复合疲劳对大鼠不同组织矿物质代谢影响研究

目的:研究复合疲劳大鼠血液、肌肉、肝脏和脑中矿物元素代谢变化的影响。方法:将30只大鼠随机分为正常对照组、食物限制组和复合疲劳组。经过5天的实验干预后,提取动物的血液、腓肠肌、肝脏和脑,并利用原子吸收分光光度法测量各组织中的钾(K)、钙(Ca)、镁(Mg)、铁(Fe)、锌(Zn)和铜(Cu)。结果:相对正常对照组和食物限制组,复合疲劳大鼠的肌肉、肝脏和脑中的K(P<0.01)和肝脏中的Fe(P<005)明显升高,血液中的Cu(与正常对照组比较P<0.01,与食物限制组比较P<0.05)明显下降;与对照组相比,复合疲劳大鼠的血液中的K明显升高(P<0.05),血液中的Mg和Zn(P<0.05),肌肉中的Ca、Mg和Zn(PCa<0.05,PMg<0.05,PZn<0.01),肝脏中的Ca和Zn(PCa<0.01,PZn<0.05),以及脑中的Fe、Mg和Zn(PFe<0.05,PMg<0.05,PZn<0.01)明显降低。结论:在复合疲劳状态下,大鼠血液、肌肉、肝脏和脑中的K、Ca、Mg、Fe、Zn和Cu代谢发生变化,可能在疲劳的发生与缓解中发挥作用。     

Determination of zinc in vegetal tissue microsamples by platinum-wire loop in flame atomization atomic absorption spectrometry

The zinc content of 3 μL of vegetal samples (tree leaves, lichens and grape sap) atomized from a Pt-wire in the methane–air flame has been determined by atomic absorption spectrometry. The effect of gas flow rates and the atomization height in the flame on the absorption of zinc was evaluated at 213.9 nm. The best results were obtained at a height of 5 mm and gas flow rates of 200 L/h air and 26 L/h methane, respectively. The effect of Na, K, Ca, Mg, SO₄²⁻, and PO₄³⁻ on the absorption of zinc was studied too. The detection limit of 0.40 ± 0.21 ng was obtained at a significance level of 0.05, using the two-step Neyman–Pearson criterion. The zinc content of the samples has been determined with continuous nebulization and by atomization from the Pt-wire, using both the standard calibration curve and the standard addition method. The results of the two procedures agree within the determination errors.     

微波消解-FAAS法分析并比较旱芹(Apium graveolens L.)不同部位八种金属元素的含量

采用微波消解法处理旱芹根、茎、叶,并用火焰原子吸收法测定其中的Na、K、Ca、Mg、Fe、Mn、Zn、Cu 8种金属元素的含量。结果表明:旱芹中富含人体必需的Na、K、Mg、Fe、Ca等元素,各元素在不同部位含量有一定差异。Fe元素在旱芹根中含量为883.57μg.g-1,明显高于茎和叶;Ca、Zn和Mn元素在旱芹叶中的含量分别为11 103.74,214.04,88.07μg.g-1,明显高于茎和根;K、Na和Mg元素在旱芹茎中的含量高于根和叶中,Cu元素含量在各部位差异不大。方法的加标回收率为96.8%～105.8%,相对标准偏差(RSD)≤3.36%。     

Diagnostic potential of trace metals concentration in expressed prostatic secretion and serum of patients with category IV prostatitis

BackgroundThe National Institutes of Health (NIH) category IV prostatitis is a painless prostate gland inflammation, just as its name implies, this type of prostatitis is related with inflammation of the prostate, but most men are not conscious of it. However, category IV prostatitis is fairly common in general populations and reported having indirect relationships with prostate cancer.MethodWe analyzed the concentration of zinc (Zn), copper (Cu), calcium (Ca) and magnesium (Mg) in expressed prostatic secretion (EPS) and serum of patients with category IV prostatitis and healthy controls, investigating the diagnostic potential of different metals in category IV prostatitis using a flame atomic absorption spectrometer (FAAS).ResultsMetal concentration combined clinical characteristics analysis suggested that average level of Zn, Ca, Mg were significantly lower in the EPS of patients with category IV prostatitis (P-value< 0.000), while Cu level raised obviously (P-value< 0.000). And in the serum, mean concentrations of Ca was also found to increase significantly in the patients with category IV prostatitis compared to healthy controls. Moreover, the correlation analysis indicated that age showed a positive correlation with EPS Zn, Ca, Mg concentration (P-value< 0.05), while albumin correlates with EPS Zn, Ca, Mg concentration reversely (P-value< 0.05) in patients with category IV prostatitis.ConclusionOur report revealed that determination of the metal elements zinc, copper, calcium and magnesium in the serum and EPS could be a new and promising strategy for the rapid diagnosis of category IV prostatitis.     

Determination of Heavy Metals and Their Distribution In Different Size Fractionated Sediment Samples Using Different Analytical Techniques

Distribution of heavy metals (Pb, Cu and Cd) in different size-fractionated sediment samples was studied using different analytical techniques such as flame atomic absorption spectrometry (FAAS), inductively coupled plasma atomic emission spectrometry (ICP-AES) and differential pulse anodic stripping voltammetry (DPASV). Pb and Cu concentrations were found to have respective variations of 6.58% and 9.45% from FAAS, ICP-AES and DPASV analysis. Cadmium was detectable only by DPASV because of its lower abundance in different size fractions. The percentage distribution of total organic carbon (TOC) and heavy metals increased with decrease in particle size. Metal concentrations increase with increasing TOC content in different size-fractionated sediment samples studied. Although the smallest fractions (< 53 μm) of sediment contributed only 3.4–17.8%, they had the highest mean distribution factor of 1.08 for Pb, 1.04 for Cu and 1.06 for Cd, respectively. Pb, Cu and Cd were correlated positively with organic carbon content in the sediment samples.     

