Properties Of Whole Blood Research Articles

Influence of cell shape and aggregate formation on the optical properties of flowing whole blood.

We studied the influence of shape and secondary, or intercellular, organization on the absorption and scattering properties of red blood cells to determine whether these properties are of any practical significance for optical evaluation of whole blood and its constituents. A series of measurements of transmittance and reflectance of light from bovine blood in a flow cuvette was conducted with a 650-900-nm integrating sphere at shear rates of 0-1600 s(-1), from which the influence of cell orientation, elongation, and aggregate formation on the absorption (mu(a)) and the reduced scattering (mu(s)') coefficients could be quantified. Aggregation was accompanied by a decrease of 4% in mu(s)' compared with the value in randomly oriented single cells. Increasing the degree of cell alignment and elongation as a result of increasing shear rate reduced mu(s)' by 6% and mu(a) by 3%, evaluated at a shear rate of 1600 s(-1). Comparison with T-matrix computations for oblate- and prolate-shaped cells with corresponding elongation and orientation indicates that the optical properties of whole blood are determined by those of its individual cells, though influenced by a collective scattering factor that depends on the cell-to-cell organization. We demonstrate that cell morphological changes must be taken into consideration when one is conducting whole blood spectroscopy.

The effects of intentional hyperthermia on the Thrombelastograph and the Sonoclot analyser

The effect of whole-body hyperthermia (WBH) on viscoelastic properties of whole blood, as measured by the thrombelastogram (TEG) and Sonoclot analyser, was investigated in 10 patients undergoing WBH-carboplastin therapy for metastatic disease. Blood was taken from an existing central line at baseline (37oC), during warming (39 and 41oC) and cooling (39 and 37oC). Sonoclot and TEG samples were analysed simultaneously at 37oC and at the patient's temperature with a temperature-compensated unit, except at 41oC for the Sonoclot (maximum temperature adjustment of 40oC). TEG measurements included R time (time to initial fibrin formation [mm]), K time (mm) and alpha angle (degrees) (both reflecting fibrinogen-platelet interaction), maximum amplitude (representing qualitative platelet function [mm]) and per cent fibrinolysis at 30 and 60min. The Sonoclot ACT (SonACT-secs), initial rate of clot formation (% ), time to peak amplitude (min) and peak amplitude of the Sonoclot signature (mm) were recorded. Decreased R time of the TEG compared to a marginally elevated baseline was found at all times during warming and cooling (p < 0.05). The K time was decreased at 41oC compared to a normal baseline (p < 0.05). The SonACT was decreased (from an elevated baseline) at all other times, without differences in measures at patient temperature versus 37oC (p < 0.05). The data suggest acceleration of fibrin formation during WBH to 41oC in patients with malignancy. Implications for defining thromboembolic risk require further investigation.

Optical Properties of Whole Blood

The optical properties of whole blood are presented for the argon ion laser (488 nm) and He-Ne laser (633 nm) wavelengths. Applying the inverse adding-doubling (IAD) method, the absorption and scattering coefficients and scattering anisotropy coefficient of blood have been determined from the measurements of total diffusive reflectance and transmittance obtained by an integrating sphere at 488 nm. The scattering anisotropy coefficient obtained from the IAD method has been compared with that obtained independently by the goniometric measurements. The index of refraction of blood has been measured by the conventional minimum deviation method using an equilateral hollow quartz prism at 633 nm.

Management of a postpartum coagulopathy using thrombelastography

Thrombelastography (TEG), which evaluates the elastic properties of whole blood and provides a global assessment of hemostatic function, is useful in managing peripartum coagulopathy. A case of severe bleeding after vaginal delivery, in which TEG was used successfully to manage hemostatic defects, is presented.

