The magnetic gelatin-starch microspheres were prepared by modified emulsion cross-linking method with glutaraldehyde as the cross-linking agent. The structure, size distribution as well as morphology of magnetic micro...The magnetic gelatin-starch microspheres were prepared by modified emulsion cross-linking method with glutaraldehyde as the cross-linking agent. The structure, size distribution as well as morphology of magnetic microspheres were investigated by FT-IR spectrometer, dynamic laser scattering analyzer and scanning electron microscope, respectively. Bovine serum album(BSA)was chosen as model protein, and the adsorption processes were carried out under diversified conditions including BSA initial concentration, p H value, adsorption time and temperature to evaluate the performance of the magnetic microspheres. The average diameter of optimized spherical magnetic microspheres is 1.6 μm with excellent dispersivity, and the saturation magnetization is found to be equal to 1.056×10-2 A·m2. The adsorption isotherm of the BSA on the magnetic microspheres basically obeys the Langmuir model, with a maximum adsorption capacity of 120 mg/g and an adsorption equilibrium constant of 1.60 mL/mg.展开更多
Magnetospirillum magneticum strain AMB-1 belongs to the family of magnetotactic bacteria. It possesses a magnetosome chain aligning, with the assistance of cytoskeleton filaments MamK, along the long axis of the spira...Magnetospirillum magneticum strain AMB-1 belongs to the family of magnetotactic bacteria. It possesses a magnetosome chain aligning, with the assistance of cytoskeleton filaments MamK, along the long axis of the spiral cells. Most fresh M. magneticum AMB-1 cells exhibit spiral morphology. In addition, other cell shapes such as curved and spherical were also observed in this organism. Interestingly, the spherical cell shape increased steadily with prolonged incubation time. As the actin-like cytoskeleton protein MreB is involved in maintenance of cell shapes in rod-shaped bacteria such as Escherichia coli and Bacillus subtilis, the correlation between MreB protein levels and cell shape was investigated in this study. Immunoblotting analysis showed that the quantity of MreB decreased when the cell shape changed along with incubation time. As an internal control, the quantity of MamA was not obviously changed under the same conditions. Cell shape directs cell-wall synthesis during growth and division. MreB is required for maintaining the cell shape. Thus, MreB might play an essential role in maintaining the spiral shape of M. magneticum AMB-1 cells.展开更多
AIM: To investigate the accuracy of T2*-weighted magnetic resonance imaging (MRI T2*) in the evaluation of iron overload in beta-thalassemia major patients. METHODS: In this cross-sectional study, 210 patients with be...AIM: To investigate the accuracy of T2*-weighted magnetic resonance imaging (MRI T2*) in the evaluation of iron overload in beta-thalassemia major patients. METHODS: In this cross-sectional study, 210 patients with beta-thalassemia major having regular blood transfusions were consecutively enrolled. Serum ferritin levels were measured, and all patients underwent MRI T2* of the liver. Liver biopsy was performed in 53 patients at an interval of no longer than 3 mo after the MRIT2* in each patient. The amount of iron was assessed in both MRI T2* and liver biopsy specimens of each patient. RESULTS: Patients’ ages ranged from 8 to 54 years with a mean of 24.59 ± 8.5 years. Mean serum ferritin level was 1906 ± 1644 ng/mL. Liver biopsy showed a moderate negative correlation with liver MRI T2* (r = -0.573, P = 0.000) and a low positive correlation with ferritin level (r = 0.350, P = 0.001). Serum ferritin levels showed a moderate negative correlation with liver MRI T2* values (r = -0.586, P = 0.000). CONCLUSION: Our study suggests that MRI T2* is a non-invasive, safe and reliable method for detecting iron load in patients with iron overload.展开更多
