Microcalorimetric Study on Effect of Chromium(III) and Chromium(VI) Species on the Growth of Escherichia coli

The effects of Cr(III) and Cr(VI) species (Cr₂O₇^2?, CrO₄^2? and Cr³⁺) on the growth of Escherichia coli (E. coli) have been investigated in detail by microcalorimetry at 37 °C. Parameters including the growth rate constant (k), inhibitory ratio (I), half‐inhibitory concentration (IC₅₀), total heat output (Q_total), time of the maximum heat production (t_log) in the log phase have been obtained. The results showed that Cr(VI) and Cr(III) had the inhibition effect on the growth of E. coli in aquatic environment; however, the inhibitory ratio of Cr(III) to E. coli was smaller than that of Cr(VI). The k values of E. coli in the presence of Cr(VI) and at high concentrations of Cr(III) were decreased with increasing the concentrations of these chromium species. Among the three chromium species investigated, Cr₂O₇^2? was found to be the most poisonous species against E. coli with an IC₅₀ value of 35.52 µg·mL^?1. CrO₄^2? exhibited moderate toxicity on E. coli with an IC₅₀ of 50.24 µg·mL^?1, and Cr³⁺ had the lowest toxicity with an IC₅₀ of 84.30 µg·mL^?1. Microcalorimetry can provide a convenient, sensitive and reliable method to study the effect of various metal species on the growth of bacteria or other microorganisms.     

试谈中国特色的现代微量元素研究

中国微量元素研究取得了处于国际前沿的研究成果,逐渐形成了具有中国特色的微量元素医学的完整体系,形成了元素基础医学学派、元素形态分析学派和元素组学研究学派。微量元素知识普及、期刊论文和会议论文、学位论文、专利项目、基金资助项目、图书出版、元素形态分析、微量元素组学等8个方面发生了翻天覆地的变化。首创微量元素组学研究,成功地破解了临床医学和中药传统理论中一系列关键问题,发现微量元素的双面效应。     

Carcinogenic Chromium(VI) Compounds Formed by Intracellular Oxidation of Chromium(III) Dietary Supplements by Adipocytes

Chromium(III) nutritional supplements are widely consumed for their purported antidiabetic activities. X‐ray fluorescence microscopy (XFM) and X‐ray absorption near‐edge structure (XANES) studies have now shown that non‐toxic doses of [Cr₃O(OCOEt)₆(OH₂)₃]⁺ ( A ), a prospective antidiabetic drug that undergoes similar H₂O₂ induced oxidation reactions in the blood as other Cr supplements, was also oxidized to carcinogenic Cr^VI and Cr^V in living cells. Single adipocytes treated with A had approximately 1 μm large Cr hotspots containing Cr^III, Cr^V, and Cr^VI (primarily Cr^VI thiolates) species. These results strongly support the hypothesis that the antidiabetic activity of Cr^III and the carcinogenicity of Cr^VI compounds arise from similar mechanisms involving highly reactive Cr^VI and Cr^V intermediates, and highlight concerns over the safety of Cr^III nutritional supplements.     

Spectrophotometric Determination of Trace Chromium(VI) in Mass Chromium(III)

There is little conclusive evidence of the toxic effects of Cr(III) so far, but Cr(VI) has carcinogenic activity, so the analysis of the chromine ions is very important in environmental research and the quality control of industry products. Usually Cr(III) and Cr(VI) interfere with each other in the species analysis, the measurement of Cr(VI) of numerous previous papers is related to the Cr(VI) samples, which contain a little Cr(III). When the amount of trivalent chromine exceeds ten …     

Evaluation of Hypoglycemic Activity and Sub-Acute Toxicity of the Novel Biochanin A–Chromium(III) Complex

The novel biochanin A–chromium(III) complex was synthesized by chelating chromium with biochanin A (BCA). The structure of the complex was determined and the complex ([CrBCA₃]) was composed of chromium(III) and three ligands, and the chromium content was 55 μg/mg. The hypoglycemic activity of the complex was studied in db/db mice and C57 mice. The sub-acute toxicity test of the complex was carried out by the maximum limit method in KM mice. The hypoglycemic activity showed that the complex could reduce the weight of db/db mice and lower the fasting blood glucose and random blood glucose levels. The complex also improved the organ index, oral glucose tolerance test (OGTT) and insulin tolerance test (ITT) results of db/db mice, and some of the indicators were similar to those of the positive control group after treatment with the complex. The histopathology study showed significant improvements in the liver, kidney, pancreas and skeletal muscle compared with the diabetes model group. The complex also showed a significant improvement in serum biochemical indices and antioxidant enzyme activities, as well as glycogen levels. The sub-acute toxicity study showed that the complex did not cause death or any dangerous symptoms during the study. In addition, the sub-acute toxicity study showed that the complex had no significant effect on the serum biochemical indices, antioxidant capacity and organs of normal mice. This study showed that [CrBCA₃] had good hypoglycemic activity in vivo and had no sub-acute toxicity. This work provides an important reference for the development of functional hypoglycemic foods or drugs.     

