Thrombogenesis in myocardial infarction and related syndromes: the role of molecular markers in diagnosis and management

Anticoagulant drugs: an update

Thromboembolic disorders continue to be a major cause of morbidity and mortality, resulting in an increased need for anticoagulant therapy. In recent years, new anticoagulant drugs have been developed at a rapid pace, prompted by the recognition of many undesirable properties of currently used agents, and by a greater knowledge of the active enzymatic sites of clotting factors. Furthermore, the structure of a thrombus is better understood, so that newer drugs can inhibit thrombin or Factor Xa not only on the surface of a thrombus, as in the case of heparin, but also the fibrin-bound thrombin or Factor Xa within the thrombus. These agents are usually small molecules synthesized on the basis of their inhibition of specific active sites in the respective coagulation factors. They possess many improved characteristics, such as greater efficacy and safety, oral administration, reliable pharmacokinetics, less need for laboratory monitoring and minimal interactions with other drugs and diet. Prominent among these are lepuridin (Refludan, Pfizer), fondaparinux (Arixtra, Sanofi-Synthelabo) and ximelagatran (Exanta, Astra Zeneca). However, these new drugs are still far from fulfilling the desired objectives. Most of them possess some but not all of the needed properties. Furthermore, many do not have specific antidotes for immediate reversal of their pharmacologic actions, and all are much more costly than conventional agents. Development of newer agents with properties closer to that of the ideal drug remains a challenge.

Hemoconcentration and hemostasis during acute stress: interacting and independent effects

BACKGROUND

Acute psychological stress can produce significant hemoconcentration as well as prothrombotic changes in blood, both of which may have potentially harmful effects on the cardiovascular system. It is unclear whether these effects are independent or have influence on each other.

PURPOSE

This review discusses research investigating the effects of acute psychological stress on hemoconcentration and hemostasis and explores future directions for psychohematology research. Physiology, associations with cardiovascular disease, and relationships between acute psychological stress are discussed independently for hemoconcentration and hemostasis, followed by an examination of the effects of stress-hemoconcentration on hemostasis.

CONCLUSIONS

Traditional methods of adjusting for stress-hemoconcentration effects (e.g., calculated plasma volume or hematocrit level corrections) may not be appropriate when examining stress-induced changes in hemostasis. The effects of acute stress on hemostasis should be examined in conjunction with hemoconcentration.

Endothelin-1-induced pain and hyperalgesia: a review of pathophysiology, clinical manifestations and future therapeutic options

Pain in patients with metastatic cancer contributes to increased suffering in those already burdened by their advancing illness. The causes of this pain are unknown, but are likely to involve the action of tumour-associated mediators and their receptors. In recent years, several chemical mediators have increasingly come to the forefront in the pathophysiology of cancer pain. One such mediator, endothelin-1 (ET-1), is a peptide of 21 amino acids that was initially shown to be a potent vasoconstrictor. Extensive research has revealed that members of the ET family are indeed produced by several epithelial cancerous tumours, in which they act as autocrine and/or paracrine growth factors. Several preclinical and clinical studies of various malignancies have suggested that the ET axis may represent an interesting contributor to tumour progression. In addition, evidence is accumulating to suggest that ET-1 may contribute to pain states both in humans and in other animals. ET-1 both stimulates nociceptors and sensitises them to painful stimuli. Selective stimulation of ET receptors has been implicated as a cause of inflammatory, neuropathic and tumoural pain. ET-1-induced pain-related behaviour seems to be mediated either solely by one receptor type or via both endothelin-A receptors (ETAR) and endothelin-B receptors (ETBR). Whereas stimulation of ETAR on nociceptors always elicits a pain response, stimulation of ETBR may cause analgesia or elicit a pain response, depending on the conditions. The administration of ETAR antagonists in the receptive fields of these nociceptors has been shown to ameliorate pain-related behaviours in animals, as well as in some patients with advanced metastatic prostate cancer. The identification of tumour-associated mediators that might directly or indirectly cause pain in patients with metastatic disease, such as ET-1, should lead to improved, targeted analgesia for patients with advanced cancer. In this review, we will describe the current status of the role of ET-1 in different types of painful syndromes, with special emphasis on its role in the pathophysiology of cancer pain. Finally, potential new treatment options that are based on the role of the ET axis in the pathophysiology of cancer are elaborated.

