A comparative study of four 20-membered N_2S_4-crown ethers as ionophores for polymeric membrane silver selective electrodes

Four 20-membered N_2S_4-monoazathiacrown ethers have been synthesized and explored as neutral ionophores for Ag^+-selective electrodes.Potentiometric responses reveal that the flexibility of the ligands has great effect on the selectivity and sensitivity to Ag^+ ions.The electrode based on ionophore 9,10,20,25-tetrahydro-5H,12H-tribenzo[b,n,r][1,7,10,16,4,13]tetrathiadiaza cycloicosine 6,13-(7H,14H)-dione(C) with 2-nitrophenyl octyl ether(o-NPOE) as solvent in a poly(vinyl chloride)(PVC) membrane matrix sho...

INDUCTION OF ECTODERMAL CELLS FROM VEGETALENDODERMAL BLASTOMERES OF AMPHIOXUS(BRANCHIOSTOMA BELCHERI TSINGTAUNESE) EMBRYOS BY THE CALCIUM IONOPHORE A23187

Timing of vegetal-endodermal cell determination in amphioxus embryos remains uncertain. We tentatively testal effects of A23187, the calcium ionophore, on the deveopment of vegetal blastomeres isolated at the 16-cell stage. It was found that when vegetal blastomres committed to endodermwere treated with A23187 prior to gastrulation, they were transformed into ectodermal cells as evidenced by the cell morphology and function characteristic of epidermis. Howver, the developmental fate of the sam blastomeres untreated or treated with DMSO at the same stage or of those treated with A23187 after gastrulation remained unchanged. Thus, vegetal-endodermal cells in amphioxus embryos are not irreversibly deermined before the gastrula stage, and artificial incarease in intracelluar Ca2+ concentration can induce transdetermination of the predetermined endodermal cells into ectodermal cells.

A New Type of Dibenzoyl Tartaric Acid Selective Electrode Based on Polymer Membrane Containing Calixarene Ionophore

A new type of di benzoyl tartaric acid selective electr ode has been developed. Three double\| arm calixarene derivatives were emp loyed as the neutral ionophores. The poly(vinyl chloride) membrane electrode containing an amide derivative of ca lixarene as the neutral carrier an d a dibutyl phthalate as the plastici zer exhibited the highest sensitivity for dibenzoyl tartaric acid. The slop e of linear portion was 27.8 mV per c oncertration decade. The electrode has a fast response and a long lifetime .

Thiocyanate Ion Selective Solid Contact Electrode Based on Mn Complex of N,N'-BIs-(4-Phenylazosalicylidene)-O-Phenylene Diamine Ionophore

A thiocyanate ion selective poly(aniline) solid contact electrode based on manganese complex of N,N’-bis-(4-phenylazosalicylidene)-o-phenylene diamine ionophore was successfully developed. The electrode exhibits a good linear response of 58.1 mV/decade (at 20?C ± 0.2?C, r2 = 0.998) with in the concentration range of 1 × 10–1.0 ~ 1 × 10–5.8 M thiocyanate solution. The composition of this electrode was: ionophore 0.040, polyvinylchloride 0.300, dibutylphthalate 0.660 (mass). This dibutylphthalate plasticizer provides the best response characteristics. The electrode shows good selectivity for thiocyanate ion in comparison with any other anions and is suitable for use with aqueous solutions of pH 4.0 ~ 6.0. The standard deviations of the measured emf difference were ±1.70 and ±2.01 mV for thiocyanate sample solutions of 1.0 × 10–2 M and 1.0 × 10–3 M, respectively. The stabilization time was less than 170 sec. and response time was less than 17 sec.

Effect of Calcium Ionophore and Calcium Channel Blockers on Immediate Hypersensitivity Reactions

The release of mediators from mast cells is a model for cell secretion and is an in-vitro index for immediate hypersensitivity reactions. Calcium influx is generally accepted to be the primary biochemicalevent in mast cell activation.We studied the effect of the calcium ionophore A 23187 and calcium channelblockers,nifedipine and verapamil, in triggering the activation of rat peritoneal mast cells.At suitableconcentration nifedipine and verapamil have had the inhibition effect in the IgE-dependent roaction.