Serum zinc levels and Alzheimer’s disease

Concentrations of zinc in postmortem serum and four brain regions were measured by flame atomic absorption spectrometry and instrumental neutron activation analysis, respectively, in nine Alzheimer’s disease (AD) and eight control subjects. A statistically significant elevation of zinc serum was observed in AD subjects (136.4±66.8 μg/dL) compared with age-matched control subjects (71.1±35.0 μg/dL). No significant differences were observed between AD and control zinc concentrations in the amygdala, hippocampus, cerebellum, and superior and middle temporal gryi.     

Energetics,conformation, and recognition of DNA duplexes containing a major adduct of an anticancer azolato-bridged dinuclear Pt complex

Background

The design of anticancer metallodrugs is currently focused on platinum complexes which form on DNA major adducts that cannot readily be removed by DNA repair systems. Hence, antitumor azolato-bridged dinuclear Pt^II complexes, such as [{cis-Pt(NH₃)₂}₂(μ‐OH)(μ-pyrazolate)]²⁺ (AMPZ), have been designed and synthesized. These complexes exhibit markedly higher toxic effects in tumor cell lines than mononuclear conventional cisplatin.

Methods

Biophysical and biochemical aspects of the alterations induced in short DNA duplexes uniquely and site-specifically modified by the major DNA adduct of AMPZ, namely 1,2-GG intrastrand cross-links, were examined. Attention was also paid to conformational distortions induced in DNA by the adducts of AMPZ and cisplatin, associated alterations in the thermodynamic stability of the duplexes, and recognition of these adducts by high-mobility-group (HMG) domain proteins.

Results

Chemical probing of DNA conformation, DNA bending studies and translesion synthesis by DNA polymerase across the platinum adduct revealed that the distortion induced in DNA by the major adduct of AMPZ was significantly less pronounced than that induced by similar cross-links from cisplatin. Concomitantly, the cross-link from AMPZ reduced the thermodynamic stability of the modified duplex considerably less. In addition, HMGB1 protein recognizes major DNA adducts of AMPZ markedly less than those of cisplatin.

General significance

The experimental evidence demonstrates why the major DNA adducts of the new anticancer azolato-bridged dinuclear Pt^II complexes are poor substrates for DNA repair observed in a previously published report. The relative resistance to DNA repair explains why these platinum complexes show major pharmacological advantages over cisplatin in tumor cells.     

鸭儿芹及制品中矿质元素分析

采用空气-乙炔火焰原子吸收法,测定了鸭儿芹及制品中钾、钙、钠、镁、铁、锌、锰、铜等8种矿质元素.对测定分析条件进行了实验,以氯化铯为电离抑制剂,用氯化锶消除磷对钙的干扰,盐酸浓度控制在2%以内,获得了满意效果.实验加标回收率为90.5%～108.2%,相对偏差为0.3%～0.7%,适合于植物材料中微量元素的分析测定.实验结果表明:鲜鸭儿芹中钾含量很高,达到44.774 mg/g,钙含量达到11.296 mg/g,同一元素在不同制品中含量存在明显差异.     

中药及中药制剂中微量元素铜、铬的含量测定

应用火焰原子吸收光度法(FAAS)对苦参、黄柏及黄柏胶囊中微量元素铜、铬的含量进行了测定,并对FAAS若干条件进行了优化选择。结果表明,该法的平均回收率在95.2%～104.8%之间,相对标准偏差在1.76%以下,结果可靠,方法简便,可用于实际样品的测定。     

A Zinc Site in the C-Terminal Domain of RAG1 Is Essential for DNA Cleavage Activity

The recombination-activating protein, RAG1, a key component of the V(D)J recombinase, binds multiple Zn²⁺ ions in its catalytically required core region. However, the role of zinc in the DNA cleavage activity of RAG1 is not well resolved. To address this issue, we determined the stoichiometry of Zn²⁺ ions bound to the catalytically active core region of RAG1 under various conditions. Using metal quantitation methods, we determined that core RAG1 can bind up to four Zn²⁺ ions. Stripping the full complement of bound Zn²⁺ ions to produce apoprotein abrogated DNA cleavage activity. Moreover, even partial removal of zinc-binding equivalents resulted in a significant diminishment of DNA cleavage activity, as compared to holo-Zn²⁺ core RAG1. Mutants of the intact core RAG1 and the isolated core RAG1 domains were studied to identify the location of zinc-binding sites. Significantly, the C-terminal domain in core RAG1 binds at least two Zn²⁺ ions, with one zinc-binding site containing C902 and C907 as ligands (termed the CC zinc site) and H937 and H942 coordinating a Zn²⁺ ion in a separate site (HH zinc site). The latter zinc-binding site is essential for DNA cleavage activity, given that the H937A and H942A mutants were defective in both in vitro DNA cleavage assays and cellular recombination assays. Furthermore, as mutation of the active-site residue E962 reduces Zn²⁺ coordination, we propose that the HH zinc site is located in close proximity to the DDE active site. Overall, these results demonstrate that Zn²⁺ serves an important auxiliary role for RAG1 DNA cleavage activity. Furthermore, we propose that one of the zinc-binding sites is linked to the active site of core RAG1 directly or indirectly by E962.