Interactions In Whole Blood Research Articles

Immersed boundary simulations of cell-cell interactions in whole blood

We present a new method for the geometric reconstruction of elastic surfaces simulated by the immersed boundary method with the goal of simulating the motion and interactions of cells in whole blood. Our method uses parameter-free radial basis functions for high-order meshless parametric reconstruction of point clouds and the elastic force computations required by the immersed boundary method. This numerical framework allows us to consider the effect of endothelial geometry and red blood cell motion on the motion of platelets. We find red blood cells to be crucial for understanding the motion of platelets, to the point that the geometry of the vessel wall has a negligible effect in the presence of RBCs. We describe certain interactions that force the platelets to remain near the endothelium for extended periods, including a novel platelet motion that can be seen only in 3-dimensional simulations that we term “unicycling.” We also observe red blood cell-mediated interactions between platelets and the endothelium for which the platelet has reduced speed. We suggest that these behaviors serve as mechanisms that allow platelets to better maintain vascular integrity.

Effects of ex vivo blood anticoagulation and preanalytical processing time on the proteome content of platelets

BackgroundEx vivo assays of platelet function critically inform mechanistic and clinical hematology studies, where effects of divergent blood processing methods on platelet composition are apparent, but unspecified. ObjectiveHere, we evaluate how different blood anticoagulation options and processing times affect platelet function and protein content ex vivo. MethodsParallel blood samples were collected from healthy human donors into sodium citrate, acid citrate dextrose, EDTA or heparin, and processed over an extended time course for functional and biochemical experiments, including platelet proteome quantification with multiplexed tandem mass tag (TMT) labeling and triple quadrupole mass spectrometry (MS). ResultsEach anticoagulant had time‐dependent effects on platelet function in whole blood. For instance, heparin enhanced platelet agonist reactivity, platelet‐monocyte aggregate formation and platelet extracellular vesicle release, while EDTA increased platelet α‐granule secretion. Following platelet isolation, TMT‐MS quantified 3357 proteins amongst all prepared platelet samples. Altogether, >400 proteins were differentially abundant in platelets isolated from blood processed at 24 h versus 1 h post‐phlebotomy, including proteins pertinent to membrane trafficking and exocytosis. Anticoagulant‐specific effects on platelet proteomes included increased complement system and decreased α‐granule proteins in platelets from EDTA‐anticoagulated blood. Platelets prepared from heparinized blood had higher levels of histone and neutrophil‐associated proteins in a manner related to neutrophil extracellular trap (NET) formation and platelet:NET interactions in whole blood ex vivo. ConclusionOur results demonstrate that different anticoagulants routinely used for blood collection have varying effects on platelets ex vivo, where methodology‐associated alterations in platelet proteome may influence mechanistic, translational and biomarker studies.

Protectin DX Exhibits Protective Effects in Mouse Model of Lipopolysaccharide-Induced Acute Lung Injury.

Background:Acute lung injury (ALI) is a severe disease with high mortality and poor prognosis. Protectin DX (PDX), a pro-resolving lipid mediator, exhibits protective effects in ALI. Our experiment aimed to explore the effects and related mechanisms of PDX in mice with ALI induced by lipopolysaccharide (LPS).Methods:BALB/c mice were randomly divided into five groups: sham, LPS, LPS plus 1 ng of PDX (LPS + PDX-1 ng), LPS plus 10 ng of PDX (LPS + PDX-10 ng), and LPS plus 100 ng of PDX (LPS + PDX-100 ng). Bronchoalveolar lavage fluids (BALFs) were collected after 24 h, and total cells, polymorphonuclear leukocytes, monocyte-macrophages, and lymphocytes in BALF were enumerated. The concentration of interleukin (IL)-1β, IL-6, IL-10, tumor necrosis factor-alpha (TNF-α), macrophage inflammatory protein (MIP)-1α, and MIP-2 in BALF was determined, and histopathological changes of the lung were observed. The concentration of protein in BALF and lung wet/dry weight ratios were detected to evaluate pulmonary edema. After determining the optimal dose of PDX, neutrophil–platelet interactions in whole blood were evaluated by flow cytometry.Results:The highest dose of PDX (100 ng/mouse) failed to provide pulmonary protective effects, whereas lower doses of PDX (1 ng/mouse and 10 ng/mouse), especially 1 ng PDX, alleviated pulmonary histopathological changes, mitigated LPS-induced ALI and pulmonary edema, inhibited neutrophil infiltration, and reduced pro-inflammatory mediator (IL-1β, IL-6, TNF-α, and MIP-1α) levels. Meanwhile, 1 ng PDX exhibited pro-resolving functions in ALI including upregulation of monocyte-macrophage numbers and anti-inflammatory mediator IL-10 levels. The flow cytometry results showed that PDX could inhibit neutrophil–platelet interactions in ALI.Conclusion:PDX exerts protective effects in LPS-induced ALI by mitigating pulmonary inflammation and abrogating neutrophil–platelet interactions.

