屠宰猪体内汞含量与食物链相关研究

采用氢化物发生冷原子化法对工业区和农业区饲喂的60头猪的肝、肾、肌肉中有害重金属元素汞含量进行了调查分析,同时也分析了对应的饲料和土壤中汞含量;结果猪体、饲料、土壤中汞含量匀为工业区大于农业区,差异极显著(P<0.01):探讨了汞污染与食物链的关系,并进行了猪体内不同部位系的蓄积性比较、相关性分析及卫生评价。     

Comparison of atomic absorption and fluorescence spectroscopic methods for the routine determination of urinary arsenic

Objective: Interpretation of urinary arsenic measurements is sometimes difficult because of the absorption of seafood that contains trimethylated arsenic forms (arsenobetaine and arsenocholine). The objective of this study was to develop a rapid and robust technique for the measurement of the sum of inorganic arsenic metabolites. Methods: Measurement of arsenic was performed in urine after hydride generation in acid medium. Using atomic fluorescence spectrometry (AFS) as the detection system, we developed a rapid (one determination in less than 2min) technique using 50 l urine without pre-treatment. Standardisation was done externally with a mixed standard solution containing inorganic trivalent arsenic (As_i^III), inorganic pentavalent arsenic (As_i^V), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) (15/15/12.5/57.5) Results: Samples distributed in the frame of an international comparison programme were used to assess accuracy of the AFS procedure, which gives a linear response up to 50 g/l and proves more precise [coefficient of variation (CV)< 4% at 5 g/l] and sensitive than the atomic absorption spectroscopy (AAS) technique using a quartz cell. An additional adaptation that allows the detection of non-directly reducible arsenic forms has also been validated for samples with high arsenic concentrations. Conclusions: The present study demonstrates the superiority of AFS over atomic absorption spectrometry (AAS) in arsenic determination and the interest of online mineralisation prior AFS detection for the determination of arsenic concentration in urine.     

Ultrastructure of Dental Enamel afflicted with Hypoplasia: An Atomic Force Microscopic Study

The ultrastructure of the human tooth enamel from a patient diagnosed with hypoplasia (HYP) was investigated using atomic force microscopy (AFM) and compared with the surface of normal human tooth enamel. Hypoplasia is a hereditary defect of dental enamel in which the enamel is deficient in either quality or quantity. AFM results presented for the HYP tooth enamel clearly demonstrate that the apatite crystal morphology in hypoplasia tooth enamel is perturbed in the diseased state which could result from a defective synthesis of the extracellular matrix proteins, e.g., amelogenin, by the ameloblasts. HYP enamel consisting of loosely packed, very small grains does not present a tendency for association, as in the case of the normal healthy tooth. Indeed, the enamel surface affected by HYP is porous and is made of much smaller grains. In some samples, the HYP part of enamel surface appeared in the form of a point-defect, which we believe may be associated with the early stages of the HYP deformation.     

The effect of ions at the surface of calcium oxalate monohydrate crystals on cell-crystal interactions

Magnesium is an abundant ion in biologic systems, including renal tubular fluid; however, the precise role of magnesium during the interaction of calcium oxalate crystals with cells has not been previously defined. In addition, the respective roles of calcium and hydrogen ions during the cell-crystal bonding interaction remain poorly defined. Here we report an atomic level three-dimensional study of a single crystal of calcium oxalate monohydrate (COM; whewellite) which was bathed in a solution of magnesium hexahydrate for 1 year. Magnesium was not incorporated into the structure of whewellite to any significant degree. Instead, COM accepted magnesium primarily as an adsorbate in a binding configuration which, as a surface phenomenon, is controlled by localized charge effects. The effect of magnesium and calcium on the efficiency of calcium oxalate crystal binding to renal cells was also investigated. When present in supraphysiologic concentrations (greater than 0.1 M), magnesium progressively inhibited adhesion of pre-formed COM crystals to cultured renal cells. Therefore, even though magnesium does not incorporate into the crystal structure of calcium oxalate, magnesium can exert important surface effects and change the interaction of pre-formed COM with molecules anchored on the cell surface. Similarly, binding was nearly blocked when the exogenous calcium concentration was > or =0.1 M (supraphysiologic range), although in lower concentrations (within the physiologic range) exogenous calcium promoted crystal adhesion. Finally, the ambient hydrogen ion concentration also influenced calcium oxalate crystal interactions with renal cells, with maximal binding occurring at a pH of 4. Therefore, hypercalciuria and/or an acidic urine could each promote renal stone formation via increased crystal adhesion to renal cells, a previously under-appreciated potential mechanism.     

