Methylated and thiolated arsenic species for environmental and health research——A review on synthesis and characterization

Hundreds of millions of people around the world are exposed to elevated concentrations of inorganic and organic arsenic compounds, increasing the risk of a wide range of health effects. Studies of the environmental fate and human health effects of arsenic require authentic arsenic compounds. We summarize here the synthesis and characterization of more than a dozen methylated and thiolated arsenic compounds that are not commercially available. We discuss the methods of synthesis for the following14 trivalent（Ⅲ） and pentavalent（） arsenic compounds： monomethylarsonous acid（MMA~Ⅲ）, dicysteinylmethyldithioarsenite（MMA~Ⅲ（Cys）_2）, monomethylarsonic acid（MMA~Ⅴ）,monomethylmonothioarsonic acid（MMMTAⅤ） or monothio-MMA~Ⅴ, monomethyldithioarsonic acid（MMDTA~Ⅴ） or dithio-MMA~Ⅴ, monomethyltrithioarsonate（MMTTA~Ⅴ） or trithio-MMA~Ⅴ,dimethylarsinous acid（DMA~Ⅲ）, dimethylarsino-glutathione（DMA~Ⅲ（SG））, dimethylarsinic acid（DMA~Ⅴ）, dimethylmonothioarsinic acid（DMMTA~Ⅴ） or monothio-DMAⅤ, dimethyldithioarsinic acid（DMDTA~Ⅴ） or dithio-DMA~Ⅴ, trimethylarsine oxide（TMAO~Ⅴ）, arsenobetaine（AsB）, and an arsenicin-A model compound. We have reviewed and compared the available methods,synthesized the arsenic compounds in our laboratories, and provided characterization information. On the basis of reaction yield, ease of synthesis and purification of product, safety considerations, and our experience, we recommend a method for the synthesis of each of these arsenic compounds.

Editorial: Effects of metal contamination on ammonia-oxidizing microorganisms in a freshwater reservoir

Ammonia-oxidizing microorganisms,including ammoniaoxidizing bacteria(AOB)and archaea(AOA),are important to the global nitrogen cycle.These microbes catalyze the oxidization of ammonia(NH3)to nitrite(NO2-),the ratelimiting step in the biogeochemical cycling of nitrogen(Stahl and de la Torre,2012).

Cadmium in soybeans and the relevance to human exposure

Introduction Cadmium is considered a human carcinogen by the International Agency for Research on Cancer（IARC,1993）and the US National Toxicology Program（NTP,1997）.Cadmium contamination of food crops is a persistent issue for both the agricultural industry as well as consumers.This is an issue for agriculture because cadmium can be present in soils naturally or as a result of industrial processes and can contaminate foods that are consumed by humans.Industrial

Fluorescence imaging of Cu(Ⅰ) in endoplasmic reticulum of live cells and tissue

Copper (Cu) is an essential element to living organisms. The redox activity of Cu gives rise to redox cycling reactions between Cu^2+ and Cu^+. Organisms harness this redox cap? ability for their biological functions by tightly regulating copper homeostasis in the processes of cellular uptake, intracellular transport, protein loading and storage [1].

Safety of high-carbohydrate fluid diet 2 h versus overnight fasting before non-emergency endoscopic retrograde cholangiopancreatography:A single-blind,multicenter,randomized controlled trial

Background:Although overnight fasting is recommended prior to endoscopic retrograde cholangiopancreatography(ERCP),the benefits and safety of high-carbohydrate fluid diet(CFD)intake 2 h before ERCP remain unclear.This study aimed to analyze whether high-CFD intake 2 h before ERCP can be safe and accelerate patients’recovery.Methods:This prospective,multicenter,randomized controlled trial involved 15 tertiary ERCP centers.A total of 1330 patients were randomized into CFD group(n=665)and fasting group(n=665).The CFD group received 400 mL of maltodextrin orally 2 h before ERCP,while the control group abstained from food/water overnight(>6 h)before ERCP.All ERCP procedures were performed using deep sedation with intravenous propofol.The investigators were blinded but not the patients.The primary outcomes included postoperative fatigue and abdominal pain score,and the secondary outcomes included complications and changes in metabolic indicators.The outcomes were analyzed according to a modified intention-to-treat principle.Results:The post-ERCP fatigue scores were significantly lower at 4 h(4.1±2.6 vs.4.8±2.8,t=4.23,P<0.001)and 20 h(2.4±2.1 vs.3.4±2.4,t=7.94,P<0.001)in the CFD group,with least-squares mean differences of 0.48(95%confidence interval[CI]:0.26-0.71,P<0.001)and 0.76(95%CI:0.57-0.95,P<0.001),respectively.The 4-h pain scores(2.1±1.7 vs.2.2±1.7,t=2.60,P=0.009,with a least-squares mean difference of 0.21[95%CI:0.05-0.37])and positive urine ketone levels(7.7%[39/509]vs.15.4%[82/533],χ^(2)=15.13,P<0.001)were lower in the CFD group.The CFD group had significantly less cholangitis(2.1%[13/634]vs.4.0%[26/658],χ^(2)=3.99,P=0.046)but not pancreatitis(5.5%[35/634]vs.6.5%[43/658],χ^(2)=0.59,P=0.444).Subgroup analysis revealed that CFD reduced the incidence of complications in patients with native papilla(odds ratio[OR]:0.61,95%CI:0.39-0.95,P=0.028)in the multivariable models.Conclusion:Ingesting 400 mL of CFD 2 h before ERCP is safe,with a reduction in post-ERCP fatigue,abdominal pain,and cholangitis during recovery.Trail Registration:ClinicalTrials.gov,No.NCT03075280.