Blood oxygen transport and hemoglobin function in three tropical fish species from northern Australian freshwater billabongs

The oxygen binding properties of whole blood and hemoglobin were studied in three phylogenetically distant tropical teleosts inhabiting freshwater billabongs that exhibit marked seasonal oxygen stratification. The water breathing saratoga (Scleropages jardinii, Family Osteoglossidae), derived from an ancient divergence of the stem line leading to all other extant teleosts, has a low blood oxygen carrying capacity, Bohr and Root effect, and a high blood oxygen affinity. Erythrocytes contain a single major hemoglobin component, and equimolar concentrations of ATP and GTP. The tarpon (Megalops cyprinoides, Family Megalopidae), a facultative air-breather, has the highest blood oxygen carrying capacity and Bohr effect, and a low blood oxygen affinity and Root effect. Erythrocytes contain a single major hemoglobin and ATP as a putative regulator of hemoglobin oxygen affinity. Barramundi (Lates calcarifer, Family Centropomidae), is an obligate water-breather with intermediate blood oxygen binding properties, and the smallest Root effect. Erythrocytes contain at least 7 hemoglobins, and equimolar concentrations of ATP and GTP. Functional properties of these three blood oxygen transport systems are considered in terms of the respiratory environment and demand for oxygen. Our interpretation supports the hypothesis that the process of speciation can lead to divergence in physiological mechanisms, irrespective of past or present selection pressures.

Does colloid-induced plasma hyperviscosity in haemodilution jeopardize perfusion and oxygenation of vital organs?

The infusion of dextran solutions is associated with haemodilution and, under some conditions, with a slight increase in plasma viscosity. To clarify the compound effects of simultaneous haemodilution and plasma viscosity increases on macro- and microhaemodynamics, we investigated the changes in arterial perfusion (radiolabelled microspheres, 15 microns ø) and oxygenation (tissue Po2) of vital organs using an animal model of plasma hyperviscosity. In nine splenectomized beagles plasma viscosity was increased step by step from 1.06 (baseline) to 2.14, and 2.99 mPa.s by infusion of small amounts (4% of total blood volume) of an ultra-high-molecular-weight dextran (50% w/v, mw: 500,000). Despite the significant increase in plasma viscosity, cardiac output as well as specific organ blood flows in heart, brain, liver, and muscle rose steadily with each step of viscosity, while the haematocrit declined from 0.31 to 0.24 and 0.20, respectively. Medians of tissue Po2 in liver peaked at a viscosity of 2 mPa.s and returned to baseline values at 3 mPa.s, whereas in non-working skeletal muscle Po2 values were maximal at 3 mPa.s. These results indicate that the impact of plasma viscosity on the rheological properties of whole blood is completely offset by the concomitant reduction of haematocrit. Thus, the comparatively minor changes in plasma viscosity observed after prolonged use of clinical dextrans and other colloids in no way compromise the perfusion and oxygenation of vital organs.

Oxygen Transport Properties in Malaria-Infected Rodents — A Comparison Between Infected and Noninfected Erythrocytes

Abstract This study was performed to investigate oxygen transport properties in whole blood (WB) of malaria-infected rats as well as in infected erythrocytes (IE) and noninfected erythrocytes (NIE) separated by density centrifugation. One week after inoculation with Plasmodium berghei, mean parasitemia was 26.5% and high correlations were found between parasitemia and hemoglobin concentration ([Hb]; r = -.902), mean cellular Hb concentration (MCHC; r = -.712), MetHb (r = .923), and base excess (r = -.922). Compared with control animals (C), the oxygen affinity was lower in WB under standard (pH 7.40) and simulated “in vivo” (pH 7.00) conditions (difference in P50, 5.7 and 5.1 mm Hg, respectively; 2P &lt; .01, 2P &lt; .05). In IE Hb and 2,3-biphosphoglycerate (2,3-BPG) concentrations were decreased (MCHC: IE 14.6 +/- 1.0, NIE 33.1 +/- 1.7 g/100 mL; [2,3-BPG]: IE 2.0 +/- 0.6, NIE 7.6 +/- 1.8 mmol/L), whereas [MetHb] and [ATP] were increased ([MetHb]: IE 19.0 +/- 3.7, NIE 0.7% +/- 0.8%; [ATP]: IE 33.5 +/- 2.4, NIE 6.2 +/- 1.0 mumol/g Hb). At pH 7.40, half-saturation oxygen tension (P50) was reduced in IE (29.6 +/- 2.6, NIE 39.2 +/- 5.4 mm Hg, 2P &lt; .001), which correlates with lower [2,3-BPG], increased MetHb content, and higher intrinsic Hb- O2 affinity. However, at pH 7.00, the oxygen affinity was lower in IE when compared with NIE, which was most likely due to high [ATP] in IE. The resulting Bohr coefficients (BC) calculated for CO2 and lactic acid were extremely high in IE and low in NIE (at 50% O2-saturation BCCO2: IE -1.04 +/- 0.06, NIE -0.26 +/- 0.10, 2P &lt; .001; BCLac: IE -0.82 +/- 0.16, NIE -0.47 +/- 0.07, 2P &lt; .001), which was caused by different [2,3-BPG] and [ATP] as well as probably by structural changes of the Hb molecule. The O2 capacity was 14.1 mL per 100 mL erythrocytes in IE compared with 44.4 mL/100 mL in NIE. On the basis of the calculated arterio-venous O2 difference under “in vivo” conditions, the infected red blood cell fraction transports 30% of the O2 amount delivered to the tissues by the noninfected cells (IE 8.0, NIE 26.9 mL/100 mL red blood cells). We conclude that the O2 transport in malaria infected blood is not only affected by the degree of anemia but also by the percentage of infected erythrocytes.

