| 1. |
- Tynngård, Nahreen, et al.
(författare)
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Platelet adhesion changes during storage studied with a novel method using flow cytometry and protein-coated beads
- 2015
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Ingår i: Platelets. - : Taylor & Francis. - 0953-7104 .- 1369-1635. ; 26:2, s. 177-185
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to set up and evaluate a novel method for studies of platelet adhesion and activation in blood and platelet suspensions such as platelet concentrate (PC) samples using protein-coated polystyrene beads and flow cytometry. To demonstrate its usefulness, we studied PCs during storage. PCs were prepared by aphaeresis technique (n = 7). Metabolic variables and platelet function was measured on day 1, 5, 7 and 12 of storage. Spontaneous and TRAP-6-induced adhesion to fibrinogen-and collagen-coated beads was analyzed by flow cytometry. P-selectin and phosphatidyl serine (PS) expression was assessed on platelets bound to beads as well as on non-adherent platelets. Platelet adhesion to fibrinogen beads had increased by day 12 and adhesion to collagen beads at day 7 of storage (p<0.05). TRAP-6 stimulation significantly increased the platelet adhesion to fibrinogen beads (p<0.05) as well as the P-selectin and PS exposure on platelets bound to beads (p<0.01) during the first 7 days of storage, but by day 12, significant changes were no longer induced by TRAP-6 stimulation. We demonstrate that our adhesion assay using protein-coated polystyrene beads can be used to assess the adhesion properties of platelets during storage without the addition of red blood cells. Therefore it may offer a useful tool for future studies of platelet adhesive capacity in transfusion medicine and other settings.
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| 2. |
- Wallstedt, Anna
(författare)
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Temporal variation and phytotoxicity of Batatasin-III produced by Empetrum hermaphroditum
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In northern Sweden, the clonal dwarf shrub Empetrum hermaphroditum Hagerup exerts strong inhibitory effects on other plant species. These inhibitory effects may, at least in part, be attributed to the high production of the secondary metabolite, batatasin-III, which is released from leaves and transported to the soil by rain (throughfall) and snowmelt. Considerable amounts of batatasin-III are also added to the soil by senescent leaves and litter. The quantification of batatasin-III in soil solution throughout one growing season showed that the concentration was high both in early spring and in August, coinciding with the periods of snowmelt, maximum litter fall, and with higher production of batatasin-III in E. hermaphroditum foliage. Under laboratory conditions, batatasin-III was found to interfere with physiological functions of birch, Betula pendula L. When the birch seedlings were exposed to batatasin-III for a short period (i.e. two hours), dry weights were reduced by more than 70 %, even ten weeks after the treatment. The growth inhibition may be explained by the findings that batatasin-III interfered with both the photosynthesis and ammonium uptake. The interference of batatasin-III with membrane processes and the presence of batatasin-III in soil solutions throughout the whole growing season suggest that batatasin-III not only has the potential to inhibit soil microorganisms, but also to exert phytotoxic effects in field. Reducing growth of surrounding plants would be advantageous for E. hermaphroditum, since it is shade intolerant and competes with difficulty under a closed canopy.
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| 3. |
- Wallstedt, Anna, et al.
(författare)
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The inhibition of ammonium uptake in excised birch (Betula pendula) roots by batatasin-III.
- 2001
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Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317. ; 113:3, s. 368-376
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Tidskriftsartikel (refereegranskat)abstract
- In northern Sweden, plants growing in association with the clonal dwarf shrub Empetrum hermaphroditum usually exhibit limited growth and are N-depleted. Previous studies suggest that this negative effect by E. hermaphroditum may be explained, at least in part, by the release of phenolic compounds, particularly the dihydrostilbene, batatasin-III from foliage to soil. In the present work, we investigated whether batatasin-III has the potential to interfere with NH4+ uptake in birch (Betula pendula) roots. Excised birch roots were exposed to batatasin-III during brief periods in 15NH4+ solutions, and then analyzed for labeled N. Batatasin-III inhibited N-NH4+ uptake by 28, 89 and 95% compared with the control, when roots were treated with 0.1, 1.0 and 2.8 mM of batatasin-III, respectively. The effect of 1.0-mM batatasin-III was greater at pH 4.2 than at pH 6.8. In addition, the inhibition of N-NH4+ uptake by batatasin-III was not reversed after rinsing the roots in water and transferring them to a batatasin-III free solution. Furthermore, birch seedlings immersed in a 1.0-mM batatasin-III solution for 2 h, and then replanted in pots with soil, had decreased growth, such that 10 weeks after treatment, the dry mass of both shoots and roots was reduced by 74 and 73%, respectively, compared with control seedlings. This suggests that a brief exposure to batatasin-III may have a long-term inhibitory effect on whole plant growth. Using plasma membrane vesicles isolated from easily extractable spinach (Spinacia oleracea) leaves, it was found that batatasin-III strongly inhibited proton pumping in isolated plasma membrane vesicles, while it only slightly inhibited ATP hydrolytic activity. The uncoupling of proton pumping from ATP hydrolytic activity suggests that batatasin-III disturbs membrane integrity. This hypothesis was further supported by a greater efflux of ions from birch roots immersed in a batatasin-III solution than from roots in a control solution.
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