Leukocyte capture and modulation of cell-mediated immunity during human sepsis: an ex vivo study

Promising preclinical results have been obtained with blood purification therapies as adjuvant treatment for sepsis. However, the mechanisms by which these therapies exert beneficial effects remain unclear. Some investigators have suggested that removal of activated leukocytes from the circulation might help ameliorate remote organ injury. We designed an extracorporeal hemoadsorption device capable of capturing both cytokines and leukocytes in order to test the hypothesis that leukocyte capture would alter circulating cytokine profiles and influence immunological cell-cell interactions in whole blood taken from patients with sepsis. We performed a series of ex vivo studies in 21 patients with septic shock and 12 healthy volunteers. Blood circulated for four hours in closed loops with four specially designed miniaturized extracorporeal blood purification devices including two different hemoadsorption devices and a hemofilter in order to characterize leukocyte capture and to assess the effects of leukocyte removal on inflammation and immune function. Hemoadsorption was selective for removal of activated neutrophils and monocytes. Capture of these cells led to local release of certain cytokines, especially IL-8, and resulted in complex cell-cell interactions involved in cell-mediated immunity. Inhibition of cell adherence reversed the cytokine release and the effects on lymphocyte function. Monocyte and neutrophil capture using a sorbent polymer results in upregulation of IL-8 and modulation of cell-mediated immunity. Further studies are needed to understand better these cellular interactions in order to help design better blood purification therapies.

Microfluidic device to study arterial shear-mediated platelet-surface interactions in whole blood: reduced sample volumes and well-characterised protein surfaces

We report a novel device to analyze cell-surface interactions under controlled fluid-shear conditions on well-characterised protein surfaces. Its performance is demonstrated by studying platelets interacting with immobilised von Willebrand Factor at arterial vascular shear rates using just 200 μL of whole human blood per assay. The device's parallel-plate flow chamber, with 0.1 mm² cross sectional area and height-to-width ratio of 1:40, provides uniform, well-defined shear rates along the chip surface with negligible vertical wall effects on the fluid flow profile while minimizing sample volumetric flow. A coating process was demonstrated by ellipsometry, atomic force microscopy, and fluorescent immunostaining to provide reproducible, homogeneous, uniform protein layers over the 0.7 cm² cell-surface interaction area. Customized image processing quantifies dynamic cellular surface coverage vs. time throughout the whole-blood-flow assay for a given drug treatment or disease state. This device can track the dose response of anti-platelet drugs, is suitable for point-of-care diagnostics, and is designed for adaptation to mass manufacture.

Aggregates of Reticulocytes, Monocytes and Platelets Exist in Whole Blood of Sickle Cell Patients: Roles for Plasma Fibronectin, α4 Integrins and PSGL-1.