Oxygen transport properties in malaria-infected rodents--a comparison between infected and noninfected erythrocytes

This study was performed to investigate oxygen transport properties in whole blood (WB) of malaria-infected rats as well as in infected erythrocytes (IE) and noninfected erythrocytes (NIE) separated by density centrifugation. One week after inoculation with Plasmodium berghei, mean parasitemia was 26.5% and high correlations were found between parasitemia and hemoglobin concentration ([Hb]; r = -.902), mean cellular Hb concentration (MCHC; r = -.712), MetHb (r = .923), and base excess (r = -.922). Compared with control animals (C), the oxygen affinity was lower in WB under standard (pH 7.40) and simulated "in vivo" (pH 7.00) conditions (difference in P50, 5.7 and 5.1 mm Hg, respectively; 2P < .01, 2P < .05). In IE Hb and 2,3-biphosphoglycerate (2,3-BPG) concentrations were decreased (MCHC: IE 14.6 +/- 1.0, NIE 33.1 +/- 1.7 g/100 mL; [2,3-BPG]: IE 2.0 +/- 0.6, NIE 7.6 +/- 1.8 mmol/L), whereas [MetHb] and [ATP] were increased ([MetHb]: IE 19.0 +/- 3.7, NIE 0.7% +/- 0.8%; [ATP]: IE 33.5 +/- 2.4, NIE 6.2 +/- 1.0 mumol/g Hb). At pH 7.40, half-saturation oxygen tension (P50) was reduced in IE (29.6 +/- 2.6, NIE 39.2 +/- 5.4 mm Hg, 2P < .001), which correlates with lower [2,3-BPG], increased MetHb content, and higher intrinsic Hb-O2 affinity. However, at pH 7.00, the oxygen affinity was lower in IE when compared with NIE, which was most likely due to high [ATP] in IE. The resulting Bohr coefficients (BC) calculated for CO2 and lactic acid were extremely high in IE and low in NIE (at 50% O2-saturation BCCO2: IE -1.04 +/- 0.06, NIE -0.26 +/- 0.10, 2P < .001; BCLac: IE -0.82 +/- 0.16, NIE -0.47 +/- 0.07, 2P < .001), which was caused by different [2,3-BPG] and [ATP] as well as probably by structural changes of the Hb molecule. The O2 capacity was 14.1 mL per 100 mL erythrocytes in IE compared with 44.4 mL/100 mL in NIE. On the basis of the calculated arterio-venous O2 difference under "in vivo" conditions, the infected red blood cell fraction transports 30% of the O2 amount delivered to the tissues by the noninfected cells (IE 8.0, NIE 26.9 mL/100 mL red blood cells). We conclude that the O2 transport in malaria infected blood is not only affected by the degree of anemia but also by the percentage of infected erythrocytes.

