cs and 87Rb. The ratio of Rb to Cs was varied as well as the concentration of surfactant and octanol, whereas the ratio of surfactant to octanol was kept constant at 1:3. It turned out that there is no significant difference between both ions in their affinity towards carboxylate head groups.

Survival of Juvenile Chinook Salmon during Barge Transport

AbstractTo estimate survival during barge transport over a distance of 470 km from Lower Granite Dam on the Snake River to a release area downstream of Bonneville Dam (the lowermost dam on the Columbia River), we used a novel adaptation of a release–recapture model with 1,494 acoustic‐tagged yearling Chinook salmon Oncorhynchus tshawytscha smolts. Smolts were collected at Lower Granite Dam, received surgically implanted acoustic transmitters, and were divided into three groups: (1) a barge group (RB) that was released into the raceway with fish that were later loaded into transportation barges (general barge population); (2) a control group (RA) that was held in a net‐pen suspended within the barge hold containing the general barge population until 5–6 h prior to barge evacuation (i.e., fish release into the river), at which time they were confirmed to be alive and then released into the barge hold; and (3) a dead group (RD) that was euthanized and then released into the barge hold 5–6 h prior to barge evacuation in order to validate a model assumption. Six replicates of each group were loaded onto fish transport barges that departed from Lower Granite Dam between 29 April and 13 May 2010. Detections on acoustic receiver arrays between 70 and 220 km downstream of the barge evacuation site served as the basis for estimation of survival within the barge. The ratio of RB: RA survival from release to river kilometer 153 provided the estimate of within‐barge survival. The replicate survival estimates ranged from 0.9503 ( = 0.0253) to 1.0003 ( = 0.0155). The weighted average of the replicate estimates of survival during the barge transportation experience was 0.9833 ( = 0.0062). This study provides the first active telemetry documentation that the assumed survival rate of 98% during the barge transportation experience appears to be justified for yearling Chinook salmon smolts.Received March 4, 2011; accepted August 30, 2011

The Source of Natural Arsenic Contamination in Groundwater, West of Iran

Geochemical characteristics and arsenic content of groundwater in the Kurdistan and West Azerbaijan provinces (west of Iran) were analyzed. Groundwater is the local source of drinking water and travertine springs are mainly used for bathing and balneological purposes. The results indicate that total arsenic in travertine springs and groundwater range between 212 to 986.9 and 0.4 to 688.9 μg/L, respectively. Speciation of arsenic suggests arsenite the dominant arsenic species in travertine spring (68.2 to 98.9%). The variations of Br/Cl and B/Cl ratio, negative ORP (Oxygen Redox Potential) and high concentrations of Cl, Na, Cs, Li, Rb, Sr, B, Br and Rb in travertine spring samples confirm deep groundwater circulation in the volcanic basement. The results of saturation indices show that groundwater samples are supersaturated with respect to iron oxides, calcite, dolomite and aragonite and undersaturated with respect to gypsum and halite. In spite of gold mineralization, dissolution of arsenic-containing sulfide minerals is not the main source of arsenic contamination in groundwater. Spatial coincidence between the arsenic anomaly in groundwater and the travertine springs distribution illustrates they are the main source of arsenic in groundwater. The present study is useful in addressing future measures in groundwater resource management, in the volcanic regions in the west of Iran.

The Effect of Growth Regulators on Quality Parameters and Ginsenosides Accumulation in Panax quinquefolium L. Roots

