Recent advances in research on chelators as metallo-β-lactamase inhibitors / 中国药科大学学报

@#The major reason for the resistance of Gram-negative bacteria to β-lactam antibiotics is the expression of β-lactamases.Metallo-β-lactamases (MBL) hydrolyze almost all types of β-lactam antibiotics including carbapenems, posing a challenge to global public health. Developing MBL inhibitors is an important method to treat the infections caused by resistant bacteria. As an important type of MBL inhibitors, chelating agents can inhibit MBL by chelating, stripping, and binding Zn2+ in the active center of MBL.This review summarizes recent publications on chelators as MBL inhibitors, discussing their chemical structures, inhibitory potency, synergistic effects with antibiotics, selectivity and mechanism of action, including EDTA and related compounds, aspergillomarasmine A (AMA) and its derivatives, NOTA and related compounds, pyridine carboxylic acid and pyridine methylamine compounds, aiming to provide reference for future development of potent, selective and safe clinical MBL inhibitors.

Application progress of time-resolved fluorescence in immunoassay / 公共卫生与预防医学

Time resolved fluoroimmunoassay (TRFIA) is an immunoassay technology developed on the basis of the unique fluorescence properties of rare earth elements. TRFIA combines the advantages of radioimmunoassay, enzyme-linked immunoassay and common fluorescence immunoassay. It has high sensitivity, strong specificity, good stability, wider measurement range, long fluorescence life, simple operation and non-radiation, and shows a good prospect in the field of immunoassay. In this paper, several common TRFIA materials are discussed based on the latest research progress of time-resolved fluorescence in immunoassay. The application of TRFIA in immunodiagnosis, food detection, environmental monitoring and so on is elaborated, and its development direction and application are prospected.

Establishment of an in vitro screening model for uranium decorporation chelators based on the competitive ELISA method / 药学学报

Uranium [U(Ⅵ)] in the blood is known to form stable complexes with apotransferrin (apo-Tf), which plays an important role in mediating the cytotoxicity induced by U(Ⅵ) transported to cells. The present study aimed to establish an new in vitro screening model of U(Ⅵ) decorporation agents through exploring the capability of chelating agents competing with U(Ⅵ) binding to apo-transferrin based on enzyme-linked immunosorbent assay (ELISA). The optimal concentrations of apo-Tf coated antigen, Tf antibody, secondary antibody and U(Ⅵ) treatment were achieved and the stability and reproducibility of this method were validated by methodology study. Using this model, the ability of four chelating agents to mobilize the U(Ⅵ) binding to apo-Tf was evaluated, and the rank of competitiveness was catechol-3,6-bis(methyleiminodiacetic acid） (CBMIDA) ≈ Tiron > apo-Tf > DTPA-CaNa3 ≈ DTPA-ZnNa3. The efficacy of these chelating agents in removal of U(Ⅵ) was tested by animal experiments. The results showed that immediate administration of CBMIDA or Tiron after injection of U(Ⅵ) in mice significantly promoted urinary U(Ⅵ) excretion and reduced U(Ⅵ) accumulation in kidneys and femurs, while DTPA-CaNa3 and DTPA-ZnNa3 have no obvious effects as compared to U(Ⅵ)-exposed mice alone, which was consistent with the results of competitive ELISA method. The animal experiments conform to the rules of the Animal Research Ethics Committee of School of Pharmacy of Fudan University. These results show that the new proposed method is rapid, simple and convenient with good reproducibility and has the potential to be used for in vitro screening of U(Ⅵ) decorporation agents.

Mesilato de desferroxamina como candidato a adjuvante farmacêutico e cosmético / Desferroxamine mesylate as a candidate for pharmaceutical and cosmetic adjuvant