The Effect of Pentoxifylline on Retinal Capillary Blood Flow Velocity and Whole Blood Viscosity

Ten normal, healthy, nonsmoking volunteers participated in a double-masked, placebo-controlled one-day trial of 2,000 mg of oral pentoxifylline to determine the short-term effects of orally administered pentoxifylline on retinal circulation and rheologic properties of whole blood. Retinal capillary blood velocity and leukocyte density, whole blood viscosity, and whole blood filterability were measured before and after therapy by the blue-field entoptic phenomenon computer simulation, rotational viscometry, and micropore filtration techniques, respectively. Treatment with pentoxifylline for one day resulted in a significant improvement in retinal capillary blood flow velocity (P = .02) and in viscosity (P < .01), but not filterability, of whole blood. These results suggest that pentoxifylline may be useful in the treatment of early diabetic retinopathy.

Pulse oximetry: Theoretical and experimental models

In the paper a pulse oximetry model is developed using an approach which combines both theoretical and empirical modelling. The optical properties of whole blood are measured as a function of cuvette depth by transmission spectrophotometry using red (660 nm) and infra-red (950 nm) light-emitting diodes as light sources. Twersky's theoretical model gives the best fit to the experimental data. A simple theoretical model which takes into account the nonlinear relationship between optical density and cuvette depth is then used to obtain an expression for the R:IR ratio, which relates the measurement of transmission at the two wavelengths. The R:IR ratio is found to be more or less independent of cuvette depth (SD = 0.14 at 100 per cent SaO2). To validate the predictions of the theoretical model, the results of a previous experiment in which the relationship between SaO2 and the R:IR ratio was recorded using a flexible cuvette are used. The experimental values are found to lie within one standard deviation from the theoretical curve relating SaO2 and the R:IR ratio. It is argued that a reasonably accurate model for pulse oximetry which is based on whole blood and not haemoglobin solutions has been developed.

Effects of gender and age on thixotropic properties of whole blood from healthy adult subjects

The thixotropic parameters of whole blood from 314 healthy subjects (154 women, 160 men) were measured with our modified method by Low shear 30 Rheometer and calculated according Huang's equation. This communication offered the reference range of thixotropic parameters from man and woman group. The results demonstrated that no significant differences existed in the plasma viscosity and fibrinogen between man and woman group. Man group had statistically higher values in HCT, yield stress (tau 0), Newtonian contribution of viscosity (mu), non-Newtonian contribution of viscosity (eta s--mu), apparent viscosity at 2.37 sec-1 (eta s), the equilibrium value of the structural parameter (A) and apparent kinetic rate constant of rouleaux breakdown (ARC) than those in woman group. The man and woman groups could be separately divided into five subgroups in terms of age. It was found that the levels of fibrinogen and plasma viscosity had a tendency of increasing with aging. In the old subgroup (greater than 60 years) of men and women HCT, tau v, mu, eta s, (eta s--mu) and A had significant lower values than those in young and middle-age subgroups. However, it was very interested that there were differences of ARC versus age between man group and woman group, i.e. ARC in the man subgroup II, IV had lower and the woman subgroup II, III, IV had higher values than their respective older subgroup did.

Soluble haemoglobin-induced rheological impairment: A role for oxygen free radical formation

It has been demonstrated that iron and iron compounds facilitate hydroxyl radical generation from activated oxygen species. Free haemoglobin (Hb), like other iron-rich substances, might also me­ diate hydroxyl radical production and induce lipid peroxidation and cell damage. On the basis of the hypothesis that Hb may influence circulating blood cells, namely red cells, studies have been carried out on the effect of Hb on rheological properties of whole blood. Hb is capable of significantly influencing whole blood filterabi-· lity and, to a lesser extent, whole blood viscosity. The addition of Fe2+ has a potentiating effect; superoxide dismutase and thio­ urea which are respectively selective inhibitors of superoxide anion and hydroxyl radicals are able to antagonize the Hb-induced rheological impairment. From these observations, the hypothesis may suggest that Hb negati­ vely influences some rheological properties of whole blood by pro­ ducing oxygen free radicals. Hb released in vivo at the site of arterial stenosis and of atherosclerotic plaque rupture may induce a rheological impairment and, so doing, playa role in microcircu­ latory derangement.