Solid-Contact Perchlorate Sensor with Nanomolar Detection Limit Based on Cobalt Phthalocyanine Ionophores Covalently Attached to Polyacrylamide

Novel solid-contact perchlorate sensors based on cobalt phthalocyanine-C-monocarboxylic acid (I), and cobalt phthalocyanine-C,C,C,C-tetracarboxylic acid (II) as free ionophores and covalently attached to polyacryla- mide (PAA)—ionophores III and IV, respectively were prepared. The all solid-state sensors were constructed by the application of a thin film of a polymer cocktail containing a phthalocyanine ionophore and cetyltrimethylammonium bromide (CTMAB) as a lipophilic cationic additive onto a gold electrode precoated with the conducting polymer poly (3,4-ethylenedioxythiophene) (PEDOT) as an ion and electron transducer. The sensor with 10.3% of ionophore (III) covalently attached to plasticizer-free poly (butyl methacrylate-co-do- decyl methacrylate) (PBDA) exhibited a good selectivity for perchlorate and discriminated many ions, in- cluding F–, Cl–, Br–, I–, SCN–, , S2– and . The covalent attachment of the ionophore to the polymer resulted in a near-Nernstian anionic slope of –62.3 mV/decade whereas a super-Nernstian slope of –79.9 mV/ decade was obtained for the free ionophore. The sensor covered a linear concentration range of 5 × 10–9 - 1 × 10–2 mol?L–1 with a lower detection limit (LDL) of 1 × 10–9 mol?L–1 and gave a stable response over a pH range of 4 - 10.5. The all-solid state sensors were utilized for the selective flow injection potentiometric determination of perchlorate in natural water and human urine samples in the nanomolar concentration range.

Is There Any Role for Calcium Ionophore in ICSI Cycles for Cases of Non Obstructive Azoospermia?

Objectives: Evaluate the effect of artificial oocyte activation (AOA) using calcium ionophore (A23187) on the rate of fertilization and cleavage of embryos in surgically retrieved sperm of patients with non-obstructive azoospermia undergoing intracytoplasmic sperm injection (ICSI). Study design: This study was conducted on 60 infertile couples undergoing ICSI cycles as a randomized controlled parallel group’s experimental study in a private IVF center in Egypt from January 2018 to July 2019. ICSI cycles were divided into two groups: Group A: includes 30 ICSI patients with surgically retrieved sperms of non-obstructive azoospermia treated with calcium ionophore (A23187). Group C/Control: includes 30 ICSI patients with surgically retrieved sperms of non-obstructive azoospermia non-treated with calcium ionophore (A23187). Results: There was no statistical difference between both groups regarding the fertilization rate (p = 0.853). There was no statistical difference between them regarding implantation rate (p = 0.237). The percentage of Class A embryos in the ca ionophore group was 81.7%, while it was 82.8% in the control group. There was insignificant difference between them (p = 0.782). There was no statistical significant difference between the two groups regarding the clinical pregnancy rate, it was (56.7%) in the ca ionophore group while it was (53.3%) in the control group. Conclusion: AOA by Ca2++ ionophore didn’t improve the outcome of ICSI cycle in cases of non obstructive azoospermia in terms of fertilization, implantation and pregnancy rate.

Revealing the kinetics of ionophore facilitating ion transport across lipid bilayers by surface enhanced infrared absorption spectroscopy

Ionophore can prominently improve the ion permeability of cell membrane and disrupt cellular ion homeostasis.Most studies regarding ionophore facilitating ion transmembrane transport focus on artificial liquid-liquid interfaces,which have large difference from the actual environment of cell membrane.Here,we construct a supported lipid bilayeron a gold nanoparticles film modified ZnSe prism as an appropriate model of cell membrane to investigate the dynamic of the ion transport facilitated by ionophore using surface enhanced infrared absorption spectroscopy(SEIRAS).We find that the ion transmembrane transport consists of two steps:The ion transmembrane transport starts with the association/disassociation between ion and ionophore at the edge of lipid bilayer;The second step is the transfer of ion-ionophore complex across lipid bilayer.Our results show that the complex transfer across the lipid bilayer is the rate determining step.

