Point of Care Testing (POCT) to assess drug concentration in patients treated with non-vitamin K antagonist oral anticoagulants (NOACs).

BACKGROUND: Non-vitamin K antagonist oral anticoagulants (NOACs) do not need routine laboratory monitoring but measurement of drug concentration is important in emergency conditions. Specific laboratory tests are not readily available or not implemented in every hospital. Point-of-Care Tests (POCT) may bridge this gap and be used as a bedside solution. OBJECTIVES: Feasibility of POCT to assess plasma levels of dabigatran, rivaroxaban and apixaban. PATIENTS/METHODS: Activated Coagulation Time-Low Range (ACT - LR) using a portable Hemochron Signature Elite for dabigatran and prothrombin time (expressed as INR) by Coaguchek XS Pro for rivaroxaban and apixaban were obtained at trough and peak in 136 consecutive patients taking NOACs (70 on dabigatran, 45 on rivaroxaban and 20 on apixaban). Using a paired study design, drug concentrations were concurrently determined by functional specific tests. RESULTS AND CONCLUSIONS: The correlation between NOACs concentration and the values obtained using the POCTs was high for dabigatran and rivaroxaban (r = 0.80 and r = 0.82, respectively) and low for apixaban (r = 0.21). ACT-LR ≤ 188 s better detected dabigatran levels ≤ 50 ng/ml, with a sensitivity of 87.5% and a specificity of 84.1%. ACT-LR values > 217 s better discriminated value of dabigatran > 200 ng/ml, with a sensitivity of 86.7% and a specificity of 81.4%. INR Coaguchek values ≤ 1.2 better identified patients with rivaroxaban values < 100 ng/ml, with sensitivity of 90%, specificity of 88.5%. This analysis was not possible for apixaban. CONCLUSION: In emergency situations POCT use may provide useful immediate information on dabigatran and rivaroxaban concentration.

Electrostatically stabilized hybrids of carbon and maghemite nanoparticles: electrochemical study and application.

Binary hybrids have been investigated for the past few decades due to the emerging properties of nanoparticle composites. Electrostatically stabilized core-shell nanostructures composed of surface active magnetic nanoparticles (SAMNs) and differently charged carbon nanomaterials display specific electrochemical properties. In this work, a set of binary hybrids that include a new class of magnetic nanoparticles is presented and the electrochemical features of the hybrids are reported. Gallic acid derived carbon dots (GA-CDs), PEG derived graphene dots (PEG-GDs), and quaternized carbon dots (Q-CDs) characterized by different charged groups were used for the preparation of different complexes with SAMNs. Thus, a set of six binary nanomaterials was obtained, and characterized by electrochemical impedance spectroscopy, cyclic voltammetry and chronoamperometry, demonstrating significant differences in the charge transfer resistance, capacitive current, electrochemical performance, and reversibility with respect to the isolated subunits. Among them, the combination of Q-CDs with an excess of SAMNs led to a Q-CD@SAMN hybrid, which displayed peculiar electrocatalytic properties attributable to the influence of the strong electrostatic interactions exerted by Q-CDs on the SAMN surface. Notwithstanding their small fraction (around 1% w/w), Q-CDs oriented the electrocatalysis of SAMNs toward the selective electro-oxidation of polyphenols at low applied potentials (+0.1 V vs. SCE). Finally, the Q-CD@SAMN hybrid was used for the development of a coulometric sensor for polyphenols, composed of a simple carbon paste electrode in a small volume electrochemical flow cell (1 µL), and used for the complete direct electro-oxidation of polyphenols from plant extracts.

The role of platelets in antiphospholipid syndrome.

Despite extensive research, the pathogenesis of antiphospholipid syndrome (APS) remains obscure in many aspects. However, it is widely accepted that thrombosis is the result of a hypercoagulable state caused by antibodies directed against ß2-glycoprotein I (ß2-GPI), a protein whose physiological role is unknown. Although underestimated, platelets may be involved in APS and its thrombotic manifestations, especially arterial, in several ways. Thrombocytopenia is the most relevant non-criteria manifestation of APS, possibly caused by direct binding of anti-ß2-GPI antibodies or anti-ß2-GPI-ß2-GPI complexes. On the other hand, platelets may have a key role in APS-related thrombosis due to the presence of multiple receptors that can interact with anti-ß2-GPI antibodies (especially apolipoprotein E receptor 2' (apoER2') and glycoprotein Ibα (GPIbα)) with consequent release of different procoagulant mediators such as thromboxane B2, platelet factor 4 (PF4), and platelet factor 4 variant (CXCL4L1). The aim of this review is to put together evidence on the possible role of platelets in APS and to stimulate further research on the issue.

