Modulation of gene expression and DNA adduct formation in HepG2 cells by polycyclic aromatic hydrocarbons with different carcinogenic potencies

Polycyclic aromatic hydrocarbons (PAHs) can occur in relatively high concentrations in the air, and many PAHs are known or suspected carcinogens. In order to better understand differences in carcinogenic potency between PAHs, we investigated modulation of gene expression in human HepG2 cells after 6 h incubation with varying doses of benzo[a]pyrene (B[a]P), benzo[b]fluoranthene (B[b]F), fluoranthene (FA), dibenzo[a,h]anthracene (DB[a,h]A), 1-methylphenanthrene (1-MPA) or dibenzo[a,l]pyrene (DB[a,l]P), by using cDNA microarrays containing 600 toxicologically relevant genes. Furthermore, DNA adduct levels induced by the compounds were assessed with P-32-post-labeling, and carcinogenic potency was determined by literature study. All tested PAHs, except 1-MPA, induced gene expression changes in HepG2 cells, although generally no dose-response relationship could be detected. Clustering and principal component analysis showed that gene expression changes were compound specific, since for each compound all concentrations grouped together. Furthermore, it showed that the six PAHs can be divided into three groups, first FA and 1-MPA, second B[a]P, B[b]F and DB[a,h]A, and third DB[a,l]P. This grouping corresponds with the carcinogenic potencies of the individual compounds. Many of the modulated genes are involved in biological pathways like apoptosis, cholesterol biosynthesis and fatty acid synthesis. The order of DNA adduct levels induced by the PAHs was: B[a]P >> DB[a,l]P > B[b]F > DB[a,h]A > 1-MPA >= FA. When comparing the expression change of individual genes with DNA adduct levels, carcinogenic potency or Ah-receptor antagonicity (the last two were taken from literature), several highly correlated genes were found, of which CYP1A1, PRKCA, SLC22A3, NFKB1A, CYP1A2 and CYP2D6 correlated with all parameters. Our data indicate that discrimination of high and low carcinogenic PAHs by gene expression profiling is feasible. Also, the carcinogenic PAHs induce several pathways that were not affected by the least carcinogenic PAHs

Binary PAH-mixtures cause additive or antagonistic effects on gene expression but synergistic effects on DNA adduct formation.

Polycyclic aromatic hydrocarbons (PAHs) cover a wide range of structurally related compounds which differ greatly in their carcinogenic potency. PAH exposure usually occurs through mixtures rather than individual compounds. Therefore, we assessed whether the effects of binary PAH mixtures on gene expression, DNA adduct formation, apoptosis and cell cycle are additive compared with the effects of the individual compounds in human hepatoma cells (HepG2). Equimolar and equitoxic mixtures of benzo[a]pyrene (B[a]P) with either dibenzo[a,l]pyrene (DB[a,l]P), dibenzo[a,h]anthracene (DB[a,h]A), benzo[b]fluoranthene (B[b]F), fluoranthene (FA) or 1-methylphenanthrene (1-MPA) were studied. DB[a,l]P, B[a]P, DB[a,h]A and B[b]F dose-dependently increased apoptosis and blocked cells cycle in S-phase. PAH mixtures showed an additive effect on apoptosis and on cell cycle blockage. DNA adduct formation in mixtures was higher than expected based on the individual compounds, indicating a synergistic effect of PAH mixtures. Equimolar mixtures of B[a]P and DB[a,l]P (0.1, 0.3 and 1.0 mu M) were assessed for their effects on gene expression. Only at 1.0 mu M, the mixture showed antagonism. All five compounds were also tested as a binary mixture with B[a]P in equitoxic concentrations. The combinations of B[a ]P with B[b]F, DB[a,h]A or FA showed additivity, whereas B[a]P with DB[a,l]P or 1-MPA showed antagonism. Many individual genes showed additivity in mixtures, but some genes showed mostly antagonism or synergism. Our results show that the effects of binary mixtures of PAHs on gene expression are generally additive or slightly antagonistic, suggesting no effect or decreased carcinogenic potency, whereas the effects on DNA adduct formation show synergism, which rather indicates increased carcinogenic potency

Design and Realization of Robust Controller on the Stylus Probe For a Roundness Test Machine

