| 11. |
- Wadenvik, Hans, 1955, et al.
(author)
-
Effect of Iloprost (ZK 36 374), a novel prostacyclin analogue, on ADP-induced platelet aggregation.
- 1985
-
In: Acta haematologica. - 0001-5792. ; 73:4, s. 224-7
-
Journal article (peer-reviewed)abstract
- The effect of Iloprost (ZK 36 374), a chemically stable carboprostacyclin derivative, on ADP-induced platelet aggregation was investigated using platelet-rich plasma obtained from healthy male volunteers. It was shown that Iloprost in a dose-dependent fashion powerfully inhibits both the primary and secondary wave of ADP-induced platelet aggregation. Similarly, Iloprost immediately and most effectively disaggregates preformed platelet aggregates.
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| 12. |
- Wadenvik, Hans, 1955, et al.
(author)
-
In vitro and in vivo behavior of 111In-labelled platelets: an experimental study of healthy male volunteers.
- 1987
-
In: European journal of haematology. - 0902-4441. ; 38:5, s. 415-25
-
Journal article (peer-reviewed)abstract
- The aim of this study was to obtain a critical evaluation of a simple method for labelling platelets with 111In-oxine. All experiments were carried out on healthy volunteers. 65 +/- 7 (SD) % of the platelets in collected blood were labelled and reinjected. As compared to control experiments, only in response to a low final ADP concentration (1.0 mumol/l) did 111In-labelled platelets show reduced in vitro aggregability. The mean platelet volume for 111In-labelled platelets was slightly lower than the mean platelet volume in whole blood. The results for initial platelet recovery and platelet mean lifespan closely agreed with those of other studies in which considerably higher platelet extraction from whole blood was obtained. After injection, the splenic uptake and blood disappearance of 111In-labelled platelets followed a monoexponential function with almost identical rate constants. By compartmental analysis of the equilibration of platelets between blood and spleen, the splenic blood flow was estimated to be 4.8 +/- 1.9 (SD) % of the total blood volume/min; the intrasplenic platelet transit time was 9.7 +/- 1.6 (SD) min, and the exchangeable splenic platelet pool 31 +/- 8 (SD) %. Highly significant relationships were present between the splenic blood flow and the splenic platelet pool size, as well as between the splenic blood flow and the initial platelet recovery. It is concluded that the requirements for adequate interpretation of platelet kinetics are well met with the present method for harvesting and labelling of platelets.
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| 13. |
- Wadenvik, Hans, 1955, et al.
(author)
-
Splenic blood flow and intrasplenic platelet kinetics in relation to spleen volume.
- 1987
-
In: British journal of haematology. - 0007-1048. ; 67:2, s. 181-5
-
Journal article (peer-reviewed)abstract
- The relationship between the splenic blood flow and the intrasplenic platelet kinetics on the one hand, i.e. the two factors which govern the size of the exchangeable splenic platelet pool, and the spleen size on the other were assessed in 21 patients afflicted with haematologic disorders and variable splenomegaly. The splenic blood flow and intrasplenic platelet kinetics were measured using 111In-labelled platelets and compartmental analysis of their equilibration between circulating blood and splenic pool; the spleen size was determined by scintigraphy using 99mTc-labelled stannous colloid. Significant correlations were recorded between the spleen size and the splenic platelet pool size (r = 0.76; P less than 0.001) and between the spleen size and the splenic blood flow (r = 0.56; P less than 0.01). Splenic perfusion decreased significantly with increasing spleen size, but there was no relationship between the spleen size and the intrasplenic platelet transit time. However, an association was present between splenic perfusion and intrasplenic platelet transit time (r = -0.44; P less than 0.05). It is concluded that the splenic blood flow is the major determinant of the size of the exchangeable splenic platelet pool in splenomegalic states, and that the determination of spleen size using 99mTc-scintigraphy gives a rough estimation of the pool size. Splenic perfusion appears to be one of the factors which determine the intrasplenic platelet transit time.
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| 14. |
- Wadenvik, Hans, 1955, et al.
