AIM: To investigate the fluid shear stress induced changes of [Ca^2+]i in neutrophils in pancreatic microcirculation of experimental acute pancreatitis (AP).METHODS: Wistar rats (n = 36) were randomized into three gro...AIM: To investigate the fluid shear stress induced changes of [Ca^2+]i in neutrophils in pancreatic microcirculation of experimental acute pancreatitis (AP).METHODS: Wistar rats (n = 36) were randomized into three groups. A model of AP was established by subcutaneous injection of caerulein. Low-shear 30 viscometer was used to provide steady fluid shear stress on separated neutrophils. The mean fluorescent intensity tested by flow cytometry was used as the indication of [Ca2+]i quantity.RESULTS: Under steady shear, cytosolic [Ca^2+]i showed biphasic changes. The shear rate changed from low to high, [Ca^2+]i in different groups decreased slightly and then increased gradually to a high level (P<0.05). A close correlation was observed between the cytosolic [Ca^2+]i level and the alteration of fluid shear stress in regional microcirculation of AP. CONCLUSION: The increase of [Ca^2+]i is highly related to the activation of neutrophils, which contributes to neutrophil adhesion to endothelium in the early phase of AP. The effect of fluid shear stress on [Ca^2+]i may play a crucial role in pancreatic microcirculatory failure of AP.展开更多
To develop a novel degradable poly (L-lactic acid)/β-tricalcium phosphate (PLLA/β-TCP) bioactive materials for bone tissueengineering, β-TCP powder was produced by a new wet process. Porous scaffolds were prepared ...To develop a novel degradable poly (L-lactic acid)/β-tricalcium phosphate (PLLA/β-TCP) bioactive materials for bone tissueengineering, β-TCP powder was produced by a new wet process. Porous scaffolds were prepared by three steps, i.e. solventcasting, compression molding and leaching stage. Factors influencing the compressive strength and the degradation behaviorof the porous scaffold, e.g. weight fraction of pore forming agent-sodium chloride (NaCl), weight ratio of PLLA: β-TCP,the particle size of β-TCP and the porosity, were discussed in details. Rat marrow stromal cells (RMSC) were incorporatedinto the composite by tissue engineering approach. Biological and osteogenesis potential of the composite scaffold weredetermined with MTT assay, alkaline phosphatase (ALP) activity and bone osteocalcin (OCN) content evaluation. Resultsshow that PLLA/β-TCP bioactive porous scaffold has good mechanical and pore structure with adjustable compressive strengthneeded for surgery. RMSCs seeding on porous PLLA/β-TCP composite behaves good seeding efficacy, biocompatibility andosteoinductive potential. Osteoprogenitor cells could well penetrate into the material matrix and begin cell proliferation andosteogenic differentiation. Osseous matrix could be formed on the surface of the composite after culturing in vitro. It isexpected that the PLLA/β-TCP porous composites are promising scaffolds for bone tissue engineering in prosthesis surgery.展开更多
A novel biomaterial scaffold was created from collagen chitosan/GAG. Its tensile strength was 8.6MPa(wet state)and degree of swelling water was 60%～75% with higer ultimate elongation 300%. Rabbit corneas of collagen ...A novel biomaterial scaffold was created from collagen chitosan/GAG. Its tensile strength was 8.6MPa(wet state)and degree of swelling water was 60%～75% with higer ultimate elongation 300%. Rabbit corneas of collagen chitosan/GAG implantation samples in vivo for biodegradation showed that the inplantion samples was complets biodegrable and digested afere 120 day. There was enought time to maintain cell growth,immigrating and proliferation. This biomaterials scaffold can be used for cell culture and in various tissue engineering fields.展开更多
A novel algorithm for Bayesian document segmentation is proposed based on the wavelet domain hidden Markov tree (HMT) model. Once the parameters of model are known, according to the sequential maximum a posterior prob...A novel algorithm for Bayesian document segmentation is proposed based on the wavelet domain hidden Markov tree (HMT) model. Once the parameters of model are known, according to the sequential maximum a posterior probability (SMAP) rule, firstly, the likelihood probability of HMT model for each pattern is computed from fine to coarse procedure. Then, the interscale state transition probability is solved using Expectation Maximum (EM) algorithm based on hybrid-quadtree and multiscale context information is fused from coarse to fine procedure. In order to get pixel-level segmentation, the redundant wavelet domain Gaussian mixture model (GMM) is employed to formulate pixel-level statistical property. The experiment results show that the proposed scheme is feasible and robust.展开更多