新型抗糖尿病铬(III)配合物的合成和生物活性及机理探究

为了寻找新型的抗糖尿病分子,以苯乙双胍为前体,制备了苯乙双胍铬（III）配合物.通过元素分析、摩尔电导率、电喷雾质谱、红外光谱、紫外可见光谱和核磁共振波谱对配合物的结构进行了表征,并研究了配合物在不同温度、不同pH值下溶液的稳定性、与H₂O₂的反应性和形貌.同时,构建了糖尿病C57小鼠模型,研究了其生物活性和毒性.结果证明,配合物对其活性指标均有好的抑制作用,保留了苯乙双胍的降糖性质,对机体是无毒的,并且通过MTT（3-（4,5-二甲基噻唑-2）-2,5-二苯基四氮唑溴盐）实验说明配合物的生物相容性较好,实现了金属配合物降糖与控脂的多功能化应用.在此基础上,通过光谱法研究了配合物与胰高血糖素的相互作用,表明配合物对胰高血糖素是静态猝灭以较强的作用力结合,条件结合常数为1.29×10⁵ L·mol^-1,结合位点数约为1,初步提出了配合物的新的降糖机制.     

Minor and Trace Element Analysis in Breast Milk Using Inductively Coupled Plasma Mass Spectrometry (ICP-MS)

 Thirty-two breast milk samples provided voluntarily by healthy women living in the Dongting Lake area were investigated by Inductively Coupled Plasma Mass Spectrometry (ICP/MS). Eleven minor and trace elements (Na, Mg, K, Ca, Mn, Fe, Cu, Zn, As, Se and Pb) were quantified and compared with literature reports. The results provide useful data for further studies in the nutritional field. Author for correspondence. E-mail: zhengmh@mail. rcees.ac.cn Received September 4, 2002; accepted February 11, 2003 Published online May 15, 2003     

Speciation Determination of Chromium(VI) and Chromium(III) in Soil Samples after Cloud Point Extraction

Abstract

To measure the different activity of chromium(VI) and chromium(III) in soil samples, chromium(VI) and total chromium (CrVI + CrIII) was extracted by KCl extracting agent and alkali fusion, respectively. Cloud point extraction (CPE) for speciation determination of chromium with double-slotted quartz tube atom trap–flame atomic absorption spectrometry (STAT-FAAS) was developed. Preconcentration of chromium(VI) and total chromium in different pH solutions was achieved by CPE, with ammonium pyrrolidine dithiocarbamate (APDC) as the chelating agent and Triton X-114 as the cloud point extractant. The conditions of CPE and determination were studied. Under the optimal conditions, the enrichment factor was 50 for chromium from the initial 100-mL sample solution to the final 2-mL determined solution. Compared to the FAAS method, the sensitivity was improved seven-fold for chromium by the STAT-FAAS method. The limit of detection was 0.082 µg/L for chromium.     

Kinetic and Equilibrium Studies of Chromium(III) Removal by Macroporous Ion Exchanger Amberlyst‐15 (H+)

Chromium(III) sorption on macroporous strong cation exchanger Amberlyst‐15 (H⁺) was studied as a function of time and temperature. The rate constant values for chromium(III) sorption were calculated both for film and particle diffusion processes. The temperature was found to have a positive effect on both the diffusional processes. From the rate constant values, the energy of activation was calculated using the well‐known Arrhenius equation. The high values of energy of activation confirmed the film diffusional nature of the process. Equilibrium data were explained with the help of Langmuir equation. Various thermodynamic parameters (ΔH^?, ΔS^? and ΔG^?) from chromium(III) exchange on the resin were calculated. The ΔG^? values were found to be negative while both the ΔH^? and ΔS^? were positive.     