Thixotropic properties of whole blood in the patients with ischemic stroke and high risk factors

Thixotropic properties of whole blood in the patients with ischemic stroke and high risk factors

Effect of whole blood and plasma on the permeability of glucose through different cellulose and cellulose acetate membranes

Model experiments were made with a flow-through dialysis cell to study how glucose in whole blood, plasma and aqueous standards is transferred through different membranes. Detection was via a glucose dehydrogenase reaction and NADH monitoring with a chemically modified electrode. The detector response was linear with the glucose concentration in all cases. The non-Newtonian properties of whole blood seem to be of great importance for the response. Theoretical models are proposed both for the effect of plasma viscosity and the red cell volume fraction (haematocrit) dependence on the glucose transfer rate. The models could only partially explain the differences between measurements in aqueous solutions and body fluids. Better agreement and less haematocrit dependence were obtained with low-permeability membranes.

Thixotropic properties of whole blood from healthy human subjects.

The steady state non-Newtonian viscosity of whole human blood has been widely studied as a function of the shear rate; and used to characterize the blood in various pathological disorders. In our previous studies, we demonstrated that blood is a thixotropic fluid. Its time-dependency and shear rate dependency of rheological behavior can be represented by an equation developed by Huang. Parameters of the equation can be used for the characterization of an individual's blood. They provide information, such as the kinetic rate constant of breakdown of RBC rouleaux to individual erythrocytes and the relative amount of rouleau formation in the dynamic equilibrium between rouleaux and individual erythrocytes. In this communication, the thixotropic parameters from blood samples of fifteen apparently healthy human subjects were investigated. When compared to the use of apparent viscosity values for the correlation with a pathological disorder, thixotropic parameters are preferable. The mean values of thixotropic parameters obtained from apparently healthy human subjects provide a base for comparison with the same parameters as obtained from blood samples of patients with certain pathological disorders involving the circulation.

Diffuse reflectance of whole blood: model for a diverging light beam.

Previous theories describing the optical properties of whole blood have assumed a collimated light source in the derivation of reflectance and transmittance equations. However, many practical instruments which measure blood oxygen rely on noncollimated LED's and optical fibers as light sources. In addition, in the case of blood-perfused cuvettes, the light source is not in direct contact with the blood. Thus, many theories have limited applicability to practical instruments. Therefore, we present here an existing photon diffusion theory that we have generalized to account for the effects of a diverging light source and a thickness of transparent material between the light source and the blood. Comparisons to experimental data are made for both the new equation and the previous one. Better results are obtained with the new equation when applied to a cuvette geometry which is more accurately described by the generalized parameters. Limitations of both the new equation and the photon diffusion approximation in general are discussed.

Protein binding of tolfenamic acid in the plasma from patients with renal and hepatic disease.

The protein binding of tolfenamic acid in plasma from patients with renal and hepatic disorders was studied by equilibrium dialysis. Drug binding to the cellular components of whole blood and blood cell suspensions was also measured. Salicylic acid was used as the reference drug in all experiments. Renal and hepatic diseases increased the unbound fraction of tolfenamic acid. Free drug fractions were significantly correlated with changes in creatinine, urea, and total bilirubin, but not with those in albumin or total protein in plasma. Comparison of the theoretical binding parameters in control plasma and similar changes in protein binding in all the plasma samples studied revealed that tolfenamic acid and salicylic acid probably share a common primary binding site. The significance of the correlation permits use of salicylic acid as a model drug for predicting changes in the protein binding of tolfenamic acid. The measurements of binding properties in whole blood and blood cell--buffer suspension showed that tolfenamic acid interacts with the lipid membrane structures of blood cells, while salicylic acid is distributed into the aqueous cell space.