APS - Diagnostics and challenges for the future.

Diagnosis of antiphospholipid syndrome (APS) is essentially based on the detection of circulating antiphospholipid (aPL) antibodies. Progress have been made on the standardization of tests exploring the presence of aPL as guidelines on coagulation and immunological tests were recently published in the literature. Clinical relevance of aPL profile has come from prospective cohort studies in populations with a homogeneous antibody profile supporting the view that triple positivity is a high risk pattern in patients and carriers. In addition to the classic ones, several other tests have been proposed for the diagnosis of APS. The detection of antibodies directed to domain 1 and 4/5 of ß2-Glycoprotein I (ß2GP1) were found to be particularly sound. Several issues remain to be addressed. We do not yet know what is the physiological function of ß2GP1 and the pathophysiology of thrombosis and pregnancy loss in these patients. Moreover, treatment is poorly defined especially in the case of feared catastrophic APS.

Reasons for and consequences of vitamin K antagonist discontinuation in very elderly patients with non-valvular atrial fibrillation.

Essentials Anticoagulation in the elderly is still a challenge and suspension of warfarin is common. This is an observational study reporting reasons and consequences of warfarin suspension. Vascular disease, age, time in therapeutic range, and bleedings are associated with suspension. After suspension for bleeding or frailty, patients remain at high-risk of death or complications. SUMMARY: Background Anticoagulation in elderly patients with non-valvular atrial fibrillation (NVAF) is still a challenge, and discontinuation of warfarin is common. The aim of this study was to analyze the aspects related to warfarin discontinuation in a real-world population. Methods This was an observational cohort study on very elderly NVAF patients naive to warfarin therapy (VENPAF). The included subjects were aged at least 80 years, and started using warfarin after a diagnosis of NVAF. Warfarin discontinuation was assessed, and the reason reported for discontinuation, the person who decided to stop treatment, subsequent antithrombotic therapy and mortality, ischemic and bleeding events were collected. Results Over a period of 5 years, warfarin was discontinued in 148 of 798 patients. Despite similar CHA2 DS2 -VASc scores, the frequencies of thromboembolic and major bleeding events were significantly higher (P = 0.01 and P = 0.001, respectively) and the time in therapeutic range (TTR) was significantly lower (P < 0.001) in patients who discontinued warfarin. Independent risk factors for warfarin discontinuation were vascular disease (hazard ratio [HR] 2.5, P < 0.001), age ≥ 85 years (HR 1.4, P = 0.04), TTR < 60% (HR 1.8, P = 0.001), and bleeding events (HR 2.3, P < 0.001). The main reasons for warfarin discontinuation were physician-perceived frailty or low life-expectancy (45.9%), bleeding complications (19.6%), and sinus rhythm restoration (16.9%). Event and death rates were very high, especially in frail patients and in those with bleeding complications. Conclusions Warfarin discontinuation is frequent in very elderly patients, and is associated with increased risks of death and adverse events. Identification of elderly patients who are at high risk of bleeding and the poor quality of anticoagulation during warfarin are still unsolved clinical problems.

Laboratory testing for antiphospholipid syndrome.

This is a practical report on laboratory tests for the diagnosis of antiphospholipid syndrome (APS). After a general definition of APS, this study deals with appropriateness and timing in requesting the determination of antiphospholipid (aPL) antibodies. Lupus anticoagulant (LAC), anticardiolipin (aCL), and anti ß2-glycoprotein I (aßGPI) are the mandatory tests to be performed, while other tests are not yet validated for clinical use. Interpretation of results is an important discussed issue that implies a close liaison between clinical pathologists and clinicians. Finally, a personal definition of APS according to aPL antibody profile closes the manuscript.

Efficacy and safety of rivaroxaban vs warfarin in high-risk patients with antiphospholipid syndrome: Rationale and design of the Trial on Rivaroxaban in AntiPhospholipid Syndrome (TRAPS) trial.

