[Establishment of New Zealand rabbit models of aplastic anemia].

OBJECTIVE: To screen for the optimal dose of benzene and cyclophosphamide using an orthogonal design for establishment of New Zealand rabbit models of aplastic anemia. METHODS: Following an orthogonal experimental design, the effects of 3 levels of 4 factors, namely the dose of benzene (A), the dose of cyclophosphamide (B), the number of benzene injections (C), and the number of cyclophosphamide injections (D) were tested in the establishment of New Zealand rabbit models of aplastic anemia using a L9 (34) orthogonal table, and the optimal protocol for the model establishment was selected from the 9 experimental groups. Each rabbit received subcutaneous injection of benzene on the back every other day, followed by daily cyclophosphamide injection via the ear vein for prescribed times. The blood routine was examined every 6 days, and before modeling and at 36 days after modeling, a small sample of the femoral bone was collected for bone marrow histopathological examination. RESULTS: Comparison of the white blood cell, erythrocyte and platelet counts among the 9 groups showed successful modeling in Groups 4-9, and daily mean reduction rates of the cell counts in Groups 7, 8, and 9 differed significantly from those in the other groups (P<0.05). In Group 7, bone marrow sections showed low myelodysplasia, reduced hematopoietic tissue, reduced or even absence of megakaryocytes, and increased fat cells. Further observation found that the rabbits in Group 7 had sustained bone marrow suppression, consistent with the clinical characteristics of the disease. CONCLUSION: Stable models of aplastic anemia can be established efficiently in New Zealand rabbits by a combination of 8 subcutaneous injections of benzene at 1.5 mL/kg and 4 intravenous injections of cyclophosphamide at 10 mg/kg.

[Pollution Characteristics Analysis in Shallow Groundwater of Typical Farmland Area, Southern China].

To analyze the characteristics of shallow groundwater pollution in farmland ecosystem in south China and geochemical behavior of major pollutants in the environment, taking the typical farmland in Taihu River Basin as the object, combined with conventional analysis method of the water quality, fluorescence spectrum technology and multivariate statistical analysis method, the characteristics of the water chemistry in shadow groundwater and the distribution of the dissolved organic matter and the heavy metals were studied. The reasons for all the phenomena were researched as well. The result showed that, water body in the study area showed the reducing atmosphere, the main chemical types of shallow groundwater were HCO3-Ca·Na, and compared to the contents of NH3--N and NH2--N, the concentration of NH4+-N was higher. Dissolved organic matter of the shallow groundwater was composed of humic acid, tryptophan and tyrosine. And they were mainly derived from terrestrial and biological source. The distribution was affected by the flow direction of the surface water supplies and groundwater. In the detection of nine kinds of heavy metal elements, the average concentrations of Fe and Cr were higher than the national groundwater environmental quality in class Ⅲ standard. And the contents of Fe, Cr, Mn, Zn elements at some points exceeded the standard. The results showed that fluorescent organic matter characteristics could better reflect the status of shallow groundwater pollution, in which the kind of protein-like substances was closely related to the ammonia nitrogen. The heavy metal elements Cu and Ni were associated with the dissolved organic matter and they were mainly complexed in small molecular fluorescent organic matter.

[Determination of Bi in Soils and Sediments by Atomic Fluorescence Spectrometry].

A method for determination of the contents of Bi in soils and sediments by atomic fluorescence spectrophotometry (AFS) was established by using aqua regia as the dissolved medium. In this paper, the instrument parameters, load flow and reducing agent concentration were optimized. Compared with microwave digestion and electric heating plate digestion, water bath digestion demonstrated the better digestion efficiency and was most commonly used. Under the optimal experimental conditions, the detection limit (LOD) was 0.01 mg·kg-1 (sample quantity 0.500 0 g, sample volume 50 mL), and the limit of quantitation (LOQ) was 0.04 mg·kg-1. The results were in good agreement with the centified value, and the relative error was -4.7%~-2.0%. For determination of soil and sediment actual samples, the relative standard deviation (RSD) were 2.5%~3.4% and 3.1%~3.4%, respectively, and the recoveries of the method respectively ranged from 97.6%~102% and 99.5%~104%.

Determination of Beryllium in Soil and Sediment by Graphite Furnace Atomic Absorption with a Microwave-Acid Digestion Method.

A method for determination of beryllium in soils and sediments by microwave-acid digestion/graphite furnace atomic absorption (GFAA) is described. In this paper, the working conditions of the instrument are optimized, the drawing of calibration curve is expounded, the pretreatment process of soil and sediments (including microwave heating process and the selection of digestion system) is discussed, and the interference of coexisting elements is examined. The sample was pretreated by microwave digestion parameters using HNO3/ HCl/HF mixed acid system. The method is fast and simple without matrix modifier, and has no interference by coexisting ions, and has high repeatability and reproducibility. Under the optimal experimental conditions, the limit of detection (LOD) is 0.004 9 mg · kg⁻¹ (sample quantity 0.200 0 g, sample volume 25 mL), and the limits of quantitation (LOQ) is 0.20 mg · kg⁻¹. This method is used to measure the standard samples and actual samples, whether in the laboratory, or between laboratories, has good accuracy and precision.

Permissible value for vanadium in allitic udic ferrisols based on physiological responses of green Chinese cabbage and soil microbes.

Greenhouse experiments were conducted to study the permissible value of vanadium (V) based on the growth and physiological responses of green Chinese cabbage (Brassica chinensis L.), and effects of V on microbial biomass carbon (MBC) and enzyme activities in allitic udic ferrisols were also studied. The results showed that biomass of cabbage grown on soil treated with 133 mg V kg(-1) significantly decreased by 25.1% compared with the control (P < 0.05). Vanadium concentrations in leaves and roots increased with increasing soil V concentration. Contents of vitamin C (Vc) increased by 10.3%, while that of soluble sugar in leaves significantly decreased by 54.0% when soil V concentration was 133 mg kg(-1), respectively. The uptake of essential nutrient elements by cabbage was disturbed when soil V concentration exceeded 253 mg kg(-1). Soil MBC was significantly stimulated by 15.5%, while dehydrogenase activity significantly decreased by 62.8% and urease activity slightly changed at treatment of 133 mg V kg(-1) as compared with the control, respectively. Therefore, the permissible value of V in allitic udic ferrisols is proposed as 130 mg kg(-1).