Liver, as an important metabolic and detoxi- cological organ of human body, can be used as a good bioin- dicator for evaluating body burden of environmental pollut- ants. Its elemental contents and their chemical form...Liver, as an important metabolic and detoxi- cological organ of human body, can be used as a good bioin- dicator for evaluating body burden of environmental pollut- ants. Its elemental contents and their chemical forms are closely related to the status of human health and disease. In this paper, the liver samples collected from normal subjects were separated to different subcellular fractions of nuclei, mitochondria, lysosome, microsome and cytosol by differen- tial centrifugation. Then their concentrations of heavy metals of As, Pb, Cd, and Hg were determined by atomic absorption and atomic fluorescent spectroscopy. Our results show no significant difference with literature ones when comparing their gross concentrations. In the case of their subcellular distribution, the Hg concentrations are higher in mitochon- drial, microsomal and cytosolic fractions; the Cd concentra- tions are higher in cytosolic and mitochondrial fractions, while As highest in nuclear fraction. The highest concentra- tion of Pb is found in microsomal fraction with similarity to Fe. Mercury in liver is mainly in the form of inorganic, and methylmercury ranged from 9% to 50% with the average value of 20.9%±13.3%. These results indicate that the cellu- lar distribution and the accumulated target organelles are quite different among these heavy metals, which suggest their various pathways and toxic mechanism in vivo.展开更多
Causation is a distinct concept from association and more important than association inepidemiologic studies.This paper proposes the concept of uniform non-confounding for causal distributioneffects over multiple cova...Causation is a distinct concept from association and more important than association inepidemiologic studies.This paper proposes the concept of uniform non-confounding for causal distributioneffects over multiple covariates,and gives the sufficient conditions for uniform non-confoundingover a covariate set C including confounders or non-confounders,and also shows the conditions forconditionally non-confounding in the subpopulations.All these conditions can be tested by observeddata.展开更多
基金This work was financially supported by the National Natural Science Foundation of China(Grant Nos.10490180and 20071032)the Chinese Academy of Sciences(Grant No.KJCX2-Nl0l).
文摘Liver, as an important metabolic and detoxi- cological organ of human body, can be used as a good bioin- dicator for evaluating body burden of environmental pollut- ants. Its elemental contents and their chemical forms are closely related to the status of human health and disease. In this paper, the liver samples collected from normal subjects were separated to different subcellular fractions of nuclei, mitochondria, lysosome, microsome and cytosol by differen- tial centrifugation. Then their concentrations of heavy metals of As, Pb, Cd, and Hg were determined by atomic absorption and atomic fluorescent spectroscopy. Our results show no significant difference with literature ones when comparing their gross concentrations. In the case of their subcellular distribution, the Hg concentrations are higher in mitochon- drial, microsomal and cytosolic fractions; the Cd concentra- tions are higher in cytosolic and mitochondrial fractions, while As highest in nuclear fraction. The highest concentra- tion of Pb is found in microsomal fraction with similarity to Fe. Mercury in liver is mainly in the form of inorganic, and methylmercury ranged from 9% to 50% with the average value of 20.9%±13.3%. These results indicate that the cellu- lar distribution and the accumulated target organelles are quite different among these heavy metals, which suggest their various pathways and toxic mechanism in vivo.
基金supported by the Natural Science Foundation China under Grant Nos. 10801019 and 10726037
文摘Causation is a distinct concept from association and more important than association inepidemiologic studies.This paper proposes the concept of uniform non-confounding for causal distributioneffects over multiple covariates,and gives the sufficient conditions for uniform non-confoundingover a covariate set C including confounders or non-confounders,and also shows the conditions forconditionally non-confounding in the subpopulations.All these conditions can be tested by observeddata.
