Enhanced thrombolytic effect induced by acoustic cavitation generated from nitrogen-doped annealed nanodiamond particles

In biomedical research, ultrasonic cavitation, especially inertial cavitation (IC) has attracted extensive attentions due to its ability to induce mechanical, chemical and thermal effects. Like ultrasound contrast agent (UCA) microbubbles or droplets, acoustic cavitation can be effectively triggered beyond a certain pressure threshold through the interaction between ultrasound and nucleation particles, leading to an enhanced thrombolytic effect. As a newly developed nanocarbon material, nitrogen-doped annealed nanodiamond (N-AND) has shown promising catalytic performance. To further explore its effects on ultrasonic cavitation, N-AND was synthesized at the temperature of 1000 °C. After systematic material characterization, the potential of N-AND to induce enhanced IC activity was assessed for the first time by using passive cavitation detection (PCD). Based on experiments performed at varied material suspension concentration and cycle number, N-AND demonstrated a strong capability to generate significant cavitation characteristics, indicating the formation of stable bubbles from the surface of the materials. Furthermore, N-AND was applied in the in vitro thrombolysis experiments to verify its contribution to ultrasound thrombolysis. The influence of surface hydrophobicity on the cavitation potentials of ND and N-AND was innovatively discussed in combination with the theory of mote-induced nucleation. It is found that the cavitation stability of N-AND was better than that of the commercial UCA microbubbles. This study would provide better understanding of the potential of novel carbonous nanomaterials as cavitation nuclei and is expected to provide guidance for their future biomedical and industrial applications.

Optimized acoustic streaming generated at oblique incident angles to improve ultrasound thrombolysis effect

BACKGROUND

Combined with thrombolytic drugs and/or microbubbles (MBs), ultrasound (US) has been regarded as a useful tool for thrombolysis treatment by taking its advantages of non-invasive, non-ionization, low cost and accurate targeting of tissues deep in body. Recently, low-intensity pulsed ultrasound (LIPUS), which can cause fewer complications by stable cavitation and acoustic streaming other than more violent effects, has attracted broad attention.

PURPOSE

However, the thrombolysis effect in practice might not achieve expectation because there is not an ideal parallel multilayer structure between the skin and the targeted vessel. Therefore, the current work aims to better elucidate the influence of US incident angle on the generation of acoustic streaming and thrombolysis effect.

METHODS

Systemic numerical and experimental studies, viz., finite element modeling (FEM), particle image velocimetry (PIV) and in vitro thrombolysis measurements, were performed to estimate the acoustical/streaming field pattern, maximum flow velocity and shear stress on the surface of thrombus, as well as the lysis rate generated at different conditions. These methods aim at verifying the hypothesis that streaming-induced vortices can further accelerate the dissolution of the thrombus and optimized thrombolysis effected can be achieved by adjusting US incident angles.

RESULTS

The pool data results showed that the variation trends of the flow velocity and shear stress obtained from FEM simulation and PIV experiments are qualitatively consistent with each other. There exists an optimal incident angle that can maximize the flow velocity and shear stress on the surface of thrombus, so that superior stirring and mixing effect can be generated. Furthermore, as the flow velocity and shear stress on thrombus surface are both highly correlated with the thrombolysis effect (the correlation coefficient R1 = 0.988, R2 = 0.958, respectively), the peak value of lysis rate (increase by at least 5.02%) also occurred at 10°.

CONCLUSIONS

The current results demonstrated that, with appropriately determined incident angle, higher thrombolysis rate could be achieved without increasing the driving pressure. It may shed the light on future US thrombolysis planning strategy that, if combined with other advanced technologies (e.g., machine-learning-based image analysis and image-guided adaptive US emission modulation), more efficient thrombolytic effect could be realized while minimizing undesired side-effects caused by excessively high pressure. This article is protected by copyright. All rights reserved.

Hereditary Thrombophilia in the Era of COVID-19

Thrombophilia, also called hypercoagulability or prothrombotic condition, usually reflects a certain imbalance that occurs either in the coagulation cascade or in the anticoagulation/fibrinolytic system. A similar imbalance may be induced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Thrombotic complications are associated with multiorgan failure and increased mortality. In this context, activation of coagulation and thrombocytopenia appeared as prognostic markers in COVID-19. Our work provides a structured and updated analysis of inherited thrombophilia and its involvement in COVID-19, emphasizing the importance of diagnosing and initiating thromboprophylaxis. Since the state of hypercoagulation is directly correlated with COVID-19, we consider that studies on the genetic profiles of proteins involved in thrombophilia in patients who have had COVID-19 and thrombotic events are of great importance, both in treating and in preventing deaths due to COVID-19.

Hereditary thrombophilia and thrombosis of tunneled hemodialysis catheters: A single center study

Introduction: Vascular access thrombosis increases the risk of mortality and morbidity in end-stage renal disease (ESRD) patients on hemodialysis (HD). This study aimed to evaluate hereditary thrombophilia factors in HD patients and its association with tunneled cuffed catheters’ thrombosis.

Methods: In this cross-sectional study, 60 consecutive patients with ESRD on HD with tunneled cuffed catheters were selected. Inherited thrombophilia factors (Anti-thrombin III, Protein C, Protein S, and Factor V Leiden) were measured and the patients were followed for 3 months to evaluate the incidence of catheter-related thrombosis. The association between these factors and catheter thrombosis was assessed.

Results: The mean age of patients was 60.30 ± 8.69 years. Forty-seven patients (78.30%) were female and thirteen patients (21.70%) were male. The most common cause of ESRD was diabetes mellitus (41.67%). The most catheter site was the right internal jugular vein (55%). There were 22 (36.67%) and 8 (13.33%) cases of thrombosis and mortality, respectively. The association between hereditary thrombophilia factors and catheter thrombosis was not statistically significant (P > 0.05).

Conclusion: In this small group of our patients, the frequency of hereditary thrombophilia was not significantly different between those with and without thrombosis of tunneled HD catheter.