Dissociation and oxygen equilibrium properties of the extracellular hemoglobin of Eisenia foetida

The dissociation and oxygen equilibrium properties of whole blood and the purified hemoglobin from Eisenia foetida were compared. Oxygen affinities agreed approximately with each other in the range of pH 6.0 to 9.5. The values of n 1 2 were higher in whole blood than in the purified hemoglobin between pH 7.0 and 9.5. The maximum values, obtained near pH 8, were about 6 in whole blood and 3.5 in the purified hemoglobin. In the purified hemoglobin, alkaline dissociation started at pH 7.8, and the ~60 S whole molecule dissociated completely into ~10 S and 5–6 S components at pH 9.1. In whole blood, however, the dissociation started at pH 8.2 and the complete disappearance of the ~60 S molecule occurred at pH 9.6. The values of n 1 2 for the dissociation products were lower than those of the purified hemoglobin between pH 7.0 and 9.0. The value of n 1 2 decreased with increasing dissociation of the ~60 S whole molecule with a pH rise in both whole blood and the purified hemoglobin. Addition of CaCl 2 or MgCl 2 up to 10 m m to the purified hemoglobin at pH 8.0–8.1 induced increases in oxygen affinity and cooperativity and in the stability of the ~60 S whole molecule. The effect on the oxygenation properties was greater with CaCl 2 than MgCl 2 at the same molar concentration. The stabilizing effect on the ~60 S molecule was almost the same with both CaCl 2 and MgCl 2. These results suggest that the dissociation property of the hemoglobin in whole blood is controlled by both Ca 2+ and Mg 2+, and that its oxygenation property is controlled by Ca 2+.

Respiration during chronic hypoxia and hyperoxia in larval and adult bullfrogs (Rana catesbeiana). II. Changes in respiratory properties of whole blood.

Rana catesbeiana Shaw tadpoles and adults were maintained at 20-23 degrees C under aerial and aquatic normoxia (PO2 150 mmHg), hyperoxia (PO2 275 mmHg) and hypoxia (PO2 75 mmHg) for 4 weeks, after which the following blood measurements were made: haematocrit, red blood cell count, haemoglobin concentration, mean corpuscular haemoglobin concentration, O2 capacity, O2 equilibrium curve, Bohr shift, Hill's coefficient and intraerythrocytic concentration of nucleotide triphosphates (ATP + GTP) and 2,3-DPG. Normoxic tadpoles had much higher blood O2 affinity (P50 9-10 mmHg) than adults (P50 35 mmHg) but a lower haemoglobin concentration, haematocrit and O2 capacity. The concentration of intraerythrocytic phosphates was higher in normoxic tadpoles than in adults, indicating that the higher O2 affinity of normoxic tadpole blood was due to the haemoglobins themselves, rather than affinity modulators. Chronic hypoxia in tadpoles produced little change in whole blood P50, and no significant change in any other blood variable. In adult bullfrogs, on the other hand, O2 capacity doubled through polycythaemia, and the P50 decreased by 11 mmHg (35%), though apparently not from any significant change in concentration of intraerythrocytic phosphates. Hyperoxia produced no haematological changes in either larvae or adults. In adult bullfrogs exposed to chronic hypoxia, the morphology of the gas exchange organs does not change (Burggren & Mwalukomo, 1983), but instead profound adjustments occur in the blood, favouring O2 transport under these conditions. The blood of the tadpole shows little or no response to chronic hypoxia, with morphological adjustments in skin, gills and lungs constituting the major response.

Respiratory properties of blood from embryos of highland vs. lowland geese.

Respiratory properties of whole blood during development were studied in embryos of the bar-headed and Canada geese. In both species, affinity of the blood for O2 [expressed as O2 half-saturation pressure (P50)] increased with development, to a low and stable value. The low and stable P50 at pH 7.4 for the bar-headed goose, 20.1 +/- 0.3 Torr, is significantly lower than that for the Canada goose, 26.9 +/- 0.8 Torr. The data suggest a higher Bohr effect for the bar-headed goose. Hill's coefficients, buffering capacity, red cell 2,3-diphosphoglycerate, and blood hemoglobin concentrations are similar in both species. We suggest that the affinity of the whole blood for O2 is an important genetically based adaptation to ensure a high O2 content in the blood in the face of reductions in ambient PO2 associated with nesting at high altitudes. The higher Bohr effect may ensure high tissue PO2 in the presence of the high-affinity hemoglobin.