摘要 真圓度機是建立精密儀器設計技術的必要量測儀器，其中負責量測的探針系統包括機械設計、組裝以及精密的伺服迴授，更是直接牽涉到系統整體量測的準確度。本論文針對真圓度機開發出由音圈馬達、彈簧剛片所組成的智慧型探針系統，並將之整合到真圓度機台的移動機構上，使探針系統能夠移動到最適當的測量位置，藉著應變規來偵測接觸力的大小，並透過力迴授控制法則來建立穩定的探針接觸力，同時以減振控制來壓制探針因摩擦工件表面所產生的振動，此時光纖位移感測器可測得探針的位置，再利用後部軟體分析，亦可反映出待測工件的表面粗糙度，水平度等定性資料。在控制器的設計方面，先對系統作不確定度分離後，藉由 合成理論設計出一具有強韌穩定性與強韌性能的控制器，透過實驗測試，此一強韌控制器除了可反映出工件表面輪廓外，其較傳統的PID控制器更可有效的減低突來的外部干擾，具有較佳的強韌要求。 關鍵字：真圓度機、μ合成、力迴授、強韌性、不確定度。Abstract This thesis presents the integration design of a roundness test machine using a novel smart stylus probe with a high stiffness air-bearing. The high stiffness air-bearing minimizes the effect of the spindle runout. The smart stylus design enables active control on the stylus force. The stylus design is based on the mechatronics concept and is made of relatively inexpensive parts. The force control is based on the strain gauge output to control the stylus movement. An optical fiber sensor detects the stylus position for the roundness measurement. The stylus force control enables active adjustment of the system response. It is also possible to use a high bandwidth loop for surface roughness measurement. This realization uses the µ-synthesis procedure to implement the performance and the uncertainty specifications. The realization allows the measurement of very small profile change without scratching the test object with the active stylus. The roundness tester is also built for experimental verification. Keywords：Stylus, roundness test machine, µ-synthesis, robust performance目錄 致謝 I 摘要 II Abstract III 目錄 IV 圖表索引 VIII 第一章 緒論 1 1-1. 研究動機與目的 1 1-2. 研究方法 3 1-2-1. 控制器設計方面 3 1-2-2. 機電整合實驗設計方面 3 1-3. 文獻回顧 4 1-4. 內容大鋼 6 第二章 真圓度機系統的介紹 8 2-1. 高精度旋轉平台 9 2-2. 探針位移系統 12 2-2 -1. 水平軸的移動機構 12 2-2 -2. 垂直軸的移動機構 13 2-3. 探針系統 14 2-3-1. 音圈馬達 16 2-3-2. 懸臂樑與探針 19 2-3-3. 應變規 19 2-3-4. 光纖位移感測器 22 2-4. 探針系統動態模型的推導 24 第三章 控制器的設計 29 3-1. 理論介紹 29 3-1-1. 不確定性的描述方法 29 3-1-2. 系統性能與強韌性 35 3-1-3. 結構化奇異值μ 38 3-1-4. 利用µ來描述系統的強韌穩定性 40 3-1-5. 利用µ來描述系統的強韌性能 42 3-1-6. μ合成 44 3-2. 探針系統問題描述 47 3-2-1. 系統識別 47 3-2-2. 頻率響應不確定度的描述 50 3-2-3. 誤差上界 50 第四章 實驗設備與測試 54 4-1. 音圈馬達與電流驅動器 56 4-2. 光纖位移感測器的訊號放大器 58 4-2-1. 放大器規格 58 4-2-2. 光纖位移感測器的測試 59 4-3. 電橋接盒與應變規訊號放大器 60 4-4. 濾波電路 64 4-5. 編碼器與解碼電路 68 4-5-1. 編碼器 69 4-5-2. 解碼器 70 4-6. 步進馬達與伺服馬達的驅動器 70 4-7. 資料轉換卡與人機介面 71 4-7-1. 資料轉換卡 71 4-7-2. 人機介面 73 4-8. 輔助設備 74 4-8-1. 正反電路 74 4-8-2. 實際軌跡位移與量測值的幾何轉換 75 4-8-3. 氣壓系統 76 第五章 實驗結果與討論 77 5-1. 實驗模擬 77 5-1-1. 開迴路系統的頻率響應圖 77 5-1-2. 以Simulink分析與模擬探針系統 78 5-2. 實驗步驟 80 5-3. 實驗結果 84 5-3-1. 軌跡重覆性的驗證 87 5-3-2. 無任何力回授控制 87 5-3-3. 靜態控制μ與PID之比較 89 5-3-4. 動態控制μ與PID之比較 94 5-3-5. 工件在轉速不同的比較 97 5-3-6. 工件表面輪廓 100 第六章 結論與展望 102 參考文獻 104 附錄 10