25 research outputs found

    Photoacclimation strategies in northeastern Atlantic seagrasses: Integrating responses across plant organizational levels

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    Seagrasses live in highly variable light environments and adjust to these variations by expressing acclimatory responses at different plant organizational levels (meadow, shoot, leaf and chloroplast level). Yet, comparative studies, to identify species' strategies, and integration of the relative importance of photoacclimatory adjustments at different levels are still missing. The variation in photoacclimatory responses at the chloroplast and leaf level were studied along individual leaves of Cymodocea nodosa, Zostera marina and Z. noltei, including measurements of variable chlorophyll fluorescence, photosynthesis, photoprotective capacities, non-photochemical quenching and D1-protein repair, and assessments of variation in leaf anatomy and chloroplast distribution. Our results show that the slower-growing C. nodosa expressed rather limited physiological and biochemical adjustments in response to light availability, while both species of faster-growing Zostera showed high variability along the leaves. In contrast, the inverse pattern was found for leaf anatomical adjustments in response to light availability, which were more pronounced in C. nodosa. This integrative plant organizational level approach shows that seagrasses differ in their photoacclimatory strategies and that these are linked to the species' life history strategies, information that will be critical for predicting the responses of seagrasses to disturbances and to accordingly develop adequate management strategies.Fundacao para a Ciencia e Tecnologia (FCT), Portugal [PTDC/MAR-EST/4257/2014

    Kinesiophobia and related factors in systemic lupus erythematosus patients

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    Tamoxifen-Induced Tissue Factor Pathway Inhibitor Reduction: A Clue for an Acquired Thrombophilic State?

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    Background: Current understanding of hemostatic systems enables us to better explore the enigmatic pathobiology of tamoxifen (TAM)-induced thrombotic diathesis. We have therefore aimed to assess the hemostatic changes in breast cancer patients receiving TAM on an adjuvant basis. Patients and methods: The study population consisted of 43 female patients with hormone receptor-positive breast cancer who received TAM 20 mg/day as part of their adjuvant treatment. Mean age was 52+/-12 years (range 25-74). Twenty-one patients (49%) were premenopausal. Plasma samples were collected prior to and following 6 months of TAM therapy and were assayed for total tissue factor pathway inhibitor (TFPI), free TFPI, lipid-bound TFPI, thrombomodulin, D dimer, activated protein C resistance (APC res), factors VIIa, II, V, VII and X, and global fibrinolytic capacity (GFC). Results: Median total TFPI decreased significantly from 48.5 ng/ml to 36.2 ng/ml (P=0.001), free TFPI from 10 to 7.6 ng/ml (P=0.001) and lipid-bound TFPI from 39.1 to 28.7 ng/ml (P=0.001). There were significant decreases in the levels of factor 11 (P=0.03), factor V (P=0.001), factor VII (P=0.06), thrombomodulin (P=0.01) and D dimer (P=0.001). However, APC res times were significantly prolonged (P=0.04). The remaining parameters that we have studied were not significantly affected. Conclusion: Our findings suggest that TAM tends to activate the coagulation pathway by counteracting major molecules involved in coagulation inhibition, namely TFPI and TM. As reflected by unchanged GFC, the drug appears to impair the expected compensatory activation of the fibrinolytic system, which removes fibrin polymers resulting from coagulation activation.WoSScopu

    Serum Thrombopoietin Levels in Haemodialysis Patients: Involvement of Arteriovenous Fistula

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    Background. Thrombopoietin (Tpo) is a recently cloned growth factor which plays a critical role in the regulation of thrombopoiesis. Tpo has also been shown to stimulate in vitro and in vivo erythroid cell growth. Although Tps transcripts were detected in hepatocytes, proximal tubules and endothelium, mechanisms regulating the level of circulating Tpo have not been fully delineated. Changes in the vessel wall and blood flow in arteriovenous fistula (AVF)might alter Tpo activity. Methods. Serum thrombopoietin levels and serum erythropoietin levels in samples concurrently obtained from venous returns of AVF and contralateral peripheral veins in 31 haemodialysis patients were determined and compared with 12 healthy controls. Levels were also compared between 14 haemodialysis patients (group I) treated with recombinant human erythropoietin (rHu-Epo) and 17 haemodialysis patients (group II) not requiring rHu-Epo. Results. Serum Tpo levels (44.8 +/- 23.9 pg/ml, vs 129.9 +/- 113.6 pg/ml, P < 0.05) and platelet counts (194 +/- 55. 10(6)/ml vs 273 +/- 94. 10(6)/ml, P < 0.05) of haemodialysis patients were lower than healthy controls. Serum Tpo levels were inversely correlated with platelet counts in the control group (R=-0.61, P < 0.05), but not in haemodialysis patients. Tpo concentrations of AVF samples were lower than peripheral venous samples (31.6 +/- 17.7 pg/ml vs 44.8 +/- 23.9 pg/ml, P=0.001). No significant difference was present between the serum Tpo concentrations of haemodialysis patients in group I and group II. Serum Tpo levels were not correlated with haemoglobin levels or serum erythropoietin levels in haemodialysis patients. Conclusion. Decreased serum Tpo levels despite low platelet counts in haemodialysis patients suggest that the proposed feedback mechanism of platelet uptake of Tpo is not fully operative in these patients. Moreover, AVF might affect the local production and/or catabolism of this growth factor.WoSScopu
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