The Cohesive-Adhesive Balances in Dry Powder Inhaler Formulations II: Influence on Fine Particle Delivery Characteristics

PURPOSE: To investigate the influence of the cohesive-adhesive balances on dry powder formulation aerosolization and delivery characteristics. METHODS: De-agglomeration properties of pharmaceutical powders were investigated using an Aerosizer at various shear forces. Aerosol drug deposition properties of drug-only formulations and carrier-based formulations were investigated using a low-resistance device (Rotahaler) and a high-resistance device (Turbuhaler) via a twin-stage impinger. RESULTS: A paradoxical relationship between particle cohesive strength and de-agglomeration efficiencies of drug-only formulations was observed, where an increase in cohesive strength led to a higher fine particle fraction. A possible explanation for the variation in the fluidization and aerosolization properties between low and high cohesive particles was modeled on the relationship between cohesion, metastable agglomerate size, and the resulting aerodynamic drag force acting on the fluidized agglomerates. The addition of a fine particle lactose carrier influenced the drug deposition patterns in different ways depending on the relative cohesive and adhesive force balances within the formulation. CONCLUSIONS: The use of the colloid Atomic Force Microscrope (AFM) technique in combination with the cohesive-adhesive balance (CAB) system provides a novel preformulation tool for investigating the likely behavior of a dry powder formulation and a possible means of interpreting the possible de-aggregation and dispersion mechanisms of carrier-based formulations.     

原子荧光光谱法同时测定发酵虫草菌粉中砷和汞

目的：建立采用原子荧光光谱法同时测定发酵虫草菌粉中砷和汞的方法。方法：标准及样品经消解,直接用AFS-9130型双道原子荧光仪分析,并对实验条件进行优化。结果：在选定的最佳条件下,测得砷和汞的相对标准偏差分别为0.75和1.86。砷和汞的回收率分别为94.5%～104.0%和89.4%～107.8%。结论：该方法具有较高的灵敏度、准确度和精密度。     

ICP-AES法同时测定天然植物中金属元素的研究

用微波消解和湿热消解两种前处理方法对海南天然植物荔枝和茄子进行对比处理,用电感耦合等离子体发射光谱法对其中的铁、镍、锰、铜、钾、锌、镁、钙等8种元素含量进行了测定。测定数据证明微波消解方法优于传统的湿热消解法。将微波消解前处理技术优化后再采用微波消解处理时方法的回收率为92.99%~115.57%,RSD<10.0%,各元素的测定检出限也表明该方法更快速、方便,测定结果准确可靠。     

半夏中锌含量测定的比较研究

目的：为半夏中锌含量的测定提供一定的方法和数据参考。方法：采用原子吸收光谱法和分光光度法测定半夏中Zn的含量。结果：分光光度法测量值是53．20μg／g,火焰原子吸收光普法测定值是48．56μg／g,说明半夏中富含微量元素Zn。结论：原子吸收光谱法和分光光度法都可用于测定半夏中的微量元素锌,但原子吸收光谱法准确度高于分光光度法,因此测定半夏中的微量元素最好的方法是原子吸收光谱法。     

虎皮兰中营养元素含量的测定

采用火焰法对虎皮兰中的营养元素进行测定,结果表明：虎皮兰中含有铜、锌、铁、锰、钾、钠、镁、钙等营养元素,其中钙含量最高,为172．85mg／g,镁含量次之,为42．87mg／g,钾、铁、锰的含量也较高,分别为钾0．1212mg／g,铁0．1066mg／g,锰0．0770mg／g。为进一步深入研究虎皮兰提供科学的理论依据。     

Case studies putting the decision-making framework for the grouping and testing of nanomaterials (DF4nanoGrouping) into practice

Case studies covering carbonaceous nanomaterials, metal oxide and metal sulphate nanomaterials, amorphous silica and organic pigments were performed to assess the Decision-making framework for the grouping and testing of nanomaterials (DF4nanoGrouping). The usefulness of the DF4nanoGrouping for nanomaterial hazard assessment was confirmed. In two tiers that rely exclusively on non-animal test methods followed by a third tier, if necessary, in which data from rat short-term inhalation studies are evaluated, nanomaterials are assigned to one of four main groups (MGs). The DF4nanoGrouping proved efficient in sorting out nanomaterials that could undergo hazard assessment without further testing. These are soluble nanomaterials (MG1) whose further hazard assessment should rely on read-across to the dissolved materials, high aspect-ratio nanomaterials (MG2) which could be assessed according to their potential fibre toxicity and passive nanomaterials (MG3) that only elicit effects under pulmonary overload conditions. Thereby, the DF4nanoGrouping allows identifying active nanomaterials (MG4) that merit in-depth investigations, and it provides a solid rationale for their sub-grouping to specify the further information needs. Finally, the evaluated case study materials may be used as source nanomaterials in future read-across applications. Overall, the DF4nanoGrouping is a hazard assessment strategy that strictly uses animals as a last resort.