| Element is the fundamental unit of biosysterms, playing an important role in the functions of the biology. Both the elemental composition of the environment and the elemental metablism (absorption, transportation,distribution and excretion) in biology system are closely linked with the initialization and development of human diseases. The concept of"metallomics", defined as the study of metals and metal species and their interactions, transformations and functions in biological systems, was recently proposed to integrate the various fields of research related to the study of biometals including both qualitative and quantitative analyses of metallic elements and their speciation in both simple and complex biological systems (cell, organ, whole body, etc.). However, limited by the analytical techniques, experimental metallomics work based on comprehensive characterization of metals and their speciation in biological samples such as serum or plasma specimens (the most commonly used samples in other"omics"research) has not been reported to date. Accordingly, we propose here a novel, practically achievable"trace element profiling"approach to quantitatively measure the time-related variation of low concentration metal and non-metal elements in biological systems as a response to pathophysiological stimuli or genetic modification.Gout, characterized by hyperuricemia, recurring attacks of acute and chromic arthritis, and kidney stones, is a group of heterogenetic diseases caused by the metabolic disorder of the purine and/or the decreased excretion of the uric acid resulting in deposits of the acid and its salts in the blood and joints. A number of serious diseases have been found strongly associated with the gout, such as obesity, hypertension (HBP), hyperlipemia, diabetes and cardiovascular disease. The prevalence of gout is 600/100,000 in men and 100/100,000 in women, and the total prevalence of hyperuricemia is 5%~30%. Acute gouty arthritis is the most common type of inflammatory joint disease in men, affecting approximately 1–2% of adult men in eastern countries. Gout is a disease of antiquity, yet has been growing in prevalence during the past 30 years. In the next 20~30 years, the prevalence of gout is considered to be the second place in metabolic diseases in china, only next to diabetes. Although acute gouty arthritis had already been elucidated as the direct effect of deposits of uric acid for many years, its further pathology were still unclear. Demonstrating the presence of momosodium urate (MSU) crystals by aspiration of SF is the gold standard for the diagnosis of gout, however, it is an invasive method. The other criteria for gout diagnosis including the serum uric acid (SUA) level is too subjective and complicated to provide an accarute result and to be applied in population screening. Furthermore, to our knowledge, no paper has reported the correlation between metals and AGA up to now.Our study proposed and evaluated a new serum trace element profiling method using ICP-MS. The method was then applied into the study of the osteoarthritis (OA), acute gouty arthritis (AGA) and its complication-hypertension, to evaluate the potential of the method in clinical study and explore the diagnosis and the pathology of both diseases at the level of elements. The main methods and results in this study are as followed:1.The investigation and evaluation of the ICP-MS based serum trace element profiling method We proposed a new serum trace element profiling method using ICP-MS, and performed the recovery and permutation test, etc. to optimize the selection of the masses of individual element for detection and evaluate its stability and the reliability. The results showed that in spite of the existence of some interferences, the result from this method can not be influenced significantly, and the method is stable and reliable.2.The application of the serum element profiling in OA study To further validate the serum element profiling method and exhibit its study procedure, we applied the serum trace element profiling method in the clinical study of OA. The result indicated that the serum trace element profile of OA patients and healthy controls (HC) can be separated clearly in the score plot of OPLS-DA model. The multivariate and univariate statistical result showed that the concentration of Li and Sn in serums of OA patients was significantly different from that of healthy controls.3.Serum trace element profiling study of acute gouty arthritis Serum trace element profiling method was employed to study AGA (including the periods of acute attack (AGA_OP) and remission (AGA_RP)) and its complication - hypertension. The multivariate statistical model OPLS-DA was constructed to distinguish AGA from HC, and the significant separation was observed in the score plot of OPLS-DA model which displayed good stability and ability of prediction. The result of differential elements revealed that Li, Fe, Cu, Ce, U, etc. were changed compared with that of HC, which suggested that the serum trace element profiling method has the potential to be further developed as a new tool for clinical diagnosis of AGA. The abnormality of serum concentration of Cu and Fe was assumed to be associated with oxidative stress and/or inflammation state. The univariate statistic result showed the slight but significant differences between serum concentration of Fe, Rb and Cs of AGA_OP and AGA_RP. The mean concentration level of Fe during remission period moved slightly towards that of healthy state. The cycle of the Fe concentration (from normal stage to acute attack to remission stage) could be considered to be correlated with the recurrent inflammation. Furthermore, the correlation between individual elements and serum uric acid (SUA) was studied in HC and AGA group, respectively. The pearson correlation and logistic regression analysis in HC group found that Sr is a potential risk factor of hyperuricemia. Meanwhile, Li, V, Cr, Fe, Se are the potential risk factors of hyperuricemia. With the aid of general physical knowledge about SUA, we speculated that high concentration Li might work as a"catalyst"to promote the precipitation of SUA, Fe and Se, however, might have an inhibitive effect on the precipitation of SUA. The sera trace element profile from AGA patients were further analysed using multivariate and univariate statistical method to test if a mathematical model can be established to distinguish AGA patients with and without HBP, and disclose the elements most responsible for the model. Finally, the separation model was successfully constructed and some elements such as Li,Sr,Mo,Cs,U were indentified as the potential markers of AGA patients with HBP complication.4.The quantitative validation of AGA related element markers from the trace element profiling study The conventional quatification method of trace elements in serum sample was established to validate quantitatively the result of AGA related trace element markers which is derived from the trace element profiling method. The result demonstrated that the majority of the AGA related elements detected from profiling study were reproducible, which suggested that the results from our trace element profiling were reliable, and deserved to be further study.Our study proposed and evaluated a new serum trace element profiling method using ICP-MS. Compared with traditional method which usually dedicated great efforts in quantifying the elements pre-hypothesed, the incorporation of"Omics"strategy into ICP-MS based metallomics will provide a more systematic and convenient comparative methodology to the study of the biology relating fields, facilitating their researches and their integration with the information from other"omics". The evaluation of the serum trace element profiling method and its application results in OA and AGA study have validated its stability and reliability, and demonstrated its application potential in the diagnosis of diseases (including their complications) and identification of the elemental markers. Combined with the other"omics"data, this comparative profiling method will enhance our understanding of the biology and mechanism of diseases. The diseases related elements found in our study can be ragarded as the potential bioelement markers to be further studied in the future.
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