MRSI plays a more and more important role in clinical application. In this paper,we compare several fast MRSI technologies and data reconstruction methods. For the conventional phase encoding MRSI,the data reconstruct...MRSI plays a more and more important role in clinical application. In this paper,we compare several fast MRSI technologies and data reconstruction methods. For the conventional phase encoding MRSI,the data reconstruction using FFT is simple. But the data acquisition is very time consuming and thus prohibitive in clinical settings. Up to now,the MRSI technologies based on echo-planar, spiral trajectories and sensitivity encoding are the fastest in data acquisition,but their data reconstruction is complex. EPSI reconstruction uses shift of odd and even echoes. Spiral SI uses gridding FFT. SENSE-SI,a new approach to reducing the acquisition time,uses the distinct spatial sensitivities of the individual coil elements to recover the missing encoding information. These improvements in data acquisition and image reconstruction provide a potential value of metabolic imaging as a clinical tool.展开更多
The objective of this study was to produce the porous col lagen-chitosan/Gl ycosanminglycans(GAG) for corneal cell-seed implant as a t hree-dimensional tissue engineering scaffold to improve the regeneration cornea s....The objective of this study was to produce the porous col lagen-chitosan/Gl ycosanminglycans(GAG) for corneal cell-seed implant as a t hree-dimensional tissue engineering scaffold to improve the regeneration cornea s.The effect of various content of glycerol as form porous agent to collagen-ch i tosan/GAG preserved a porous dimensional structure was investigated.The heat-dr ying was used to prepare porous collagen-chitosan /GAG scaffold.The pore morpho logy of collagen-chitosan/GAG was controlled by changing the concentration of g lycerol solution and drying methods.The porous structure morphology was observed by SEM.The diameter of the pores form 10 to 50 μm.The highly porous scaffold had interconnecting pores.The corneal cell morphology was observed under the li ght microscope.These results suggest that collagen-chitosan/GAG showed that cor neal cell have formed confluent layers and resemble the surface of normal cornea l cell surface.展开更多
The objective of this study was to investigate the influences of organic solvents on particle size, drug content, loading efficiency and yield for 5 Fluorouracil Poly(lactic acid) nanoparticles . The 5 Fluorouracil wa...The objective of this study was to investigate the influences of organic solvents on particle size, drug content, loading efficiency and yield for 5 Fluorouracil Poly(lactic acid) nanoparticles . The 5 Fluorouracil was entrapped into poly(lactic acid)(PLA) nanoparticles using a water in oil in water solvent evaporation technique. During the preparation process, ethyl acetate and acetone were used as organic solvents since they are less toxic than the more commonly used dichloromethane. The effect of the three solvents on particle size, drug content, loading efficiency and yield of nanopartcles was compared. When the solvent of the oil phase was acetone, the highest drug content, smallest particle size and lowest yield were obtained for the PLA nanoparticles.展开更多
Background 5-dihydroxyanthraquinone-2-carboxylic acid (rhein) inhibits oxidoreduction induced by reducing nicotingamide adenine dinucleotide in the mitochondria and reducing reactive oxygen species, it also suppresses...Background 5-dihydroxyanthraquinone-2-carboxylic acid (rhein) inhibits oxidoreduction induced by reducing nicotingamide adenine dinucleotide in the mitochondria and reducing reactive oxygen species, it also suppresses lipid peroxidation in rat brain homogenates. This study was to assess the effects of anthraquinone derivatives, rhein on synaptic transmission in the rat hippocampal CA_1 pyramidal cell layer by intracellular recording.Methods The excitatory postsynaptic potential (EPSP) evoked by stimulation of the Schaffer collaterals in the presence of bicuculline (15 μmol/L) was depressed by application of rhein (0.3-30 μmol/L). The amplitude of the EPSP was restored within 20 minutes after removal of rhein from the supernatant. At a concentration of 30 μmol/L, rhein reduced the amplitude of the EPSP to 42%±3.7% (n=24) of the control. Subsequently, wavelet spectral entropy was used to analyze the EPSP. Results A strong positive correlation was observed between the wavelet spectral entropy and other parameters such as amplitude, slope of rising phase and slope of descending phase of the EPSP. The paired-pulse facilitation (PPF) of the EPSP was significantly increased by rhein (30 μmol/L). The inhibitory postsynaptic potential (IPSP) recorded in the presence of CNQX (20 μmol/L) and APV (40 μmol/L) is not altered by rhein (30 μmol/L). Conclusions Rhein (30 μmol/L) can decrease the frequency but not the amplitude of the miniature EPSP (mEPSP). It is suggested that rhein inhibits excitatory synaptic transmission by decreasing the release of glutamate in rat hippocampal CA_1 pyramidal neurons.展开更多