Este trabalho propôs o uso do fármaco quelante mesilato de desferroxamina (DFO) como agente adjuvante para estabilização química e microbiológica de formulações. Soluções de ácido ascórbico (AA) 5,0% (p/v) foram preparadas com sistemas antioxidantes constituídos por diferentes combinações de DFO, ácido etilenodiamino tetra-acético (EDTA) e metabissulfito de sódio, cada adjuvante na concentração máxima de 0,1% (p/v). Os sistemas foram testados previamente quanto à atividade antioxidante, mediante adição de um complexo de ferro (III) redox-ativo e ensaio baseado em fluorescência. Os sistemas também foram associados ao metilparabeno e avaliados quanto à atividade antimicrobiana pelo método turbidimétrico, utilizando-se a técnica de microdiluição em meios líquidos e cepas padrão de bactérias e fungos, incluindo S. aureus (ATCC 6538), E. coli (ATCC 8739), P. aeruginosa (ATCC 9027), C. albicans (ATCC 10231) e A. brasiliensis (ATCC 16404). As soluções de AA foram expostas a condições de teste de estabilidade acelerada e avaliadas quanto à estabilidade química, empregando-se método volumétrico validado para quantificar AA. Verificou-se que o EDTA foi o agente quelante que melhor contribuiu na estabilidade química da solução de AA, entretanto, o DFO apresentou desempenho muito superior ao EDTA para bloquear a atividade pró-oxidante do ferro. Além disso, o DFO foi fator relevante na inibição do crescimento microbiano e demonstrou sinergia com o metilparabeno. A otimização estatística dos resultados indicou que o uso do DFO nos sistemas antioxidante e conservante pode reduzir consideravelmente a concentração dos adjuvantes convencionais, EDTA, metabissulfito e metilparabeno, os quais são muitas vezes associados a reações de hipersensibilidade ou a danos ao meio ambiente

In this work it was proposed the use of the chelating drug desferroxamine mesylate (DFO) as adjuvant for chemical and microbiological stabilization of formulations. Ascorbic acid (AA) solutions 5.0% (w/v) were prepared with antioxidant systems containing different combinations of DFO, ethylenediaminetetraacetic acid (EDTA) and sodium metabisulphite, using a maximum concentration of 0.1% (w/v) for each adjuvant. Previously, the systems were spiked with a redox-active iron (III) complex and tested for antioxidant activity by fluorescence-based assay. The systems also were associated with methylparaben and evaluated for antimicrobial activity by turbidimetric method, using the microdilution technique and standard strains of bacteria and fungi, including S. aureus (ATCC 6538), E. coli (ATCC 8739), P. aeruginosa (ATCC 9027), C. albicans (ATCC 10231) and A. brasiliensis (ATCC 16404). The AA solutions were exposed to accelerated stability test conditions and evaluated for chemical stability, using a volumetric method that was validated to quantify AA. It was found that EDTA was the chelating agent that most contributed to the chemical stability of AA solution, however, DFO demonstrated a much higher performance to EDTA to block the pro-oxidant activity of iron. In addition, DFO was a relevant factor in the inhibition of microbial growth and showed synergy with methylparaben. The statistical optimization of the results indicated that the use of DFO in the antioxidant and preservative systems might considerably reduce the concentration of the conventional adjuvants, EDTA, metabisulphite and methylparaben, which are often associated with hypersensitivity reactions or environmental damage

Interaction of Hydroxyethylidene bisphosphonate (HEBP) with other endodontic irrigants on tissue dissolving capacity and antimicrobial effect

PURPOSE: The purpose of this study was to evaluate tissue dissolving capacity, antimicrobial effect of Hydroxyethylidene bisphosphonate (HEBP) interacting with sodium hypochlorite (NaOCl), Ethylenediaminetetraacetic acid (EDTA) as conventional endodontic irrigants and to determine tissue dissolving efficacy depended on temperature. MATERIALS AND METHODS: A total of 80 bovine muscles were randomly distributed into 8 groups (n = 10). After their initial weights determined on a precision scale, the specimens in each group were immersed in the solutions for 5, 10 and 15 min and reweighted at each time period. Agar diffusion test inoculated with Enterococcus faecalis was performed for antimicrobial effect of each endodontic irrigants. RESULTS: The ability to dissolve organic matter was greater in NaOCl group following NaOCl and HEBP mixture. Heated NaOCl (40℃) and NaOCl/HEBP mixture was greater tissue dissolving efficacy than room temperature (25℃). Antimicrobial effect was greater and significant in the following order EDTA > EDTA + 1% NaOCl > 1% NaOCl ≥ 1% NaOCl + HEBP. CONCLUSION: HEBP as soft chelating agent does not disturb antimicrobial effect and less affected tissue dissolving efficacy as inherent properties of NaOCl. In the heated NaOCl/HEBP mixture analyzed, it dissolved more the organic matter than room temperature.

