Based on the EAM potential, a molecular dynamics study on the tensile properties of ultrathin nickel nanowires in the (100〉 orientation with diameters of 3.94, 4.95 and 5.99 nm was presented at different temperature...Based on the EAM potential, a molecular dynamics study on the tensile properties of ultrathin nickel nanowires in the (100〉 orientation with diameters of 3.94, 4.95 and 5.99 nm was presented at different temperatures and strain rates. The temperature and strain rate dependences of tensile properties were investigated. The simulation results show that the elastic modulus and the yield strength are gradually decreasing with the increase of temperature, while with the increase of the strain rate, the stress--strain curves fluctuate more intensely and the ultrathin nickel nanowires rupture at one smaller and smaller strain. At an ideal temperature of 0.01 K, the yield strength of the nanowires drops rapidly with the increase of strain rate, and at other temperatures the strain rate has a little influence on the elastic modulus and the yield strength. Finally, the effects of size on the tensile properties of ultrathin nickel nanowires were briefly discussed.展开更多
Microstructure refinement of a dual phase titanium alloy, Ti-3AI-4.5V-5Mo, by severe room temperature compression was investigated. Nanocrystalline grains were observed in the sample with 75% reduction, in which the g...Microstructure refinement of a dual phase titanium alloy, Ti-3AI-4.5V-5Mo, by severe room temperature compression was investigated. Nanocrystalline grains were observed in the sample with 75% reduction, in which the grain sizes of a phase and β phase were approximately 50 and 100 nm. Conversely, the average thicknesses of a phase and β phase in as-received microstructure were measured to be 0.7 and 0.5 μm, respectively. TEM and XRD methods were used to analyze the microstructure and texture changes after severe deformation. Microstructure refinement was deduced to the complex interaction among slip dislocations in the a phase, the complex interaction among slip dislocations and martensites in the β phases. In addition, the interaction between the a phase and the β phase also contributed to the microstructure refinement.展开更多
Objective:To investigate possible effects of nanophase powder of hydroxyapatite on proliferation of periodontal ligament cells. Methods: With sol-gel method, the nanophase hydroxyapatite powders were fabricated. These...Objective:To investigate possible effects of nanophase powder of hydroxyapatite on proliferation of periodontal ligament cells. Methods: With sol-gel method, the nanophase hydroxyapatite powders were fabricated. These powders were proved nanopaticles by transmission electron microscope. The effects on proliferation of periodontal ligament cell(PDLC) were observed in vitro with MTT [3-(4,5dimethylthiazo;-2-yl)-2,5-diphenytetralium bromide] method. Results: On the 2nd,3rd,4th day after treated with nanoparticles of hydroxyapatite, the proliferate activity of the PDLC increases significantly, compared with those with dense hydroxyaoatite and control but no significant difference could be found between the dense hydroxyapatite and the control. Conclusion: Nanophase hydroxyapatite can promote the regeneration of periodontal tissue.展开更多
Large scale of sexual cell fusion was carried out in order to observe the fusion pattern during in vitro fertilization with special interest in the influence of cell volume on the membrane behavior. Three patterns cou...Large scale of sexual cell fusion was carried out in order to observe the fusion pattern during in vitro fertilization with special interest in the influence of cell volume on the membrane behavior. Three patterns could be recognized in sexual cell fusion, which was supported by fluorescent microscopy with the aid of video enhanced system and cooled CCD. It was found that the fusion pattern and cell membrane behavior were related to the cell volume ratio of two fusing cells. The results reported here might be useful for interpreting and evaluating data from in vitro fertilization experiments and for explaining male cytoplasm exclusion during fertilization.展开更多