ABO Blood Groups and Thrombophilia Markers in Patients With Unstimulated Thrombosis in Kurdistan Region of Iraq

Thromboembolism (TE) is a complex disease caused by various acquired and inherited factors. The common mutations; factor V Leiden G1691A (FVL G1691A), prothrombin G20210A (PTG20210A), and methylene tetrahydrofolate reductase C677T (MTHFR C677T) are important inherited causes in both venous and arterial thrombosis. The association between ABO blood groups and thrombophilia has been noted by researchers. We aimed to determine the frequency and association of ABO blood groups as a risk factor along with 3 thrombophilia mutations and another 3 thrombophilia markers in a group of patients with unstimulated thrombosis. In a prospective case-control study, we focused on 100 samples, 50 patients with documented thrombosis as well as 50 healthy age-matched controls. Multiplex polymerase chain reaction and reverse hybridization to oligonucleotide particular probes were employed to detect FVL G1691A, PT G20210A, and MTHFR C677T mutations. Analysis of other thrombophilia markers including protein C (PC), protein S (PS), and antithrombin (AT) assays was also performed. ABO blood group typing was done according to standard methods. Non-O blood group was significantly more frequent among cases than controls (76% vs 54%) with high odds of TE (odds ratio [OR] = 2.69). Positivity for at least 1 thrombophilia marker was more in cases (60%) than controls (34%; OR = 2.9). The combined effect of non-O blood group and thrombophilia markers raised the risk of TE (OR = 4.16, P = .001), particularly FVL (OR = 6.76). This study illustrates that harboring the non-O blood group poses an additive effect with other thrombophilia markers in the causation of TE.

The impact of physician education regarding the importance of providing complete clinical information on the request forms of thrombophilia-screen tests at Tygerberg hospital in South Africa

BACKGROUND

Thrombophilia-screen tests are specialised haemostasis tests that are affected by numerous unique patient variables including the presence of acute thrombosis, the concomitant use of medication and patient demographics. Complete information on the request form is therefore crucial for the haematological pathologist to make patient-specific interpretation of patients' results.

OBJECTIVES

To assess the completeness of thrombophilia-screen test request forms and determine the impact of provision of incomplete information, on the interpretive comments generated by reporting haematological pathologists. To assess the impact of an educational session given to clinicians on the importance of providing all the relevant information on the request forms.

METHOD

Two retrospective audits, each covering 3 months, were performed to evaluate the completeness of demographic and clinical information on thrombophilia-screen request forms and its impact on the quality of the interpretive comments before and after an educational intervention.

RESULTS

One hundred and seventy-one request forms were included in the first audit and 146 in the second audit. The first audit revealed that all 171 thrombophilia-screen request forms had complete patient demographic information but none had clinical information. Haematological pathologists only made generic comments which could not be applied to a specific patient. The second audit, conducted after a physician educational session, did not reveal any improvement in the clinical information provision by the test-ordering physicians. This was reportedly due to the lack of space on the request form. The interpretive comments therefore remained generic and not patient-specific.

CONCLUSION

Physicians' failure to provide relevant clinical information made it impossible for pathologists to make patient-specific interpretation of the results. A single physician education session did not change the practice, reportedly due to the inappropriate design of the test request form. Further studies are required to investigate the impact of an improved request form and the planned electronic test requesting.

Effect of poor glycaemic control on plasma levels and activity of protein C, protein S, and antithrombin III in type 2 diabetes mellitus

BACKGROUND

Type 2 diabetes mellitus (T2DM) patients are predisposed to several diabetes-related complications. Dysregulation of the haemostatic mechanisms have been implicated. There are however no current studies assessing the levels and activity of protein C (PC), protein S (PS), and antithrombin III (AT III), which are essential in haemostatic regulation, in a single cohort of T2DM patients. This study evaluated the effect of poorly-managed T2DM on the levels and activity of PC, PS, and AT III.

METHODS

This cross-sectional study was conducted at the Diabetes Clinic, Cocoa Clinic in Kumasi, Ghana. A total of 242 T2DM patients, comprising 152 patients with poorly-managed diabetes and 90 well-managed diabetes patients, were recruited for the study. Fasting blood glucose, liver function tests and lipid profile were performed for each respondent. Glycated haemoglobin (HbA1c) was estimated by turbidimetric inhibition immunoassay. The levels and activity of PC, PS and AT III were measured by solid phase sandwich ELISA method.

RESULTS

There was a negative correlation between HbA1c and the levels and activity of PC, PS and AT III. The levels and activity of PC [(5.78 vs 4.64 μg/ml, p<0.0001) and (42.22 vs 36.21 U/ml, p = 0.01) respectively], PS [(22.55 vs 20.29 μg/ml, p = 0.010) and (235.94 vs 211.67 U/ml, p<0.0001) respectively] and AT III [(16.28 vs 14.41μg/ml, p<0.0001) and (176.01 vs 160.09 U/ml, p = 0.03) respectively] were significantly increased in patients with well-managed T2DM compared to the poorly-managed diabetes patients. Likewise, the levels and activity of PC, PS, and AT III was higher among T2DM patients using statins than patients who were statin-naïve. Among patients with well-managed T2DM, those who were on statins had significantly higher levels and activities of PC, PS, and AT III compared to well-managed T2DM patients not on statins. However, there no statistically significant differences between the level and activity of PC, PS, and AT III among poorly-managed T2DM patients with respect to statin status.

CONCLUSION

Poorly-managed type 2 diabetes mellitus is associated with reduced levels and activity of PC, PS and AT III compared to well-managed T2DM. Though use of statins may improve the levels and activity of the PC, PS and AT III in T2DM, their effect is limited in the presence of poorly-controlled T2DM. Proper management of diabetes is essential to reduce the likelihood of thrombotic events among T2DM patients.