熊射出精子体外获能的研究

本文报道了用咖啡因和Ionophore A23187(Ⅰ-A)诱导熊射出精子体外获能的研究。用去透明带仓鼠卵穿透试验评价获能效果,用台盼兰—姬姆萨(TG)染色检测精子的死活及顶体形态。结果发现,咖啡因与Ⅰ-A能诱导熊精子体外获能,经获能处理的精子能穿入卵内,穿透率达70％以上,并能形成发育良好的雄原核。咖啡因与Ⅰ-A能在体外诱导熊精子的顶体反应,相关分析表明,有顶体反应活精子百分率与穿透率呈强正相关(r=0.94,n=6,P<0.01)。TG染色是检测精子顶体反应的有效手段,并能预测获能处理后精子的受精能力。

PVC Membrane Selective Electrode for Determination of Cadmium(Ⅱ) Ion in Chocolate Samples

Benzil bis(carbohydrazone)(BBC) is prepared and explored as new N N Schiff's base, which plays the role of an excellent ion carrier in the construction of a Cd(II) ion membrane sensor. The tris(2-ethylhexyl) phosphate best performance corresponds to a membrane composition of 30% poly(vinyl chloride), 65%(TEHP), 3.5% BBC and 1.5% tetradodecyl-ammoniumtetrakis(4-chlorophenyl) borate(ETH 500). This sensor shows very good selectivity and sensitivity towards cadmium ion over a wide variety of cations, including alkali, alkaline earth, transition and heavy metal ions. The effect of membrane composition, selectivity, pH and influence of additive on the response properties of electrode were investigated. The response mechanism was discussed in the view of UV-spectroscopy. The electrode exhibits a Nernstian behavior(with slope of 29.7 mV per decade) over a very wide concentration range from 1.0×10?1 to 1.0×10?8 mol·L?1 with a detection limit of 3.2×10?8 mol·L?1. It shows rela-tively fast response time in whole concentration range(<8 s) and can be used for at least 10 weeks in the pH range of 2.0-9.0. The proposed sensor is successfully used for the determination of cadmium in different chocolate sam-ples and as indicator electrode in titration with ethylene diamine tetraacetate(EDTA).

Correlation between inhibition of calcium-dependent apoptosis by cyclosporin A and calcium transportation in HL-60 cells

Both calcium ionophore A23187 and endoplasmic reticulum Ca2+- ATPase inhibitor thapsigargin (Tg) could increase intracellular free calcium concentration and induce apoptosis in some cell lines. In the present study, we found that HL-60 cells treated with A23187 (1μg/ml) for 4 h or with Tg (0.5μg/ml) for 2 h showed typical characteristics of apoptosis. Pretreatment with nontoxic concentration of cyclosporin A (CsA) (1μg/ml) Could block these effects. Flow cytometric analysis of intracellular Ca2+ after staining with fluo-3 AM showed that CsA did not prevent the increase of intracellular calcium induced by A23187 or Tg, but it could maintain the high level of intracellular Ca2+ for a long time. These results suggest that CsA may prevent calcium- induced apoptosis by blocking the transportation of Ca2+ in HL-60cells.

Study of Non-Ideal Effects for Extended Gate Field Effect Transistor Chlorine Ion Sensing Device

We use the extended gate field effect transistor (EGFET)as the structure of the chlorine ion sensor,and the chlorine ion ionophores (ETH9033 and TDDMAC1)are incorporated into solvent polymeric membrane (PVC/DOS),then the chlorine ion selective membrane is formed on the sensing window,and the fabrication of the EGFET chlorine ion sensing device is completed.The surface potential on the sensing membrane of the EGFET chlorine ion sensing device will be changed in the different chlorine ion concentration solutions,then changes further gate voltage and drain current to detect chlorine ion concentration.We will study non-ideal effects such as temperature,hysteresis and drift effects for the EGFET chlorine ion sensing device in this paper,these researches will help us to improve the sensing characteristics of the EGFET chlorine ion sensing device.

