Compositional differences in commercially available prothrombin complex concentrates.

Prothrombin complex concentrates (PCCs) are used in the management of bleeding complications with conventional oral anticoagulant drugs. Since the activation of these complexes results in the generation of factor Xa and IIa, these agents may potentially neutralize the newly developed Xa and thrombin inhibitors. Although the potency of these agents is defined in units that represent the level of factor IX (FIX), other factors including factor II, VII, and X are also present. Protein C, protein S, and protein Z are also present. The purpose of this study is to compare the compositional differences in the currently available PCCs along with the older agents. Measurement of compositional parameters including protein and FIX, mass spectrometric analysis of the native and activated PCCs, Western blotting studies on the native and activated PCCs for the activation products including thrombin, and their effect on blood and plasma coagulation parameters were carried out.

Increased expression of secreted frizzled-related protein-1 and microtubule-associated protein light chain 3 in keratoconus.

PURPOSE: To study the expression of secreted frizzled-related protein-1 (SFRP-1) and microtubule-associated protein light chain 3 (LC3), an autophagy marker, in keratoconus. METHODS: Under an institutional review board-approved protocol, de-identified and/or surgically discarded normal donor (n = 10) and keratoconus corneas (n = 10) were obtained. The corneal samples were fixed in formalin and embedded in paraffin. Immunohistochemical staining using SFRP-1 and LC3 antibodies was performed. RESULTS: The majority of expression of SFRP-1 was seen in the epithelium; however, in 3 tissues that showed high expression, staining was also present in the stroma and endothelium. Like SFRP-1, the LC3 expression in keratoconus tissues occurred at 3 different levels: low, medium, and high. Collectively these data suggest that there are differences in the expression levels of SFRP-1 and LC3 in keratoconus tissue compared with the normal tissue. Low expressivity of SFRP-1 seemed to correspond to low expressivity of LC3, whereas medium to high expressivity of SFRP-1 corresponded to medium to high expressivity of LC3. CONCLUSIONS: Increased expression of SFRP-1 and LC3 was observed in keratoconus corneas. Keratocyte autophagy seen with keratoconus may play a role in the pathogenesis of keratoconus.

Structural and pharmacological profile of generic enoxaparins used in Brazil.

Generic active pharmaceutical ingredients (APIs) have been commonly used in Brazil, since 1999, but most of them are synthetic and small molecules. Recently, a large number of generic enoxaparins were introduced into the market raising concerns related to product-to-product interchangeability, efficiency, and drug counterfeiting. These drugs are produced from biological sources and their production involves complex procedures and purification processes. The present article evaluates several generic enoxaparins, structurally and pharmacologically, and compares them with the branded products. Structural analysis showed that the generic products are, indeed, quite similar to the branded products, however, this similarity cannot be extended to their pharmacological activities. The results showed that generic products must go through extensive structural, pharmacological, and clinical evaluation in order to assess their quality, efficacy and, ultimately, avoid drug counterfeiting before clinical use. Variation was also observed between the branded products, showing that such drugs must be at constant surveillance.

Cross-reactivity of various thrombin products with anti-rabbit antibodies to bovine, human, and recombinant thrombin.

JMI-thrombin is used as topical hemostatic agent. While earlier clinically available JMI were reported to produce immunologic responses upon repeated exposure, the improved JMI, Recothrom?, and Evithrom? are claimed to be less immunogenic. Recothrom, despite its reduced immunogenic nature, upon repeated administration may result in the generation of antibodies (Abs) and that may cross react with bovine and human thrombin. Therefore, groups of rabbits were challenged repeatedly with Recothrom, Evithrom, and JMI over a 9-month period. Pre-immune blood and antiserum were collected from each rabbit on different time point. To determine their relative cross reactivity, JMI, Recothrom, and Evithrom were evaluated by western blotting using the rabbit IgG fractions. The results suggest that anti-Recothrom Abs cross-react with Evithrom and JMI in a time dependent fashion. Anti-JMI Abs did not cross-react with Recothrom, and Evithrom. Also, anti-Evithrom did not show any cross-reactivity with Recothrom and JMI at any time.

Gender-based differences in hemostatic responses.

AIM: Recent reports indicate increased mortality in women owing to cardiovascular diseases necessitating more gender-based studies. It is hypothesized that women have variable hemostatic responses to anticoagulant drugs. MATERIALS & METHODS: The hemostatic responses in healthy males (n = 10) and females (n = 10) were evaluated by performing various assays in the presence of anticoagulant drugs. Citrated whole blood from healthy volunteers (n = 20) was supplemented with rivaroxaban (final concentration [FC] = 0.3 µg/ml) and enoxaparin (FC =5 µg/ml). RESULTS: Differences between males and females were noted in the whole blood activated partial thromboplastin time (p = 0.0442) and Heptest® (p = 0.0345) assays in the saline control values. In the plasma system, rivaroxaban at a FC of 0.3 µg/ml and enoxaparin at 5 µg/ml showed a gender-based difference in the Heptest (p = 0.0423). Females showed faster fibrin formation than males. In the plasma system, plasminogen activator inhibitor-1 and domain-dimer assays (American Diagnostica, CT, USA) were performed with domain-dimer showing differences (p = 0.035). In the von Willebrand factor multimers, only band 5 showed differences (p = 0.032). Gender-based differences were observed. CONCLUSION: Careful adjustment of the dosages of anticoagulant drugs may be necessary to avoid bleeding or thrombosis.

Review: contaminants in heparin: review of the literature, molecular profiling, and clinical implications.

BACKGROUND: The contaminant isolated from contaminated heparin was oversulfated chondroitin sulfate (OSCS). Other possible contaminants should be evaluated. METHODS: Contaminants were isolated from recalled contaminated heparin and were compared to OSCS from animal sources and to heparin by-products synthetically persulfated. RESULTS: A great variability in molecular weight was observed in the isolated contaminants. Dermatan sulfate with high-molecular-weight in addition to OSCS was detected. Oversulfated chondroitin sulfate from different sources as well as heparin by-products produced activation of prekallikrein to kallikrein at variable rates as measured by the generation of kallikrein. All agents produced activation of the complement system. All compounds formed complexes with platelet factor 4 (PF4) and all produced (14)C serotonin release in the heparin-induced thrombocytopenia (HIT) analysis. The agents also exhibited variable anticoagulant responses that were mostly mediated via heparin cofactor II. CONCLUSION: These results suggest that heparin contaminants represent a heterogeneous group of oversulfated glycosaminoglycans (OSGAGs) which may mediate multiple pathophysiologic responses.