Magnetic nanoparticles （Fe304） were prepared by chemical precipitation method using Fe^2＋ and Fe^3＋ salts with sodium hydroxide in the nitrogen atmosphere. Fe3O4 nanoparticles were coated with human serum albumin...Magnetic nanoparticles （Fe304） were prepared by chemical precipitation method using Fe^2＋ and Fe^3＋ salts with sodium hydroxide in the nitrogen atmosphere. Fe3O4 nanoparticles were coated with human serum albumin（HSA） for magnetic resonance imaging as contrast agent. Characteristics of magnetic particles coated or uncoated were carried out using scanning electron microscopy and X-ray diffraction. Zeta potentials, package effects and distributions of colloid particles were measured to confirm the attachment of HSA on magnetic particles. Effects of Fe3O4 nanoparticles coated with HSA on magnetic resonance imaging were investigated with rats. The experimental results show that the adsorption of HSA on magnetic particles is very favorable to dispersing of magnetic Fe3O4 particles, while the sizes of Fe3O4 particles coated are related to the molar ratio of Fe3O4 to HSA. The diameters of the majority of particles coated are less than 100 nm. Fe3O4 nanoparticle coated with HSA has a good biocompatibility and low toxicity. This new contrast agent has some effects on the nuclear magnetic resonance imaging of liver and the lowest dosage is 20μmol/kg for the demands of diagnosis.展开更多
The Mycobacterium tuberculosis protein Rv2302 has been characterized using nuclear magnetic resonance （NMR） and circular dichroism （CD） spectroscopy. While the biochemical function of Rv2302 is still unknown, rece...The Mycobacterium tuberculosis protein Rv2302 has been characterized using nuclear magnetic resonance （NMR） and circular dichroism （CD） spectroscopy. While the biochemical function of Rv2302 is still unknown, recent microarray analyses show that Rv2302 is upregulated in response to starvation and overexpression of heat shock proteins and, consequently, may play a role in the biochemical processes associated with these events. Rv2302 is a monomer in solution as shown by size exclusion chromatography and NMR spectroscopy. CD spectroscopy suggests that Rv2302 partially unfolds upon heating and that this unfolding is reversible. Using NMR-based methods, the solution structure of Rv2302 was determined. The protein contains a five-strand, antiparalle β-sheet core with one C-terminal α-helix （A61 to A75） nestled against its side. Hydrophobic interactions between residues in the α-helix and β-strands 3 and 4 hold the α-helix near the β-sheet core. The electrostatic potential on the solvent-accessible surface is primarily negative with the exception of a positive arginine pocket composed of residues R18, R70, and R74. Steady-state {^1H}-^15N heteronuclear nuclear Overhauser effects indicate that the protein＇s core is rigid on the picosecond timescale. The absence of amide cross-peaks for residues G 13 to H 19 in the ^1H-^15N heteronuclear single quantum correlation spectrum suggests that this region, a loop between β-strands 1 and 2, undergoes motion on the millisecond to microsecond timescale. Dali searches using the structure closest to the average structure do not identify any high similarities to any other known protein structure, suggesting that the structure of Rv2302 may represent a novel protein fold.展开更多
The eukaryotic genome is organized into functionally and structurally distinct domains, representing regulatory unitsfor gene expression and chromosome behavior. DNA sequences that mark the border between adjacent dom...The eukaryotic genome is organized into functionally and structurally distinct domains, representing regulatory unitsfor gene expression and chromosome behavior. DNA sequences that mark the border between adjacent domains are theinsulators or boundary elements, which are required in maintenance of the function of different domains. Some insula-tors need others enable to play insulation activity. Chromatin domains are defined by distinct sets of post-translationallymodified histones. Recent studies show that these histone modifications are also involved in establishment of sharpchromatin boundaries in order to prevent the spreading of distinct domains. Additionally, in some loci, the high-orderchromatin structures for long-range looping interactions also have boundary activities, suggesting a correlation betweeninsulators and chromatin loop domains. In this review, we will discuss recent progress in the field of chromatin domainboundaries.展开更多