Chemically Modified Carbon Paste Electrode for Determination of Cesium Ion by Potentiometric Method

A new chemically modified carbon paste electrode for cesium(I) ion determination based on potassium zinc hexacyan-oferrate (PZHCF) as an ionophore was prepared. The electrode exhibits a Nernstian response for Cs(I) ions over a wide concentration range from 1 × 10-6 to 1 × 10-1 mol·L-1 with a slope of 58 ± 0.5 mV·decade-1. It has a response time of about 35 s and can be used for a period of 3 months with good reproducibility. Detection limit obtained in the optimal conditions was 3 × 10-7 mol·L-1. The potentiometric response is independent of the pH of the solution in the pH range 4.0 - 8.0. The electrode possesses the advantages of low resistance, fast response over a variety of other cations. The proposed electrode is applied as a sensor for the determination of Cs(I) ion concentration in different samples solutions. The results showed a good correlation with the data obtained by atomic absorption spectrometric method.

LINEAR POLYSILOXANE WITH DIBENZO-18-CROWN-6 MOIETIES AS LIQUID MEMBRANE CARRIER

A modified method of preparing crown functionalized linear polysiloxane has been described. 4'-Allyldibenzo-18-crown-6 was subjected to hydrosilylation with methyldichlorosilane, followed by polycondensation with silanol-terminated polydimethylsiloxane to give the title crown functionalized linear polysiloxane. The transport properties of sodium, potassium, and ammonium salt through a bulk liquid membrane system using the new type of crown functionalized linear polysiloxane as a carrier were investigated. It is worthy to point out that the carrier can be used repeatedly at least six runs with no apparent change in the transport rate of potassium ion.

APOPTOSIS INDUCED BY HYPERTHERMIA IN HUMAN GLIOBLASTOMA CELL LINE AND MURINE GLIOBLASTOMA

Objective: To study the role of apoptosis in tumor cell of malignant glioma death following treatment with hyperthermia and calcium ionophore. Methods: The apoptosis induced by hyperthermia and calcium ionophore, A23187, in human glioblastoma cell line TJ905 and murine glioblastoma G422 was evaluated by characteristic findings in DNA agarose gel electrophresis, ultrastructural examination and flow cytometric analysis. Results: Apoptosis could be induced by moderate hyperthermia, but not by mild hyperthermia, calcium ionophore enhanced significantly the effect of mild hyperthermia on the induction of apoptosis. Conclusion: This result indicates that apoptotic cell death is one of the mechanisms of hyperthermic therapy for malignant glioma and taking measures to increase the cytolic calcium may enhance the effect of hyperthermia.

Synthesis of N-(2-Hydroxy-1-Phenoxyacetyl)Prolyproline

Ionophores consist of molecules which surround and carry positive metal ions and other ions through biological membranes. One classe of ionophores which we have been developing contains dipeptides which are encouraged to become part of a ring because of possible hydrogen bond formation between the 2-hydroxy on the phenyl group and carboxyl group (COOH) of the final amide proline. Formation of a ring should increase the complexation ability of the ionophore. We report that the synthesis of N-(2-hydroxyl-1-phenoxyacetyl) prolyproline(1), a novel ionophore is prepared from activated 2-acetoxy phenoxyacetic acid (3a) and the appropriate dipeptide ester using coupling methods such as dicyclohexyl carbodiimide with hydroxyben-ztriazole or carbonyl diimidazole.

