Knowledge on single platelet behavior and intracellular mechanisms during thromboembolism in vivo is scarce. In the present study, we used a new method that enables real-time detection and quantification of activation of individual platelets participating in a thromboembolic process in vivo, using their intracellular free Ca2+ concentration ([Ca2+]i) as a marker of activation. Isolated platelets were labeled with the Ca2+-sensitive fluorescent probe fluo-3 and injected into anesthetized rabbits so that 0.5–1% of their circulating platelets were labeled. Wall puncture of mesenteric arterioles resulted in thrombus formation followed by embolization. Fluorescence intensity changes of labeled platelets participating in this process were quantified. Within 30 min after injection, labeled platelets behaved similarly to native platelets, and fluorescence intensity was not influenced by dye leakage. Upon adherence to the stationary thrombus, platelets exhibited a prolonged [Ca2+]i increase, accompanied by shape change and degranulation, which is consistent with a role for strong platelet agonists like collagen. In contrast, when platelets adhered to a growing embolus their [Ca2+]i rise was transient, and they hardly showed shape change and degranulation, suggesting the involvement of weaker agonists like ADP. These results show, for the first time, the relation between single platelet activation patterns, which are different during thrombus growth and embolus formation, and their behavior in a thromboembolic process in vivo.
There are limited data available on health-related quality of life (QoL) in patients with complex regional pain syndrome (CRPS). In the present study we examined QoL in 975 CRPS patients attending 6 different clinics in the Netherlands. QoL was assessed using the MOS 36-Item Short-Form Health Survey (SF-36) with the Mental Health Summary Score (MHS) and the Physical Health Summary Score (PHS) as dependent variables. The influences of gender, type of affected limb, disease duration, pain scores, CRPS severity and set of diagnostic criteria used were investigated. We found the lowest scores of QoL in the physical domains of the SF-36, with lower-limb CRPS patients reporting poorer results than patients with an affected upper limb. Influence of gender on QoL was not observed, and correlations of QoL with disease duration and the CRPS severity score were weak. Pain correlated moderately with QoL. In addition, patients fulfilling stricter diagnostic criteria (ie, the Budapest criteria) had lower QoL scores than patients fulfilling less strict criteria (ie, the Orlando criteria). We conclude that loss of QoL in CRPS patients is due mainly to reduced physical health. A comparison with data available from the literature shows that CRPS patients generally report poorer QoL than patients with other chronic pain conditions, particularly in the physical domains. Pain correlated moderately with QoL and therefore deserves ongoing attention by physicians. Finally, patients meeting the diagnostic Budapest criteria have lower QoL scores than patients meeting the Orlando criteria, highlighting the impact of different sets of criteria on population characteristics.
Atherothrombosis and embolization are main causes of morbidity and mortality in the Western world. To optimize treatment, better understanding of the factors involved in thromboembolism in vivo is needed. The course and outcome of a thromboembolic process are determined by the local balance between anti and prothrombotic factors. In healthy vessels, endothelial antithrombotic properties prevent blood platelets from interacting with the vessel wall. Upon vessel wall damage or endothelial activation, however, prothrombotic factors temporarily overrule the antithrombotic factors, leading to thrombus formation and embolization. According to this concept, thromboembolism ends when the balance is restored. Animal models on microvascular thromboembolism have provided evidence that the endothelium is eminently involved in the regulation of thromboembolism, and that shear forces are an important determinant of endothelial function. Therefore, in this review focus is on the endothelial regulation of platelet-vessel wall interactions during thromboembolism in vivo. Anti- and prothrombotic properties of vascular endothelium will be discussed, paying special attention to the endothelium-derived platelet inhibiting substances nitiric oxide (NO) and prostacyclin (PGl(2)) and to differences between arteriolar and venular endothelium. In addition, the involvement of shear forces in microvascular thromboembolic processes in vivo will be described
Objectives-Exercise training is known to enhance skeletal muscle blood flow capacity, with highintensity interval sprint training (IST) primarily affecting muscles with a high proportion of fast twitch glycolytic fibers. The objective of this study was to determine the relative contributions of new arteriole formation and lumenal arteriolar remodeling to enhanced flow capacity and the impact of these adaptations on local microvascular hemodynamics deep within the muscle.Methods-The authors studied arteriolar adaptation in the white/mixed-fiber portion of gastrocnemius muscles of IST (6 bouts of running/day; 2.5 min/bout; 60 m/min speed; 15% grade; 4.5 min rest between bouts; 5 training days/wk; 10 wks total) and sedentary (SED) control rats using whole-muscle Microfil casts. Dimensional and topological data were then used to construct a series of computational hemodynamic network models that incorporated physiological red blood cell distributions and hematocrit and diameter dependent apparent viscosities.Results-In comparison to SED controls, IST elicited a significant increase in arterioles/order in the 3A through 6A generations. Predicted IST and SED flows through the 2A generation agreed closely with in vivo measurements made in a previous study, illustrating the accuracy of the model. IST shifted the bulk of the pressure drop across the network from the 3As to the 4As and 5As, and flow capacity increased from 0.7 mL/min in SED to 1.5 mL/min in IST when a driving pressure of 80 mmHg was applied.Conclusions-The primary adaptation to IST is an increase in arterioles in the 3A through 6A generations, which, in turn, creates an approximate doubling of flow capacity and a deeper penetration of high pressure into the arteriolar network. Keywordsangiogenesis; arteriogenesis; exercise training; microcirculation; network modelThe purpose of this study was to use a computational network model to examine mechanisms responsible for the increased blood flow capacity we previously reported in white and mixed gastrocnemius skeletal muscle of rats following interval sprint exercise training (high speed, uphill running) (3,10). These previous studies indicate that white and mixed gastrocnemius
These findings indicate that making use of "resting" as a pain coping strategy contributes significantly to limitations in activity and participation in patients with CRPS-1 of the legs. Indications for a negative influence of kinesiophobia or a positive influence of an active pain coping style were not found.
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