Update on Management of Portal Vein Thrombosis and the Role of Novel Anticoagulants

The clinical management of portal vein thrombosis (PVT) remains ambiguous due to its heterogeneous presentations and its associations with liver disease, malignancy, and hypercoagulable states. The natural history and clinical outcome of PVT are highly variable, dependent upon size, extent and degree of the thrombotic occlusion, as well as the physiological impact of patient comorbidities. While existing clinical guidelines consistently recommend low molecular weight heparin or vitamin K antagonist anticoagulation in cirrhotic patients with symptomatic acute PVT, management of asymptomatic and chronic PVT may need to be determined on a case-by-case basis, factoring in the state of underlying liver disease. In general, patients with PVT and underlying malignancy should be anticoagulated to alleviate symptoms and prevent recurrences that could disrupt the cancer management. However, existing clinical data does not support routine anticoagulation of cirrhotic patients with asymptomatic PVT in the absence of underlying cancer. While low molecular weight heparin and vitamin K antagonist remain the most commonly used agents in PVT, an emerging body of clinical evidence now suggests that direct-acting oral anticoagulants may be used safely and effectively in PVT. As such, direct-acting oral anticoagulants may offer a more convenient anticoagulation alternative for PVT management in future practice.

Hemostatic state augmented with platelet indices among Sudanese diabetic septic foot

Background

Diabetes mellitus is a very rampant metabolic disorder, particularly type II. It has many complications such as the septic foot. Diabetic septic foot (DSF) patients are at high risk for coagulation abnormalities as well as surgical hazards. Owing to the potential sequelae of coagulation and vascular abnormalities, this work aimed at studying the hemostatic state and platelet indices in diabetes type II patients with septic foot.

Methods

A case-control study was conducted during the period from July to September 2017 at Dr. Awaad medical center, Red Sea State, Sudan. 57 diabetic patients with septic foot, aged between 17 and 78 years along with 57 non-diabetic subjects as control were enrolled. Sociodemographic data were collected using a structured questionnaire. Venipuncture blood was taken with necessary safety measures. Diabetes profile, coagulation studies as well as platelet indices were estimated. Data was analyzed using SPSS version 24.0 for windows. Ethical approval was considered and written consent from each participant was obtained.

Results

The mean age of diabetic patients with septic foot and healthy controls were 48.49 ± 15.8 and 32.77 ± 14.0, respectively. The duration of the diabetes onset was 10.43 ± 9.5 years. Plasma prothrombin time (PT) value (12.61 ± 2.6 vs 13.67 ± 1.5, P < 0.009) was found to be significantly shorter in DSF compared to control. Plasma activated partial thromboplastin time (APTT) value was significant in diabetic septic foot (32.64 ± 5.2 vs 28.49 ± 4.13, P < 0.000), and thrombin time (TT) did not changed in DSF. Mean platelet volume (MPV), platelet distribution width (PDW), and platelet large cell ratio (P-LCR) values were significantly decreased in DSF compared to control (P < 0.013, 0.034, and 0.020, respectively). PDW values were positively correlated with PT, APTT, and D-Dimer (DD) (r = 0.28/p < 0.003, r = 0.29/p < 0.029, and r = 0.32/p < 0.016, respectively). FVIII activity (121.86 ± 174.4 vs 98.66 ± 31.83, P < 0.951) was insignificant with DSF, as the DD was also insignificant (P < 0.081).

Conclusion

Diabetes mellitus is associated with prothrombotic tendency. Hypercoagulable state in DSF is indicated by shortened PT finding. PDW is a manifesting evidence that proves the presence of more reactive and aggregable platelets in DSF patients.

Laboratory assessment of Activated Protein C Resistance/Factor V-Leiden and performance characteristics of a new quantitative assay

Activated Protein C Resistance is mainly associated to a factor V mutation (RQ506), which induces a deficient inactivation of activated factor V by activated protein C, and is associated to an increased risk of venous and arterial thrombosis in affected individuals, caused by the prolonged activated factor V survival. Its prevalence is mainly in Caucasians (about 5%), and this mutation is absent in Africans and Asians. Presence of Factor V-Leiden is usually evidenced with clotting methods, using a two-step APTT assay performed without or with APC: prolongation of blood coagulation time is decreased if this factor is present. The R506Q Factor V-Leiden mutation is now usually characterized using molecular biology, and this technique tends to become the first intention assay for characterization of patients. Both techniques are qualitative, and allow classifying tested individuals as heterozygotes or homozygotes for the mutation, when present. A new quantitative assay for Factor V-Leiden, using a one-step clotting method, has been developed, and designed with highly purified human coagulation proteins. Clotting is triggered with human Factor Xa, in presence of calcium and phospholipids (mixture which favours APC action over clotting process). Diluted tested plasma, is supplemented with a clotting mixture containing human fibrinogen, prothrombin, and protein S at a constant concentration. APC is added, and clotting is initiated with calcium. Calibration is performed with a pool of plasmas from patients carrying the R506Q Factor V mutation, and its mixtures with normal plasma. Homozygous patients have clotting times of about <40sec; heterozygous patients have clotting times of about 40-60sec and normal individuals yield clotting times >70sec. Factor V-Leiden concentration is usually >75% in homozygous patients, 30-60% in heterozygous patients and below 5% in normal. The assay is insensitive to clotting factor deficiencies (II, VII, VIII: C, IX, X), dicoumarol or heparin therapies, and has no interference with lupus anticoagulant (LA). This new assay for Factor V-Leiden can be easily used in any coagulation laboratory, is performed as a single test, and is quantitative. This assay has a high robustness, is accurate and presents a good intra- (<3%) and inter-assay (<5%) variability. It contributes solving most of the laboratory issues faced when testing factor V-Leiden. Quantitation of Factor V-L could contribute to a better assessment of thrombotic risk in affected patients, as this complication is first associated to and caused by the presence of a defined amount of FVa.

Coagulation factors, anticoagulant proteins, and plasminogen in Mexican older adults

INTRODUCTION

Hemostasis protects upon the occurrence of vascular endothelial damage, with involving of different factors. The interaction of these factors in older adults is poorly known, and has been associated with different disorders. Therefore, we determined the activity of coagulation factors (CF), anticoagulant proteins (AP), and plasminogen (Plg), as well as the frequency of deficiencies of these proteins in a population of healthy Mexican older adults (OA).