Five cytoplasmic male sterile (CMS) lines were used as parents in an incomplete diallet cross and six restorer lines of rice design (Nc II design). Thirty hybrid combinations with the same growth period were selec...Five cytoplasmic male sterile (CMS) lines were used as parents in an incomplete diallet cross and six restorer lines of rice design (Nc II design). Thirty hybrid combinations with the same growth period were selected as experimental ma- terials to investigate the heterosis, combined ability and heredity of Cd content in brown rice of indica hybrid rice. According to the results, Cd content in brown rice showed a significantly negative heterosis; the general combining ability and specific combination ability of Cd content in CMS and restorer lines both reached extremely significant level (P〈0.01), indicating that both genetic improvement of parents and e- valuation of combinations are important to the breeding of hybrid combinations with low accumulation of Cd; the broad-sense heritabitity and narrow-sense heritability of Cd content were both relatively high with slight differences, which respectively reached 97.73% and 80.10%, indicating that Cd content in brown rice mainly de- pends on the additive action of genes; in addition, parent improvement showed bet- ter effect on the selection of early generation.展开更多
A novel type nano TiN/Ti composite grain refiner (TiN/Ti refiner) was prepared by high energy ball milling, and its effect on as-cast and hot-working microstructure of commercial purity aluminum (pure Al) was inve...A novel type nano TiN/Ti composite grain refiner (TiN/Ti refiner) was prepared by high energy ball milling, and its effect on as-cast and hot-working microstructure of commercial purity aluminum (pure Al) was investigated. The results show that TiN/Ti refiner exhibits excellent grain refining performances on pure Al. With an addition of 0.2% TiN/Ti refiner, the average grain size of pure Al decreases to 82 μm, which is smaller than that of pure Ti and Al 5Ti 1B master alloy as refiners. The microstructure of weld joint of pure Al with 0.1% TiN/Ti refiner is fine equiaxed grains and the hardness of weld joint is higher than that of the base metal. For pure Al with 40% cold deformation and recrystallization at 250 °C for 1.0 h, the grains of the sample added 0.1% Ti powder have an obvious grain growth behavior. In contrast, oriented grains caused by deformation have been eliminated, and there is no obvious grain growth in pure Al refined with 0.1% TiN/Ti refiner, indicating that nano TiN in the refiner inhibits the growth of grain during recrystallization.展开更多
The function of protein in long-range biological electron transfer is a question of debate. We report some preliminary results in femtosecond spectroscopic study of photosynthetic bacterial light-harvesting antenna co...The function of protein in long-range biological electron transfer is a question of debate. We report some preliminary results in femtosecond spectroscopic study of photosynthetic bacterial light-harvesting antenna complex assembled onto TiO2 nanoparticle with an average size of 8 nm in diameter. Crystal structure shows that photosynthetic bacterial antenna complex LH2 has a ring-like structure composed by alpha- and beta-apoprotein helices. The alpha- and beta-transmembrance helices construct two concentric cylinders with pigments bacteriochlorophyll a (Bchl a) and carotenoid (Car) buried inside the protein. We attempt to insert TiO2 nanoparticle into the cavity of the inner cylindrical hollow of LH2 to investigate the nature of the electron transfer between the excited-state Bchl a and the TiO2 nanoparticle. A significant decrease in the ground state bleaching recovery time constant for Bchl a at 850 run (B850) in respect to that of the Bchl a in free LH2 has been observed. By using the relation of distance-dependent long-range electron transfer rate in protein, the distance between the donor B850 and the acceptor TiO2 nanoparticle has been estimated, which is about 0.6 nm. The proposed method of assembling proteins onto wide-gap semiconductor nanoparticle can be a promising way to determine the role of the protein playing in biological electron transfer processes.展开更多
Objective To study the antineoplastic effect of the calcium channel blocker verapamil and 5-fluorouracil intraperitoneal chemotherapy onhepatocarcinoma-bearing rats, and examine the action between calcium channel bloc...Objective To study the antineoplastic effect of the calcium channel blocker verapamil and 5-fluorouracil intraperitoneal chemotherapy onhepatocarcinoma-bearing rats, and examine the action between calcium channel blockers and cytotoxic drugs.Methods We adopted the method of subcapsular implantation of carcinoma tissues of walker-256 in the left liver lobe as a model of livercarcinoma-bearing rats. All experimental animals were divided into four groups. On the sixth