过渡金属离子荧光探针——2,6-二氨基吡啶的研究

研究了2,6-二氨基吡啶(DAPD)与金属离子作用前后的荧光光谱和吸收光谱。结果表明,在加入过渡金属离子后,其发射光谱和吸收光谱产生红移,且光谱强度随金属离子浓度的加大而增强;但加入K+,Na+,Mg2+,Ca2+,Pd2+等金属离子后,DAPD无响应。根据Irving-Williams顺序,以过渡金属中络合能力较强的Cu2+为代表,考察了其对DAPD吸收光谱及荧光光谱的影响。Cu2+浓度在2.5×10-7～3.5×10-6mol/L范围内与荧光强度呈线性关系,求算出DAPD与Cu2+的结合比为2∶1。比     

Protein cleavage by transition metal complexes bearing amino acid substituents

In this report, we describe protein damage by a series of metal complexes that mediate the formation of hydroxyl radical. The protein targets used are bovine serum albumin (BSA) and carboxypeptidase A (CPA). BSA contains several electrostatic, hydrogen bonding and hydrophobic binding sites for potential interaction with the metal complexes, and CPA contains a specific phenylalanine binding site. The data presented in this study show that aromatic side chain damage and backbone cleavage occur to similar extents with all the complexes. Reasonable levels of backbone cleavage specificity can be attained with relatively few recognition elements, despite the fact that a diffusible radical mediates cleavage. Incorporation of additional recognition elements can enlarge the set of cleavage sites. We show that the chemical environment of the cleavage reaction, manipulated by using different buffers, can dramatically affect the outcome of the cleavage reaction. Our work suggests that backbone cleavage site is determined by three factors: the binding sites of the metal complexes, the role of reactive sites on the protein backbone, and the influence of the chemical environment on the reaction.     

Role of sodium ions in the protective action of nucleotides and their hydrolytic products in calcium paradox

Nucleotides were examined for their effects on the development of calcium paradox in the isolated rat heart. The protective action of nucleotides was found to be unassociated with the structure of their nitrogen base. The products of extracellular hydrolysis, such as ribose (deoxyribose), uridine or adenosine at a concentration of 100 microM caused no less protective effects than nucleotides. In calcium paradox, the protective action of adenosine was not suppressed by theophylline, but sensitive to dipyridamole and transmembrane Na gradient values. Nucleotides and their hydrolytic products were demonstrated to exert a positive myocardial effect not only at the physiological (140 microM), but increased Na ion concentrations. The high extracellular Na concentration-induced potentiation of the protective action of nucleotides or their hydrolytic products was blocked by strophanthin. It is suggested that the high Na gradient can increase the protective action of nucleotides and their hydrolytic products due to decreased Na-Ca metabolism and to the altered metabolism of nucleotide hydrolytic products.     

Selective absorption of copper,nickel, cobalt and other transition metal ions from sulfuric acid solutions with the chelating ion exchange resin XFS 4195

Data for the distribution of a number of common metal cations between sulfate solutions and the chelating ion exchange resin XFS 4195 are presented. The effects of pH and metal ion concentration are shown, and some data are presented on the effects of sulfates on absorption and on the selectivities for various pairs of ions. The general order of affinity of the resin for ions is Cu(II) ? UO₂(VI) > Ni(II) > Fe(III) > Zn(II) > Co(II) > Cd(II) > Fe(II). Except for copper, which is strongly absorbed even in 3 N sulfuric acid, absorption of all metal ions is relatively low in acid solutions below pH 1, but rises to a maximum at about pH 3. Elution of most metal ions is therefore readily accomplished with dilute mineral acid; elution of copper requires ammonium hydroxide.     

The effects of alkaline earth metal ions and halogen ions on the chromium oxide activities in alkaline earth metal oxide-halide-Cr2O3 system fluxes

The solid electrolyte cell — Mo|Cr + Cr₂O₃‖ZrO₂(MgO)‖{Cu-Cr}_alloy + (Cr₂O₃)_fluxes|Mo+ is used at 1673 K to determine Cr₂O₃ activities in MO-MX ₂-Cr₂O₃ (M = Ca²⁺, Ba²⁻, X = F⁻ or Cl⁻) ternary fluxes, which are in equilibrium with the copper-chromium binary alloy. The ternary isothermal phase diagrams of CaO-CaF₂-Cr₂O₃ and BaO-BaCl₂-Cr₂O₃ system fluxes are inferred on the basis of the experimental results and binary phase diagrams. The results indicate that Cr₂O₃ activities in all fluxes always decrease with the increase of the X _MO /X _MX2 ratio. Partial replacement of BaO in BaO-BaF₂-Cr₂O₃ fluxes by CaO is acceptable for economy and efficiency considerations. At the same time, partial substitution of BaO for CaO in CaO-CaF₂-Cr₂O₃ fluxes is advantageous for phosphorus removal and chromium retention as a result of the increased Cr₂O₃ activities, increased basicities, and widening of the liquid zones. Compared to those in BaO-BaF₂-Cr₂O₃ fluxes, Cr₂O₃ activities in CaO-CaF₂-Cr₂O₃ fluxes approximately follow the same curve as the former, although the position and the width of the liquid zones are considerably different, and activities in BaO-BaCl₂-Cr₂O₃ fluxes are higher at the lower Cr₂O₃ content, or vice versa. The activity coefficients of Cr₂O₃ in the fluxes decrease with the increase of the X _MO /X _{MX 2} ratios.     