Leukocyte and platelets are understudied contributors to the overall pathology of sickle cell disease (SCD). Elevated leukocyte counts are common in these patients and correlate inversely with patient lifespan and overall disease severity. For example, a drop in neutrophil count typically predicts a patient's response to hydroxyurea, while increased monocyte counts correlate directly with increased reporting of pain crises. Moreover, both RBCs and WBCs have been detected as components in vaso-occlusive blockages in mouse models, where adhesive RBCs appear to interact directly with WBCs at the vaso-occlusive site. Platelets are activated in SCD and are thought to promote the hypercoagulability in these patients. Despite the potential contribution of all blood cells to the pathology of sickle cell disease, neither a mechanism of adhesion between the WBC and RBC nor a role for soluble matrix proteins in this interaction has been elucidated in humans. To detect potential adhesive interactions between the blood cells in SCD, we collected whole blood into anticoagulants that spare divalent cations (PPACK or factor Xa inhibitor) and assayed for heterotypic cell associations by two and three color flow cytometry. Our results indicate that RBCs, WBCs and platelets exist in heterotypic, multi-cellular aggregates in blood from SCD patients but not unaffected (AA) individuals. By detecting monocyte specific markers, we determined that the primary WBC component of these aggregates was the monocyte, and the primary RBC was the young SS “stress” reticulocyte. Using both in vitro RBC/monocyte adhesion studies and whole blood samples, we demonstrate that α4-containing integrins on both SS RBCs and WBCs mediate this interaction by interacting directly with endogenous plasma fibronectin. Furthermore, we show that the α4 integrin on SS RBCs binds to the RGDS site in fibronectin, whereas the α4 integrin on monocytes binds to the CS-1 site in the molecule, suggesting a novel mechanism of interaction between SS RBCs and monocytes via a fibronectin bridge. Antibodies against the CS-1 binding site in fibronectin substantially disrupt the monocyte/RBC interaction in whole blood, further underscoring the role of fibronectin as a linker between the two cell types. However, platelet incorporation in the aggregate was insensitive to inhibition of the α4 integrin, but was sensitive to inhibition of PSGL-1, suggesting that platelet inclusion likely occurs via a P-selectin/PSGL-1-mediated interaction between the platelet and the monocyte. Interestingly, similar aggregates were also detected in two patients with chronic hemolysis and brisk reticulocytosis, potentially extending the relevance of such aggregates beyond SCD. Taken together our results suggest a new adhesive paradigm for SS RBCs and monocytes as central components of heterotypic blood cell aggregates that include platelets and that are present in whole blood of patients with SCD. Our data therefore illustrate a potentially pathological interaction of all major blood cell types in SCD patients that may impact vaso-occlusion and contribute to other erythrocyte disorders.

Quantification of staphylococcal-collagen binding interactions in whole blood by use of a confocal microscopy shear-adhesion assay.

In bloodborne staphylococcal infections, bacteria and platelets often combine, forming thrombi on the subendothelium, where collagen is exposed. In this process, the collagen serves as a potential binding surface for Staphylococcus aureus. However, the extent and importance of S. aureus-collagen binding interactions in the development of infected thrombi is uncertain. We quantified S. aureus adhesion to collagen in a whole-blood suspension under defined physiologically relevant fluid shear conditions. S. aureus-collagen binding interactions, mediated by both the S. aureus collagen adhesin (CNA) and protein A-von Willebrand factor (vWf), were evaluated using mutant strains and antibody-blocking techniques. The position of adherent bacteria (at the collagen surface or above the surface in the platelet aggregate) was measured using confocal laser microscopy. Results demonstrated significant CNA-collagen interactions and protein A-vWf-collagen binding interactions under physiological shear conditions. We conclude that collagen binding interactions are important in the development of infected thrombi.