day post implantation, in group A (controlgroup) 6 ml of saline was injected intraperitoneally once a day for 3 days. In group B (single chemotherapy group) 6 ml of 5-Fu 75 mg/kg was injected intraperitoneally once a day for 3 days. In group C (combination of treatment group) both 5-Fu (75 mg/kg) and verapamil(25 mg/kg) were administered simultaneously as in A and B. In group D (simple verapamil group) only 6 ml of verapamil (25 mg/kg)was administered as above.Results Compared with groups A, B and D, The volume of cancer and the contents of liver cancer DNA and protein were significantlyreduced. The rates of inhibiting cancer (89.9% in group C and 35.4% in group B) were significantly increased in group C. Group C hadsignificantly long survival time compared to groups A, B and D ( P < 0.05) . By light microscopy, a number of focal necroses were foundin cancer tissue in group C.Conclusion Calcium channel blockers can enhance the antineoplastic effect of 5-Fu intraperitoneal chemotherapy to liver cancer ; Theuse of verapamil can not increase the toxicity of 5-Fu.展开更多
To investigate the Fe^2+ effects on root tips in rice plant, experiments were carried out using border cells in vitro. The border cells were pre-planted in aeroponic culture and detached from root tips. Most border c...To investigate the Fe^2+ effects on root tips in rice plant, experiments were carried out using border cells in vitro. The border cells were pre-planted in aeroponic culture and detached from root tips. Most border cells have a long elliptical shape. The number and the viability of border cells in situ reached the maxima of 1600 and 97.5%, respectively, at 20---25 mm root length. This mortality was more pronounced at the first 1-12 h exposure to 250 mg/L Fe^2+ than at the last 12-36 h. After 36 h, the cell viability exposed to 250 mg/L Fe^2+ decreased to nought, whereas it was 46.5% at 0 mg/L Fe^2+. Increased Fe^2+ dosage stimulated the death of detached border cells from rice cultivars. After 4 h Fe^2+ treatment, the cell viabilities were _〉80% at 0 and 50 mg/L Fe^2+ treatment and were 〈62% at 150, 250 and 350 mg/L Fe^2+ treatment; The viability of border cells decreased by 10% when the Fe^2+ concentration increased by 100 mg/L. After 24 h Fe^2+ treatment, the viabilities of border cells at all the Fe^2+ levels were 〈65%; The viability of border cells decreased by 20% when the Fee+ concentration increased by 100 mg/L. The decreased viabilities of border cells indicated that Fe^2+ dosage and treatment time would cause deadly effect on the border cells. The increased cell death could protect the root tips from toxic harm. Therefore, it may protect root from the damage caused by harmful iron toxicity.展开更多
AIM: To investigate the influence of high dose of dexamethasone on inflammatory mediators and apoptosis of rats with severe acute pancreatitis (SAP). METHODS: SAP rats were randomly assigned to the model group and tre...AIM: To investigate the influence of high dose of dexamethasone on inflammatory mediators and apoptosis of rats with severe acute pancreatitis (SAP). METHODS: SAP rats were randomly assigned to the model group and treatment group while the normal rats were assigned to the sham operation group. The mortality,ascite volumes,ascites/body weight ratio and pancreas pathological changes of all rats were observed at 3,6 and 12 h after operation. Their contents of amylase and endotoxin in plasma and contents of tumor necrosis factor (TNF-α),phospholipase A2 (PLA2) and IL-6 in serum were also determined. The microarray sections of their pancreatic tissues were prepared,terminal transferase dUTP nick end labeling (TUNEL) staining was performed and apoptotic indexes were calculated. RESULTS: There was no marked difference between treatment group and model group in survival. The contents of amylase and endotoxin in plasma and contents of TNF-α,PLA2 and IL-6 in serum,ascite volumes,ascites/body weight ratio and pancreas pathological scores were all lower in treatment group than in model group to different extents at different time points P < 0.05,58.3 (26.4) ng/L vs 77.535 (42.157) ng/L in TNF-α content,8.00 (2.00) points vs 9.00 (2.00) points in pathological score of pancreas respectively; P < 0.01,0.042 (0.018) EU/mL vs 0.056 (0.0195) EU/mL in endotoxin content,7791 (1863) U/L vs 9195 (1298) U/L in plasma amylase content,1.53 (0.79) vs 2.38 (1.10) in ascites/body weight ratio,8.00 (1.00) points vs 11.00 (1.50) points in pathological score of pancreas; P < 0.001,3.36 (1.56) ng/L vs 5.65 (1.08) ng/L in IL-6 content,4.50 (2.00) vs 7.20 (2.00),4.20 (1.60) vs 6.40 (2.30),3.40 (2.70) vs 7.90 (1.70) in ascite volumes,respectively. The apoptotic indexes of pancreas head and pancreas tail were all higher in treatment group than in model group at 6 h P < 0.01,0.00 (2.00)% vs 0.00 (0.00)%,0.20 (1.80) vs 0.00 (0.00) in apoptosis indexes,respectively. CONCLUSION: The mechanism of dexamethasone treatment in acute pancreatitis is related to its inhibition of inflammatory mediator generation and induction of pancreatic acinar cell apoptosis.展开更多