The chelator BPCBG decorporates uranium and protects against uranium-induced kidney injury in rats / 中华放射医学与防护杂志

Objective To explore the dose- and time-responses of BPCBG on the decorporation of uranium and its protective effects for uranium-induced kidney injury in rats. Methods Sprague-Dawley (SD) male rats were randomly divided into 4 -7 groups:normal control group,uranium poisoning group,different doses of BPCBG groups and DTPA-CaNa3 group. Rats in chelating agents-treated groups were either injected intramuscularly with 60,120 and 600 μmol/kg of BPCBG or 120 and 600 μmol/kg of DTPA-CaNa3 immediately after intraperitoneal injection of uranyl acetate dihydrate,or injected with 120 μmol/kg of BPCBG 0.5,2 h before or 0,0.5,1 and 2 h after injection of uranium. Uranium poisoning group rats were injected with normal saline after intraperitoneal injection of uranyl acetate dihydrate,and the normal control group rats were merely injected with normal saline. The uranium content in urine,kidney and femurs were detected 24 h after chelator injections by ICP-MS method.After injecting a dose of 500 μg uranyl acetate dihydrate,rats were injected with 600 μmol/kg of BPCBG or 1200 μmol/kg of DTPA-CaNa3. Histopathological changes in the kidney and serum creatinine and urea nitrogen were examined 48 h after chelator administration.Results Prompt injections of BPCBG resulted in 37％ -61％ ( t =2.22,4.43,5.80,P ＜ 0.05 ) increase in 24 h-urinary uranium excretion,and significantly decreased the levels of uranium in kidney and bone by 59％ -69％ (t=3.33,5-59,4-53,P＜0.01) and 14％ -58％ (t =2.15,8.70,9.10,P ＜ 0.05 ) respectively in a dose-dependent manner. BPCRG injection obviously reduced the severity of the uranium-induced histological alterations in the kidney,which was in parallel with the amelioration noted in serum indicators,serum creatinine and urea nitrogen,of uranium nephrotoxicity.Advanced 0.5 h or delayed 0.5 and 1 h administrations of BPCBG were effective in 24 h-urinary uranium excretion ( advanced 0.5 h:t =4.34,delayed 0.5 h:t =3.35,P ＜ 0.05 ),decreasing accumulation of kidney uranium ( t =5.75,7.74,5.87,P ＜ 0.05 ) and accumulation of hone uranium (t =6.43,5.222,2.60,P ＜0.05),but the efficacy decreased with the interval time between uranium and BPCBG injection. Although DTPA-CaNa3 markedly reduced uranium retention in kidney (120,600 μmol/kg,t =2.28,3.35,P ＜ 0.05 ),its efficacy in uranium removal was significantly lower than that of BPCBG,and it had no protective effects against uranium-induced nephrotoxicity.Conclusions BPCBG can effectively decorporate uranium from rats and protect against uranium-induced kidney injury of rats.

Chitosan: effect of a new chelating agent on the microhardness of root dentin

The effect of solutions of 0.2% chitosan, 15% EDTA and 10% citric acid on the microhardness of root dentin was evaluated comparatively in this study. Thirteen sound human maxillary central incisors were selected and decoronated at the cementoenamel junction. Ten roots were set into rapid polymerization acrylic resin and the root/resin block was fitted to the cutting machine to obtain slices from the cervical third. The first slice was discarded and the second slice was divided into four quadrants. Each quadrant was used to construct a sample, so that 4 specimens were obtained from each root slice, being one for each chelating solution to be tested: 15% EDTA, 10% citric acid, 0.2% chitosan and distilled water (control). The specimens were exposed to 50 μL of the solution for 5 min, and then washed in distilled water. A microhardness tester (Knoop hardness) with a 10 g load was used for 15 s. Data were analyzed statistically by one-way ANOVA and Tukey-Kramer test (α=0.05). The other 3 roots had the canals instrumented and irrigated at the end of the biomechanical preparation with the test solutions, and then examined by scanning electron microscopy (SEM) for qualitative analysis. All solutions reduced the microhardness of root dentin in a way that was statistically similar to each other (p>0.05) but significantly different from the control (p>0.05). The SEM micrographs showed that the three solutions removed smear layer from the middle third of the root canal. In conclusion, 0.2% chitosan, 15% EDTA and 10% citric acid showed similar effects in reducing dentin microhardness.