Effects of insulin on platelet and leukocyte activity in whole blood

Diabetes mellitus (DM) is associated with platelet and leukocyte dysfunction. Previous observations with regard to insulin effects on platelet and leukocyte function are less than consistent. We thus investigated the effects of insulin on platelets and leukocytes, as well as on platelet–leukocyte interactions in whole blood. Hirudinized whole blood from 20 healthy subjects was preincubated at 37 °C in the absence or presence of insulin (30 and 300 μU/ml), and further incubated without or with adenosine diphosphate (ADP) (10 −5 M) or N-formyl-methionyl-leucyl-phenylalanine (fMLP) (10 −7 M), respectively. Platelet P-selectin expression, platelet fibrinogen binding, single platelet and platelet–platelet aggregate (PPA) counts, and leukocyte CD11b expression and superoxide anion production were monitored by flow cytometry. Insulin decreased single platelet counts ( P<0.05) and increased PPAs ( P<0.01) at 300 μU/ml in unstimulated samples, but did not significantly influence the P-selectin expression or fibrinogen binding of single platelets. Insulin also enhanced ADP-induced platelet aggregation, seen as an augmented decrease of single platelet counts. Insulin (30 μU/ml) increased leukocyte CD11b mean fluorescence intensity (MFI) in unstimulated, as well as fMLP- and ADP-stimulated samples ( P<0.05 for all). fMLP-induced superoxide anion (O 2 −) production was, however, attenuated by insulin. Furthermore, fMLP-activation of leukocytes was associated with enhanced platelet fibrinogen binding and P-selectin expression. In conclusion, clinically relevant concentrations of insulin enhance platelet aggregability and leukocyte CD11b expression, but attenuate leukocyte respiratory burst activity. Our results suggest that insulin may modulate thrombotic and inflammatory processes in vivo in a complex manner.

Thrombopoietin Induces P-Selectin Expression on Platelets and Subsequent Platelet/Leukocyte Interactions

Ligation of thrombopoietin (TPO) to the platelet c-Mpl receptor induces numerous biochemical pathways in the absence of aggregation. Two forms of recombinant TPO are currently in clinical trials for the treatment of thrombocytopenia. This study focuses on the effects of the full-length recombinant human TPO (rhTPO) on platelets in a whole blood system. Platelet–leukocyte associations (PLAs) were visualized following rhTPO stimulation as CD42b/CD 45 double positive clusters by FACS analysis. Treatment of washed platelets with rhTPO induced granule release and expression of the leukocyte adhesion receptor P-selectin (CD 62P) in the absence of aggregation and calcium mobilization. RhTPO also induced platelet–leukocyte interactions in whole blood. Following stimulation, leukocytes were recruited by platelets through P-selectin in a calcium-dependent manner. rhTPO stimulates platelet–leukocyte associations in whole blood through expression of platelet P-selectin. To our knowledge, this is the first report that identifies TPO as a promoter of platelet–leukocyte interactions.

Investigation of platelet–neutrophil interactions in whole blood by flow cytometry

Evidence is increasing that platelets can initiate and propagate inflammatory processes by interacting with leucocytes and the vascular endothelium. Platelets have been shown to bind to neutrophils, existing as platelet/neutrophil complexes (PNC) within the circulation. We describe a simple flow cytometric method for assessing and investigating platelet interactions with neutrophils in small volumes of whole blood. Twenty-five percent (sd 6%) of circulating neutrophils from healthy adults were associated with platelets. Formation of these platelet–neutrophil complexes was CD62P (P-selectin) and divalent cation dependent. Platelet activation (with ADP or thrombin) caused a rapid and sustained rise in %PNC which differed from the pattern of free platelet activation as assessed by CD62P expression. F–met–leu–phe induced neutrophil activation but did not increase the percentage PNC. Platelet activation also caused increased neutrophil CD11b/CD18 expression which was most marked on neutrophils complexed with platelets. This straightforward technique is simple, reproducible, and allows assessment of platelet–neutrophil interactions and activation of neutrophils. It may also provide a method for estimating platelet activation in whole blood.

In Vitro Evaluation of Platelet/Biomaterial Interactions in an Epifluorescent Video Microscopy Combined with a Parallel Plate Flow Cell