精制蝮蛇抗栓酶对人体内锌铜铁的影响

对126例脑血栓形成患者用精制蝮蛇抗栓酶（Svate-3)治疗,探讨了用药前后头发微量元素锌、铜、铁的变化。结果表明,用药后人体内Zn含量高地用药前,且有显著性差异（P＜0.01)。Zn/Cu比值降低。     

Crystal Structure and Spin Frustration Behavior of an Oxo‐centered Trinuclear Chromium(III) Complex

A trinuclear chromium(III) complex, [Cr₃O(HCO₂)₆(CH₃OH)₃]NO₃·H₂O·CH₃OH ( 1 ), is synthesized and structurally characterized by single‐crystal X‐ray diffraction. Three chromium(III) ions are bridged by one oxygen atom in the center, forming a triangular structure. The HCOO ^? anion acts as bidentate ligand and bridges couples of Cr(III) ions. Magnetic susceptibility measurement indicates that a strong antiferromagnetic interaction is operative between chromium(III) ions, and the S = 1/2 ground state reveals normal spin frustration behavior.     

Biosorption of Chromium(III) by Biomass of Seaweed Sargassum sp. in a Fixed-Bed Column

This work aimed at modeling chromium biosorption using the biomass of seaweed Sargassum sp. in a fixed-bed column. The mathematical model used was obtained from the mass balance of the component in the liquid phase and in the biosorbent material. The effects of both axial dispersion in the column and the resistance to mass transfer in the solid were considered for the solution of the partial differential equations of the model, using the Galerkin method on finite elements. To represent the equilibrium data of the batch system the Langmuir isotherm were used. The chromium ion adsorption capacity of the seaweed Sargassum sp., at a temperature of 30°C and pH 3.5, was 2.61 mmol/g. The model performance was evaluated from experimental data obtained at 30°C for flow rates of 2, 6 and 8 mL/min. The parameters of the model, mass transfer and axial dispersion coefficients, were adjusted from these experimental data. The model proved adequate to describe chromium biosorption dynamics in fixed-bed columns.     

Trace,Alkaline and Alkaline-Earth Elements in Sea Water Samples from Terra Nova Bay - Ross Sea (ANTARCTICA): A Three-Year Period of Observation

Abstract

This report concerns the correlation of the analytical results relevant to some elements obtained in filtered sea water samples collected in Terra Nova Bay and the Ross Sea (Antarctica) during three Italian expeditions. The following ranges of variability of the medians of total concentrations (ng/l) - which include time effect among expeditions and bias effect among participant groups - were found for trace elements (single values refer to elements which were only determined once by one laboratory): Sb (260), As (1.2 10³), Cd (5–50), Cr (120), Co (4), Cu (110–230), Fe (435–445), Pb (6–52), Mn (15–88), Hg (3), Ni (185–580), Se (30) and Zn (242–265). Speciation studies pointed out that 10–40% of Cd, 15–60% of Cu and 20–50% of Pb were present in the samples as an ASV-labile fraction.

As for alkaline and alkaline-earth elements, the following concentration ranges in surface sea waters, expressed in mM, were found: Li ([1.4–3.0] 10^?2), Na (394–480), K(5.1–9.9), Ca (6.4–14.7), Mg (46.2–59.0) and Sr ([7.6–10] 10^?2).

Inter- and intra-laboratory data comparison, incorrect results, local variations of concentration, including pollution effects and pack melting effect, are discussed in detail.     

微波等离子体原子发射光谱法(MP-AES)测定米粉中的常量、微量和痕量元素

采用4200型微波等离子体原子发射光谱法(MP-AES)分析米粉中的镉和其它常量、微量以及痕量元素。对标准样品(CRM)的测定值与标准值十分吻合,检出限(MDL)足以满足分析需求,并且具有出色的长期稳定性。实验中无需使用改性剂或离子抑制剂,从而简化了样品前处理过程。4200 MPAES具有出色的分析性能,可分析火焰原子吸收法(FAAS)无法分析的磷元素、能够进行多元素无人值守操作、拥有更高的安全性和易用性,是期望获得新技术的FAAS用户的理想选择     

Chromium speciation studies in human plasma and stability studies of Cr(III) and Cr(VI) species in a candidate water reference material

The aim of the research on Cr-speciation in plasma is to study the distribution of Cr over the plasma proteins. Cr is known to be mainly bound to transferrin and albumin. Therefore, a suitable separation procedure was developed for the two proteins. It consisted of a combination of FPLC cation and anion exchange, ensuring a complete resolution of both proteins and a total recovery of the Cr.In order to investigate the environmental impact of Cr(III) and Cr(VI) discharges, an aqueous reference material is needed to assess the quality of measurement between different laboratories. A pilot study was initiated to investigate the stability of a Cr(III) and Cr(VI) mixture in a bicarbonate/ carbonate buffer. Different parameters liable to influence the stability of the solutions have been investigated.     