In macrophages, the accumulation of cholesteryl esters synthesized by the activated acyl-coenzyme A:cholesterol acyltransferase-1 (ACAT1) results in the foam cell formation, a hallmark of early atherosclerotic lesions...In macrophages, the accumulation of cholesteryl esters synthesized by the activated acyl-coenzyme A:cholesterol acyltransferase-1 (ACAT1) results in the foam cell formation, a hallmark of early atherosclerotic lesions. In this study, with the treatment of a glucocorticoid hormone dexamethasone (Dex), lipid staining results clearly showed the large accumulation of lipid droplets containing cholesteryl esters in THP-1-derived macrophages exposed to lower concentration of the oxidized low-density lipoprotein (ox-LDL). More notably, when treated together with specific anti-ACAT inhibitors, the abundant cholesteryl ester accumulation was markedly diminished in THP-1-derived macrophages, confirming that ACAT is the key enzyme responsible for intracellular cholesteryl ester synthesis. RT-PCR and Western blot results indicated that Dex caused up-regulation of human ACAT1 expression at both the mRNA and protein levels in THP-1 and THP-1-derived macrophages. The luciferase activity assay demonstrated that Dex could enhance the activity of human ACAT1 gene P1 promoter, a major factor leading to the ACAT1 activation, in a cell-specific manner. Further experimental evidences showed that a glucocorticoid response element (GRE) located within human ACAT1 gene P1 promoter to response to the elevation of human ACAT1 gene expression by Dex could be functionally bound with glucocorticoid receptor (GR) proteins. These data supported the hypothesis that the clinical treatment with Dex, which increased the incidence of atherosclerosis, may in part due to enhancing the ACAT1 expression to promote the accumulation of cholesteryl esters during the macrophage-derived foam cell formation, an early stage of atherosclerosis.展开更多
基金Project(51205302)supported by the National Natural Science Foundation of ChinaProject(2013JM7017)supported by the Natural Science Basic Research Plan in Shanxi Province of ChinaProject(K5051304006)supported by the Fundamental Research Funds for the Central Universities,China
文摘Based on the EAM potential, a molecular dynamics study on the tensile properties of ultrathin nickel nanowires in the (100〉 orientation with diameters of 3.94, 4.95 and 5.99 nm was presented at different temperatures and strain rates. The temperature and strain rate dependences of tensile properties were investigated. The simulation results show that the elastic modulus and the yield strength are gradually decreasing with the increase of temperature, while with the increase of the strain rate, the stress--strain curves fluctuate more intensely and the ultrathin nickel nanowires rupture at one smaller and smaller strain. At an ideal temperature of 0.01 K, the yield strength of the nanowires drops rapidly with the increase of strain rate, and at other temperatures the strain rate has a little influence on the elastic modulus and the yield strength. Finally, the effects of size on the tensile properties of ultrathin nickel nanowires were briefly discussed.
文摘Microstructure refinement of a dual phase titanium alloy, Ti-3AI-4.5V-5Mo, by severe room temperature compression was investigated. Nanocrystalline grains were observed in the sample with 75% reduction, in which the grain sizes of a phase and β phase were approximately 50 and 100 nm. Conversely, the average thicknesses of a phase and β phase in as-received microstructure were measured to be 0.7 and 0.5 μm, respectively. TEM and XRD methods were used to analyze the microstructure and texture changes after severe deformation. Microstructure refinement was deduced to the complex interaction among slip dislocations in the a phase, the complex interaction among slip dislocations and martensites in the β phases. In addition, the interaction between the a phase and the β phase also contributed to the microstructure refinement.
