Toad red blood cells were used to measure regional bone blood flow in the canine mandibular ramus. The blood cells were labelled with sodium pertechnetate and fixed in 1 0%formalin; they were 22 × 15 μm in size ...Toad red blood cells were used to measure regional bone blood flow in the canine mandibular ramus. The blood cells were labelled with sodium pertechnetate and fixed in 1 0%formalin; they were 22 × 15 μm in size and had a specific gravity close to that of dog red blood cells. These cells had no discernible effect on systemic hemodynamics after injection, did not agglutinate, were well mixed and evenly distributed throughout the body, and were completely extracted in one circulation through the mandible. The mandibular ramus was divided into six regions. and the blood flow rates in each were found to be similar to those reported in previous studies with radiolabelled carbonized, microspheres. Furthermore, the blood flow distribution pattern of the mandibular ramus determined in this study was identical to that of our previous study using the bone-seeking radionuclide method. We suggest that radiolabelled toad red blood cells are an ideal marker for measuring regional blood flow in the canine mandible.展开更多
Eosinophilic esophagitis (EE) and gastroesophageal reflux disease (GERD) have overlapping clinical, manometric, endoscopic and histopathologic features. The diagnosis of EE is nowadays based upon the presence of 15 or...Eosinophilic esophagitis (EE) and gastroesophageal reflux disease (GERD) have overlapping clinical, manometric, endoscopic and histopathologic features. The diagnosis of EE is nowadays based upon the presence of 15 or more eosinophils per high power field (eo/HPF) in esophageal biopsies. We report the cases of two young males suffering from dysphagia and recurrent food impaction with reflux esophagitis and more than 20 eo/HPF in upper-mid esophagus biopsies, both of which became asymptomatic on proton pump inhibitor (PPI) therapy. The first patient also achieved a histologic response, while EE remained in the other patient after effective PPI treatment, as shown by 24-h esophageal pH monitoring. Topical steroid therapy combined with PPI led to complete remission in this latter patient. GERD and EE may be undistinguishable, even by histology, so diagnosis of EE should only be established after a careful correlation of clinical, endoscopic and pathologic data obtained under vigorous acid suppression. These diagnostic difficulties are maximal when both diseases overlap. Limited data are available about this topic, and the interaction between EE and GERD is a matter of debate. In this setting, upper-mid esophagus step biopsies and esophageal pH monitoring of patients on PPI therapy are pivotal to evaluate the role of each disease. A PPI trial is mandatory in patients with a histopathologic diagnosis of EE; in those unresponsive to PPI treatment, EE should be suggested. However, a clinical response to PPI may not rule out quiescent EE, as shown in this report.展开更多
A lattice Boltzmann model is presented to simulate the deformation and motions of a red blood cell （RBC） in a shear flow. The curvatures of the membrane of a static RBC with different chemical potentiM drops calcula...A lattice Boltzmann model is presented to simulate the deformation and motions of a red blood cell （RBC） in a shear flow. The curvatures of the membrane of a static RBC with different chemical potentiM drops calculated by our model agree with those computed by a shooting method very well. Our simulation results show that in a shear flow, biconcave RBC becomes highly flattened and undergoes tank-treading motion. With intrinsically parallel dynamics, this lattice Boltzmann method is expected to find wide applications to both single and multi-vesicles suspension as well as complex open membranes in various fluid flows for a wide range of Reynolds numbers.展开更多
A two-dinmnsional red blood cell （RBC） membrane model based on elastic and Euler- Bernoulli beam theories is introduced in the frame of immersed boundary-lattice Boltz- mann method （IB-LBM）. The effect of the flex...A two-dinmnsional red blood cell （RBC） membrane model based on elastic and Euler- Bernoulli beam theories is introduced in the frame of immersed boundary-lattice Boltz- mann method （IB-LBM）. The effect of the flexible membrane is handled by the immersed boundary method in which the stress exerted by the RBC on the ambient fluid is spread onto the collocated grid points near the boundary. The fluid dynamics is obtained by solving the discrete lattice Boltzmann equation. A ＂ghost shape＂, to which the RBC returns when restoring, is introduced by prescribing a bending force along the bound- ary. Numerical examples involving tumbling, tank-treading and RBC aggregation in shear flow and deformation and restoration in poiseuille flow are presented to verify the method and illustrate its efficiency. As an application of the present method, a ten-RBC colony being compressed through a stenotic microvessel is studied focusing the cell-cell interaction strength. Quantitative comparisons of the pressure and velocity on speci- fled microvessel interfaces are made between each aggregation case. It reveals that the stronger aggregation may lead to more resistance against blood flow and result in higher pressure difference at the stenosis.展开更多
