Iodine-129 in Thyroid Glands: A Sensitive Biological Marker of Fission Product Exposure

Iodine-129 may have no radiation hazard but it is a useful marker. Animal thyroids concentrate the isotope to 4 orders of magnitude greater than the intake. This results in a potential biological and physical indicator of radioiodine contamination. Since 1943, ¹²⁹I/¹²⁷I ratio in animal thyroids from the Northern Hemisphere has increased 2 to 5 orders of magnitude. Since 1985, thyroids of deer living near a nuclear reprocessing facility have contained ¹²⁹I, which are 3 to 7 orders of magnitude greater than pre-nuclear levels. Limited measurements of ¹²⁹I in thyroids from the Southern Hemisphere have shown little increase. An appendix is presented to show that ¹²⁹I, may be helpful to evaluate past radiation hazard from fission products.     

Analysis of Iodine-129 in Environmental Materials: Quality Assurance and Applications

The long-lived radionuclide ¹²⁹I (T _1/2 = 15.7 My) occurs in the nature in very low concentrations. Since the middle of our century the environmental levels of ¹²⁹I have been dramatically changed as a consequence of civil and military use of nuclear fission. Its investigation in environmental materials is of interest for environmental surveillance, retrospective dosimetry and for the use as a natural and man-made fracers of environmental processes. We are comparing two analytical methods which presently are capable of determining ¹²⁹I in environmental materials, namely radiochemical neutron activation analysis (RNAA) and accelerator mass spectrometry (AMS). Emphasis is laid upon the quality control and detection capabilities for the analysis of ¹²⁹I in environmental materials. Some applications are discussed.     

A Sensitive Colorimetric Method for the Determination of Arsenic in Environmental and Biological Samples

Results of a thorough study and application of leucocrystal violet for the determination of arsenic in parts per million (ppm) levels in environmental and biological samples is described here. The proposed method is based on the reaction of arsenic with potassium iodate to liberate iodine. The liberated iodine selectively oxidises leucocrystal violet to form crystal violet dye in the presence of sodium hydroxide. The dye formed shows maximum absorbance at 592 nm. The detection limit of arsenic is 0.002 μgmL^?1 and the method obeys Beer's law over the concentration range of 0.1 μg - 1.0 μg of per 25 mL of final solution (0.004–0.04 ppm). The molar absorptivity was found to be 1.49 × 10⁶ L mol^?1 cm^?1. The proposed method was successfully applied for the determination of arsenic in various environmental and biological samples. The results are in good agreement with the standard reported method.     

A Multi‐electrochemical Competitive Immunosensor for Sensitive Cocaine Determination in Biological Samples

A multi‐electrochemical competitive immunosensor for the rapid determination of unmetabolized cocaine (COC) in urine, saliva and human serum matrices is reported. Anti‐cocaine polyclonal antibodies were immobilized in an oriented way onto protein‐G functionalized magnetic beads. The immunosensor is based on an array of eight carbon‐based screen‐printed electrodes for simultaneous electrochemical determinations. The treatments of the biological samples were simplified and optimized for avoiding matrix interferences. The immunosensor was sensitive (EC₅₀≈2.92–3.88 ng mL^?1 COC), required a very small volume of sample (200 µL), was reproducible (%RSD was lesser than about 18 %), and accurate (recovery percentages ranged 88–117 %).     

A New and Highly Sensitive Spectrophotometric Determination of Monocrotophos in Environmental,Agricultural and Biological Samples

A new and highly sensitive spectophotometric method is developed for the determination of parts per million levels of widely used organophosphorus pesticide monocrotophos. The method is based on alkaline hydrolysis of monocrotophos to N‐methylacetoacetamide followed by coupling with diazotized p‐amino acetophenone in alkaline medium. The absorption maxima of the reddish‐violet coloured compound formed is measured at 560 nm. Beer's law is obeyed over the concentration range of 1.2 to 6.8 μg in a final solution volume of 25 mL. The molar absorptivity and Sandell's sensitivity were found to be 7.1 × 10⁵ (±100) L mole^?1 cm^?1 and 0.008 μg cm^?2, respectively. The standard deviation and relative standard deviation were found to be ± 0.005 and 2.05%, respectively. The method is simple, sensitive and free from interferences of other pesticides and diverse ions. The method has been satisfactorily applied to the determination of monocrotophos in environmental, agricultural and biological samples.     

毛细管电泳免疫化学发光高灵敏检测人血清中肿瘤标志物甲胎蛋白

本文首次报道了人血清免疫反应后直接进样并利用毛细管电泳分离化学发光灵敏检测AFP的新方法, 检测结果与医院使用的全自动微粒子化学发光仪检测结果吻合.     

Synthesis and Biological Evaluation of the Antimicrobial Natural Product Lipoxazolidinone A

Natural products have historically been a major source of antibiotics and therefore novel scaffolds are constantly of interest. The lipoxazolidinone family of marine natural products, with an unusual 4‐oxazolidinone heterocycle at their core, represents a new scaffold for antimicrobial discovery; however, questions regarding their mechanism of action and high lipophilicity have likely slowed follow‐up studies. Herein, we report the first synthesis of lipoxazolidinone A, 15 structural analogues to explore its active pharmacophore, and initial resistance and mechanism of action studies. These results suggest that 4‐oxazolidinones are valuable scaffolds for antimicrobial development and reveal simplified lead compounds for further optimization.     

