Dog Red Blood Cells : Adjustment of density in vivo

Red blood cells from mature dogs contain less Na and more K than would be the case if they were in Donnan equilibrium with plasma. They have no ouabain-sensitive Na pump, and their membranes are deficient in Na, K-ATPase. Experiments are reported in which dog red cells were first loaded with supranormal quantities of Na and water and then reinjected into the dog. Over the course of 26–40 h the Na- and water-loaded cells returned to a normal state of hydration as judged by their density. It is concluded that dog red cells possess some means of correcting their swollen status in vivo, despite their lack of a ouabain-sensitive cation transport apparatus.     

Cation Transport in Dog Red Cells

Studies have been made on the cation transport system of the dog red cell, a system of particular interest because it has been shown that there is a marked dependence of cation fluxes on the cell volume. We have found that a 10% decrease in cell volume causes a large increase in 1 hr uptake of ²⁴Na as well as a considerable inhibition of ⁴²K uptake. This effect cannot be produced by a difference in medium osmolality but rather requires the cell volume to change. Dog red cell uptake of ²⁴Na is not inhibited by iodoacetate. Phloretin inhibits ²⁴Na uptake and lactate production, and virtually abolishes the volume effect on Na uptake. These several observations may be accounted for in terms of a working hypothesis which presupposes a cation carrier complex which pumps K into and Na out of cells of normal volume. When the cells are shrunken the carrier specificity shifts to an external Na-specific mode and there is a large increase in ²⁴Na uptake, driven by the inwardly directed Na electrochemical potential gradient.     

Cryopreservation of Sheep Red Blood Cells

The protection of sheep erythrocytes at freezing temperatures was investigated using glycerol, dimethylsulfoxide (DMSO), glucose and four different types of polyvinylpyrrolidone (PVP) as cryoprotective agents. Depending on type (molecular weight) and concentration good protection was obtained with PVP, whereas glycerol, DMSO and glucose were unsatisfactory. Recovery of cells after thawing was most successful when the cells had been frozen at a concentration of 1–2 × 109 cells/ml. No cells tolerated freezing at −20 °G. Best results were obtained when the cells were frozen directly in liquid nitrogen (−196°G).     

Phosphate Compounds in Vertebrate Red Blood Cells

This review brings together and discusses the significance ofexisting information about water-soluble (small molecule) organicphosphate constituents of red blood cells in different vertebratespecies, with emphasis on 2,3 diphosphoglycerate (DPG), inositolpentaphosphate (IP₅) ATP and guanosine triphosphate (GTP), compoundswhich may play an important role in respiratory physiology bymodifying the affinity of hemoglobin for oxygen. Results onthe distribution and concentration of these compounds in redcells of vertebrate animals can be summarized as follows 1)DPG High in mammals (except cats and ruminants) Absent in crocodilianssquamata and fishes. High briefly in the bird embryo absentin adult. High briefly in turtle embryo low in juvenile lowto absent in adult 2 IP₅. High in birds. Absent in mammals,crocodilians squamata and fishes (with the exception of Arapaimagigas). Low in turtles 3 ATP Intermediate in mammals. High inbirds and turtles. Very high in squamata Intermediate to veryhigh in fishes. Low in crocodilians 4) GTP Very low in mammalsbirds, reptiles and amphibians (except for small pool in Ranatadpole). Low to very high in fishes.     

Plasma Factor in Red Blood Cells Adhesion to Endothelial Cells: Humans and Rats

Erythrocyte adhesion to the vascular endothelium is one of the key determinants of microcirculatory blood flow. Adhesion is a complex process determined by the intricate interaction among red blood cells (RBC), plasma factors, and the vascular endothelium. Rats are commonly used as disease models to investigate the pathophysiology of various hematological disease processes occurring in humans and their response to prospective treatments. The aim of our study was to characterize the adhesion of RBC in adult blood from rat and human subjects, in order to test the validity of rat models for adhesion-related disease processes. We demonstrated that adhesion of RBC from rats (rRBC), to endothelial cells (EC) in plasma-free buffer, is stronger than from human subjects (hRBC). In addition, plasma proteins induced elevation of hRBC (eightfold) but depression of rRBC (threefold) adhesion to EC. It is thus suggested to be aware of the difference in RBC/EC interaction for human and rat subjects, when studying models of blood flow.     

Cellular Inhomogeneity in Dog Red Cells As Revealed by Sodium Flux

Unidirectional ²⁴Na fluxes across the dog red blood cell membrane were measured. The kinetics were incompatible with a single time constant but could be accounted for in terms of a two-series compartment cell model, with approximately 1% of cell Na in the outer compartment. Dog red blood cells are known to be inhomogeneous in their Na and K permeabilities. Theoretical analysis showed that such cellular inhomogeneity in the Na permeability coefficient might in principle account for the flux data. In order to evaluate the inhomogeneity effect, a technique based on the differential response of cells suspended in isosmolar high K buffers was devised to measure the variations in Na permeability in the cell population. A variation in the Na permeability coefficient of approximately 30% was found. This inhomogeneity is insufficient to account for the flux data.     

