Evaluation of a prolonged prothrombin time

Development of a paper-based lateral flow prothrombin assay

Disorders of haemostasis result in both excessive bleeding and clotting and are a major global cause of morbidity and mortality, particularly in the developing world. A small number of simple tests can be used to screen and monitor for such dysfunctions, one of which is the prothrombin time (PT) test and associated International Normalisation Ratio (INR). PT/INR is routine in hospital laboratories in developed countries, and can also be performed using point-of-care instruments. However, neither of these approaches is appropriate in low-resource settings. Significant interest has grown in paper-based devices to form the basis of simple and low-cost assays that may have the potential for application in such environments. This study describes the development of a simple, low-cost, paper-based lateral flow prothrombin assay. The assay employed wax printing on chromatography paper to define test channels, with deposition of thromboplastin reagent and calcium chloride onto the resulting strips. These were placed in a test housing and measurement of the flow rates of deposited plasma samples were performed in triplicate. The flow dynamics of the assay was optimised according to the type of paper substrate used, the nature and quantity of the thromboplastin reagent, the amount of calcium chloride required, and the volume of sample employed. An optimised assay configuration demonstrated a dynamic range of 6 mm between normal and factor-deficient plasmas. The assay showed good correlation with laboratory-based PT assay (Yumizen G200) in artificial plasmas in the 9.8 to 36 s range (r² = 0.8112). The assay also demonstrated good dynamic range and correlation in patient plasma samples in comparison with hospital PT, with a range of 9.8 to 45 s (r² = 0.7209).

Evaluating for Suspected Child Abuse: Conditions That Predispose to Bleeding

Child abuse might be suspected when children present with cutaneous bruising, intracranial hemorrhage, or other manifestations of bleeding. In these cases, it is necessary to consider medical conditions that predispose to easy bleeding or bruising. When evaluating for the possibility of bleeding disorders and other conditions that predispose to hemorrhage, it is important for pediatricians to consider the child's presenting history, medical history, and physical examination findings before initiating a laboratory investigation. Many medical conditions can predispose to easy bleeding. Before ordering laboratory tests for a disease, it is useful to understand the biochemical basis and clinical presentation of the disorder, condition prevalence, and test characteristics. This technical report reviews the major medical conditions that predispose to bruising or bleeding and should be considered when evaluating for abusive injury.

Temperature Monitorable Kinetics Study of Human Blood Coagulation by Utilizing a Dual-Mode AlN-Based Acoustic Wave Resonator

In this study, we reported an acoustic wave resonator for temperature monitorable kinetic analysis of human blood coagulation. The resonator is operated in both Lamb wave mode at 860 MHz and Rayleigh wave mode at 444 MHz. The electrical parameter variation of the resonator induced by the increased plasma viscosity can be used to monitor the coagulation process. The Lamb mode of the resonator is sensitive to both plasma viscosity and plasma temperature, while the Rayleigh mode responds only to the temperature which is not affected by viscosity. These unique characteristics of the two modes are due to different spatial distributions of the acoustic energy. Taking advantage of the aforementioned features, an acoustic wave resonator to study the human blood coagulation is designed to simultaneously monitor the temperature and plasma viscosity. The coagulation time and plasma temperature were provided by fitting the time-frequency curves. Our design holds great promise for biological reaction monitoring with possible temperature changes.

In vitro anticoagulant effect of Crassocephalum crepidioides leaf methanol extract and fractions on human blood

Background

Blood coagulation is a rapid and efficient process that produces clot formation which requires regulation. A derangement of blood coagulation is a feature of many disease conditions. This study investigated the in vitro effects of Crassocephalum crepidioides Benth S. Moore leaf methanol (crude) extract and its partitioned solvent fractions on blood coagulation of Healthy human volunteers.

Methods

The secondary metabolites from dried and ground C. crepidioides leaves were extracted with 70% methanol, and the concentrated crude extract was subsequently subjected to solvent partitioning with Hexane, Ethyl acetate, and Butanol. Varying concentrations (5–20 mg/mL) of the extract and fractions were tested in vitro on blood coagulation profile; clotting time (CT), prothrombin time (PT), and activated partial thromboplastin time (aPTT) of apparently healthy human volunteers, while phytochemical characterization of the Hexane fraction was done by gas chromatography-mass spectrometry (GC-MS).