加速器质谱法测定环境和生物样品中的129I

建立了环境和生物样品中的129I的分析方法,采用碱式灰化、萃取-反萃、沉淀等步骤对环境和生物样品中的碘进行预浓集,用131I[NaI] 为放射性示踪剂优化各分步的制备条件,运用加速器质谱法测定了北京地区松针和干草、青岛地区海藻和海水中的129I/127I.用超热中子活化法测定样品中的稳定碘(即127I)含量.上述松针、干草、海藻和海水样品中的129I/127I分别为8.11×10-9、5.97×10-9、1.70×10-10和6.05×10-10;相应的129I浓度分别为3.22×10-15、1.24×10-14、1.27×10-14 g/g干重和2.30×10-14 g/L.与文献报道值相比,我国与国外同类地区相当甚至更低,比法国和英国乏核燃料后处理厂附近环境中的129I低2～3个数量级,表明我国这些非核设施影响地区的129I处于当今全球环境的本底放射性沉降水平.     

A Multiwell-Based Assay for Screening Thyroid Hormone Signaling Disruptors Using thibz Expression as a Sensitive Endpoint in Xenopus laevis

There is a need for rapidly screening thyroid hormone (TH) signaling disruptors in vivo considering the essential role of TH signaling in vertebrates. We aimed to establish a rapid in vivo screening assay using Xenopus laevis based on the T3-induced Xenopus metamorphosis assay we established previously, as well as the Xenopus Eleutheroembryonic Thyroid Assay (XETA). Stage 48 tadpoles were treated with a series of concentrations of T3 in 6-well plates for 24 h and the expression of six TH-response genes was analyzed for choosing a proper T3 concentration. Next, bisphenol A (BPA) and tetrabromobisphenol A (TBBPA), two known TH signaling disruptors, were tested for determining the most sensitive TH-response gene, followed by the detection of several suspected TH signaling disruptors. We determined 1 nM as the induction concentration of T3 and thibz expression as the sensitive endpoint for detecting TH signaling disruptors given its highest response to T3, BPA, and TBBPA. And we identified betamipron as a TH signaling agonist, and 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) as a TH signaling antagonist. Overall, we developed a multiwell-based assay for rapidly screening TH signaling disruptors using thibz expression as a sensitive endpoint in X. laevis.     

LC with Fluorimetric Detection for Sensitive Analysis of Reduced Flubendazole in Biological Samples

A validated LC method is proposed for analysis of flubendazole and its metabolites in biological samples of Haemonchus contortus. Two detectors were used—photodiode-array and spectrofluorimetric. The native fluorescence of reduced flubendazole, the key substance investigated during biological experiments, was used for its fluorimetric detection with a very low limit of quantification (0.63 nmol L^?1).     

Sensitive Adsorptive Stripping Voltammetric Methodologies for the Determination of Melatonin in Biological Fluids

The reversible redox process that melatonin presented on carbon paste electrodes was the basis of a sensitive methodology for the determination of this hormone. From all the processes presented by this hormone, this was never used before as the basis of voltammetric measurements for melatonin determination. Therefore, parameters that affected the cyclic voltammetric signal were studied. A limit of detection as low as 9×10^?11 M was obtained when optimized alternating current voltammetry was employed. The reproducibility was excellent due to an adequate pretreatment of the solid electrode (RSD=2.7%, n=10). A comparison with methodologies that employ different electrochemical techniques from the point of view of their analytical characteristics was made. This methodology has proved to be suitable for the determination of melatonin in biological fluids.     

Observation and Measurement of 79Se in Savannah River Site High Level Waste Tank Fission Product Waste

We report the first observation of confirmed ⁷⁹Se activity in Savannah River Site high level fission product waste. ⁷⁹Se was measured after a seven step chemical treatment to remove interfering activity from ¹³⁷Cs, ⁹⁰Sr, and plutonium at levels 10⁵ times higher than the observed ⁷⁹Se content and to remove ⁹⁹Tc at levels 300 times higher than observed ⁷⁹Se. ⁷⁹Se was measured by liquid scintillation -decay counting after specific tests to eliminate uncertainties from possible contributions from ⁹⁹Tc, ¹⁴⁷Pm, ¹⁵¹Sm, ⁹³Zr, or ²⁴¹Pu, whose -decay spectra could appear similar to that of ⁷⁹Se, and whose content would be expected at levels near or greater than ⁷⁹Se.     

Iodine-129 and natural iodine-127 in deer thyroids from the environment of a small nuclear fuel reprocessing plant and from sites remote from nuclear facilities

Concentrations of the fission product¹²⁹I and natural¹²⁷I were determined in deer thyroids collected in the environment of the small Karlsruhe nuclear fuel reprocessing plant (WAK) and in a region remote from¹²⁹I sources of nuclear facilities. The isotopic ratio¹²⁹I/¹²⁷I in thyroids from the environment of WAK varies from 1.0×10^–6 to 12.9×10^–6, which is about one order of magnitude higher than the¹²⁹I/¹²⁷I ratios in thyroids from deer in a region remote from nuclear facilities. These ratios were between 0.2×10^–6 and 0.7×10^–6.     