Stretching and Relaxation of Malaria-Infected Red Blood Cells

The invasion of red blood cells (RBCs) by malaria parasites is a complex dynamic process, in which the infected RBCs gradually lose their deformability and their ability to recover their original shape is greatly reduced with the maturation of the parasites. In this work, we developed two types of cell model, one with an included parasite, and the other without an included parasite. The former is a representation of real malaria-infected RBCs, in which the parasite is treated as a rigid body. In the latter, where the parasite is absent, the membrane modulus and viscosity are elevated so as to produce the same features present in the parasite model. In both cases, the cell membrane is modeled as a viscoelastic triangular network connected by wormlike chains. We studied the transient behaviors of stretching deformation and shape relaxation of malaria-infected RBCs based on these two models and found that both models can generate results in agreement with those of previously published studies. With the parasite maturation, the shape deformation becomes smaller and smaller due to increasing cell rigidity, whereas the shape relaxation time becomes longer and longer due to the cell’s reduced ability to recover its original shape.     

Stretching and Relaxation of Malaria-Infected Red Blood Cells

The invasion of red blood cells (RBCs) by malaria parasites is a complex dynamic process, in which the infected RBCs gradually lose their deformability and their ability to recover their original shape is greatly reduced with the maturation of the parasites. In this work, we developed two types of cell model, one with an included parasite, and the other without an included parasite. The former is a representation of real malaria-infected RBCs, in which the parasite is treated as a rigid body. In the latter, where the parasite is absent, the membrane modulus and viscosity are elevated so as to produce the same features present in the parasite model. In both cases, the cell membrane is modeled as a viscoelastic triangular network connected by wormlike chains. We studied the transient behaviors of stretching deformation and shape relaxation of malaria-infected RBCs based on these two models and found that both models can generate results in agreement with those of previously published studies. With the parasite maturation, the shape deformation becomes smaller and smaller due to increasing cell rigidity, whereas the shape relaxation time becomes longer and longer due to the cell’s reduced ability to recover its original shape.     

Viscoelastic Transient of Confined Red Blood Cells

The unique ability of a red blood cell to flow through extremely small microcapillaries depends on the viscoelastic properties of its membrane. Here, we study in vitro the response time upon flow startup exhibited by red blood cells confined into microchannels. We show that the characteristic transient time depends on the imposed flow strength, and that such a dependence gives access to both the effective viscosity and the elastic modulus controlling the temporal response of red cells. A simple theoretical analysis of our experimental data, validated by numerical simulations, further allows us to compute an estimate for the two-dimensional membrane viscosity of red blood cells, ηmem2D ∼ 10⁻⁷ N⋅s⋅m⁻¹. By comparing our results with those from previous studies, we discuss and clarify the origin of the discrepancies found in the literature regarding the determination of ηmem2D, and reconcile seemingly conflicting conclusions from previous works.     

新型人工红细胞的制备

目的:接枝淀粉包裹血红蛋白制备新型人造红细胞的代替品。方法:利用油酸接枝淀粉,在超声条件下下自组装,包裹天然牛血红蛋白,并鉴定其物理化学及生物学性能。测定包封率、红外光谱分析(FTIR)、电镜观察形态学及粒径,测定P50和Hill系数。结果:人工红细胞呈圆球形,平均粒径250nm,包封率高,具有良好的携氧、释氧能力。结论:成功制备了人工纳米红细胞,为进一步临床应用提供了基础。     

The Selective Staining of Red Blood Cells

A method for the selective staining of red blood cells is described. Material is fixed in 10% neutral formalin in .85% NaCl and imbedded in paraffin or celloidin. Sections 6-10 μ are stained 1-5 minutes in chromotrope 2R. Basophilic and the less strongly acidophilic elements are decolorized with 5% phosphotungstic acid in 95% ethyl alcohol. Red blood cells and other strongly acidophilic elements that may be present in the preparation retain the chromotrope 2R. A counterstain of methyl blue may be used for staining the decolorized basophilic elements. As a result, erythrocytes are stained red by the chromotrope 2R, and basophilic elements blue, by the methyl blue. Less strongly acidophilic elements, having little affinity for either primary or secondary dye, are colorless or gray.     

糖尿病病人的红细胞能量代谢

糖尿病病人内环境的改变影响了其体内红细胞的葡萄糖摄取率、胞内糖酵解酶活性、能量代谢中间产物含量以及ATP的储存与利用。这些因素共同作用于红细胞能量代谢的整个过程,使病人红细胞能量代谢发生改变,从而影响红细胞自身的结构、性质以及功能,引起机体组织微循环紊乱、供氧不足等,促进糖尿病并发症的产生。本文对糖尿病病人红细胞能量代谢的相关研究及分子机制进行总结,这些有助于了解糖尿病病人红细胞能量代谢发生的改变,并为糖尿病病人微血管病变的预防、诊断及治疗提供新的思路。     

Characteristics of Chloride Transport in Human Red Blood Cells

The efflux of chloride-36 from human erythrocytes under steady-state conditions is a saturable process that is competitively inhibited by bicarbonate and noncompetitively inhibited by acetate. This chloride self-exchange flux is reversibly dependent on the pH of the medium between 5.7 and 9.6 with a maximum flux at pH 7.8. The increase in chloride flux between pH 5.7 and 7.8 is inexplicable by the fixed charge hypothesis. The interpretations are made that chloride transport in human erythrocytes is carrier mediated, that bicarbonate utilizes the same transport mechanism, and that the mechanism can be titrated with hydrogen ions into less functional forms for chloride transport.     