American ginseng (Panax quinquefolium L.) is a perennial medicinal herb originally grown in Canada and USA, and recently also in China, Australia, Holland and Poland. Several commercial preparations are produced from ginseng roots, that are known for their antifatigue, antitumor, antistress and immune system stimulating functions. The medicinal properties are due mainly to the active components – ginsenosides. In this work, the results of field cultivation experiments are presented that examine the effects of foliar application of several growth regulators on quality parameters and ginsenoside content of P. quinuefolium roots. The growth regulators tested, i.e., kinetin, daminozide, mixture of gibberellic acid (GA3) with potassium salt of α-naphthalene acetic acid (kNAA) and new preparation – IPO-1 – benzimidazole derivative (obtained from the Institute of Organic Industry in Warsaw – at present during the process of patent), were applied at a concentration of 100 or 200 mg l−1 in the middle of June in the 2nd year of vegetation. After 4 years of cultivation, the roots were dug up and dried, and subsequently the quantitative analysis of individual saponins (Rb1, Rb2, Rc, Rd, Re, Rg1) by HPLC was performed. Growth regulators significantly affected quality parameters, morphological features and accumulation of individual and total ginsenosides in ginseng roots. Regardless of doses, the plant roots treated with growth regulators had a higher content of total ginsenosides in comparison to the control. The growth regulators also affected individual ginsenosides level and narrowed the ratio of Rb:Rg group. The application of kinetin, daminozide and benzimidazole derivative for foliar spray during 2nd year of American ginseng vegetation caused a significant increase in air dry weight of roots and aboveground parts whereas the mixture of GA3 and kNAA showed a decreasing effect. An increase of roots size was observed using higher doses (200 mg l−1) of kinetin and daminozide while a decreasing tendency appeared with the application of the other preparations.

Validation of an Atomic Absorption Rubidium Ion Efflux Assay for KCNQ/M-Channels Using the Ion Channel Reader 8000

M-channels (M-current), encoded by KCNQ2/3 K+ channel genes, have emerged as novel drug targets for a number of neurological disorders. The lack of direct high throughput assays combined with the low throughput of conventional electrophysiology (EP) has impeded rapid screening and evaluation of K+-channel modulators. Development of a sensitive and efficient assay for the direct measurement of M-current activity is critical for identifying novel M-channel modulators and subsequent investigation of their therapeutic potential. Using a stable CHO cell line expressing rat KCNQ2/3 K+ channels confirmed by EP, we have developed and validated a nonradioactive rubidium (Rb+) efflux assay in a 96-well plate format. The Rb+ efflux assay directly measures the activity of functional channels by atomic absorption spectroscopy using the automated Ion Channel Reader (ICR) 8000. The stimulated Rb+ efflux from KCNQ2/3-expressing cells was blocked by the channel blockers XE991 and linopirdine with IC50 values of 0.15 µM and 1.3 µM, respectively. Twelve compounds identified as KCNQ2/3 openers were further assessed in this assay, and their EC50 values were compared with those obtained with EP. A higher positive correlation coefficient between these two assays (r = 0.60) was observed than that between FlexStation membrane potential and EP assays (r = 0.23). To simplify the assay and increase the throughput, we demonstrate that EC50 values obtained by measuring Rb+ levels in the supernatant are as robust and consistent as those obtained from the ratio of Rb+ in supernatant/lysate. By measuring the supernatant only, the throughput of ICR8000 in an eight-point titration is estimated to be 40 compounds per day, which is suitable for a secondary confirmation assay.

Validation of an Atomic Absorption Rubidium Ion Efflux Assay for KCNQ/M-Channels Using the Ion Channel Reader 8000

M-channels (M-current), encoded by KCNQ2/3 K(+) channel genes, have emerged as novel drug targets for a number of neurological disorders. The lack of direct high throughput assays combined with the low throughput of conventional electrophysiology (EP) has impeded rapid screening and evaluation of K(+)-channel modulators. Development of a sensitive and efficient assay for the direct measurement of M-current activity is critical for identifying novel M-channel modulators and subsequent investigation of their therapeutic potential. Using a stable CHO cell line expressing rat KCNQ2/3 K(+) channels confirmed by EP, we have developed and validated a nonradioactive rubidium (Rb(+)) efflux assay in a 96-well plate format. The Rb(+) efflux assay directly measures the activity of functional channels by atomic absorption spectroscopy using the automated Ion Channel Reader (ICR) 8000. The stimulated Rb(+) efflux from KCNQ2/3-expressing cells was blocked by the channel blockers XE991 and linopirdine with IC(50) values of 0.15 microM and 1.3 microM, respectively. Twelve compounds identified as KCNQ2/3 openers were further assessed in this assay, and their EC(50) values were compared with those obtained with EP. A higher positive correlation coefficient between these two assays (r = 0.60) was observed than that between FlexStation membrane potential and EP assays (r = 0.23). To simplify the assay and increase the throughput, we demonstrate that EC(50) values obtained by measuring Rb(+) levels in the supernatant are as robust and consistent as those obtained from the ratio of Rb(+) in supernatant/lysate. By measuring the supernatant only, the throughput of ICR8000 in an eight-point titration is estimated to be 40 compounds per day, which is suitable for a secondary confirmation assay.