基金Supported by the National Natural Science Foundation of China,No.39770722 and the Key Project of National Outstanding Youth Foundation of China,No.39925032
文摘AIM: To investigate the fluid shear stress induced changes of [Ca^2+]i in neutrophils in pancreatic microcirculation of experimental acute pancreatitis (AP).METHODS: Wistar rats (n = 36) were randomized into three groups. A model of AP was established by subcutaneous injection of caerulein. Low-shear 30 viscometer was used to provide steady fluid shear stress on separated neutrophils. The mean fluorescent intensity tested by flow cytometry was used as the indication of [Ca2+]i quantity.RESULTS: Under steady shear, cytosolic [Ca^2+]i showed biphasic changes. The shear rate changed from low to high, [Ca^2+]i in different groups decreased slightly and then increased gradually to a high level (P<0.05). A close correlation was observed between the cytosolic [Ca^2+]i level and the alteration of fluid shear stress in regional microcirculation of AP. CONCLUSION: The increase of [Ca^2+]i is highly related to the activation of neutrophils, which contributes to neutrophil adhesion to endothelium in the early phase of AP. The effect of fluid shear stress on [Ca^2+]i may play a crucial role in pancreatic microcirculatory failure of AP.
基金This study was financially supported by 863 Hj-Tech ResearchDevelopment Program of China(2002AA326080)The Fund for Youth Teacher of Education Mlinistry of China(2002123).
文摘To develop a novel degradable poly (L-lactic acid)/β-tricalcium phosphate (PLLA/β-TCP) bioactive materials for bone tissueengineering, β-TCP powder was produced by a new wet process. Porous scaffolds were prepared by three steps, i.e. solventcasting, compression molding and leaching stage. Factors influencing the compressive strength and the degradation behaviorof the porous scaffold, e.g. weight fraction of pore forming agent-sodium chloride (NaCl), weight ratio of PLLA: β-TCP,the particle size of β-TCP and the porosity, were discussed in details. Rat marrow stromal cells (RMSC) were incorporatedinto the composite by tissue engineering approach. Biological and osteogenesis potential of the composite scaffold weredetermined with MTT assay, alkaline phosphatase (ALP) activity and bone osteocalcin (OCN) content evaluation. Resultsshow that PLLA/β-TCP bioactive porous scaffold has good mechanical and pore structure with adjustable compressive strengthneeded for surgery. RMSCs seeding on porous PLLA/β-TCP composite behaves good seeding efficacy, biocompatibility andosteoinductive potential. Osteoprogenitor cells could well penetrate into the material matrix and begin cell proliferation andosteogenic differentiation. Osseous matrix could be formed on the surface of the composite after culturing in vitro. It isexpected that the PLLA/β-TCP porous composites are promising scaffolds for bone tissue engineering in prosthesis surgery.
文摘A novel biomaterial scaffold was created from collagen chitosan/GAG. Its tensile strength was 8.6MPa(wet state)and degree of swelling water was 60%～75% with higer ultimate elongation 300%. Rabbit corneas of collagen chitosan/GAG implantation samples in vivo for biodegradation showed that the inplantion samples was complets biodegrable and digested afere 120 day. There was enought time to maintain cell growth,immigrating and proliferation. This biomaterials scaffold can be used for cell culture and in various tissue engineering fields.
文摘A novel algorithm for Bayesian document segmentation is proposed based on the wavelet domain hidden Markov tree (HMT) model. Once the parameters of model are known, according to the sequential maximum a posterior probability (SMAP) rule, firstly, the likelihood probability of HMT model for each pattern is computed from fine to coarse procedure. Then, the interscale state transition probability is solved using Expectation Maximum (EM) algorithm based on hybrid-quadtree and multiscale context information is fused from coarse to fine procedure. In order to get pixel-level segmentation, the redundant wavelet domain Gaussian mixture model (GMM) is employed to formulate pixel-level statistical property. The experiment results show that the proposed scheme is feasible and robust.