文摘Objective:To investigate possible effects of nanophase powder of hydroxyapatite on proliferation of periodontal ligament cells. Methods: With sol-gel method, the nanophase hydroxyapatite powders were fabricated. These powders were proved nanopaticles by transmission electron microscope. The effects on proliferation of periodontal ligament cell(PDLC) were observed in vitro with MTT [3-(4,5dimethylthiazo;-2-yl)-2,5-diphenytetralium bromide] method. Results: On the 2nd,3rd,4th day after treated with nanoparticles of hydroxyapatite, the proliferate activity of the PDLC increases significantly, compared with those with dense hydroxyaoatite and control but no significant difference could be found between the dense hydroxyapatite and the control. Conclusion: Nanophase hydroxyapatite can promote the regeneration of periodontal tissue.
文摘Large scale of sexual cell fusion was carried out in order to observe the fusion pattern during in vitro fertilization with special interest in the influence of cell volume on the membrane behavior. Three patterns could be recognized in sexual cell fusion, which was supported by fluorescent microscopy with the aid of video enhanced system and cooled CCD. It was found that the fusion pattern and cell membrane behavior were related to the cell volume ratio of two fusing cells. The results reported here might be useful for interpreting and evaluating data from in vitro fertilization experiments and for explaining male cytoplasm exclusion during fertilization.
基金Supported by Youth Fund Project of Sichuan Academy of Agricultural Sciences(2009QNJJ015)~~
文摘Five cytoplasmic male sterile (CMS) lines were used as parents in an incomplete diallet cross and six restorer lines of rice design (Nc II design). Thirty hybrid combinations with the same growth period were selected as experimental ma- terials to investigate the heterosis, combined ability and heredity of Cd content in brown rice of indica hybrid rice. According to the results, Cd content in brown rice showed a significantly negative heterosis; the general combining ability and specific combination ability of Cd content in CMS and restorer lines both reached extremely significant level (P〈0.01), indicating that both genetic improvement of parents and e- valuation of combinations are important to the breeding of hybrid combinations with low accumulation of Cd; the broad-sense heritabitity and narrow-sense heritability of Cd content were both relatively high with slight differences, which respectively reached 97.73% and 80.10%, indicating that Cd content in brown rice mainly de- pends on the additive action of genes; in addition, parent improvement showed bet- ter effect on the selection of early generation.
文摘A novel type nano TiN/Ti composite grain refiner (TiN/Ti refiner) was prepared by high energy ball milling, and its effect on as-cast and hot-working microstructure of commercial purity aluminum (pure Al) was investigated. The results show that TiN/Ti refiner exhibits excellent grain refining performances on pure Al. With an addition of 0.2% TiN/Ti refiner, the average grain size of pure Al decreases to 82 μm, which is smaller than that of pure Ti and Al 5Ti 1B master alloy as refiners. The microstructure of weld joint of pure Al with 0.1% TiN/Ti refiner is fine equiaxed grains and the hardness of weld joint is higher than that of the base metal. For pure Al with 40% cold deformation and recrystallization at 250 °C for 1.0 h, the grains of the sample added 0.1% Ti powder have an obvious grain growth behavior. In contrast, oriented grains caused by deformation have been eliminated, and there is no obvious grain growth in pure Al refined with 0.1% TiN/Ti refiner, indicating that nano TiN in the refiner inhibits the growth of grain during recrystallization.