Tight coupling of rubidium conductance and inactivation in human KCNQ1 potassium channels.

KCNQ1 K+ channels in humans are important for repolarization of cardiac action potentials and for K+ secretion in the inner ear. The pore-forming channel subunits form heteromeric complexes with small regulatory subunits of the KCNE family, in particular with KCNE1 to form channels that conduct a slow delayed rectifier K+ current, IKs. This association leads to alteration of biophysical properties, including a slowing of activation, a suppression of inactivation and an increase of the apparent single-channel conductance. In addition, inward Rb+ currents conducted by homomeric KCNQ1 channels are about threefold larger than K+ currents, whereas heteromeric KCNQ1-KCNE1 channels have smaller inward Rb+ currents compared to K+ currents. We determined inactivation properties and compared K+ vs. Rb+ inward currents for channels formed by co-assembly of KCNQ1 with KCNE1, KCNE3 and KCNE5, and for homomeric KCNQ1 channels with point mutations in the pore helix S5 or S6 transmembrane domains. Several of the channels with point mutations eliminated the apparent inactivation of KCNQ1, as described previously (Seebohm et al. 2001). We found that the extent of inactivation and the ratio of Rb+/K+ currents were positively correlated. Since the effect of Rb+ on the current size has been shown previously to be related to a fast 'flickery' process, our results suggest that inactivation of KCNQ1 channels is related to a fast flicker of the open channel. A kinetic model incorporating two open states, no explicit inactivated state and a fast flicker that is different for the two open states is able to account for the apparent inactivation and the correlation of inactivation and large Rb+ currents. We conclude that an association between KCNQ1 and KCNE subunits or removal of inactivation by mutation of KCNQ1 stabilizes the open conformation of the pore principally by altering an interaction between the pore helix and the selectivity filter and with S5/S6 domains.

Manipulation of ginsenoside heterogeneity in cell cultures of Panax notoginseng by addition of jasmonates

Manipulation of the heterogeneity of ginsenosides with different pharmacological activities was attempted by adding methyl jasmonate (MJA) or dihydro-methyl jasmonate (HMJA) to suspension cultures of a high-saponin-producing cell line of Panax notoginseng. Compared with HMJA, MJA not only increased ginsenoside content to a large degree but also significantly altered the ratio of Rb to Rg groups of ginsenosides. The ginsenoside Rd was not detected in either control cultures (without MJA addition) or when HMJA was added, but interestingly was detected upon supplementation of MJA. By increasing the concentration of MJA added from 0 to 500 μM, the ratio of Rb to Rg groups also increased from 0.49±0.06 to 2.49±0.06 (on day 15). The cells exhibited their maximal ginsenoside content when 200 μM MJA was added. The maximal Rb 1 content was 3.15±0.08 mg/100 mg DW (day 15), which was about ninefold that of the control. The maximal Rg 1 and Re contents were 0.90±0.01 (day 12) and 0.80±0.01 (day 15) mg/100 mg DW, respectively, which were about twofold that of the control. The information obtained will be useful for the exploitation of the diversity of biopharmaceutical molecules and for the large-scale bioprocessing of heterogeneous products.