The molecular genetics of familial venous thrombosis

State-of-the-Art Review: Usefulness of Laboratory Techniques for Evaluating Antithrombotic Efficacy of New Therapeutic Strategies

New drugs and new therapeutic strategies are being introduced for the prevention and the management of cardiovascular and thromboembolic disorders. Extensive clinical studies and large-scale epidemiological investigations are conducted to demonstrate the efficacy of these therapeutic approaches. Laboratory assays are invaluable tools for this exploration. We discuss how the new understanding concerning the regulation of the coagulolytic equilibrium offers novel investigation tools. Parameters reflecting the activities of new drugs targeted to their impact site and presenting few side effects are available. In addition to global clotting methods and chromogenic substrate-based assays, introduction of immunoassays has allowed measurement of most of the molecular markers of hemostatic activation. We recommend use of a panel of markers exploring the endothelial damage, the blood cell involvement, the early coagulant pathways' activation (XIIa and VIIa), the thrombin-formation pathways, the fibrin formation, and the evaluation of the global fibrinolytic capacity. When related to the clinical end points, all these laboratory assays offer useful and reliable monitoring of new drugs. They contribute to the establishment of new therapeutic strategies. Key Words: Hemostasis—Activation—Antithrombotic—Therapy— Laboratory monitoring.

State-of-the-Art Review: Molecular Markers in Thrombosis and Hemostasis

Molecular markers for exploring the different stages of hemostasis activation are now available. These markers allow investigation of endothelial functions, blood cell activation, stimulation of coagulation pathways, involvement of the fibrinolytic system, and profiling of the coagulolytic-equilibrium that regulates hemostasis. Additionally, these markers find useful applications for monitoring therapies, following-up clinical states associated with high thrombotic risk, and validating new drugs and analyzing their mode of action. Furthermore, these markers may allow for recognition of the evolution of early disease in the clinically silent phase. Large scale epidemiological and longitudinal studies are required for establishing this latter approach. Up to now, only D. Dimer is used in routine clinical application for exclusion diagnosis of deep-veinous-thrombosis and pulmonary embolism. Other markers must prove their sensitivity for the early asymptomatic period and demonstrate their applicability throughout disease evolution. According to pathology and application, different markers may provide complementary information. Some markers, e.g., D. Dimer, soluble thrombomodulin, and modified AT-III (ATM), are used on standard citrated plasma samples. Modem and flexible technologies are now available for point-of-care testing (when required), quick and sensitive measurements in emergency conditions, and full automation when necessary. Lastly, factors that trigger hemostatic activation can now be evaluated and provide information on etiology. In this latter respect, autoimmunity may be important in thrombotic disease induction. Key Words: Hemostatic activation—Molecular markers— Thrombosis—Predictivity—Monitoring antithrombotic therapies.

Effect of microgravity on gene expression in mouse brain

Changes in gravitational force such as that experienced by astronauts during space flight induce a redistribution of fluids from the caudad to the cephalad portion of the body together with an elimination of normal head-to-foot hydrostatic pressure gradients. To assess brain gene profile changes associated with microgravity and fluid shift, a large-scale analysis of mRNA expression levels was performed in the brains of 2-week control and hindlimb-unloaded (HU) mice using cDNA microarrays. Although to different extents, all functional categories displayed significantly regulated genes indicating that considerable transcriptomic alterations are induced by HU. Interestingly, the TIC class (transport of small molecules and ions into the cells) had the highest percentage of up-regulated genes, while the most down-regulated genes were those of the JAE class (cell junction, adhesion, extracellular matrix). TIC genes comprised 16% of those whose expression was altered, including sodium channel, nonvoltage-gated 1 beta (Scnn1b), glutamate receptor (Grin1), voltage-dependent anion channel 1 (Vdac1), calcium channel beta 3 subunit (Cacnb3) and others. The analysis performed by GeneMAPP revealed several altered protein classes and functional pathways such as blood coagulation and immune response, learning and memory, ion channels and cell junction. In particular, data indicate that HU causes an alteration in hemostasis which resolves in a shift toward a more hyper-coagulative state with an increased risk of venous thrombosis. Furthermore, HU treatment seems to impact on key steps of synaptic plasticity and learning processes.

Ligneous conjunctivitis: a clinicopathological, immunohistochemical, and genetic study including the treatment of two sisters with multiorgan involvement

Ligneous conjunctivitis (LC) is a rare disease characterized by wood-like pseudomembranes developing on the ocular and extraocular mucosae secondary to plasminogen (PLG) deficiency. In this paper, we report two cases of LC in two sisters of 57 and 62 years of age that presented with recurrent, bilateral pseudomembranes on conjunctiva and a history of consanguinity and deafness. Pseudomembranes showed superficial and/or subepithelial deposits of eosinophilic amorphous hyaline, amyloid-like material with a variable proportion of granulation tissue, and inflammatory cells. The eosinophilic deposits were negative for Congo red stain, immunoreactive for fibrinogen, and consistently negative for amyloid A component, transthyretin, beta(2)-microglobulin, albumin, fibronectin, collagen type IV, vimentin, and cytokeratins. Among inflammatory cells, a percentage of positivity of roughly 60% for lymphocytes T (CD3+) and 40% for lymphocytes B (CD8+), with a relation of cytotoxic/helper (CD8/4) T cells of 3:2, was found. In one case, nasal polyps and recurrent gastric peptic ulcer were also characterized by the same subepithelial hyaline deposits. A novel homozygous point mutation c.1856 C>T was found in exon 15 of the PLG gene in both patients. Amniotic membrane transplantation was done in one case with promising results.

Ischemic stroke in congenital (type II C) defective antithrombin III

Type II C is a subtype of defective antithrombin III deficiency in which there is a molecular defect in the heparin binding site. Usually, heterozygous patients with this defect have little or no thrombotic symptoms. Ischemic stroke has never been described. We report the case of a young woman who had an episode of right-sided hemiparesis. The computed tomographic scan showed an ischemic lesion in the left hemisphere. There were no previous thrombotic episodes in the patient's history and the sole risk factor for thrombosis was taking of an oral contraceptive. Her family history was midly positive for thrombosis (superficial thrombophlebitis in two relatives). Laboratory tests showed normal antithrombin III antigen, low heparin cofactor activity and an increased slow-moving peak in crossed-immunoelectrophoresis with heparin. The same pattern was found in 7 of 20 relatives. Thus, a diagnosis of congenital type II C defective antithrombin III was made. This report suggests that young patients with ischemic stroke should be screened for defective antithrombin III.