文摘The function of protein in long-range biological electron transfer is a question of debate. We report some preliminary results in femtosecond spectroscopic study of photosynthetic bacterial light-harvesting antenna complex assembled onto TiO2 nanoparticle with an average size of 8 nm in diameter. Crystal structure shows that photosynthetic bacterial antenna complex LH2 has a ring-like structure composed by alpha- and beta-apoprotein helices. The alpha- and beta-transmembrance helices construct two concentric cylinders with pigments bacteriochlorophyll a (Bchl a) and carotenoid (Car) buried inside the protein. We attempt to insert TiO2 nanoparticle into the cavity of the inner cylindrical hollow of LH2 to investigate the nature of the electron transfer between the excited-state Bchl a and the TiO2 nanoparticle. A significant decrease in the ground state bleaching recovery time constant for Bchl a at 850 run (B850) in respect to that of the Bchl a in free LH2 has been observed. By using the relation of distance-dependent long-range electron transfer rate in protein, the distance between the donor B850 and the acceptor TiO2 nanoparticle has been estimated, which is about 0.6 nm. The proposed method of assembling proteins onto wide-gap semiconductor nanoparticle can be a promising way to determine the role of the protein playing in biological electron transfer processes.
文摘Objective To study the antineoplastic effect of the calcium channel blocker verapamil and 5-fluorouracil intraperitoneal chemotherapy onhepatocarcinoma-bearing rats, and examine the action between calcium channel blockers and cytotoxic drugs.Methods We adopted the method of subcapsular implantation of carcinoma tissues of walker-256 in the left liver lobe as a model of livercarcinoma-bearing rats. All experimental animals were divided into four groups. On the sixth day post implantation, in group A (controlgroup) 6 ml of saline was injected intraperitoneally once a day for 3 days. In group B (single chemotherapy group) 6 ml of 5-Fu 75 mg/kg was injected intraperitoneally once a day for 3 days. In group C (combination of treatment group) both 5-Fu (75 mg/kg) and verapamil(25 mg/kg) were administered simultaneously as in A and B. In group D (simple verapamil group) only 6 ml of verapamil (25 mg/kg)was administered as above.Results Compared with groups A, B and D, The volume of cancer and the contents of liver cancer DNA and protein were significantlyreduced. The rates of inhibiting cancer (89.9% in group C and 35.4% in group B) were significantly increased in group C. Group C hadsignificantly long survival time compared to groups A, B and D ( P < 0.05) . By light microscopy, a number of focal necroses were foundin cancer tissue in group C.Conclusion Calcium channel blockers can enhance the antineoplastic effect of 5-Fu intraperitoneal chemotherapy to liver cancer ; Theuse of verapamil can not increase the toxicity of 5-Fu.
基金Project (Nos. Y307535 and Y304185) supported by the Natural Science Foundation of Zhejiang Province,China
文摘To investigate the Fe^2+ effects on root tips in rice plant, experiments were carried out using border cells in vitro. The border cells were pre-planted in aeroponic culture and detached from root tips. Most border cells have a long elliptical shape. The number and the viability of border cells in situ reached the maxima of 1600 and 97.5%, respectively, at 20---25 mm root length. This mortality was more pronounced at the first 1-12 h exposure to 250 mg/L Fe^2+ than at the last 12-36 h. After 36 h, the cell viability exposed to 250 mg/L Fe^2+ decreased to nought, whereas it was 46.5% at 0 mg/L Fe^2+. Increased Fe^2+ dosage stimulated the death of detached border cells from rice cultivars. After 4 h Fe^2+ treatment, the cell viabilities were _〉80% at 0 and 50 mg/L Fe^2+ treatment and were 〈62% at 150, 250 and 350 mg/L Fe^2+ treatment; The viability of border cells decreased by 10% when the Fe^2+ concentration increased by 100 mg/L. After 24 h Fe^2+ treatment, the viabilities of border cells at all the Fe^2+ levels were 〈65%; The viability of border cells decreased by 20% when the Fee+ concentration increased by 100 mg/L. The decreased viabilities of border cells indicated that Fe^2+ dosage and treatment time would cause deadly effect on the border cells. The increased cell death could protect the root tips from toxic harm. Therefore, it may protect root from the damage caused by harmful iron toxicity.