基金National NaturalScinece Foundation of China.Grant number:30 0 70 336.U niversity FoundationofHUST.Grant number:0 10 1170 0 5 4
文摘MRSI plays a more and more important role in clinical application. In this paper,we compare several fast MRSI technologies and data reconstruction methods. For the conventional phase encoding MRSI,the data reconstruction using FFT is simple. But the data acquisition is very time consuming and thus prohibitive in clinical settings. Up to now,the MRSI technologies based on echo-planar, spiral trajectories and sensitivity encoding are the fastest in data acquisition,but their data reconstruction is complex. EPSI reconstruction uses shift of odd and even echoes. Spiral SI uses gridding FFT. SENSE-SI,a new approach to reducing the acquisition time,uses the distinct spatial sensitivities of the individual coil elements to recover the missing encoding information. These improvements in data acquisition and image reconstruction provide a potential value of metabolic imaging as a clinical tool.
文摘The objective of this study was to produce the porous col lagen-chitosan/Gl ycosanminglycans(GAG) for corneal cell-seed implant as a t hree-dimensional tissue engineering scaffold to improve the regeneration cornea s.The effect of various content of glycerol as form porous agent to collagen-ch i tosan/GAG preserved a porous dimensional structure was investigated.The heat-dr ying was used to prepare porous collagen-chitosan /GAG scaffold.The pore morpho logy of collagen-chitosan/GAG was controlled by changing the concentration of g lycerol solution and drying methods.The porous structure morphology was observed by SEM.The diameter of the pores form 10 to 50 μm.The highly porous scaffold had interconnecting pores.The corneal cell morphology was observed under the li ght microscope.These results suggest that collagen-chitosan/GAG showed that cor neal cell have formed confluent layers and resemble the surface of normal cornea l cell surface.
文摘The objective of this study was to investigate the influences of organic solvents on particle size, drug content, loading efficiency and yield for 5 Fluorouracil Poly(lactic acid) nanoparticles . The 5 Fluorouracil was entrapped into poly(lactic acid)(PLA) nanoparticles using a water in oil in water solvent evaporation technique. During the preparation process, ethyl acetate and acetone were used as organic solvents since they are less toxic than the more commonly used dichloromethane. The effect of the three solvents on particle size, drug content, loading efficiency and yield of nanopartcles was compared. When the solvent of the oil phase was acetone, the highest drug content, smallest particle size and lowest yield were obtained for the PLA nanoparticles.
文摘Background 5-dihydroxyanthraquinone-2-carboxylic acid (rhein) inhibits oxidoreduction induced by reducing nicotingamide adenine dinucleotide in the mitochondria and reducing reactive oxygen species, it also suppresses lipid peroxidation in rat brain homogenates. This study was to assess the effects of anthraquinone derivatives, rhein on synaptic transmission in the rat hippocampal CA_1 pyramidal cell layer by intracellular recording.Methods The excitatory postsynaptic potential (EPSP) evoked by stimulation of the Schaffer collaterals in the presence of bicuculline (15 μmol/L) was depressed by application of rhein (0.3-30 μmol/L). The amplitude of the EPSP was restored within 20 minutes after removal of rhein from the supernatant. At a concentration of 30 μmol/L, rhein reduced the amplitude of the EPSP to 42%±3.7% (n=24) of the control. Subsequently, wavelet spectral entropy was used to analyze the EPSP. Results A strong positive correlation was observed between the wavelet spectral entropy and other parameters such as amplitude, slope of rising phase and slope of descending phase of the EPSP. The paired-pulse facilitation (PPF) of the EPSP was significantly increased by rhein (30 μmol/L). The inhibitory postsynaptic potential (IPSP) recorded in the presence of CNQX (20 μmol/L) and APV (40 μmol/L) is not altered by rhein (30 μmol/L). Conclusions Rhein (30 μmol/L) can decrease the frequency but not the amplitude of the miniature EPSP (mEPSP). It is suggested that rhein inhibits excitatory synaptic transmission by decreasing the release of glutamate in rat hippocampal CA_1 pyramidal neurons.