METHODS

CF (I, II, V, VII, VIII, IX, X, and XI y XII), AP [protein C (PC), protein S (PS), and antithrombin (AT)], and Plg were determined from 244 plasma samples of OA using commercial kits in a coagulometer ACL Elite Pro.

RESULTS

A total of 139 women and 105 men were under study. They were divided into age range groups (50-59, 60-69, 70-79, and ˃80 years). Activity of CF, AP, and Plg was determined. Frequencies of CF, AP, and Plg activity values were obtained for each age group according to gender. Differences were found between both frequencies for each protein.

CONCLUSION

Significant differences were found, so it is recommended to establish reference values (RV) for the activity of fibrinogen and FX by decade and gender, FVII and FXII by gender, FII, FV, FVIII, PC, PS, and Plg by decade, whereas for FIX, FXI, and AT, they are not modified by age or gender, so the RV described for adult Mexican population can be used. It is important to integrate these results into established diagnostic algorithms, which can be taken into account to provide an accurate diagnosis and treatment for patients with suspected hemorrhagic or thrombotic processes, as well as suggest those habits that improve their quality of life, to maintain optimal health and prevent thrombotic and hemorrhagic events.

Hypercoagulable States: A Review

Vascular surgeons are often asked to evaluate patients with recurrent thromboses or thromboses in unusual locations either arterial or venous. There may be obvious inciting factors, but in many of these patients the possibility of a previously undiagnosed hypercoagulable state must be considered. Hypercoagulable states can be acquired (smoking, medication, change in physiologic status as occurs with pregnancy) or congenital. Congenital hypercoagulable disorders are more prevalent in families or patients with a history of thromboembolic events early in life or multiple miscarriages and include conditions such as protein C or S deficiencies, factor V Leiden mutation, and prothrombin gene variant. This article reviews the hypercoagulable states that are encountered in clinical practice as well as guidelines for testing and goals of therapy.

Association Between Thrombophilic Gene Mutations and the Risk of Vascular Access Thrombosis in Hemodialysis Patients

The cause of thrombosis in hemodialysis vascular access is considered to be of a multifactorial nature, including stenosis of the venous or arterial connection. Therefore, identification of relevant thrombotic risk factors could lead to an improved antithrombotic therapy. This case control study was performed to evaluate the relationship between Factor V (G1691A and A4070G) and Factor II polymorphisms and vascular access thrombosis in hemodialysis patients. One hundred and twenty-one patients undergoing dialysis were selected as subjects. This sample was divided into two groups; a case group of 60 patients who had sustained one or more thrombotic events that resulted in vascular access failure and a control group of 61 patients, who never had a thrombotic occlusion of a functioning permanent dialysis access. Our data demonstrated a significantly increased risk of vascular access thrombosis in carriers of the mutant FV (G1691A and A4070G) polymorphisms (P < 0.05).Further studies on a large-scale population and other genetic variants will be needed to find candidate genes for vascular access thrombosis in hemodialysis patients.

Cooperation experience in a multicentre study to define the upper limits in a normal population for the diagnostic assessment of the functional lupus anticoagulant assays

BACKGROUND

Phospholipid-dependent coagulation tests for lupus anticoagulant (LA) are considered an important step for the diagnosis of anti-phospholipid syndrome; however, LA laboratory detection is difficult because of many variables. Five hospital laboratories, located in a North-Italy area and using the same method for LA testing, cooperated to standardise sample treatment and analytical procedure in order to define the upper values for LA negativity.

METHODS

In total, 200 normal subjects (40 for each centre) were studied for six LA functional assays, using the same procedure, reagent lot and analyser type. The first tests done were LA screen and LA confirm assays, based on diluted Russell's Viper Venom Time, with low and high phospholipid content, respectively. The second tests performed were silica clotting time screen and confirm assays, based on activated partial thromboplastin time, with low and high phospholipid content, respectively. Finally, two mixing assays were executed for both screening assays, diluting patient sample with a pool prepared with plasma collected from the study population.

RESULTS

Data analysis demonstrated a difference between centres for all assays when results were expressed in seconds; the difference disappeared when results are normalised with the local mean normal value of each centre and are expressed as a normalised ratio. The study population was normally distributed; so the value corresponding to 99th percentile was used as limit value for LA negativity. Values expressed as normalised ratio, for LA and silica clotting time screenings were 1.22 and 1.23, respectively.

CONCLUSIONS

The study allowed us to define a uniform approach to LA testing and evaluation for laboratories employing the same methods.

Evaluation of the GeneXpert assay in the detection of Factor V Leiden and prothrombin 20210 in stored, previously classified samples

BACKGROUND

In this study, we evaluated the GeneXpert HemosIL Factor II and Factor V assay, an innovative assay for the detection of Factor V Leiden (FVL) and prothrombin G20210A mutation (GPRO).

PATIENTS AND METHODS

We evaluated 132 patients that were previously classified (with a concordant result) using two commercial real-time PCR assays supplied, by Applied Biosystems and Roche Molecular Biochemicals. The cohort comprised 75 normal subjects, 10 FVL homozygous, 35 FVL heterozygous, 7 GPRO heterozygous, 2 GPRO homozygous and 3 double heterozygous FVL and GPRO subjects. All of the samples were evaluated using the GeneXpert HemosIL Factor II and Factor V assay.

RESULTS

All of the samples were correctly identified using the GeneXpert HemosIL Factor II and Factor V assay; therefore, in this patient series, the specificity and sensitivity of the test under evaluation was 1.00.

DISCUSSION

We have shown that the GeneXpert HemosIL Factor II and Factor V assay, a rapid fully automated assay, can accurately characterise the presence of FV G1691A and FII G20210A polymorphisms with specificity and sensitivity that are comparable to other current real-time PCR-based methods. The theoretical advantages of such an assay include improved standardisation across varying healthcare environments, more thorough sample manipulation and reduced human error.