Polyamide microcapsules containing alginic acid: extractability of metal ions and surface characterization by XPS

The pathophysiological role of the Thy-1.1 molecule expressed on rat mesangial cells with regard to mesangial cell dysfunction and injury remains unknown. The mechanism of Thy-1.1-associated injury has now been investigated with two monoclonal antibodies, 1-22-3 and OX7, that recognize different epitopes of Thy-1.1. Mesangiolysis and mesangial cell proliferation were more marked in rats injected with 1-22-3 than in those treated with OX7. Immunostaining for rat complement component C3 and also C9 was similar in the kidneys of rats 1 h after injection of either antibody. Alpha smooth muscle actin was first detected 3 days after injection of 1-22-3 and peaked on day 5; type I collagen staining showed a mesangial pattern on days 5 and 10. The staining for alpha smooth muscle actin and type I collagen was less intense in OX7-treated rats than in the 1-22-3-injected rats. The amounts of mRNAs encoding collagen types I and III peaked 5 days after injection of 1-22-3 and 10 days after injection of OX7. Rats injected with 1-22-3 developed proteinuria that was already marked on day 1 and peaked at 150 mg/day on day 3, whereas OX7 induced a low grade of proteinuria with large interindividual variability on day 3. Immunostaining for rat C3 in the normal rat kidneys, incubated in vitro with 1-22-3 or OX7 followed by incubation with normal rat fresh serum as a complement source, as well as the levels of serum complement activity, CH50, 30 min after injection of 1-22-3 or OX7 were similar, suggesting that the difference in the nephritogenicity of these two antibodies is not attributable to a difference in their complement-fixing activities, but rather may result from the difference in epitope specificities. The epitope recognized by 1-22-3 thus appears to be important in the initiation and progression of antibody-induced nephritis.     

Bacteriolytic action of fluoride ions

Bacillus subtilis, Neisseria subflava, and LYT coccus were found to undergo massive lysis after growth in media containing 0.01 to 10 mM NaF. When cells of these organisms were transferred from late-exponential-phase cultures to 0.02 M sodium phosphate buffer plus 0.1 M KCl, they underwent spontaneous autolysis. Cells grown in media with fluoride were more liable to autolysis, and walls isolated from them also showed enhanced autolytic sensitivity, even though added fluoride did not directly stimulate autolysins. Sporadic or partial lysis occurred in populations of Streptococcus sanguis and Streptococcus mutans BHT or LM-7 after growth in fluoridated media. Most bacteria that were tested did not undergo fluoride-induced lysis. However, cells of all test bacteria were found to have reduced amounts of peptidoglycan per unit of cell weight when grown in the presence of fluoride. Incorporation of labeled lysine or glucosamine into peptidoglycan (Park-Hancock residue) was stimulated, instead of inhibited, by fluoride. However, fluoride also stimulated the loss of radioactivity from Park-Hancock residues of cells that had previously incorporated labeled lysine or glucosamine. Thus, fluoride appeared to enhance peptidoglycan turnover, and this turnover reduced the peptidoglycan contents of all bacteria tested, but induced lysis in only those bacteria that normally have highly active autolytic systems.     

Metal-nonmetal transition in indium-alkali metal and aluminum-alkali metal melts

The electrical resistivities of indium-alkali metal and aluminum-alkali metal melts are calculated. The Ziman theory of the electrical conductivity of metallic melts is shown to successfully describe the experimental effects of an increase in the electrical resistivity during a metal-nonmetal transition in the indium-alkali metal systems. This theory also predicts similar qualitative effects of a change in the electrical resistivities of aluminum-alkali metal melts. The melts of aluminum-alkali metal systems are assumed to undergo a metal-nonmetal transition.     

Synthesis of bis-netropsin-linked hydroxamic acids and their DNA cleavage properties in the presence of transition or lanthanide metal ions

Nobel hydroxamic acids containing bis-netropsin units coupled by polymethylenetether (BNHA) have been synthesized. BNHA-ferrous complexes sequence-specifically cleaved pBR322 DNA fragment whereas corresponding cerium complexes showed low-sequence specific cleavage pattern.     