Finishing Cattle in All-Natural and Conventional Production Systems

Beef cattle producers in the North America have a variety of production and marketing options and must choose the best production system for their situation. This review describes considerations involved in choosing between feeding cattle conventionally versus feeding them in programs that prohibit the use of certain technologies. Data from peer-reviewed journals, extension publications, nutritional consultants, governmental organizations, and feed companies were used to construct this review. Most cattle in North America are fed in conventional production systems. Conventional beef production systems typically use steroidal implants, ionophores, and beta-adrenergic agonists to improve animal productivity;as well as feed grade and injectable antimicrobials to control, treat or prevent disease and improve animal health. These technologies have been shown to lower the cost of production, allowing for beef to be competitive in the global protein market. Some consumers have expressed a preference for beef produced without these technologies. These “All-natural” (AN) cattle may bring a premium price in the market. The economic impact of differing productions systems can be described in relation to 1) cost of production, 2) operating costs of the feedlot, 3) price paid for feeder calves, and 4) price received for fed cattle. Conventional production provides the most favorable outcome for factors 1, 2, and 3, while AN production provides the most favorable outcome for item 4. There are also industry wide and societal aspects related to differing beef production systems related to health and safety of beef, land use, and cost of production allowing for a greater share of the global protein market. Technologies used in conventional production are critical tools to North American beef production. Differences in efficiencies between each type of non-conventional production systems must be re-captured in added premiums when cattle are marketed and sold. Premiums for AN cattle are enticing, but the true differences in the cost of production between the AN and conventional cattle must be evaluated in order for a producer to make the correct decision for their operation.

The Relationship between Some lons and Acrosome Reaction of Human Sperm

The acrosome reaction of sperm was induced by calcium ionophore A 23187.The letionship between some ions and acrosome reaction by removing Na+ from the medium.or by adding angtagonist of K+.TEA chloride,or antagonist of Ca++,verapamil,or anlagonist of Na+-K+-ATPase,acetyl strophanthithidin is studied.The results show that Na+,H,Ca++ and Na+ pump are necessary.for acrosome reaclion of human sperm.The Ca++ might not enter the sperms through the channel of Ca++.

Preparation and Properties of a New Carbon Paste Iron Selective Electrodes and Their Applications

The new ferrous-selective modified carbon paste electrodes (I and II) based on 5,5’-(propane-1,3-diylbis(sulfanediyl))bis(3-benzyl-4H-1,2,4-triazol-4-amine) (electrode I, A-ionophore) and 5,5’-(butane-1,4-diyl-bis(sulfane- diyl))bis(3-benzyl-4H-1,2,4-triazol-4-amine) (electrode II, B-ionophore) as ionophores are described. These electrodes exhibit Nernstian slopes of 30.2 ± 0.5 and 29.1 ± 0.5 mV·decade-1, linear range of 1.0 × 10-7 - 1.0 × 10-2 mol·L-1 Fe(II) ion and detection limit of 1.0 × 10-7 mol·L-1 Fe(II) ion for electrode (I) and electrode (II), respectively. Both electrodes (I and II) have a fast response time of about 15 sand can be used for at least 3 months. The two electrodes revealed a good selectivity for Fe(II) over a wide variety of other metal ions and could be used in the pH range of 1.8 - 3.0 without any divergence in potential. The proposed sensors were successfully applied for the determination of Fe(II) ion in different real samples.

放线菌C-411发酵液抑菌活性及活性成分

为了明确放线菌C-411发酵液中的抑菌活性成分和评价其在农林病害防治中的潜在应用价值,采用抑菌活性追踪法,经大孔树脂吸附、硅胶柱层析及反相高效液相色谱等方法,从C-411菌株发酵液中分离得到1个抑菌活性化合物Za-1,经ESI-MS、NMR等波谱技术鉴定为聚醚类抗生素ionophore X-206。Za-1对枯草芽胞杆菌Bacillus subtilis、蜡状芽胞杆菌Bacillus cereus、金黄色葡萄球菌Staphyloccocus aureuse和猕猴桃溃疡病菌Pseudomonas syingae有强烈的抑制作用,其最小抑菌浓度分别为0.78、1.56、3.13和6.25μg/mL。Za-1对茄子黄萎病菌Verticillium dahliae、核果炭疽病菌Drupe anthrax和苹果炭疽病菌Colletotrichum gloeosporioides菌丝生长亦有明显的抑制作用,其抑制率分别为85.10%、87.66%和88.99%。研究表明化合物Za-1有开发成农用杀菌剂的潜力。