Isquemia grave de membros inferiores por arterite por HIV

A isquemia aguda de membros pode se manifestar, embora de forma incomum, como consequência à vasculite associada ao vírus da imunodeficiência humana (HIV). O presente caso descreve a evolução de uma paciente soropositiva para o HIV, que apresentou quadro de isquemia distal bilateral, com diminuição da temperatura de terço distal das pernas e pés, dor intensa, cianose fixa de pododátilos e ausência de pulsos distais. Submetida ao tratamento com terapia trombolítica, apresentou sinais de lesões decorrentes da isquemia e lesão tecidual de reperfusão com perda tecidual em regiões distais dos dedos, porém com melhora dos sinais e sintomas dos membros inferiores. Trata-se de um caso raro na literatura em função da associação da vasculite com o HIV e do acometimento dos vasos distais nos membros inferiores. Entretanto, o conhecimento desta associação é de extrema importância devido à repercussão na vida dos pacientes acometidos.

Analysis of polymorphisms Leiden Factor V G1691A and prothrombin G20210A as risk factors for acute myocardial infarction

Thrombotic risk increases in elderly, therefore, the understanding of the genetic predisposition of hypercoagulability could make the difference in the prevention of venous and/or arterial thrombotic events. Laboratory evaluation of hyperfibrinogenemia, increased Factor VII levels, antiphospholipid antibodies presence and hyperhomocysteinemia are considered to have a consistent high predictivity for arterial thrombophilic diseases. Anyway, a large debate exists on the validity of testing Leiden Factor V (FV) G1691A and/or prothrombin (FII) G20210A polymorphisms in patients affected by arterial thrombotic diseases, despite of the several observations described. Here we report data strongly suggesting that at least the FII G20210A polymorphism might be considered an important risk factor for acute myocardial infarction in aged patients (55-80 years old). On the other hand, in spite of a not different genotypic and allelic distribution for the Leiden FV G1691A mutation, the presence of one or both the two polymorphisms is significantly higher among cases than in controls. In conclusion, our data suggest that FII G20210A and/or Leiden FV might be involved as risk factor for arterial disorders in about 5% of old subjects, justifying the opportunity of a genetic screening and an eventual preventive treatment, in particular in old subjects in which other and major risk factors, as hypertension and atherosclerosis, are detected.

Role of investigating thrombophilic disorders in young stroke

Our knowledge about various inherited and acquired causes of thrombophilic disorders has increased significantly during the past decade. Technology for various diagnostic tests for these rare disorders has matched the rapid advances in our understanding about the thrombophilic disorders. Inherited thrombophilic disorders predispose young patients for various venous or arterial thrombotic and thromboembolic episodes. Our understanding has also improved about various gene-gene and gene-environment interactions and their impact on the resultant heterogenous clinical manifestations. We describe various thrombophilic disorders, their diagnostic tests, pathogenic potential in isolation or with other concurrent inherited/acquired defects and possible therapeutic and prophylactic strategies. Better understanding, optimal diagnostic and screening protocols are expected to improve the diagnostic yield and help to reduce morbidity, disability, and mortality in relatively younger patients harbouring these inherited and acquired thrombophilic disorders.

Hyperhomocysteinemia and thrombophilia

It is now widely accepted that hyperhomocysteinemia (HHC) is a risk factor for thrombophilia. HHC is the result of either impaired enzyme function or a deficiency of vitamin B (folate, B₆, B₁₂), or both, and can be treated with vitamin supplements. Measuring plasma total homocysteine (tHcy) is included in the routine thrombophilia panel in many laboratories, despite having a limited value to the clinician. Many methods are available for tHcy measurements. High-pressure liquid chromatography (HPLC) with fluorescence detection is a widely used method, but is being replaced by more convenient immuno- or enzyme assays. In this paper a general overview on homocysteine is given, with an emphasis on laboratory methods.

Diagnostic algorithm for thrombophilia screening

Thrombophilia screening is aimed at detecting the most frequent and well-defined causes of venous thrombosis, such as activated protein C resistance/factor V Leiden mutation, prothrombin G20210A gene mutation, deficiencies of natural anticoagulants, such as antithrombin, protein C and protein S, the presence of antiphospholipid antibodies, hyperhomocysteinemia and increased factor VIII activity. At this time, thrombophilia screening is not recommended for those possible congenital or acquired risk factors, whose association with increased risk of thrombosis has not been proven sufficiently. Laboratory investigations should include a step-wise approach to the diagnosis of thrombotic disorders with respect to the assays and methods of analysis that are used. The assays recommended for the first diagnostic step of screening should establish, whether the subject has one of the common causes of thrombophilia. If one or more abnormal results are obtained, the second diagnostic step includes the assays recommended for confirmation and/or characterization of the defect. When performing the investigation of thrombophilia, it is important to consider all pre-analytical and other variables that may affect the results of thrombophilia testing, including time of testing, age, gender, liver function, hormonal status, pregnancy or the acute phase response to inflammatory diseases. This is necessary, in order to avoid, any misinterpretation of the results. This review summarizes the current knowledge concerning thrombophilia investigations, with special focus on the diagnostic algorithm regarding patient selection, the assays and methods of analysis used and all the variables that should be considered when employing tests for the diagnosis of thrombophilia.

Thrombophilia screening--at the right time, for the right patient, with a good reason

Thrombophilia can be identified in about half of all patients presenting with venous thromboembolism (VTE). Thrombophilia screening for various indications has increased tremendously, but whether the results of such tests help in the clinical management of patients is uncertain. Here, current recommendations for thrombophilia screening in selected groups of patients, and considerations whether other high-risk subjects should be tested are reviewed. The methods for determination of the most common thrombophilic defects (antithrombin, protein C, protein S deficiencies, Factor V Leiden and prothrombin G20210A) associated with strong to moderate risk of VTE are described, indicating the timing and location of thrombophilia screening. Circumstances when a positive result of thrombophilia screening helps clinicians decide if adjustments of the anticoagulant regime are needed are discussed. Finally, psychological, social and ethical dilemmas associated with thrombophilia screening are indicated.