Suitable evaluation systems are critical for ranking various biomaterials in order to develop a method to design and synthesize nonthrombogenic biomaterials. We have recently developed an in vitro test system to evaluate platelet/biomaterial interactions in whole blood. The system consists of a parallel plate flow cell and epifluorescent video microscopy (EVM). A glass coverslip coated with a polymer was incorporated into the flow cell, and blood was perfused using a syringe pump via a polymer-coated PVC tubing connected to the flow cell. Whole human blood was anticoagulated with heparin (2 U/ml), and the platelets were labeled with the fluorescent dye mepacrine (5 microM). This system permitted real-time and dynamic observations of platelet/biomaterial interactions in whole blood under a defined flow condition. In order to evaluate the feasibility of this system, two different segmented polyether-polyurethanes (SPEUs), PU-PTMG(650) and PU-PTMG(2000), were chosen as test polymers. Surface characteristics verified with electron spectroscopy for chemical analysis (ESCA) and contact angle measurements showed similar results in both SPEUs. Blood was perfused at a wall shear rate of 200 s-1 for 20 min. Excitation light was applied for 2 s at 1 min intervals. The real-time image was then analyzed at each time point for the percentage of surface area of platelet coverage. Plasma beta-thromboglobulin (beta-TG) levels were also measured before and after each run. PU-PTMG(650) showed a significantly higher number of adhered platelets than PU-PTMG(2000) at each time point.(ABSTRACT TRUNCATED AT 250 WORDS)

Production of a monoclonal antibody against canine GMP-140 (P-selectin) and studies of its vascular distribution in canine tissues.

Rapid upregulation of the adhesion molecule GMP-140 (P-selectin) on endothelial cells is believed to play an important role in the initial binding of leukocytes to endothelium, a very early step in the inflammatory response. Activated platelets that are involved in the coagulation system and in inflammatory processes also express GMP-140 on their surfaces. The objectives of the present study were to develop a monoclonal antibody against this adhesion molecule in the dog and to use this antibody to study platelet-neutrophil interactions in whole blood and to characterize the in vivo localization of GMP-140 in canine tissues. Five Balb/c mice were immunized with thrombin-stimulated dog platelets, and clones were screened using an enzyme-linked immunosorbent assay. The clone MD3 (IgG1) showed preferential binding to activated as compared with resting platelets. Flow cytometric analysis using MD3 revealed that 27% of circulating neutrophils in unstimulated blood had platelets bound to their surfaces; stimulation with platelet activating factor increased this percentage to 85%. Immunoblot analysis of solubilized dog platelets resolved by sodium dodecyl sulfate polyacrylamide gel electrophoresis indicated that the antibody MD3 recognized an approximately 140-kd protein. Immunohistochemical study of normal dog tissues with MD3 revealed that the antigen was present in endothelial cells of arteries, capillaries, and veins, depending on the specific tissue examined. Blood vessels staining positively with MD3 were most abundant in the digestive system (liver, stomach, small and large intestines), moderate in the lungs, kidneys, spleen, lymph nodes, and endocrine glands, and minimal in the brain, myocardium, skeletal system, and skin. Based on its presence on stimulated but not resting platelets, its molecular weight, and its vascular distribution, the antigen recognized by MD3 appears to be the selectin GMP-140 of the dog. This study documents that the cellular and tissue distribution of GMP-140 in dogs is very similar to that in human beings.

Dynamics of Leukocyte-Platelet Adhesion in Whole Blood

AbstractThe dynamics of leukocyte-platelet adhesion and platelet-platelet interaction in whole blood are not well understood. Using different platelet agonists, we have studied the whole blood kinetics of these heterotypic and homotypic interactions, the relative abilities of different leukocyte subsets to participate in platelet adhesion, and the ligands responsible for adhesion. When platelet aggregation was inhibited by the Arg-Gly-Asp-Ser (RGDS) peptide, thrombin stimulation of whole blood resulted in platelet expression of granule membrane protein 140 (GMP-140) and, simultaneously, a marked increase in the percentage of monocytes and neutrophils (PMN) binding platelets, as well as an increase in the number of platelets bound per monocyte and PMN. Lymphocytes were unaffected. Monocytes bound more platelets and at an initially faster rate than PMN. This increase in monocyte and PMN adhesion to platelets was completely inhibited by the blocking monoclonal antibody (MoAb), G1, to GMP-140. When the combination of epinephrine and adenosine diphosphate (epi/ADP) was used as a less potent agonist in the presence of RGDS, GMP-140 expression per platelet was less, and while monocyte-platelet conjugates formed, PMN-platelet conjugates did not. With epi/ADP in the absence of RGDS, there was an immediate, marked decrease in the percentage of all leukocytes with bound platelets, simultaneous with an increase in the percentage of unbound platelet aggregates. As these platelet aggregates dissociated, the percentage of monocytes and PMN with adherent platelets increased, with monocytes again binding at a faster initial rate than PMN. This recovery of monocyte and PMN adhesion to platelets was also inhibited by the G1 MoAb. We conclude that: (1) monocytes and PMN bind activated platelets in whole blood through GMP-140; (2) monocytes have a competitive advantage over PMN in binding activated platelets, particularly when less potent platelet agonists are used; and (3) platelet aggregate formation initially competes unac-tivated platelets off leukocytes; subsequent aggregate dissociation allows the now activated platelets to readhere to monocytes and PMN through GMP-140. These studies further elucidate the dynamic interaction of blood cells and possible links between coagulative and inflammatory processes.