Deformation of two-dimensional red blood cell in linear shear flow is simulated using the immersed boundary method,in which the cell is modeled as a force source instead of a real body.The effect of three constitutive...Deformation of two-dimensional red blood cell in linear shear flow is simulated using the immersed boundary method,in which the cell is modeled as a force source instead of a real body.The effect of three constitutive laws,i.e.Hookean,Neo-Hookean and Skalak elasticity,on the deformation is studied by simulating the cell movement in two linear shear flows.The results show that the effect of the constitutive laws gets more obvious as the shear rate increases.Both the aspect ratio and the inclination of the steady shapes get bigger, and the differences between the periods of the cell tank-treading motion become larger.For the same shear flow, the period with Hookean elasticity is less than the period with Neo-Hookean elasticity and bigger than the period with Skalak elasticity.展开更多
The author studies the L2 gradient flow of the Helfrich functional, which is a functional describing the shapes of human red blood cells. For any λi ≥ 0 and co, the author obtains a lower bound on the lifespan of th...The author studies the L2 gradient flow of the Helfrich functional, which is a functional describing the shapes of human red blood cells. For any λi ≥ 0 and co, the author obtains a lower bound on the lifespan of the smooth solution, which depends only on the concentration of curvature for the initial surface.展开更多
The research of the motion and deformation of the RBCs is important to reveal the mechanism of blood diseases. A numerical method has been developed with level set formulation for elastic membrane immersed in incompre...The research of the motion and deformation of the RBCs is important to reveal the mechanism of blood diseases. A numerical method has been developed with level set formulation for elastic membrane immersed in incompressible fluid. The numerical model satisfies mass and energy conservation without the leaking problems in classical Immersed Boundary Method(IBM), at the same time, computing grid we used can be much smaller than the general literatures. The motion and deformation of a red blood cell(including pathological & normal status) in microvascular flow are simulated. It is found that the Reynolds number and membrane's stiffness play an important role in the transmutation and oscillation of the elastic membrane. The normal biconcave shape of the RBC is propitious to create high deformation than other pathological shapes. With reduced viscosity of the interior fluid both the velocity of the blood and the deformability of the cell reduced. With increased viscosity of the plasma both the velocity of the blood and the deformability of the cell reduced. The tank treading of the RBC membrane is observed at low enough viscosity contrast in shear flow. The tank tread fixed inclination angle of the cell depends on the shear ratio and viscosity contrast, which can be compared with the experimental observation well.展开更多
文摘Toad red blood cells were used to measure regional bone blood flow in the canine mandibular ramus. The blood cells were labelled with sodium pertechnetate and fixed in 1 0%formalin; they were 22 × 15 μm in size and had a specific gravity close to that of dog red blood cells. These cells had no discernible effect on systemic hemodynamics after injection, did not agglutinate, were well mixed and evenly distributed throughout the body, and were completely extracted in one circulation through the mandible. The mandibular ramus was divided into six regions. and the blood flow rates in each were found to be similar to those reported in previous studies with radiolabelled carbonized, microspheres. Furthermore, the blood flow distribution pattern of the mandibular ramus determined in this study was identical to that of our previous study using the bone-seeking radionuclide method. We suggest that radiolabelled toad red blood cells are an ideal marker for measuring regional blood flow in the canine mandible.
文摘Eosinophilic esophagitis (EE) and gastroesophageal reflux disease (GERD) have overlapping clinical, manometric, endoscopic and histopathologic features. The diagnosis of EE is nowadays based upon the presence of 15 or more eosinophils per high power field (eo/HPF) in esophageal biopsies. We report the cases of two young males suffering from dysphagia and recurrent food impaction with reflux esophagitis and more than 20 eo/HPF in upper-mid esophagus biopsies, both of which became asymptomatic on proton pump inhibitor (PPI) therapy. The first patient also achieved a histologic response, while EE remained in the other patient after effective PPI treatment, as shown by 24-h esophageal pH monitoring. Topical steroid therapy combined with PPI led to complete remission in this latter patient. GERD and EE may be undistinguishable, even by histology, so diagnosis of EE should only be established after a careful correlation of clinical, endoscopic and pathologic data obtained under vigorous acid suppression. These diagnostic difficulties are maximal when both diseases overlap. Limited data are available about this topic, and the interaction between EE and GERD is a matter of debate. In this setting, upper-mid esophagus step biopsies and esophageal pH monitoring of patients on PPI therapy are pivotal to evaluate the role of each disease. A PPI trial is mandatory in patients with a histopathologic diagnosis of EE; in those unresponsive to PPI treatment, EE should be suggested. However, a clinical response to PPI may not rule out quiescent EE, as shown in this report.