Analysis of thromboembolic risk related to high-dose intravenous immunoglobulin treatment: a preliminary clinical study of 10 patients with autoimmune mucocutaneous blistering diseases

BACKGROUND

Intravenous immunoglobulin (IVIg) treatment is a well-known treatment that has been used successfully in a broad spectrum of autoimmune diseases. Currently no data are available in the literature about the role of IVIg in the pathogenesis of thromboembolic events in patients with autoimmune blistering diseases refractory to conventional immunosuppressive treatment.

AIM

To determine the relationship between IVIg and thromboembolism in patients with autoimmune blistering diseases and to establish a protocol to deal with the thromboembolic risk.

METHODS

In our preliminary clinical study, 10 patients with autoimmune blistering diseases underwent IVIg cycles to a total of 133 cycles in all (total number of infusions in the patient group: 399), at a standard dose of 2 g/kg/infusion accompanied by an accurate and a complete clinical and laboratory screening for thromboembolism. Preventive measures, such as hydration before and after IVIg, and administration of 100 mg of acetyl salicylic acid (aspirin) or 1000 IU of subcutaneous heparin calcium per day for 3 weeks, were introduced to reduce the thromboembolic risk.

RESULTS

Throughout the 2 years of IVIg treatment, no patient developed a superficial and/or deep venous or arterial thrombosis, even though some of the patients had underlying thromboembolic risk factors and had tested positive for some congenital and acquired thrombophilia markers.

CONCLUSIONS

Our results indicate that thromboembolic events are uncommon, despite the presence of risk factors. However, as these disorders are very rare and the percentage of nonresponder patients is very low, further investigations are needed to better understand whether IVIg alone is able to trigger these fatal events in blistering disorders.

Ewing's sarcoma of the fibula presenting with venous thrombosis

Malignancies account for about 20% of incidentally diagnosed venous thromboembolism. Surgery- or chemotherapy-induced risk of thrombosis is also high in patients with cancer. We report on a young male with skeletal Ewing's sarcoma who presented with deep vein thrombosis in the affected limb, which is quite a rare clinical condition. Venous thrombosis of the lower extremities in young patients should prompt the clinician to search for underlying local malignancies.

Inherited Thrombophilia

Inherited thrombophilia can be defined as a genetically determined predisposition to the development of thromboembolic complications. Since the discovery of activated protein C resistance in 1993, several additional disorders have been described and, at present, it is possible to identify an inherited predisposition in about 60 to 70% of patients with such complications. These inherited prothrombotic risk factors include qualitative or quantitative defects of coagulation factor inhibitors, increased levels or function of coagulation factors, defects of the fibrinolytic system, altered platelet function, and hyperhomocysteinemia. In this review, the main inherited prothrombotic risk factors are analyzed from epidemiological, laboratory, clinical, and therapeutic points of view. Finally, we discuss the synergism between genetic and acquired prothrombotic risk factors in particular conditions such as childhood and pregnancy.

The risk of first venous thromboembolism during pregnancy and puerperium in double heterozygotes for factor V Leiden and prothrombin G20210A

BACKGROUND

The risk of venous thromboembolism (VTE) during pregnancy in double heterozygous carriers of factor (F) V Leiden and prothrombin G20210A is not established. Hence, whether or not these women deserve antithrombotic prophylaxis when pregnant is unknown.

PATIENTS AND METHODS

In the frame of a multicenter family study, 52 double heterozygous carriers of FV Leiden and prothrombin G20210A who had remained pregnant at least once before knowledge of thrombophilia, were retrospectively investigated with respect to the occurrence of first VTE during pregnancy and puerperium. They were compared with 104 heterozygous carriers of FV Leiden, 104 of prothrombin G20210A and 104 women without thrombophilia.

RESULTS

Double heterozygotes were similar to single heterozygous carriers and non-carriers for the age at first pregnancy, age at testing and rate of full-term pregnancies. No VTE during pregnancy was observed in the four groups of women, whereas in the puerperium it occurred in two double carriers (1.8% of pregnancies, 95% CI: 0.5-6.3), three single FV Leiden carriers (1.5%, 0.5-4.3), two single prothrombin G20210A carriers (1%, 0.2-3.6) and one non-carrier (0.4%, 0-2.5).

CONCLUSIONS

The risk of first VTE during pregnancy and puerperium in double heterozygous carriers of FV Leiden and prothrombin G20210A is low and similar to that of single carriers. As for single heterozygotes, antithrombotic prophylaxis in asymptomatic double heterozygous carriers appears to be justified only in puerperium.

Clinical evaluation of a functional prothrombin time-based assay for identification of factor V Leiden carriers in a group of Italian patients with venous thrombosis

The efficiency of a new prothrombin-based activated protein C (APC) resistance test to detect factor V Leiden (FVL) was clinically evaluated in 150 Italian patients with deep venous thrombosis. Patient samples are diluted in factor-V-deficient plasma, an APC-containing reagent, and specific factor V activator; after incubation, clotting is initiated by addition of activated-factor-FV-dependent prothrombin activator. Two prothrombin time determinations were performed under identical assay conditions except that no APC was added to one. A ratio over 4.2 for normal individuals and under 2.0 for FVL patients is expected: between 1.3 and 1.9 for FVL heterozygotes, and between 1.0 and 1.1 for FVL homozygotes. Using a predefined cut-off ratio of 2.0, a specificity and a sensitivity of 1.00 for detection of FVL mutation were found. With a cut-off ratio of 1.1, a specificity of 0.98 and a sensitivity of 1.00 were found for discrimination between FVL heterozygous (n = 60) and homozygous (n = 6). No interferences by heparins, oral contraceptives, oral anticoagulant therapy, protein C, protein S, D-dimer, homocysteine, MTHFR mutations and antiphospholipid autoantibodies were detected. In our experience, this new prothrombin time-based APC resistance assay provides improved discrimination between normal individuals and FVL carriers compared with the classical methods. Moreover, this new assay allows good discrimination between homozygous and heterozygous FVL carriers. In the authors' experience this prothrombin time-based method was not influenced by many factors compared with the classical activated partial thromboplastin time-based method.