超临界萃取与气相色谱-质谱联用技术在岩石样品生物标志物分析中的应用

生油岩、原油的抽提物都是由直链烃、异戊二烯类、蓓半萜、二萜、三萜和各种甾烷的成分组成.为了进行分析检测工作,测定感兴趣的生物标志化合物,通常要在样品分析之前进行分馏,采用硅胶-氧化铝柱层析法分别得到饱和烃、芳烃、非烃类馏分.但这种分馏方法进样量大,一般需要岩样150 g,而且手动操作,时间长,毒性大,分馏点控制稍有不慎就会造成芳烃、饱和烃中混有非烃而影响气质联用的检测,容易出现基线突起,或堵塞色谱柱等问题.超临界流体萃取是近几年来应用较多的1种新的采样技术,它已广泛应用于各个邻域,主要在食品工业[1]、天然产物和药物分析、化工产品、土壤分析[2]等领域得到了广泛地应用.也有关于超临界状态CO2对岩石中烃类物质的萃取与分离的报道[3],以及沉积岩中生物标识剂的分析[4],但没有做系统的工作.而我们则采用美国惠普公司生产的HP 7680T型超临界流体萃取仪,萃取效率高,芳烃、饱和烃1次得到,选择好色-质谱联用的分析条件,1次进样,就可定性感兴趣的大部分生物标志化合物.     

Electrochemical Investigation of Ruxolitinib: Sensitive Voltammetric Assay in Drug Product and Human Serum by Using Different Solid Electrodes

Ruxolitinib (RUX), a compound of the pyrrolopyrimidines class with activity as a tyrosine kinase inhibitory drug, is used to treat myelofibrosis. This study is reported for the detailed electrochemical behavior of RUX. The effects of supporting electrolyte, pH, and scanning rate on the peak potentials and currents of RUX were investigated by BDDE and GCE using different voltammetric techniques. Under optimum experimental conditions, calibration curves for RUX were obtained as 4 μM–80 μM and 1 μM–80 μM with a limit of detection (LOD) of 0.517 μM and 0.192 μM by the GCE and BDDE, respectively using DPV.     

中药制剂中绿原酸的电化学敏感测定及其与DNA的相互作用

制备了铂纳米粒子和聚3,4-乙烯二氧噻吩(PEDOT)修饰玻碳电极,并将此电极用于绿原酸的电化学研究。实验结果表明,相比裸电极,绿原酸在此修饰电极上的氧化还原峰电流均有所增加,尤以氧化峰电流增加显著。最佳实验条件下,绿原酸的氧化峰电流与其浓度在0.2~100μmol/L范围内呈良好的线性关系,检出限为0.05μmol/L。相比较已报道的其它方法,此方法线性范围较宽,检出限较低。将此电极用于中药制剂双黄连注射液中绿原酸含量的测定,测得加标回收率为97.7%~102.1%。对绿原酸与DNA的相互作用进行研究,得到它们的结合数为3,结合常数为1.62×103L/mol。相关参数可为绿原酸的药理研究以及相似药物的筛选提供参考与理论指导。     

A Novel Fission Process in Mini-emulsion RAFT Polymerization: Shell Crosslinked Nanoparticles as a Model

Shell crosslinked nanoparticles, prepared from copolymerization of styrene and disulfide crosslinker, using poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) as stabilizer and macroinitiator, exhibited a special fission behavior during the mini-emulsion RAFT polymerization process.     

A Simple and Sensitive Poly‐1,5‐Diaminonaphthalene Modified Sensor for the Determination of Sulfamethoxazole in Biological Samples

Sulfamethoxazole (SMZ), an antibacterial sulfonamide drug, has been selectively determined using poly‐1,5‐diaminonaphthalene (p‐DAN) modified glassy carbon electrode (GCE). The modified sensor was characterized by field emission scanning electron microscopy (FE‐SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). SMZ showed linear response in the concentration range of 0.5–150 µM by using square wave voltammetry (SWV) and the detection limit was found to be 0.05 nM with sensitivity of 0.085 µA µM^?1. The proposed sensor has been successfully employed to determine SMZ in the pharmaceutical tablets and human urine samples.     

Utilization of Immonium Product Ions for the Determination of Peptides with Intra-loops in Biological Matrices

Abstract

Triple quadrupole mass spectrometers are generally not considered a choice of instrument for determination of peptide molecules, for the reason that a collision cascade or a multiple fragmentation in the triple quadrupoles tends to decrease the sensitivity of peptide detection. Vasopressin, a peptide drug with an intra-chain disulfide bond, however, was found to generate a different fragmentation pattern. Its 20 member intra-loop went through an abrupt bond cleavage and structurally distinctive immonium ions produced in the secondary fragmentation were observed in abundance. With these immonium ions, an effective methodology for analyzing the peptides with intra-loops in biological matrices was developed in this report.