BACKGROUND: New oral anticoagulants may simplify long-term therapy in conditions requiring anticoagulation. Rivaroxaban is a direct factor Xa inhibitor that has been extensively studied and is now approved for the prevention and therapy of a number of thromboembolic conditions. OBJECTIVE AND METHODS: This is a multicentre, randomized, open-label, study that will evaluate if Rivaroxaban 20 mg od (or 15 mg od in patients with moderate renal insufficiency) is non-inferior to warfarin (INR target 2.5), for the prevention of thromboembolic events, major bleeding and death in high risk (triple positive) patients with antiphospholipid syndrome. Secondary endpoints will assess the incidence of any individual component of the composite end point. An external adjudication committee will evaluate all suspected outcome events. This will be a unique trial, as it will enrol the biggest homogenous cohort of high risk APS individuals. CONCLUSION: The methods and the study design should be appropriate to achieve study results that are both scientifically valid and relevant to clinical practice.

Antibodies to Domain 4/5 (Dm4/5) of ß2-Glycoprotein 1 (ß2GP1) in different antiphospholipid (aPL) antibody profiles.

BACKGROUND: Determination of the three recommended tests for the diagnosis of antiphospholipid syndrome [Lupus Anticoagulant (LA), anticardiolipin (aCL) and anti ß2-Glycoprotein 1 (aß2GP1) antibodies] allow physicians to allocate patients into classification (risk) categories. OBJECTIVES: To measure antibodies of IgG isotype directed towards Domain 4/5 (Dm4/5) of ß2GP1. PATIENTS/METHODS: In this cross-sectional study we measured IgG aß2GP1-Dm4/5 in a group of individuals positive for IgG aß2GP1 and classified as triple (LAC+, IgG aCL+, IgG aß2GP1+, n=32), double (LAC-, IgG aCL+, IgG aß2GP1+, n=23) or single positive (LA-, IgG aCL-, IgG aß2GP1+, n=10). RESULTS: Geometric mean and standard deviation of IgG aß2GP1 values expressed as Chemiluminescent Units (CU) in triple, double, single positive groups and in 40 healthy individuals were 1795±783, 321±181, 29±8 and 5.0±1.0, respectively (ANOVA p<0.0001). Geometric mean and standard deviation of IgG aß2GP1-Dm4/5 expressed as Optical Density (OD) in triple, double and single positive groups and in 40 healthy individuals were 0.16±0.13, 0.16±0.15 and 0.26±0.15, 0.13±0,11, respectively (ANOVA p<0.002). Individuals in the single positive group, expressed significantly higher values with respect to triple (p=0.04) and double (p=0.03) positive groups. Approximate OD cut-off value (99° percentile) calculated in 40 normal control subjects is 0.404. Positivity to IgG aß2GP1-Dm4/5 according to this cutoff was found in only 5 individuals, 3 in triple positive and 2 in single positive groups and was not associated with thromboembolism. CONCLUSION: Mean level of IgG aß2GP1-Dm4/5 is higher in single positive group. There is no association between positivity to IgG aß2GP1-Dm4/5 and thromboembolic events.

NZVI modified magnetic filter paper with high redox and catalytic activities for advanced water treatment technologies.

The in situ synthesis of air-stable zero-valent iron nanoparticles (NZVI) embedded in cellulose fibers leads to the assembly of highly reactive magnetic filter papers. These engineered materials display a wide range of applications in the treatment of wastewater and drinking water, including chromium removal, phenol degradation, environmental bioremediation, and catalysis.

Quaternized carbon dot-modified graphene oxide for selective cell labelling--controlled nucleus and cytoplasm imaging.

Cationic quaternized carbon dots (QCDs) and anionic graphene oxide sheets (GO) are combined via non-covalent interactions following a self-assembly pathway to form highly biocompatible and fluorescent hybrid materials. These hybrids act as selective probes with controlled labelling of the cell nucleus or cytoplasm depending on the QCD loading.

Chiral kagomé lattice from simple ditopic molecular bricks.

Self-assembly techniques allow for the fabrication of highly organized architectures with atomic-level precision. Here, we report on molecular-level scanning tunneling microscopy observations demonstrating the supramolecular engineering of complex, regular, and long-range ordered periodic networks on a surface atomic lattice using simple linear molecular bricks. The length variation of the employed de novo synthesized linear dicarbonitrile polyphenyl molecules translates to distinct changes of the bonding motifs that lead to hierarchic order phenomena and unexpected changes of the surface tessellations. The achieved 2D organic networks range from a close-packed chevron pattern via a rhombic network to a hitherto unobserved supramolecular chiral kagomé lattice.

