Fourier Transform Infrared Spectroscopy of Protein Adsorption from Whole Blood: Ex Vivo Dog Studies

1981 ◽  
Vol 35 (4) ◽  
pp. 353-357 ◽  
Author(s):  
R. M. Gendreau ◽  
S. Winters ◽  
R. I. Leininger ◽  
D. Fink ◽  
C. R. Hassler ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Protein Adsorption ◽  
Whole Blood ◽  
Experimental Approach ◽  
Ex Vivo ◽  
Fourier Transform Infrared ◽  
Ex Vivo Model ◽  
Flowing Blood ◽  
The Relationship ◽  
Exact Relationship

A Fourier transform infrared/attenuated total reflectance technique has been developed to study protein adsorption onto surfaces. The application of this technique to an ex vivo model using a beagle dog as the source of whole, flowing blood is described (currently, high-quality infrared spectra are being collected at 5-s intervals of protein adsorption). This approach has enabled the authors to identify albumin and glycoproteins as the initially adsorbing species, with the subsequent competitive replacement of part of this protein layer with fibrinogen and other proteins. The exact relationship between the pattern of protein adsorption from whole blood and the generation of a thrombus (clot) is not yet clear, but it is hoped that this type of experimental approach will help clarify the relationship.

Monitoring Anticoagulant Therapy by Activated Partial Thromboplastin Time: Hirudin Assessment

1994 ◽  
Vol 72 (05) ◽  
pp. 685-692 ◽  
Author(s):  
Michael T Nurmohamed ◽  
René J Berckmans ◽  
Willy M Morriën-Salomons ◽  
Fenny Berends ◽  
Daan W Hommes ◽  
...  
Keyword(s):  
Whole Blood ◽  
Partial Thromboplastin Time ◽  
Ex Vivo ◽  
Fold Increase ◽  
Heparin Therapy ◽  
Activated Partial Thromboplastin Time ◽  
Recombinant Hirudin ◽  
Interindividual Differences ◽  
The Relationship

SummaryBackground. Recombinant hirudin (RH) is a new anticoagulant for prophylaxis and treatment of venous and arterial thrombosis. To which extent the activated partial thromboplastin time (APTT) is suitable for monitoring of RH has not been properly evaluated. Recently, a capillary whole blood device was developed for bed-side monitoring of the APTT and it was demonstrated that this device was suitable to monitor heparin therapy. However, monitoring of RH was not evaluated.Study Objectives. To evaluate in vitro and ex vivo the responsiveness and reproducibility for hirudin monitoring of the whole blood monitor and of plasma APTT assays, which were performed with several reagents and two conventional coagulometers.Results. Large interindividual differences in hirudin responsiveness were noted in both the in vitro and the ex vivo experiments. The relationship between the APTT, expressed as clotting time or ratio of initial and prolonged APTT, and the hirudin concentration was nonlinear. A 1.5-fold increase of the clotting times was obtained at 150-200 ng/ml plasma. However, only a 2-fold increase was obtained at hirudin levels varying from 300 ng to more than 750 ng RH/ml plasma regardless of the assays. The relationship linearized upon logarithmic conversion of the ratio and the hirudin concentration. Disregarding the interindividual differences, and presuming full linearity of the relationship, all combinations were equally responsive to hirudin.Conclusions. All assays were equally responsive to hirudin. Levels up to 300 ng/ml plasma can be reliably estimated with each assay. The manual device may be preferable in situations where rapid availability of test results is necessary.

Rate of Synthetic Oligosaccharide Degradation as a Novel Measure of Amylase Activity in Peritoneal Dialysis Patients

2008 ◽  
Vol 28 (3) ◽  
pp. 296-304 ◽  
Author(s):  
Elvia García–López ◽  
Andrzej Werynski ◽  
Olof Heimbürger ◽  
José C. Divino Filho ◽  
Bengt Lindholm ◽  
...  
Keyword(s):  
Peritoneal Dialysis ◽  
Amylase Activity ◽  
Ex Vivo ◽  
Total Activity ◽  
Activity Level ◽  
Dialysis Patients ◽  
Ex Vivo Model ◽  
Patient Groups ◽  
Uremic Patients ◽  
The Relationship

Background Plasma α–amylase activity is elevated in uremic patients but lower in peritoneal dialysis (PD) patients using icodextrin in comparison to healthy controls. We studied the rate by which an exogenous oligosaccharide (maltoheptaose; G7) is degraded ex vivo by amylase in plasma from PD patients treated with glucose or icodextrin PD solutions. Methods Plasma amylase (pancreatic and total) activity and concentration were measured in 11 controls and in PD patients treated with glucose ( n = 11) and icodextrin ( n = 19). The plasma was spiked with G7 and/or synthetic amylase and the metabolites formed were measured by HPLC following incubation at 37°C for 4 hours. Results The relationship between amylase activity and amylase concentration was similar in all patients and controls. The G7 degradation rate was slower in plasma from icodextrin patients but it was also reduced in patients using glucose compared with the controls, in spite of the higher amylase activity in the glucose group. Normalization (by spiking) of patient plasma with porcine amylase increased but did not normalize the speed of G7 degradation. At a given endogenous amylase activity level, the efficiency of G7 degradation was similar for both patient groups. Conclusions An ex vivo model to study the relationship between amylase activity and the actual rate of carbohydrate (represented by G7) breakdown was developed and showed that PD patients using glucose and icodextrin degrade G7 at a slower speed than controls. This suggests that amylase-mediated carbohydrate metabolism is reduced in PD patients. Further clinical studies are needed to confirm if these findings hold true also in other groups of uremic patients with varying degrees of kidney failure, as well as in patients undergoing hemodialysis.