Increase of classic and nonclassic cardiovascular risk factors in patients with acromegaly

OBJECTIVE

To evaluate the prevalence of classic and nonclassic cardiovascular risk factors in patients with acromegaly.

METHODS

Sixty-two patients with acromegaly (50 with active disease and 12 with controlled acromegaly) and 36 healthy persons (the control group) underwent measurement of lipids, fasting plasma glucose, homeostasis model assessment of insulin resistance (HOMA-IR) index, Lp(a), high-sensitivity C-reactive protein (hsCRP), homocysteine, and variables primarily related to thrombogenesis (fibrinogen, antithrombin III, protein C, and protein S).

RESULTS

In comparison with control subjects, patients with active acromegaly had significantly higher mean values of fasting plasma glucose, total cholesterol, low-density lipoprotein cholesterol, very-low-density lipoprotein (VLDL) cholesterol, triglycerides, Lp(a), HOMA-IR, and fibrinogen as well as lower mean levels of high-density lipoprotein cholesterol and protein S. In both groups, homocysteine, antithrombin III, protein C, and hsCRP levels were similar. Moreover, patients with active acromegaly, in comparison with those who had controlled acromegaly, presented with significantly higher values of fasting plasma glucose, HOMA-IR, triglycerides, VLDL cholesterol, Lp(a), and fibrinogen, whereas hsCRP and protein S were significantly lower. Finally, low levels of high-density lipoprotein cholesterol and protein S as well as elevated values of VLDL cholesterol, triglycerides, HOMA-IR, and fasting plasma glucose were more prevalent in patients with active acromegaly than in the other groups.

CONCLUSION

Our findings demonstrate that, in comparison with control subjects and patients with controlled acromegaly, patients with active acromegaly had a higher frequency of classic and nonclassic cardiovascular risk factors. These findings are potentially very important because acromegaly is associated with a 2- to 3-fold increase in mortality rate, predominantly related to cardiovascular disease.

Interference of factor V Leiden on protein S activity: evaluation of a new prothrombin time-based assay

Protein S activity in plasma from factor V Leiden (FVL)-positive patients may be lower than expected. We investigated a new commercially available method for protein S for such interference. Protein S activity was measured for plasmas from 50 individuals with FVL and their results were compared with those obtained for plasmas from 47 sex-matched and age-matched individuals without FVL. We assumed that the median protein S activity value from a relatively large number of individuals with or without FVL would not be significantly different if there is no influence from FVL. The FVL-positive plasmas gave relatively (albeit not significantly) lower protein S levels than FVL-negative plasmas when both were tested undiluted (86 versus 93 IU/dl, P = 0.06). Those differences were reduced (98 versus 102 IU/dl, P = 0.58) when testing was performed on diluted plasmas. Furthermore, the proportion of patients with FVL identified as low-abnormal on the basis of the specific cut-off values (undiluted = 64 U/dl; diluted = 71 IU/dl), which was 8% when testing was performed on undiluted plasmas, was reduced to 4% when testing was performed on diluted plasmas. Conversely, the corresponding proportions of patients without FVL remained unaltered (4.3 versus 4%). In conclusion, these results indicate that the evaluated method is somewhat affected by FVL and that dilution of plasma prior to testing improves specificity. Protein S activity measurement for FVL-positive patients should be performed on diluted plasma and the results interpreted on the basis of the cut-off value specifically determined for diluted plasmas.

Factor V Leiden, prothrombin G20210A substitution and hormone therapy: indications for molecular screening

Venous thromboembolism is a well-known complication of oral contraception and hormonal replacement therapy. Inherited thrombophilia is viewed as an important determinant in modulating the effects of estrogens on thrombotic risk. An increasing number of kits for thrombophilic mutations [factor V Leiden, G20210A prothrombin and methylenetetrahydrofolate reductase (MTHFR) C677T genes] are becoming commercially available, and screening for inherited thrombotic risk is among the most requested genetic tests in molecular diagnostic laboratories. However, the question of routine genetic screening for thrombophilia before prescribing hormones is still a matter of debate. The purpose of this article is to discuss the usefulness and practical applications of thrombotic genetic testing to identify which women should be tested to improve both the safety and efficacy of individualized estrogen therapy.

Hypercoagulability markers in young asymptomatic heterozygous carriers of factor V Leiden (G1691A) or prothrombin (G20210A) variant

BACKGROUND

Mutations in factor V (factor V Leiden-G1691A) and prothrombin (G20210A) genes are important risk factors for thrombophilia due to their high incidence in patients with thromboembolic events, especially among the young. However, it is not clear if levels of hypercoagulability markers are significantly altered in asymptomatic young carriers of factor V Leiden or prothrombin G20210A.

METHODS

Hemostatic status of 32 asymptomatic young individuals carrying these mutations and of 18 normal control individuals was investigated through the determination of plasma thrombomodulin (TM), prothrombin fragment 1+2 (F1+2), thrombin-antithrombin complex (TAT) and D-dimer.

RESULTS

No significant differences were observed in these hemostatic markers when comparing groups of individuals carrying mutations and the control group.

CONCLUSION

Analysis of these results leads to the conclusion that the presence of these mutations, in the absence of acquired risk factors, does not constantly predispose these young carriers to a state of hypercoagulability.

Genomic medicine and thrombotic risk: Who, when, how and why?

Major advances in Human Genome research could significantly change the clinical medical practice, providing new possibilities for both diagnosing and treating common pathologies. Many genetic tests are now commercially available for predicting future risk of common disorders. However, genetic testing has potential benefits but also limitations for the patients, and it should not be used to 'screen' the general population. Diagnostic assays for a predisposition of both venous and arterial thrombosis are among the most requested genetic tests in molecular diagnostics laboratories. However, there is considerable uncertainty as to how this information should be utilized in patient management. Both the medical community and the patients need to obtain accurate information concerning the appropriate use of genetic testing. The purpose of this article is to discuss the usefulness and the practical applications of thrombotic genetic testing in order to define which patients should be tested for both venous and arterial thrombotic risk as well as to have an acceptable cost/benefit ratio and to prevent patients' anxiety.