Strong electronic correlations in LixZnPc organic metals.

Nuclear magnetic resonance, electron paramagnetic resonance and magnetization measurements show that bulk LixZnPc are strongly correlated one-dimensional metals. The temperature dependence of the nuclear spin-lattice relaxation rate 1/T_{1} and of the static uniform susceptibility chi_{S} on approaching room temperature are characteristic of a Fermi liquid. Moreover, while for x approximately 2 the electrons are delocalized down to low temperature, for x-->4 a tendency towards localization is noticed upon cooling, yielding an increase both in 1/T_{1} and chi_{s}. The x dependence of the effective density of states at the Fermi level D(E_{F}) displays a sharp enhancement for x approximately 2, at the half filling of the ZnPc lowest unoccupied molecular orbitals. This suggests that LixZnPc is on the edge of a metal-insulator transition where enhanced superconducting fluctuations could develop.

Metal-organic honeycomb nanomeshes with tunable cavity size.

We present a systematic study of metal-organic honeycomb lattices assembled from simple ditopic molecular bricks and Co atoms on Ag(111). This approach enables us to fabricate size- and shape-controlled open nanomeshes with pore dimensions up to 5.7 nm. The networks are thermally robust while extending over microm2 large areas as single domains. They are shape resistant in the presence of further deposited materials and represent templates to organize guest species and realize molecular rotary systems.

A novel mixed valence form of Rhus vernicifera laccase and its reaction with dioxygen to give a peroxide intermediate bound to the trinuclear center.

Rhus vernicifera laccase, in a novel mixed valence state [T1oxT23red: type 1 Cu as Cu(II), and type 2 and 3 Cus as Cu(I)], was formed by reacting Cu(I) on the type 2 Cu-depleted laccase [T1oxT3red: type 1 Cu as Cu(II) and type 3 Cus as Cu(I)] under argon. Contrary to T1oxT3red, T1oxT23red was highly reactive with dioxygen, and gave the three transient bands at 340, 475, and 680 nm due to the two-electron reduced form of dioxygen [charge transfer bands from peroxide to Cu(II)]. The first order decays were highly dependent on pH, which led to the successful detection of the intermediate for ca. 2 h at pH 7.5. Another mixed valence derivative, T12oxT3red [type 1 and type 2 Cus as Cu(II), and type 3 Cus as Cu(I)] prepared through the action of Cu(II) on T1oxT3red was not reactive with dioxygen, but showed high enzyme activity as to the oxidation of N,N-dimethyl-p-phenylenediamine. The whole reaction mechanism of the reduction of dioxygen by laccase was proposed based on the present results together with data for the former detection and characterization of the three-electron reduced form of dioxygen [Huang, H. et al. (1999) J. Biol. Chem. 274, 46, 32718-32724].

Spectroscopic and kinetic studies on the oxygen-centered radical formed during the four-electron reduction process of dioxygen by Rhus vernicifera laccase.

The oxygen-centered radical bound to the trinuclear copper center was detected as an intermediate during the reoxidation process of the reduced Rhus vernicifera laccase with dioxygen and characterized by using absorption, stopped-flow, and electron paramagnetic resonance (EPR) spectroscopies and by super conducting quantum interface devices measurement. The intermediate bands appeared at 370 nm (epsilon approximately 1000), 420 nm (sh), and 670 nm (weak) within 15 ms, and were observable for approximately 2 min at pH 7.4 but for less than 5 s at pH 4.2. The first-order rate constant for the decay of the intermediate has been determined by stopped-flow spectroscopy, showing the isotope effect, k(H)/k(D) of 1.4 in D(2)O. The intermediate was found to decay mainly from the protonated form by analyzing pH dependences. The enthalpy and entropy of activation suggested that a considerable structure change takes place around the active site during the decay of the intermediate. The EPR spectra at cryogenic temperatures (<27 K) showed two broad signals with g approximately 1.8 and 1.6 depending on pH. We propose an oxygen-centered radical in magnetic interaction with the oxidized type III copper ions as the structure of the three-electron reduced form of dioxygen.