基金supported by National Natural Science Foundation of China under Grant No. 10747004the Guangxi Science Foundation under Grant Nos. 0640064 and 0542045
文摘A lattice Boltzmann model is presented to simulate the deformation and motions of a red blood cell （RBC） in a shear flow. The curvatures of the membrane of a static RBC with different chemical potentiM drops calculated by our model agree with those computed by a shooting method very well. Our simulation results show that in a shear flow, biconcave RBC becomes highly flattened and undergoes tank-treading motion. With intrinsically parallel dynamics, this lattice Boltzmann method is expected to find wide applications to both single and multi-vesicles suspension as well as complex open membranes in various fluid flows for a wide range of Reynolds numbers.
文摘A two-dinmnsional red blood cell （RBC） membrane model based on elastic and Euler- Bernoulli beam theories is introduced in the frame of immersed boundary-lattice Boltz- mann method （IB-LBM）. The effect of the flexible membrane is handled by the immersed boundary method in which the stress exerted by the RBC on the ambient fluid is spread onto the collocated grid points near the boundary. The fluid dynamics is obtained by solving the discrete lattice Boltzmann equation. A ＂ghost shape＂, to which the RBC returns when restoring, is introduced by prescribing a bending force along the bound- ary. Numerical examples involving tumbling, tank-treading and RBC aggregation in shear flow and deformation and restoration in poiseuille flow are presented to verify the method and illustrate its efficiency. As an application of the present method, a ten-RBC colony being compressed through a stenotic microvessel is studied focusing the cell-cell interaction strength. Quantitative comparisons of the pressure and velocity on speci- fled microvessel interfaces are made between each aggregation case. It reveals that the stronger aggregation may lead to more resistance against blood flow and result in higher pressure difference at the stenosis.
基金the National Natural Science Foundation of China(No.10472070)the Shanghai Leading Academic Discipline Project(No.B206)
文摘Deformation of two-dimensional red blood cell in linear shear flow is simulated using the immersed boundary method,in which the cell is modeled as a force source instead of a real body.The effect of three constitutive laws,i.e.Hookean,Neo-Hookean and Skalak elasticity,on the deformation is studied by simulating the cell movement in two linear shear flows.The results show that the effect of the constitutive laws gets more obvious as the shear rate increases.Both the aspect ratio and the inclination of the steady shapes get bigger, and the differences between the periods of the cell tank-treading motion become larger.For the same shear flow, the period with Hookean elasticity is less than the period with Neo-Hookean elasticity and bigger than the period with Skalak elasticity.
基金Project supported by the National Natural Science Foundation of China(No.11026121)the TrainingProgramme Foundation for the Excellent Talents of Beijing(No.2012D005003000004)
文摘The author studies the L2 gradient flow of the Helfrich functional, which is a functional describing the shapes of human red blood cells. For any λi ≥ 0 and co, the author obtains a lower bound on the lifespan of the smooth solution, which depends only on the concentration of curvature for the initial surface.
基金supported by the National Key Project of Scientific and Technical Supporting Programs of China(Grant No.2014BAI11B06)the National Natural Science Foundation of China(Grant No.11172156)
文摘The research of the motion and deformation of the RBCs is important to reveal the mechanism of blood diseases. A numerical method has been developed with level set formulation for elastic membrane immersed in incompressible fluid. The numerical model satisfies mass and energy conservation without the leaking problems in classical Immersed Boundary Method(IBM), at the same time, computing grid we used can be much smaller than the general literatures. The motion and deformation of a red blood cell(including pathological & normal status) in microvascular flow are simulated. It is found that the Reynolds number and membrane's stiffness play an important role in the transmutation and oscillation of the elastic membrane. The normal biconcave shape of the RBC is propitious to create high deformation than other pathological shapes. With reduced viscosity of the interior fluid both the velocity of the blood and the deformability of the cell reduced. With increased viscosity of the plasma both the velocity of the blood and the deformability of the cell reduced. The tank treading of the RBC membrane is observed at low enough viscosity contrast in shear flow. The tank tread fixed inclination angle of the cell depends on the shear ratio and viscosity contrast, which can be compared with the experimental observation well.