Antimicrobial treatment of dermatologic preparations with peracetic acid. 1]

The therapeutic effect of orally administered zinc in 3 patients affected with Acrodermatitis enteropathica is reported. Single daily doses of zinc resulted in rapid improvement of the general condition of these patients and in clinical remission within a week. Serum, urine and hair zinc levels as well as alkaline phosphatase, which were very low before treatment, returned to normal after therapy. This brief report confirms the efficacy of oral zinc in the treatment of Acrodermatitis enteropathica.     

Effects of contaminant metal ions on precipitation recovery of rare earth elements using oxalic acid

Solution equilibrium calculations were performed in this study to understand the impact of contaminant metal ions on the precipitation efficiency of selected ra...     

Brain metal ions and regulation of neural functions

Research contradicts the common assumption that older people are not sexually active. Questions about the patient's sexual health should be included in the assessment. Health professionals must recognise the need to offer support and advice to patients on this issue.     

The catalytic action of cupric and ferric ions in nitric acid leaching of Ni3S2

The kinetics of dissolution of synthetic Ni₃S₂ in nitric acid solution containing ⩽ 2.0 M HNO₃ in the presence of cupric and ferric ions was investigated. The effects of stirring, particle size, temperature and concentration of cupric and ferric ions were examined. Solid residues at various levels of nickel extraction were examined by SEM, X-ray diffraction, electron microprobe and chemical analysis. The constant dissolution rate of Ni₃S₂ was attributed to the electrochemical reaction occurring on the surface of flat-plate type Ni₃S₂ particles. The reaction kinetics were found to be independent of both cupric and ferric ion concentrations up to 1 mM. Cupric ion did not act as a catalyst at temperatures below 60°C. At 80°C cupric and ferric ions show the same catalytic activity. The activation energy in the presence of ferric ions was 103.6 ± 4.2 kJ/mol. A mechanism for Ni₃S₂ dissolution in the presence of cupric and ferric ions is proposed.     

Alkali metal ions and ethanol narcosis in mice

The effect of an equimolar dose of LiCl, RbCl or CsCl on the depressant action of ethanol (ETOH) was studied as a function of duration of ETOH-mediated narcosis in mice. The alkali metal ions were administered acutely or semi-chronically prior to the administration of a narcotic dose of ETOH. Semi-chronic treatment with RbCl or CsCl resulted in decreased duration of ETOH-mediated narcosis, which was persistent for 5 days after discontinued administration of RbCl and CsCl. Conversely, a prolongation of ETOH-produced narcosis in Li-treated mice occured only when ETOH was shortly administered after sub-chronic regiments of LiCl. Semi-chronic treatment with an equimolar dose of LiCl, RbCl or CsCl produced little changes in the specific activities of liver alcohol and aldehyde dehydrogenase. It is concluded that both Rb+ and Cs+ possess antidepressant properties and might be useful agents in negating the depressant action of ETOH and/or some of its toxic manifestations.     

针铁矿对重金属离子的吸附作用

对针铁矿合成试验和针铁矿吸附重金属离子进行了研究。试验结果表明，针铁矿可用铁矿废渣获得，通过酸碱中和的方式所获得的针铁矿是微细针状，针铁矿对重金属离子具有强烈的吸附作用，对Cu^2 、Zn^2 和Cd^2 的吸附边界pH值分别为4.3,5.8和7.3，且吸附率最高可达95％以上；尤其对Pb^2 的吸附作用更加强烈，在pH值为3.5时吸附率就达到95％，并且随着pH值的升高吸附率仍在95％以上。研究表明，铁矿废渣可被利用制备针铁矿，针件矿用于含重金属离子污水的处理，具有较好效果。     

腐殖质对重金属离子的吸附作用

采用腐殖质对重金属离子进行了吸附试验。其结果表明 ,腐殖质对重金属离子具有强烈的吸附作用。腐殖质对Cu2 + 、Zn2 + 、Cd2 + 的吸附边界pH值分别为 4 2 ,5 8,7 2 ,吸附率可达 95 %以上 ;对Pb2 + 的吸附作用更加强烈 ,在pH值为 3 5时吸附率就达到 95 %以上 ,并且随着pH值的升高吸附率仍在 95 %以上。腐殖质对 4种重金属离子的吸附能力由强到弱的顺序是Pb2 + >Cu2 + >Zn2 + >Cd2 + 。腐殖质可以用来处理含重金属离子的污水 ,具有过滤快、沉降稳定、效果好的优点 ;也可作为土壤改良剂 ,有效地降低土壤中重金属的含量