scholarly journals Inhibition of Stimulated Interleukin-2 Production in Whole Blood: A Practical Measure of Cyclosporine Effect

1999 ◽  
Vol 45 (9) ◽  
pp. 1477-1484 ◽  
Author(s):  
C Michael Stein ◽  
John J Murray ◽  
Alastair JJ Wood
Keyword(s):  
Whole Blood ◽  
Ex Vivo ◽  
Interleukin 2 ◽  
Major Effect ◽  
Biologically Relevant ◽  
Maximum Inhibition ◽  
Before And After ◽  
Dose Dependent Fashion ◽  
The Relationship

Abstract Background: Prediction of cyclosporine (CSA) efficacy and toxicity in individual patients is difficult. There is no practical, biologically relevant, pharmacodynamic measure of CSA effect. A major effect of CSA is to decrease interleukin-2 (IL-2) production; however, measurement of this effect in isolated lymphocytes as a marker of response to CSA has been problematic. Methods: CSA inhibition of phytohemagglutinin-P (PHA)-stimulated IL-2 production, measured by ELISA, was studied ex vivo in whole blood drawn before, and after subjects received 4 mg/kg oral CSA. Results: Four hours after CSA was administered, the mean (± SD) CSA concentration was 702 ± 196 μg/L and PHA-stimulated IL-2 production decreased by 68.7% ± 17.2% (P <0.0001; n = 17). Twenty-four hours after CSA was administered, concentrations were low (64 ± 24 μg/L), with no inhibition of IL-2 production. A rapid, concentration-dependent response occurred. Maximum CSA concentrations (944 ± 187 μg/L) and maximum inhibition of IL-2 production (86.9% ± 13.7%) occurred 90 min after subjects received CSA. In vitro, 32.5–1200 μg/L CSA also inhibited PHA-stimulated IL-2 production in whole blood in a dose-dependent fashion with a similar IC50 (∼300–400 μg/L) ex vivo and in vitro. Conclusion: In the search for a pharmacodynamic marker to better guide immunosuppressive therapy, the relationship between this simple, biologically relevant measure of CSA effect and clinical outcome should be determined.

Regulation of tissue factor-induced coagulation and platelet aggregation in flowing whole blood

2005 ◽  
Vol 93 (01) ◽  
pp. 97-105 ◽  
Author(s):  
Marijke Kuijpers ◽  
Cécile Nieuwenhuys ◽  
Marion Feijge ◽  
Willem Kloots ◽  
Peter Giesen ◽  
...  
Keyword(s):  
Tissue Factor ◽  
Whole Blood ◽  
Platelet Adhesion ◽  
Ex Vivo ◽  
Aggregate Formation ◽  
Ex Vivo Model ◽  
Platelet Surface ◽  
Inhibiting Effect ◽  
Activated Platelets ◽  
Adp Receptor

SummaryPhotochemically induced thrombosis (a thrombin-dependent process) was measured in rats treated with moderate doses of anticoagulants, but which appeared to be unchanged. We considered the possibility that platelet-inhibiting agents, which also indirectly inhibit coagulation, would act as more potent antithrombotic agents.Inhibitors used as such were prostaglandin E1 (PGE1), which elevates cyclic AMP levels, and the P2Y12 ADP-receptor antagonist,AR-C69931MX. Effects of these agents were investigated in an ex vivo model system, in which whole blood under coagulant conditions was perfused over fibrinogen at defined wall shear rate. Perfusion of blood (rat or human) in the presence of tissue factor resulted in deposition of activated platelets and subsequent aggregate formation, along with exposure of procoagulant phosphatidylserine (PS) on the platelet surface and formation of fibrin fibers. In the presence of PGE1 aggregation was completely inhibited,but platelet adhesion and PS exposure were only party reduced, while fibrin formation was hardly affected. Treatment with AR-C69931MX caused similar, but less complete effects.These results indicate that in tissue factor- triggered blood under conditions of flow:(i) the platelet procoagulant response is independent of aggregate formation; (ii) the platelet-inhibiting effect of PGE1 and AR-C69931MX is sufficient to suppress aggregation, but not platelet adhesion and coagulation. These platelet inhibitors thus maintain their aggregation- inhibiting effect at sites of thrombin formation.

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