Dynamics of leukocyte-platelet adhesion in whole blood

The dynamics of leukocyte-platelet adhesion and platelet-platelet interaction in whole blood are not well understood. Using different platelet agonists, we have studied the whole blood kinetics of these heterotypic and homotypic interactions, the relative abilities of different leukocyte subsets to participate in platelet adhesion, and the ligands responsible for adhesion. When platelet aggregation was inhibited by the Arg-Gly-Asp-Ser (RGDS) peptide, thrombin stimulation of whole blood resulted in platelet expression of granule membrane protein 140 (GMP-140) and, simultaneously, a marked increase in the percentage of monocytes and neutrophils (PMN) binding platelets, as well as an increase in the number of platelets bound per monocyte and PMN. Lymphocytes were unaffected. Monocytes bound more platelets and at an initially faster rate than PMN. This increase in monocyte and PMN adhesion to platelets was completely inhibited by the blocking monoclonal antibody (MoAb), G1, to GMP-140. When the combination of epinephrine and adenosine diphosphate (epi/ADP) was used as a less potent agonist in the presence of RGDS, GMP-140 expression per platelet was less, and while monocyte-platelet conjugates formed, PMN-platelet conjugates did not. With epi/ADP in the absence of RGDS, there was an immediate, marked decrease in the percentage of all leukocytes with bound platelets, simultaneous with an increase in the percentage of unbound platelet aggregates. As these platelet aggregates dissociated, the percentage of monocytes and PMN with adherent platelets increased, with monocytes again binding at a faster initial rate than PMN. This recovery of monocyte and PMN adhesion to platelets was also inhibited by the G1 MoAb. We conclude that: (1) monocytes and PMN bind activated platelets in whole blood through GMP-140; (2) monocytes have a competitive advantage over PMN in binding activated platelets, particularly when less potent platelet agonists are used; and (3) platelet aggregate formation initially competes unactivated platelets off leukocytes; subsequent aggregate dissociation allows the now activated platelets to readhere to monocytes and PMN through GMP-140. These studies further elucidate the dynamic interaction of blood cells and possible links between coagulative and inflammatory processes.

Dipyridamole alone or combined with low‐dose acetylsalicylic acid inhibits platelet aggregation in human whole blood ex vivo [see comments

1. In a randomized, double-blind trial we compared the inhibition of the platelet-vessel wall interactions in whole blood ex vivo. There were four groups of 24 healthy volunteers each of whom were treated orally for 3.5 days with either 200 mg dipyridamole (sustained release preparation), 25 mg acetylsalicylic acid, both drugs combined or placebo twice daily. 2. The mean area of all platelets/aggregates was reduced by 6.2% +/- 4.2% (+/- s.e. mean) by placebo (n = 23), 19.8% +/- 6.7% by dipyridamole (n = 22), 53.7% +/- 4.9% by acetylsalicylic acid (n = 23) and 71.4% +/- 3.7% by the combination of both drugs (n = 24), when compared with total inhibition of aggregation by EGTA. Thus, low-dose acetylsalicylic acid inhibited aggregation (P less than 0.001). 3. Dipyridamole reduced the size of platelet aggregates (P less than 0.01, two-fold analysis of variance). The reduction was correlated with the individual dipyridamole plasma levels (P less than 0.05, analysis of covariance). The subgroup of large and very large thrombi being formed was also reduced by dipyridamole (P less than 0.05). 4. This ex vivo study demonstrates that dipyridamole alone inhibits formation of thrombi on subendothelial matrix and enhances the inhibitory effect of low dose acetylsalicylic acid in this model of thrombosis.