(author)
-
Splenic platelet kinetics and platelet production after major reconstructive vascular surgery.
- 1988
-
In: Acta medica Scandinavica. - 0001-6101. ; 223:2, s. 147-52
-
Journal article (peer-reviewed)abstract
- By using 111In-labelled platelets and dynamic gamma camera scintigraphy, platelet production rate and intrasplenic platelet kinetics were determined in 13 patients at 1 and 4 months after aortic reconstructive vascular surgery with implantation of dacron prostheses. A significant decrease in platelet production rate and venous platelet count was recorded over time after surgery. Irrespective of whether the exchangeable splenic platelet pool was estimated from initial recovery of platelet-bound radioactivity or from compartmental analysis, the size of this pool was significantly lower at the first study; a change in intrasplenic platelet transit time accounted for the observed difference. Platelet mean life-span increased over time after surgery but the difference between the duplicate studies was not statistically significant. It can be concluded that there is a reduction of platelet production rate and venous platelet count over time after major reconstructive vascular surgery. The early postoperative elevation in the platelet count is mainly the result of an increased platelet production and to a lesser degree due to redistribution of platelets between the splenic platelet pool and general circulation.
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| 15. |
- Wadenvik, Hans, 1955, et al.
(author)
-
Splenic platelet kinetics in systemic lupus erythematosus (SLE).
- 1987
-
In: Scandinavian journal of rheumatology. - 0300-9742. ; 16:3, s. 193-8
-
Journal article (peer-reviewed)abstract
- The splenic blood flow, intrasplenic platelet kinetics and spleen size were determined in 8 females with systemic lupus erythematosus (SLE), all without signs of active disease, by using gamma-camera scintigraphy with 111In-labelled platelets and 99mTc-stannous colloid. The results for splenic blood flow, intrasplenic platelet transit time and splenic platelet pool size, obtained by compartmental analysis of the initial distribution of radiolabelled platelets between blood and spleen, did not differ from those of a control group. In all SLE patients the spleen size was within normal limits. There was a significant relationship between the spleen volume and the splenic platelet pool size (r = 0.75; p less than 0.05), and between the spleen volume and splenic blood flow (r = 0.76; p less than 0.05). A borderline, inverse correlation was present between an estimate of splenic perfusion and intrasplenic platelet transit time (r = 0.62; p = 0.1). It is concluded that the splenic function, measured as splenic blood flow and intrasplenic platelet kinetics, is not disturbed in SLE patients without active disease.
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| 16. |
- Wadenvik, Hans, 1955, et al.
(author)
-
The effect of an adrenaline infusion on the splenic blood flow and intrasplenic platelet kinetics.
- 1987
-
In: British journal of haematology. - 0007-1048. ; 67:2, s. 187-92
-
Journal article (peer-reviewed)abstract
- The effect of an adrenaline infusion on the venous platelet count, splenic blood flow and intrasplenic platelet kinetics was investigated in seven healthy male volunteers by using 111In-labelled platelets and dynamic gamma camera scintigraphy. The infusions were administered in two different doses, 0.2 microgram/kg/min and 0.1 microgram/kg/min, respectively. Regardless of the given dose, adrenaline was found to markedly decrease the splenic blood flow, decrease the exchangeable splenic platelet pool size and to prolong the intrasplenic platelet transit time. In response to the higher dose of adrenaline the splenic blood flow was 1.3 +/- 0.5 (SD) % of total blood volume per min and the intrasplenic platelet transit time 17.3 +/- 2.3 (SD) min. In contrast, after termination of infusion, the splenic blood flow was 7.0 +/- 2.1 (SD) % of total blood volume per min and the intrasplenic platelet transit time was 11.5 +/- 1.5 (SD) min. The present results firmly demonstrate that the splenic blood flow is the immediate variable governing the size of the exchangeable splenic platelet pool, and that the adrenaline-induced depletion of the splenic platelet pool is a consequence of the splenic blood flow reduction. Finally, the splenic perfusion appears to be a major determinant of the intrasplenic platelet transit time.
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| 17. |
- Wadenvik, Hans, 1955, et al.