Fibrin D-dimer: a marker of psychosocial distress and its implications for research in stress-related coronary artery disease

Psychosocial factors might mediate their adverse impact on coronary arteries by eliciting a hypercoagulable state via changes in sympathetic nervous system activity. A recent meta-analysis of prospective studies reported an association of the hypercoagulability marker D-dimer with an increased risk for coronary events. This review provides evidence that an elevated plasma D-dimer level is a suitable marker for acute and chronic psychosocial distress. Prospective studies need to show whether stress-related changes in D-dimer may help explain the increased coronary risk with psychosocial distress.

Acute procoagulant stress response as a dynamic measure of allostatic load in Alzheimer caregivers

Allostasis designates processes of bodily adaptation to stressful challenges, whereas allostatic load means the costs of wear and tear to the body as a consequence of inefficient allostasis. In distressed dementia caregivers, an acute procoagulant stress response might be one dynamic mediator of allostatic load relevant to cardiovascular endpoints. An interviewer assessed the number of negative life-events independent from caregiving over 4 weeks in 37 spousal Alzheimer caregivers (M age +/- SD = 72 +/- 6 years). Baseline procoagulability scores and procoagulability scores in response to a 15-min speech task included plasma thrombin/antithrombin III complex, D-dimer, von Willebrand factor, tissue-type plasminogen activator, and plasminogen activator inhibitor 1 levels. Allostatic load was defined as the difference in procoagulability scores from baseline to speech, using standardized (z-score) transformations. Speech stress significantly increased heart rate (p =.017), systolic blood pressure (p =.002), and diastolic blood pressure (p <.001). The number of negative life-events (M +/- SD 2.8 +/- 2.0) correlated with allostatic load (r =.367, p =.026). After controlling for age and smoking, which together explained 32% of the variance in the allostatic load (R2 =.324), F(2, 34) = 8.14, p =.001, the number of negative life-events accounted for an additional 13% of that variance (Delta R2=.125), Delta F(1, 33) = 7.49, p =.010. The finding is compatible with the concept of allostasis and allostatic load, suggesting that higher combined caregiving and life distress levels are associated with more dysfunctional hemostatic responses to acute mental stress. The acute procoagulant stress response might constitute a dynamic mediator of allostatic load in Alzheimer caregivers.

Relationship between oxidative stress and extrinsic coagulation pathway in haemodialyzed patients

Enhanced oxidative stress (SOX), endothelial dysfunction and haemostatic abnormalities are common in end-stage renal failure patients undergoing maintenance haemodialysis (HD). We studied associations among circulating immunoreactive total lipid peroxides as a marker of short-time SOX, autoantibodies against oxidized LDL as a surrogate of prolonged SOX, copper/zinc superoxide dismutase (Cu/Zn SOD) as a major antioxidant enzyme, tissue factor (TF) as a principal initiator of extrinsic coagulation pathway counteracted by its inhibitor (TFPI), and prothrombin fragment 1+2 (F 1+2) as a surrogate of activated haemostasis.Pre-dialysis blood levels of all the markers studied were higher in 24 clinically stable HD patients compared to 11 healthy controls. Spearman's correlations among the three SOX markers were positive but nonsignificant in both HD patients and controls. In HD subjects, increased Cu/Zn SOD levels directly correlated with those of TF (rho=0.551, p=0.005) and TFPI (rho=0.501, p=0.001); the coagulation markers were also positively associated with each other (rho=0.663, p=0.0004). In healthy subjects, the relations between Cu/Zn SOD, TF and TFPI levels were inverse but not significant, and the direct association between TF and TFPI was nonsignificant either. In conclusion, increased plasma levels of Cu/Zn SOD, the antioxidant enzyme with emerging endothelial cell-protective and antithrombotic properties, may be a novel part of the system counteracting activated extrinsic coagulation system in maintenance HD patients.