Parent-of-origin transmission of thrombophilic alleles to intrauterine growth-restricted newborns and transmission-ratio distortion in unaffected newborns

Findings on the role of thrombophilic polymorphisms in adverse pregnancy outcomes, particularly intrauterine growth restriction, are inconsistent. Such inconsistencies may be partly due to two types of effects which have not been considered before with regard to thrombophilic genes: parent-of-origin effects (imprinting) and transmission-ratio distortion effects (allele transmission differing from that expected in unaffected subjects). In this study of infants born at a Canadian hospital (1998-2000), the authors investigated both types of effects. Cases (n = 493) were defined as newborns whose birth weight for gestational age and sex was below the 10th percentile by national standards, and controls (n = 472) as newborns at or above the 10th percentile. Log-linear models were used to analyze the transmission of variant alleles among case- and control-parent trios. A single copy of a common polymorphism, Val34Leu in factor XIII, increased the risk of intrauterine growth restriction approximately 70% when the parent of origin was the father as opposed to the mother (p < 0.05). Among unaffected newborns, transmission of A1298C in the methylenetetrahydrofolate reductase gene (p < 0.005), transmission of the G1691A variant in factor V Leiden (p < 0.002), and transmission of the G20210A variant in the prothrombin (factor II) gene (p < 0.001) occurred significantly less often than expected (transmission-ratio distortion). Affected newborns also inherited the prothrombin G20210A variant significantly less often than expected. These results suggest that these three genes exhibit segregation distortion or reduce gestational survival.

Hypercoagulable states and stroke: a selective review

Blood disorders have been implicated in approximately 5% to 10% of ischemic stroke, with an increased frequency in younger patients. Most disorders are associated with an increased thrombotic tendency and, therefore, an increased risk of ischemic stroke. Less commonly, a bleeding diathesis may predispose a patient to intracranial hemorrhage. While many conditions predisposing to thrombosis have been associated with stroke, there are relatively few prospective, epidemiological studies addressing hypercoagulable states and arterial stroke compared with the number of studies on the genetic thrombophilias, which are predominantly associated with venous thrombosis. When ordering tests of coagulation in stroke patients, one should keep in mind whether the results will influence therapy and/or patient outcome. It is generally not advocated to screen all stroke patients for a "hypercoagulable workup". Typically, patients to be screened for coagulation defects will have a prior history of one or more unexplained thromboembolic events. The yield for diagnosing a hypercoagulable state is typically greatest for young stroke patients or those with a family history of thrombosis and who have no other explanations for their stroke (cryptogenic stroke). The yield in typically low in unselected ischemic stroke patients and older patients. Treatment of a first stroke with a documented hypercoagulable state is typically long-term or indefinite duration warfarin, although there is a paucity of clinical trial data supporting this clinical approach.

Thrombophilic Polymorphisms and Intrauterine Growth Restriction

BACKGROUND

The relationship between thrombophilic polymorphisms and intrauterine growth restriction remains unclear. Whereas a subset of these polymorphisms have received some attention, others have not.

METHODS

We conducted a case-control study of 493 cases of intrauterine growth restriction (birthweight less than the 10th percentile for gestational age and sex) and 472 controls (greater than the 10th percentile). We also conducted a family study including approximately 250 case trios (affected newborn, mother, and father) for each studied gene. Plasminogen activator inhibitor-1(PAI-1) 4G/5G and Factor XIII Val134Leu variants were compared between maternal and newborn cases and controls. Relative risks for newborn and maternal PAI-1 and Factor XIII genotypes in case trios were estimated using a log-linear model. Transmission of MTHFR C677T and 1298C haplotypes was analyzed in case trios, and the estimated haplotype distribution compared between cases and controls. Finally, we explored pairwise gene-gene interactions between all measured polymorphisms, including Factor V Leiden G1691A and Prothrombin G20210A.

RESULTS

PAI-1 and Factor XIII polymorphisms were not associated with an increased risk of intrauterine growth restriction in the case-control analysis, and the case-parent analysis showed no newborn or maternal excess genotype relative risk. No excess transmission of the MTHFR haplotypes was observed in case newborns, and the distribution of MTHFR haplotypes was similar between cases and controls. Some results were suggestive of interactions between genes.

CONCLUSIONS

Overall, there seems to be little or no indication that thrombophilic genes, at least individually, have an effect on intrauterine growth restriction.

Thrombophilia in children with cystic fibrosis

In some children with cystic fibrosis (CF), percutaneous long lines occlude sooner than expected (due to thrombophlebitis or thrombosis), and many have a totally implantable venous access device (TIVAD), a recognized complication of which is thrombosis. This complication is more likely if the child has an underlying thrombotic tendency, which may be enhanced in the presence of inflammatory lung disease. There are no reports of an identified association of heritable thrombophilia with CF, although individual cases have been recognized. Our aim was to determine the incidence of thrombophilia in children with CF. In a tertiary pediatric CF center, blood was screened for thrombophilia at annual review, and retested if abnormal. A thrombotic abnormality was found in 41/204 (20%) patients. These included activated protein C resistance (10/204, 5%) with a prevalence similar to that expected, but the following abnormalities had an increased prevalence: antithrombin deficiency (2/204, 1%), protein S deficiency (11/204, 5%), protein C deficiency (8/204, 4%), and lupus anticoagulant (18/204, 9%). There were no differences found in those with thrombophilia for the following parameters: age, gender, genotype, lung function, presence of Pseudomonas aeruginosa, prothrombin time, serum IgE, aspergillus-specific IgE, liver function, and blood inflammatory markers. Fifteen children had TIVADs, 4 of whom had evidence of thrombophilia. In conclusion, a significant proportion of patients had a thrombophilic abnormality. We recommend that thrombophilia screening be performed prior to insertion of a TIVAD, and also in those with a history of venous thrombosis, blocked TIVADs, or recurring problems with long lines.