Escherichia coli type 1 was used as a model system to determine whether static magnetic fields are a general stress factor. The bacterial broth culture were exposed to different magnetic force （400, 800, 1200 and 160...Escherichia coli type 1 was used as a model system to determine whether static magnetic fields are a general stress factor. The bacterial broth culture were exposed to different magnetic force （400, 800, 1200 and 1600 Gauss） with incubation at 37 ℃ for different times （24, 48 and 72 hrs） under aerobic conditions. The response of the cells to the magnetic fields was estimated from the change in total protein synthesis by using spectrophotometer at 550 nm and by using of SDS-PAGE （Sodium dodecyl sulfate- polyacrylamide gel electrophoresis）. Results concluded that was approximately no reproducible changes qualitatively in extracellular proteins were observed in the SDS-PAGE electrophoresis and did not act as a general stress factor. While, increases in the level of extra-cellular synthesis were observed using different magnetic field exposed samples when compared with the control.展开更多
基金Project(GC201204)supported by the Open Fund of Guangdong Provincial Key Laboratory for the Green Chemicals,China
文摘The magnetic gelatin-starch microspheres were prepared by modified emulsion cross-linking method with glutaraldehyde as the cross-linking agent. The structure, size distribution as well as morphology of magnetic microspheres were investigated by FT-IR spectrometer, dynamic laser scattering analyzer and scanning electron microscope, respectively. Bovine serum album(BSA)was chosen as model protein, and the adsorption processes were carried out under diversified conditions including BSA initial concentration, p H value, adsorption time and temperature to evaluate the performance of the magnetic microspheres. The average diameter of optimized spherical magnetic microspheres is 1.6 μm with excellent dispersivity, and the saturation magnetization is found to be equal to 1.056×10-2 A·m2. The adsorption isotherm of the BSA on the magnetic microspheres basically obeys the Langmuir model, with a maximum adsorption capacity of 120 mg/g and an adsorption equilibrium constant of 1.60 mL/mg.
基金Supported by the CAS/SAFEA International Partnership Program for Creative Research Teams (Research and Applications of Marine Functional Genomics)the Haiwaijie chuxuezhe-Fund of the Chinese Academy of Sciences (2006-1-15)+1 种基金the fund from MATHAB (No. MH200804)a CNRS scholarship for FZ, and National Natural Science Foundation of China (No. 40776094)
文摘Magnetospirillum magneticum strain AMB-1 belongs to the family of magnetotactic bacteria. It possesses a magnetosome chain aligning, with the assistance of cytoskeleton filaments MamK, along the long axis of the spiral cells. Most fresh M. magneticum AMB-1 cells exhibit spiral morphology. In addition, other cell shapes such as curved and spherical were also observed in this organism. Interestingly, the spherical cell shape increased steadily with prolonged incubation time. As the actin-like cytoskeleton protein MreB is involved in maintenance of cell shapes in rod-shaped bacteria such as Escherichia coli and Bacillus subtilis, the correlation between MreB protein levels and cell shape was investigated in this study. Immunoblotting analysis showed that the quantity of MreB decreased when the cell shape changed along with incubation time. As an internal control, the quantity of MamA was not obviously changed under the same conditions. Cell shape directs cell-wall synthesis during growth and division. MreB is required for maintaining the cell shape. Thus, MreB might play an essential role in maintaining the spiral shape of M. magneticum AMB-1 cells.
基金Supported by The Gastrointestinal and Liver Disease Research Center of Tehran University of Medical Sciences
文摘AIM: To investigate the accuracy of T2*-weighted magnetic resonance imaging (MRI T2*) in the evaluation of iron overload in beta-thalassemia major patients. METHODS: In this cross-sectional study, 210 patients with beta-thalassemia major having regular blood transfusions were consecutively enrolled. Serum ferritin levels were measured, and all patients underwent MRI T2* of the liver. Liver biopsy was performed in 53 patients at an interval of no longer than 3 mo after the MRIT2* in each patient. The amount of iron was assessed in both MRI T2* and liver biopsy specimens of each patient. RESULTS: Patients’ ages ranged from 8 to 54 years with a mean of 24.59 ± 8.5 years. Mean serum ferritin level was 1906 ± 1644 ng/mL. Liver biopsy showed a moderate negative correlation with liver MRI T2* (r = -0.573, P = 0.000) and a low positive correlation with ferritin level (r = 0.350, P = 0.001). Serum ferritin levels showed a moderate negative correlation with liver MRI T2* values (r = -0.586, P = 0.000). CONCLUSION: Our study suggests that MRI T2* is a non-invasive, safe and reliable method for detecting iron load in patients with iron overload.
