[Characteristics of Cd, As, and Pb in Soil and Wheat Grains and Health Risk Assessment of Grain-Cd/As/Pb on the Field Scale].

In recent years, heavy metal pollution in farmlands has become increasingly serious because of human activities such as metal smelting, sewage irrigation, and road traffic in China. A field survey was conducted to investigate characteristics of Cd, As, and Pb in soil and wheat grains and assess the health risk of grain-Cd/As/Pb to humans on the fields scale. The farmland was influenced by smelter and sewage irrigation in the attitude and by road traffic in the horizon. The results showed that in farmland soil with moderate pollution levels, Cd, As, and Pb concentrations in soil samples all exceeded the risk screening values of farmland soil (GB 15618-2018), and the exceeding rates were 100%, 100%, and 36.7% respectively; the exceeding rates of Cd and Pb concentrations in wheat grains were 76.7% and 13.3%, respectively (GB 2762-2017). Distance from smelter, river of sewage irrigation, and road had no significant effect on Cd, As, and Pb concentrations in soil but had a significant effect on Cd and As concentrations in wheat grains, with the median Cd and As concentrations of the closest group being 14.9% and 41.8%, respectively, higher than the highest group (P<0.05). The Pb concentrations in soil and wheat grains were influenced by road traffic; the median Pb concentrations of the closest group were 78.9% and 471%, respectively, higher than the highest group (P<0.05). Cd and As in wheat grains have carcinogenic risks (Ri>1×10-4), RCd > RAs, Rchildren > Radult, while Pb poses no health risks in this farmland.

Ion-pairing liquid chromatography with on-line electrospray ion trap mass spectrometry for the structural analysis of N-unsubstituted heparin/heparan sulfate.

The rare N-unsubstituted glucosamine (GlcNH3(+)) residues in heparan sulfate (HS) have important biological and pathophysiological roles. In this study, a high-resolution method for the separation and analysis of N-unsubstituted disaccharides of heparin/HS is described. Four N-unsubstituted disaccharides, together with eight N-substituted species, can be well-separated by ion-pair reverse-phase ultra-performance liquid chromatography. Each disaccharide can then be detected and its relative abundance quantified using electrospray ionization mass spectrometry in the negative mode. Because of its high sensitivity, without interference from proteins and other sample impurities, this method is particularly useful in the analysis of low content GlcNH3(+) residues in small amounts of biological materials, eg. sera, tissue and cell culture-derived samples. This would lead to a better understanding of the biological origin of GlcNH3(+) residues and their increasingly important function in human health and disease.

Preparation and characterization of heparin hexasaccharide library with N-unsubstituted glucosamine residues.

The rare N-unsubstituted glucosamine (GlcNH3(+)) residues in heparan sulfate (HS) have important biological and pathophysiological roles. Therefore, the ability to chemically generate a series of oligosaccharides, which have a similar structure to the naturally-occurring, GlcNH3(+)--containing oligosaccharides from HS, would greatly contribute to investigating their natural role in HS. In this study, a hexasaccharide library that possess GlcNH3(+) residues were prepared from the chemical modification of the fully sulfated dp6. Chemical reaction conditions were optimized to generate different pattern of GlcNH3(+)--containing oligosaccharides, then the structure of the library was detected by high-performance liquid chromatography-ion trap/time-of-flight mass spectrometry (LC/MS-ITTOF) analysis. EIC/MS and MS(2) analysis showed different fragmentation patterns of dp6s with different GlcNH3(+) residues. This provides a foundation for further identification and quantification of GlcNH3(+)--oligosaccharides by mass spectrum analysis.