(author)
-
The effect of an isoprenaline infusion on the splenic blood flow and intrasplenic platelet kinetics.
- 1987
-
In: European journal of haematology. - 0902-4441. ; 39:1, s. 7-13
-
Journal article (peer-reviewed)abstract
- The effect of a constant isoprenaline infusion on the venous platelet count, splenic blood flow and intrasplenic platelet kinetics was investigated in 6 healthy male volunteers. The study was carried out using autologous 111In-labelled platelets and dynamic gamma camera imaging of the initial distribution of radiolabelled platelets between blood and splenic platelet pool. The isoprenaline infusions were administered i.v. over 30 min in a dose of 0.03 micrograms/kg/min. These infusions significantly increased the splenic blood flow and the size of the exchangeable splenic platelet pool. Concomitantly, there was a decrease of labelled as well as unlabelled platelets in the peripheral blood. The intrasplenic platelet transit time was not affected. Before start of infusion, the splenic blood flow was 6.1 +/- 2.9 (SD) % of total blood volume/min and the splenic platelet pool size 34 +/- 9 (SD) %. During infusion the corresponding values were 8.7 +/- 3.9 (SD) and 41 +/- 11 (SD), respectively. It is concluded that an i.v. infusion of isoprenaline enhances splenic pooling of platelets as a result of an increase in splenic blood flow.
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| 18. |
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| 19. |
- Örtenwall, Per, 1951, et al.
(author)
-
Reduced platelet deposition on seeded versus unseeded segments of expanded polytetrafluoroethylene grafts: clinical observations after a 6-month follow-up.
- 1989
-
In: Journal of vascular surgery. - 0741-5214. ; 10:4, s. 374-80
-
Journal article (peer-reviewed)abstract
- The concept of autologous endothelial cell seeding has proved successful in animal models with respect to decrease of graft thrombogenicity and increase in patency. In the present study, application of this method in humans was explored. In 23 patients, random halves of expanded polytetrafluoroethylene grafts, used for lower limb arterial reconstructions, were seeded with endothelial cells at a seeding density of 3500 cells/cm2. These cells were derived from the saphenous vein by enzymatic harvesting. The other half was sham seeded with culture medium. Graft thrombogenicity was estimated by measuring platelet deposition on graft surface 1 and 6 months after surgery, with indium 111-labeled platelets and external gamma-camera imaging. Seeded graft segments accumulated significantly (p less than 0.03) fewer platelets at all imaging times. It is concluded that seeding of expanded polytetrafluoroethylene vascular grafts in humans reduces graft surface thrombogenicity. The clinical implications of this remain to be demonstrated.
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| 20. |
- Örtenwall, Per, 1951, et al.
(author)
-
Reduction in deposition of indium 111-labeled platelets after autologous endothelial cell seeding of Dacron aortic bifurcation grafts in humans: a preliminary report.
- 1987
-
In: Journal of vascular surgery. - : Elsevier BV. - 0741-5214. ; 6:1, s. 17-25
-
Journal article (peer-reviewed)abstract
- Autologous endothelial seeding (AES) of vascular prostheses in dogs increases thrombus-free surface and improves prosthetic prostacyclin production, patency, and the ability to withstand hematogenous challenge with bacteria. No such information is available in human subjects. In the present study one limb of an aortic Dacron bifurcation prosthesis was seeded with autologous endothelial cells (ECs) harvested from the distal portion of the saphenous vein by enzymatic treatment. The deposition of indium 111-labeled platelets on the vascular prostheses was studied 1 and 4 months after operation. In seven of nine patients seeding resulted in decreased accumulation of radiolabeled platelets compared with sham-seeded control limbs (p less than 0.04), when studied 1 month after surgery. A decrease in platelet accumulation occurred over the whole prosthesis between 1 and 4 months, and no significant difference was noted at 4 months between seeded and nonseeded graft limbs. Although the seeding density was very low (440 ECs/cm2), the observed difference in platelet accumulation for AES-treated graft limbs in the early postoperative course merits further investigation of this technique in human beings.
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