Avaliou-se o efeito das soluções de quitosana 0,2%, EDTA 15% e ácido cítrico 10% sobre a microdureza da dentina radicular. Foram utilizados 13 incisivos centrais superiores humanos, os quais tiveram suas coroas seccionadas transversalmente e desprezadas. Dez raízes foram incluídas em resina acrílica de rápida polimerização e o bloco formado raiz/resina adaptado à maquina de corte. Desprezou-se o primeiro corte transversal da porção cervical e dividiu-se o segundo, em 4 quadrantes. Cada quarto foi destinado à confecção do corpo-de-prova obtendo-se 4 espécimes para cada raiz, um para cada solução (n=10): EDTA a 15%, ácido cítrico a 10%, quitosana a 0,2% e água destilada (controle). Os espécimes receberam 50 μ L da solução por 5 min, sendo em seguida, lavados com água destilada. Utilizou-se um microdurômetro (dureza Knoop) com carga de 10 g durante 15 s. Os dados foram avaliados por meio do teste ANOVA e Tukey-Kramer (α=0,05). Três incisivos centrais superiores foram instrumentados e irrigados, ao final da biomecânica, com uma das soluções estudadas. Os espécimes foram levados para MEV e posterior análise qualitativa. Todas as soluções avaliadas reduziram a microdureza da dentina radicular de forma semelhante entre si (p>0,05) e estatisticamente diferente do controle (p<0,01). As fotomicrografias mostraram que as 3 soluções removeram a smear layer do terço médio do canal radicular. Concluiu-se que as soluções de quitosana 0,2%, EDTA 15% e ácido cítrico 10% apresentam efeito semelhante na redução da microdureza dentinária.

A preliminary study of serum-deprivation-induced release of S100A13 and flbroblast growth factor 1 from thyroid cancer TT cell / 中华内分泌代谢杂志

Objective To investigate the effect of serum-deprivation on the changes of [ Ca2+ ] i and the protein release of S100A13 and fibroblast growth factor 1 ( FGF-1 ) in thyroid cancer TT cell,and to reveal the role of Ca2+in the protein release of S100Al3 and FGF-1.Methods The protein expressions of FGF-1 and S100A13 in TT cells under serum-deprivation were detected by Western blot.The released FGF-1 protein from TT cells in the supernatant fluid was detected by ELISA.Realtime dynamic examinations on the change of 1 h [ Ca2+ ] i in TT cells under serum-deprivation were detected by confocal laser scanning microscopy.Then,the effect of EGTA( 2.5 mmol/ L),BAPTA-AM (2.5 μmol/L)on distributions of the fluorescence of S100AI 3 and FGF-1 in TT cells under serumdeprivation for6 h were detected by indirect immunofluorescence.Results The expressions of FGF-1 and S100A13 in TT cells after serum-deprivation for4 h and 6 h were reduced( P＜0.05 or P＜0.01 ),but the released FGF-1 protein from TT cells in the supernatant fluid was elevated ( P＜0.05 or P＜0.01).Confocal laser scanning of Ca2+ imaging indicated that [ Ca2+ ] i of serum-deprivation TT cells maintained the relative stabilization within 23 win,but the rapid rise of [ Ca2+ ] i achieved peak value 1.6 μmol/L after 30 min,and remained stable for about 17 win,and thereafter 40 win slowly dropped to a low level From 40 win to 60 win the [ Ca2+ ] i was about 0.3-0.6 μ mol/L.The average [ Ca2+ ] i was higher than that in normal group,EGTA group,and BAPTA-AM group within 1 h.The protein expressions of S100A13 and FGF-1 did not drop obviously in EGTA group and BAPTA-AM group.Conlusion The release of S100A13 and FGF-1 from TT cell under serum-deprivation is possibly related with the change of [ Ca2+ ]i.Both Ca2+-chelating agents EGTA and BA PTA-AM are able to inhibit the rise of [ Ca2+ ] i and release of S100A 13 and FGF-1 from TT cells under serum-deprivation.