Protein adsorption from buffer and plasma onto hydrophilic—hydrophobic poly(ethylene oxide)—polystyrene multiblock copolymers

The influence of substrate hydrophilic—hydrophobic balance on the adsorption of proteins from buffer and plasma was investigated using a series of amphiphilic multiblock copolymers composed of poly(ethylene oxide) (PEO) and polystyrene (PS). Adsorption of albumin, fibrinogen, and immunoglobulin G was monitored from single-component buffer, multicomponent buffer, and plasma solutions in contact with polymer-coated beads. Protein adsorption from buffer demonstrated kinetics and adsorption totals that correlated to the hydrophilic—hydrophobic content of the PEOPS surfaces; however, no significant correlations existed between bulk composition, in vitro, and ex vivo blood compatibility tests. From plasma, adsorption to the surfaces showed two interesting results. First, minimum levels of protein adsorption witnessed on a PEOPS (40% PEO) copolymer were not observed in the competitive adsorption of the same species from buffer. These results were correlated to minimum platelet adhesion and activation in vitro and optimal whole blood compatibility ex vivo. Second, fibrinogen uptake from plasma exhibited transient, fluctuating kinetics on both the PEO and PS homopolymer surfaces while two PEOPS copolymer surfaces showed no fluctuations. Overall, few correlations between buffer adsorption, plasma adsorption, or resulting in vivo and ex vivo analyses were observed. This suggests that buffered systems oversimplify the protein adsorption scenario and lack significant correlations to surface interactions in whole blood and plasma.

Early platelet-collagen interactions in whole blood studied by a new method (basic wave): Experiencies with dipiridamole ex vivo in the presence of absence of extracellular calcium

Early platelet-collagen interactions in whole blood studied by a new method (basic wave): Experiencies with dipiridamole ex vivo in the presence of absence of extracellular calcium

The basic wave: A method for studying early platelet-collagen interactions in whole blood. Study in normal and hypertriglyceridemic subjects

The basic wave: A method for studying early platelet-collagen interactions in whole blood. Study in normal and hypertriglyceridemic subjects

Early Platelet-Collagen Interactions in Whole Blood and Their Modifications by Aspirin and Dipyridamole Evaluated by a New Method (Basic Wave)

It is shown that the supernatant of unstirred whole blood at 37 degrees C, stimulated by 1 microgram/ml of collagen for 10 sec, produces a rapid generation of pro and antiaggregatory compounds with a final proaggregatory activity which can be detected for more than 60 min on a platelet rich plasma (PRP) by turbidometric aggregometry. A reversible aggregation wave that we have called BASIC wave (for Blood Aggregation Stimulatory and Inhibitory Compounds) is recorded. The collagen stimulation of unstirred PRP produces a similar but smaller BASIC wave. BASIC's intensity increases if erythrocytes are added to PRP but decreases if white blood cells are added instead. Aspirin abolishes "ex vivo" the ability of whole blood and PRP to generate BASIC waves and dipyridamole "in vitro" significantly reduces BASIC's intensity in whole blood in every tested sample, but shows little effect in PRP.

Influence of temperature on hemoglobin-ligand interaction in whole blood.

Temperature-dependent change in hemoglobin-oxygen affinity was measured as a function of hemoglobin-oxygen saturation. In addition, the CO2 Bohr factor and fixed acid Bohr factor were measured as a function of saturation of temperatures of 23, 30, 37, and 44 degrees C. Measurements were made on normal blood and blood with reduced 2,3-diphosphoglycerate (DPG). The influence of temperature is greatest at low saturation and is enhanced slightly by DPG depletion. The CO2 Bohr factor is increased at high temperatures; this is primarily due to increased carbamino formation with rising temperature, especially at lower oxygen saturation. The effect of DPG on oxygen affinity is reduced at a high temperature and elevated at low temperature. These diverse effects of temperature on hemoglobin-ligand interaction require consideration in assessing oxygen delivery when temperature is increased or decreased.