Results

C. crepidioides leaf methanol extract and fractions significantly (P<0.05) prolonged the clotting time, prothrombin and activated partial thromboplastin times in the blood obtained from the volunteers. The highest prolongation effect was recorded with the Hexane fraction at concentration of 10mg/mL. GC-MS analysis of the Hexane fraction indicated the presence of phytochemicals such as unsaturated fatty acids and esters, phenolic compounds, flavonoids, and coumarin-related compounds known to exhibit antiaggregant, antiplatelet and antimicrobial activities.

Conclusion

These results showed that C. crepidioides possesses bioactive components with anticoagulant properties which may be exploited in the treatment of blood coagulation disorders.

Hemolytic Uremic Syndrome: An Increasingly Recognized Public Health Problem

A 28-year-old man was referred and admitted to our hospital due to Escherichia coli O157-mediated hemorrhagic colitis with severe thrombocytopenia. A systemic workup concluded that the patient had acute pancreatitis as well as hemolytic uremic syndrome. The patient was ultimately discharged, with his platelet count having recovered. Our case serves an illustrative example of potentially serious complications of an increasingly recognized public health problem. Systemic studies on this topic are insufficient, and we strongly recommend the further accumulation of more experiences like ours. Several diagnostic and management concerns that emerged in this case are also discussed.

Biocompatible sulfenamide and sulfonamide derivatives of metformin can exert beneficial effects on plasma haemostasis

As the pharmacokinetic properties of metformin are unfavourable, several analogues and prodrugs have been synthesised to improve its bioavailability. The aim of this study was to assess the plasma stability of sulfenamide and sulfonamide derivatives of metformin and establish their effects on plasma haemostasis and integrity of red blood cells (RBCs). The overall haemostasis potential was evaluated spectrophotometrically by clot formation and lysis test (CL-test). PT (Prothrombin Time) and APTT (Activated Partial Tromboplastin Time) were used to evaluate the effects if the compounds on the extrinsic and intrinsic coagulation pathway. Haemolysis assay, microscopy and flow cytometry studies were conducted to determine the effect of the compounds on RBCs. Two sulfonamide and one sulfenamide derivatives of metformin were associated with a statistically significant decrease in the overall potential of clot formation and fibrinolysis (↓ CL_AUC), suggesting that these compounds may exert beneficial effects regarding plasma haemostasis, which is frequently impaired in diabetic patients. p- and o-Nitrobenzene sulfonamides contributed to the beneficial change in kinetic parameters of clot formation and fibrinolysis. o-Nitrobenzene sulfonamide significantly increased thrombin generation time (↑ TGt) and was also found to prolong both APTT and PT. All compounds did not exert any effects on the integrity of RBCs over the concentration range 0.006-0.6 μmol/mL which constitutes the expected therapeutic concentration. In conclusion, sulfonamide derivatives of metformin present potentially beneficial properties in terms of plasma haemostasis which is frequently impaired in T2DM patients. Therefore, metformin sulfonamides may become a prototype for further design and synthesis of novel metformin analogues and prodrugs with improved pharmacokinetic properties.

New prodrugs of metformin do not influence the overall haemostasis potential and integrity of the erythrocyte membrane

Although metformin, an oral anti-diabetic drug, has been found to have multidirectional effects over the past decade, it is characterised by unfavourable pharmacokinetic properties. This study discusses the effects of metformin, phenformin and three prodrugs of metformin on the haemostasis and integrity of Red Blood Cells (RBCs). The influence of examined biguanide derivatives on haemostasis was evaluated spectrophotometrically by clot formation and lysis test (CL-test) at 405nm. The extrinsic and intrinsic coagulation pathway were examined by measuring the PT (Prothrombin Time) and aPTT (Activated Partial Tromboplastin Time). Haemolysis assay, microscopy and flow cytometry studies were used to assess the effect of the tested compounds on RBCs. Although none of the tested biguanide derivatives significantly influenced the overall potential of clot formation and fibrinolysis (CL_AUC constants), statistically significant changes were seen in the values of the kinetic parameters of fibrinolysis. Furthermore, only prodrug 2, with an 8-carbon alkyl chain, unfavourably affected RBCs by interaction with the erythrocyte membrane leading to significant haemolysis. Our results provide a further insight into the effects of metformin and its prodrugs on haemostasis and RBCs and underscore the necessity for further research.