电感耦合等离子体质谱法(ICP-MS)测定古造液酒中微量元素含量及功能评价

目的测定古造液酒中微量元素含量,并与饮用白酒、国囍酒比较,看其微量元素含量高低情况。方法采用电感耦合等离子体质谱法(ICP-MS)测定微量元素含量。检测限为0.30~3.43μg·L~(-1),回收率范围在95.4%~104.3%,相对标准偏差(RSD)范围在1.1%~2.0%。结果测定方法准确可靠。古造液酒中的微量元素明显高于饮用白酒和国囍酒。结论古造液酒富含微量元素,具有较高的临床价值。     

Flow-Injection Chemiluminescence as a Means of Studying the Metabolism of Unbound Chromium(III) in Rabbit Blood with On-Line Microdialysis Sampling

In this paper, we present an in-vivo, on-line, real-time analytical system for monitoring the metabolism of free chromium(III) in rabbit blood. This system includes microdialysis sampling, ion-exchange on-line separation and chemiluminescence detection. The results show that none of the co-existing substances in the blood, including protein and other small molecules, interfere with the determination. CrCl₃·6H₂O was administrated orally (0.5 g), and the microdialysis probe was utilized to sample rabbit blood with a perfusion rate of 10 µL min⁻¹. The dialytic efficiency of chromium(III) under the experimental conditions was 18.1 ± 5.1% (n=3). The concentration-time curve of chromium(III) is in accordance with the one-compartmental open model, the T_1/2 is 16.62 min.     

Trace metal accumulation in tissues of sole (Solea senegalensis) and the relationships with the abiotic environment

The distribution patterns and the organ-specific accumulation trends of 10 trace metals (iron, manganese, zinc, copper, chromium, nickel, cobalt, lead, cadmium and silver) and 4 major elements (sodium, potassium, calcium and magnesium) in 10 different tissues (heart, muscle, kidney, stomach, intestine, liver, gill, gonads, white skin and dark skin) of a benthic fish species (Solea senegalensis) from a densely populated coastal area affected by anthropogenic activities, the Bay of Cadiz (SW Spain), have been investigated. High variability of metal concentrations among tissues were found for Ca, Fe, Zn, Cu, Pb and Ag. Factor analysis was applied to study this variability. Five principal components were found explaining the 92.95% of the total variance and similarities in behavioural patterns of bioaccumulation were described. They associated Mg, Cr, Ni and Mn to intestine and stomach tissues (PC1), Ag, Cu and Cd to liver (PC2), Zn, K and Co to gonads (PC3), Na, Fe and Pb to gill, heart and kidney tissues (PC4) and Ca, Pb and Mn to gill and dark skin (PC5). The metallic concentration in the sediment and water was also studied. The pollution in this area was found moderate with outstanding values of Zn, Cu and Pb (average values of 139, 50.4 and 75.6?mg?kg^?1, respectively) in sediment and dissolved Cu (average value of 2.5?µg?L^?1). Metal bioconcentration trends followed the order Zn?>?Cu?>?Cd?>?Pb for dissolved metals in seawater, Cu?>?Zn?>?Cd?>?Pb?≈?Mn?>?Fe?≈?Ni?≈?Co for metals associated to particulate matter and Zn?≈?Cu?>?Cd?>?Mn?>?Co?≈?Fe?>?Ni?≈?Pb?>?Cr for metals in the sediment. Higher values were found for copper in liver, zinc in gonads and lead in gill, showing the relationship between biotic and abiotic environment. In addition, Cd bioconcentration factors were found high in liver and gill showing the sensitivity of sole to this metal even at low concentrations.     

铬(III)离子催化铈(IV)离子氧化四氢糠醇的反应动力学及机理

在酸性介质中用氧化还原滴定法研究了铈(IV)离子在铬(III)离子催化作用下,于25～40℃区间氧化四氢糠醇的反应动力学.结果表明反应对铈(IV)和四氢糠醇均为一级.准一级速率常数kobs随催化剂[Cr(III)]增加而增大,亦随[H+]增加而增大,而随[HSO-4]增加而减小.在氮气保护下,反应不能引发丙烯酰胺聚合,说明在反应中没有自由基产生.提出了催化剂、底物和氧化剂间生成双核加合物的反应机理.通过kobs与HSO-4的依赖关系,并结合Ce(IV)在溶液中的平衡,找到了本反应体系的动力学活性物种是Ce(SO4)2.还计算出一些速率常数及相应的活化参数.