Radiolabeling of NOTA and DOTA with Positron Emitting 68Ga and Investigation of In Vitro Properties / 핵의학분자영상

PURPOSE: We established radiolabeling conditions of NOTA and DOTA with a generator-produced PET radionuclide 68Ga and studied in vitro characteristics such as stability, serum protein binding, octanol/water distribution, and interference with other metal ions. MATERIALS AND METHODS: Various concentrations of NOTA.3HCl and DOTA.4HCl were labeled with 1 mL 68GaCl3 (0.18~5.75 mCi in 0.1 M HCl) in various pH. NOTA.3HCl (0.373 mM) was labeled with 68GaCl3 (0.183~0.232 mCi/0.1 M HCl 1.0 mL) in the presense of CuCl2, FeCl2, InCl3, FeCl3, GaCl3, MgCl2 or CaCl2 (0~6.07 mM) at room temperature. The labeling efficiencies of 68Ga-NOTA and 68Ga-DOTA were checked by ITLC-SG using acetone or saline as mobile phase. Stabilities, protein bindings, and octanol distribution coefficients of the labeled compounds also were investigated. RESULTS: 68Ga-NOTA and 68Ga-DOTA were labeled optimally at pH 6.5 and pH 3.5, respectively, and the chelates were stable for 4 hr either in the reaction mixture at room temperature or in the human serum at 37 degreesC. NOTA was labeled at room temperature while DOTA required heating for labeling. 68Ga-NOTA labeling efficiency was reduced by CuCl2, FeCl2, InCl2, FeCl3 or GaCl3, however, was not influenced by MgCl2 or CaCl2. The protein binding was low (2.04~3.32%). Log P value of 68Ga-NOTA was -3.07 indicating high hydrophilicity. CONCLUSION: We found that NOTA is a better bifunctional chelating agent than DOTA for 68Ga labeling. Although, 68Ga-NOTA labeling is interfered by various metal ions, it shows high stability and low serum protein binding.

Wilson disease / 한양의대학술지

Wilson disease is an autosomal recessive disorder caused by a deficient ATP7B activity. Copper is an important mineral in the body involved in mitochondrial respiration, melanin biosynthesis, dopamin metabolism, iron homeostasis, antioxidant activity and peptide amidation. Liver is an important organ in copper metabolism related to storing and excretion of bile acids. Copper transport in the liver is a complicated process including different transporter proteins. Generally, Wilson disease shows heterogenous clinical features and symptoms may differ between siblings in a family. This finding suggests that other genes or envrionmental factors may play important roles on determination of disease phenotypes. Clinical symptoms of the disease are mainly related to liver dysfunction and neurologic deterioration. Early diagnosis is important in order to prevent serious complications. Lowered serum ceruloplasmin level and increased urine copper excretion are diagnostic criteria in practice. Histopathologic findings are nonspecific for the diagnosis. Treatment of the disease includes administration of chelating agent such as penicillamine and trientine, dietary restriction of copper, and liver transplantation when chelating agents are not successful.

Lead Poisoning by Administration of Herb Medicine / 대한산업의학회지

No abstract available.

EFFECT OF THREE TYPES OF CHELATING AGENTS ON EXCRETION AND DISTRIBUTION OF MERCURY / 中国药理学通报

After the mice had been injected im203HgCl2 185 kBq/mouse, they were injected ip with chelating agents. There were 15 chelating agents of 3 types,of which the effect of eliminate mercury of pyridoxine derivative, benzenesul-fonate cysteine and sodium dimercaptosuccinate ( DMS-Na) were better than the others. The urine excretion of 208Hg was increased and the ratio were 4.6,11.5 and 22 respectively in comparison with the control group.The minimum 203Hg content in organs of mice was in the DMS-Na group,the next was the benzenesulfonate cysteine group,but there no significant difference between these 2groups.

The effect of intermittent deferoxamine therapy on relieving iron overload in children with ? thalassemia / 实用儿科临床杂志

Objective To evaluate the effect of the intermittent deferomamine(DF) therapy on relieving iron overload caused by transfusion in children with ? thalassemia.Methods Sixteen children who were finally diagnosed as ? thalassemia major were treated with deferomamine for 124 times totally to low the iron overload. The serum iron(SI), serum ferritin(SF) and urine ferritin were detected each time with radio-immunity technique and difference was compared before and after treatment. Meanwhile, weather DF involved children′s liver and renal function was observed in whole procedure.Results Iron overload exists in 16 cases of ? thalassemia major children by a long- term hypertransfusion therapy, with average level SI 33.69?6.72 mmol/L,SF 441.19? 54.70 ?g/L,urine ferritin 8.64?6.79 ?g/L. The difference was significant (paired-samples t test,t =6.173 P 0.05).Conclusion The study suggest that intermittent low-dose DF therapy is effective for iron overload caused by transfusion in ? thalassemia children, without apparent side effects.