文摘Magnetic nanoparticles （Fe304） were prepared by chemical precipitation method using Fe^2＋ and Fe^3＋ salts with sodium hydroxide in the nitrogen atmosphere. Fe3O4 nanoparticles were coated with human serum albumin（HSA） for magnetic resonance imaging as contrast agent. Characteristics of magnetic particles coated or uncoated were carried out using scanning electron microscopy and X-ray diffraction. Zeta potentials, package effects and distributions of colloid particles were measured to confirm the attachment of HSA on magnetic particles. Effects of Fe3O4 nanoparticles coated with HSA on magnetic resonance imaging were investigated with rats. The experimental results show that the adsorption of HSA on magnetic particles is very favorable to dispersing of magnetic Fe3O4 particles, while the sizes of Fe3O4 particles coated are related to the molar ratio of Fe3O4 to HSA. The diameters of the majority of particles coated are less than 100 nm. Fe3O4 nanoparticle coated with HSA has a good biocompatibility and low toxicity. This new contrast agent has some effects on the nuclear magnetic resonance imaging of liver and the lowest dosage is 20μmol/kg for the demands of diagnosis.
文摘The Mycobacterium tuberculosis protein Rv2302 has been characterized using nuclear magnetic resonance （NMR） and circular dichroism （CD） spectroscopy. While the biochemical function of Rv2302 is still unknown, recent microarray analyses show that Rv2302 is upregulated in response to starvation and overexpression of heat shock proteins and, consequently, may play a role in the biochemical processes associated with these events. Rv2302 is a monomer in solution as shown by size exclusion chromatography and NMR spectroscopy. CD spectroscopy suggests that Rv2302 partially unfolds upon heating and that this unfolding is reversible. Using NMR-based methods, the solution structure of Rv2302 was determined. The protein contains a five-strand, antiparalle β-sheet core with one C-terminal α-helix （A61 to A75） nestled against its side. Hydrophobic interactions between residues in the α-helix and β-strands 3 and 4 hold the α-helix near the β-sheet core. The electrostatic potential on the solvent-accessible surface is primarily negative with the exception of a positive arginine pocket composed of residues R18, R70, and R74. Steady-state {^1H}-^15N heteronuclear nuclear Overhauser effects indicate that the protein＇s core is rigid on the picosecond timescale. The absence of amide cross-peaks for residues G 13 to H 19 in the ^1H-^15N heteronuclear single quantum correlation spectrum suggests that this region, a loop between β-strands 1 and 2, undergoes motion on the millisecond to microsecond timescale. Dali searches using the structure closest to the average structure do not identify any high similarities to any other known protein structure, suggesting that the structure of Rv2302 may represent a novel protein fold.
基金This work was supported by the grant from the National Natural Science Foundation of China(No.30393110).
文摘The eukaryotic genome is organized into functionally and structurally distinct domains, representing regulatory unitsfor gene expression and chromosome behavior. DNA sequences that mark the border between adjacent domains are theinsulators or boundary elements, which are required in maintenance of the function of different domains. Some insula-tors need others enable to play insulation activity. Chromatin domains are defined by distinct sets of post-translationallymodified histones. Recent studies show that these histone modifications are also involved in establishment of sharpchromatin boundaries in order to prevent the spreading of distinct domains. Additionally, in some loci, the high-orderchromatin structures for long-range looping interactions also have boundary activities, suggesting a correlation betweeninsulators and chromatin loop domains. In this review, we will discuss recent progress in the field of chromatin domainboundaries.
文摘Escherichia coli type 1 was used as a model system to determine whether static magnetic fields are a general stress factor. The bacterial broth culture were exposed to different magnetic force （400, 800, 1200 and 1600 Gauss） with incubation at 37 ℃ for different times （24, 48 and 72 hrs） under aerobic conditions. The response of the cells to the magnetic fields was estimated from the change in total protein synthesis by using spectrophotometer at 550 nm and by using of SDS-PAGE （Sodium dodecyl sulfate- polyacrylamide gel electrophoresis）. Results concluded that was approximately no reproducible changes qualitatively in extracellular proteins were observed in the SDS-PAGE electrophoresis and did not act as a general stress factor. While, increases in the level of extra-cellular synthesis were observed using different magnetic field exposed samples when compared with the control.