A sample-to-result system for blood coagulation tests on a microfluidic disk analyzer

In this report, we describe in detail a microfluidic analyzer, which is able to conduct blood coagulation tests using whole blood samples. Sample preparation steps, such as whole blood aliquoting and metering, plasma separation, decanting, and mixing with reagents were performed in sequence through microfluidic functions integrated on a disk. Both prothrombin time (PT) and activated partial thromboplastin time (aPTT) were carried out on the same platform and the test results can be reported in 5 min. Fifty clinical samples were tested for both PT and aPTT utilizing the microfluidic disk analyzer and the instrument used in hospitals. The test results showed good correlation and agreement between the two instruments.

Antithrombotic effect of repeated doses of the ethanolic extract of local olive (Olea europaea L.) leaves in rabbits

The incidence of thromboembolic diseases is increasing, and they are a major cause of mortality and morbidity worldwide. Mediterranean diet is known for its high content of olive products, especially olive oil, which has known cardiovascular health benefits, including those on blood pressure, cholesterol level, and thrombogenesis. All previous animal and clinical studies investigating the beneficial antithrombotic effects of olives have focused on olive oil and a few on olive leaves (OLEs). In this study, the ethanolic extract of OLE was evaluated for its antithrombotic activity in the rabbit model of thrombosis induced by ligature of the vena cava and intravenous administration of tissue thromboplastin. Pre-treatment with 100 or 200 mg/kg per day of the ethanolic extract for 8 weeks significantly prolonged the prothrombin time (PT) in comparison to the control group (12.10 ± 0.35 sec and 14.38 ± 0.29 sec vs. 10.8 ± 0.32 sec, p < 0.05 and 0.001, respectively). In comparison to the control group, the same doses had no statistically significant effect on thrombus weight (16.85 ± 0.67 mg, 16.32 ± 0.35 mg, and 17.81 ± 0.75 mg; p = 0.18 and 0.06) or on activated partial thromboplastin time (APTT) (19.17 ± 0.33 sec, 19.12 ± 0.73 sec, and 18.97 ± 0.41 sec; p = 0.36 and 0.43, respectively). One important finding in this study concerns thrombus morphology. In the extract treatment groups, the thrombus was filament-like and did not adhere to blood vessel walls, whereas in the control group the thrombus was thick and almost completely occluded the vein. Therefore, these results suggest that OLE ethanolic extract can modify the extrinsic coagulation pathway as evidenced by the prolongation of PT and changes in thrombus morphology, enough to justify further research to evaluate its possible antithrombotic effects.

A comparison of the biological activity of 2 formulations of enoxaparin in 12 healthy volunteers

INTRODUCTION

India is one of the few countries where biosimilar enoxaparin is available for clinical use. Despite availability since past 4 to 5 years, there is a paucity of published literature regarding their biological activity. The aim of the current study is to compare the biological activity of an endogenously developed formulation of enoxaparin with the branded formulation.

MATERIALS AND METHODS

Twelve healthy male volunteers received 1 subcutaneous injection of 2 different formulations of enoxaparin in a randomized, open-label, balanced, 2-treatment, 2-period, 2-sequence, cross-over study. The test formulation was Injection Troynoxa (enoxaparin sodium 40 mg/0.4 mL, Troikaa Pharmaceuticals Ltd., India) and reference formulation was Injection Clexane (enoxaparin sodium 40 mg/ 0.4 mL, Sanofi-Aventis, UK). The plasma anti-Xa activity and activated partial thromboplastin time (aPTT) were estimated on fully automated coagulometer predose and at 2, 4, 6, 8, and 10 hours following dosing with 40 mg/0.4 mL of enoxaparin.

RESULTS

The results of mixed model analysis of repeated measures analysis of variance (ANOVA) for estimating difference between least square means of test and reference formulations, at all time points, showed no significant differences in anti-Xa activity and plasma aPTT levels. Both formulations were well tolerated and there were no bleeding episodes.

CONCLUSION

After a single-dose injection in healthy participants, anti-Xa activities of 2 formulations of LMWH enoxaparin were comparable. No significant difference was observed in the mean plasma aPTT. It remains to be seen whether the 2 formulations would show comparable clinical efficacy.