Theory of the Sphering of Red Blood Cells

A rigorous mathematical solution of the sphering of a red blood cell is obtained under the assumptions that the red cells is a fluid-filled shell and that it can swell into a perfect sphere in an appropriate hypotonic medium. The solution is valid for finite strain of the cell membrane provided that the membrane is isotropic, elastic and incompressible. The most general nonlinear elastic stress-strain law for the membrane in a state of generalized plane stress is used. A necessary condition for a red cell to be able to sphere is that its extensional stiffness follow a specific distribution over the membrane. This distribution is strongly influenced by the surface tension in the cell membrane. A unique relation exists between the extensional stiffness, pressure differential, surface tension, and the ratio of the radius of the sphere to that of the undeformed red cell. The functional dependence of this stiffness distribution on various physical parameters is presented. A critique of some current literature on red cell mechanics is presented.     

The Homeostasis of Plasmodium falciparum-Infected Red Blood Cells

The asexual reproduction cycle of Plasmodium falciparum, the parasite responsible for severe malaria, occurs within red blood cells. A merozoite invades a red cell in the circulation, develops and multiplies, and after about 48 hours ruptures the host cell, releasing 15–32 merozoites ready to invade new red blood cells. During this cycle, the parasite increases the host cell permeability so much that when similar permeabilization was simulated on uninfected red cells, lysis occurred before ~48 h. So how could infected cells, with a growing parasite inside, prevent lysis before the parasite has completed its developmental cycle? A mathematical model of the homeostasis of infected red cells suggested that it is the wasteful consumption of host cell hemoglobin that prevents early lysis by the progressive reduction in the colloid-osmotic pressure within the host (the colloid-osmotic hypothesis). However, two critical model predictions, that infected cells would swell to near prelytic sphericity and that the hemoglobin concentration would become progressively reduced, remained controversial. In this paper, we are able for the first time to correlate model predictions with recent experimental data in the literature and explore the fine details of the homeostasis of infected red blood cells during five model-defined periods of parasite development. The conclusions suggest that infected red cells do reach proximity to lytic rupture regardless of their actual volume, thus requiring a progressive reduction in their hemoglobin concentration to prevent premature lysis.     

Hemagglutination Inhibition of Passively Sensitized Red Blood Cells

It has been shown that sheep red blood cells sensitized with the polysaccharides of Haemophilus influenzae type B and pneumococcal types I, III, IV, VII, VIII, XII, and XIV respond readily in hemagglutination-inhibition testing and exhibit antigen inhibition at levels of 0.09 to 4.0 ng.     

Viable Bacteria Associated with Red Blood Cells and Plasma in Freshly Drawn Blood Donations

Objectives

Infection remains a leading cause of post-transfusion mortality and morbidity. Bacterial contamination is, however, detected in less than 0.1% of blood units tested. The aim of the study was to identify viable bacteria in standard blood-pack units, with particular focus on bacteria from the oral cavity, and to determine the distribution of bacteria revealed in plasma and in the red blood cell (RBC)-fraction.

Design

Cross-sectional study. Blood were separated into plasma and RBC-suspensions, which were incubated anaerobically or aerobically for 7 days on trypticase soy blood agar (TSA) or blue lactose plates. For identification colony PCR was performed using primers targeting 16S rDNA.

Setting

Blood donors attending Capital Region Blood Bank, Copenhagen University Hospital, Rigshospitalet, Hvidovre, Denmark, October 29^th to December 10^th 2013.

Participants

60 donors (≥50 years old), self-reported medically healthy.

Results

Bacterial growth was observed on plates inoculated with plasma or RBCs from 62% of the blood donations. Growth was evident in 21 (35%) of 60 RBC-fractions and in 32 (53%) of 60 plasma-fractions versus 8 of 60 negative controls (p = 0.005 and p = 2.6x10^-6, respectively). Propionibacterium acnes was found in 23% of the donations, and Staphylococcus epidermidis in 38%. The majority of bacteria identified in the present study were either facultative anaerobic (59.5%) or anaerobic (27.8%) species, which are not likely to be detected during current routine screening.

Conclusions

Viable bacteria are present in blood from donors self-reported as medically healthy, indicating that conventional test systems employed by blood banks insufficiently detect bacteria in plasma. Further investigation is needed to determine whether routine testing for anaerobic bacteria and testing of RBC-fractions for adherent bacteria should be recommended.