基金Supported by Grants for Traditional Chinese Medicine Science of Zhejiang Province,and Medical Science and Technology of Zhejiang Province and Hangzhou
文摘AIM: To investigate the influence of high dose of dexamethasone on inflammatory mediators and apoptosis of rats with severe acute pancreatitis (SAP). METHODS: SAP rats were randomly assigned to the model group and treatment group while the normal rats were assigned to the sham operation group. The mortality,ascite volumes,ascites/body weight ratio and pancreas pathological changes of all rats were observed at 3,6 and 12 h after operation. Their contents of amylase and endotoxin in plasma and contents of tumor necrosis factor (TNF-α),phospholipase A2 (PLA2) and IL-6 in serum were also determined. The microarray sections of their pancreatic tissues were prepared,terminal transferase dUTP nick end labeling (TUNEL) staining was performed and apoptotic indexes were calculated. RESULTS: There was no marked difference between treatment group and model group in survival. The contents of amylase and endotoxin in plasma and contents of TNF-α,PLA2 and IL-6 in serum,ascite volumes,ascites/body weight ratio and pancreas pathological scores were all lower in treatment group than in model group to different extents at different time points P < 0.05,58.3 (26.4) ng/L vs 77.535 (42.157) ng/L in TNF-α content,8.00 (2.00) points vs 9.00 (2.00) points in pathological score of pancreas respectively; P < 0.01,0.042 (0.018) EU/mL vs 0.056 (0.0195) EU/mL in endotoxin content,7791 (1863) U/L vs 9195 (1298) U/L in plasma amylase content,1.53 (0.79) vs 2.38 (1.10) in ascites/body weight ratio,8.00 (1.00) points vs 11.00 (1.50) points in pathological score of pancreas; P < 0.001,3.36 (1.56) ng/L vs 5.65 (1.08) ng/L in IL-6 content,4.50 (2.00) vs 7.20 (2.00),4.20 (1.60) vs 6.40 (2.30),3.40 (2.70) vs 7.90 (1.70) in ascite volumes,respectively. The apoptotic indexes of pancreas head and pancreas tail were all higher in treatment group than in model group at 6 h P < 0.01,0.00 (2.00)% vs 0.00 (0.00)%,0.20 (1.80) vs 0.00 (0.00) in apoptosis indexes,respectively. CONCLUSION: The mechanism of dexamethasone treatment in acute pancreatitis is related to its inhibition of inflammatory mediator generation and induction of pancreatic acinar cell apoptosis.
基金supported by grants of the Major State Basic Research Development program of China(No.2002CB513000)National Scienses Foudation Center(No.30393110)+1 种基金State Science and Technology Committee(SSTC)(NO.02DJ14068)Chinese Academy of Science to Bo Liang LI,and NIH grant HL36709 to Ta Yuan CHANG.
文摘In macrophages, the accumulation of cholesteryl esters synthesized by the activated acyl-coenzyme A:cholesterol acyltransferase-1 (ACAT1) results in the foam cell formation, a hallmark of early atherosclerotic lesions. In this study, with the treatment of a glucocorticoid hormone dexamethasone (Dex), lipid staining results clearly showed the large accumulation of lipid droplets containing cholesteryl esters in THP-1-derived macrophages exposed to lower concentration of the oxidized low-density lipoprotein (ox-LDL). More notably, when treated together with specific anti-ACAT inhibitors, the abundant cholesteryl ester accumulation was markedly diminished in THP-1-derived macrophages, confirming that ACAT is the key enzyme responsible for intracellular cholesteryl ester synthesis. RT-PCR and Western blot results indicated that Dex caused up-regulation of human ACAT1 expression at both the mRNA and protein levels in THP-1 and THP-1-derived macrophages. The luciferase activity assay demonstrated that Dex could enhance the activity of human ACAT1 gene P1 promoter, a major factor leading to the ACAT1 activation, in a cell-specific manner. Further experimental evidences showed that a glucocorticoid response element (GRE) located within human ACAT1 gene P1 promoter to response to the elevation of human ACAT1 gene expression by Dex could be functionally bound with glucocorticoid receptor (GR) proteins. These data supported the hypothesis that the clinical treatment with Dex, which increased the incidence of atherosclerosis, may in part due to enhancing the ACAT1 expression to promote the accumulation of cholesteryl esters during the macrophage-derived foam cell formation, an early stage of atherosclerosis.