Antithrombin Cambridge II (A384S): an underestimated genetic risk factor for venous thrombosis

The antithrombin A384S mutation has a relatively high frequency in the British population but has not been identified in other populations. This variant has been associated with cases of thrombotic disease, but its clinical relevance in venous thrombosis remained unclear. We have conducted a secondary analysis of the prevalence of the mutation in a large case-control study, including 1018 consecutive Spanish patients with venous thromboembolism. In addition, we evaluated its functional consequences in 20 carriers (4 homozygous). This mutation, even in the homozygous state, did not affect anti-Xa activity or antigen levels, and it only slightly impaired anti-IIa activity. Thus, routine clinical methods cannot detect this anomaly, and, accordingly, this alteration could have been underestimated. We identified this mutation in 0.2% of Spanish controls. Among patients, this variant represented the first cause of antithrombin anomalies. Indeed, 1.7% patients carried the A384S mutation, but 0.6% had any other antithrombin deficiency. The mutated allele was associated with an increased risk of venous thrombosis with an adjusted OR of 9.75 (95% CI, 2.2-42.5). This is the first study supporting that antithrombin A384S mutation is a prevalent genetic risk factor for venous thrombosis and is the most frequent cause of antithrombin deficiency in white populations.     

Antithrombin Vicenza, Ala 384 to Pro (GCA to CCA) mutation, transforming the inhibitor into a substrate

Antithrombin (AT) Vicenza has been previously identified as a functionally abnormal antithrombin associated with familial thrombosis (Finazzi et al, 1985). It binds normally to heparin, but loses its affinity following interaction with thrombin: it is a poor inhibitor of thrombin. AT Vicenza was isolated from plasma by heparin-Sepharose and thrombin-Sepharose chromatography, fragmented with cyanogen bromide (CNBr) and its tryptic peptides were analysed by fast atom bombardment mass spectrometry mapping. An abnormal peptide mass 1112 was identified. Edman degradation confirmed a substitution of Ala to Pro in the sequence Ala 383-Arg 393. Polymerase chain reaction amplification of exon 6 of the gene followed by genomic sequencing, localized the mutation to codon 384, GCA to CCA. The same mutation has recently been reported in AT Charleville (Mohlo-Sabatier et al, 1989). Sodium dodecyl-sulphate polyacrylamide gel electrophoresis of AT Vicenza (/Charleville) under non-reducing conditions revealed an apparent increase in mol. wt following interaction with thrombin: under reducing conditions the mol. wt was less than that of normal AT. This indicated cleavage and unfolding of the molecule. The site of cleavage was determined by incubation of AT Vicenza (/Charleville) with thrombin-Sepharose, reduction and S-carboxymethylation and reverse phase FPLC. A peptide was identified with the NH2-terminal sequence beginning Ser-Leu-Asn, demonstrating the cleavage had occurred at the reactive site of the variant. It is concluded that the Ala 384 to Pro substitution transforms AT Vicenza (/Charleville) from an inhibitor into a substrate.     

Thrombosis and hemorrhage in the critically ill cirrhotic patients: five years retrospective prevalence study

Background. Cirrhotic patients present a complex interaction between deficient synthetic liver function, hemodynamic abnormalities and superimposed conditions that alter coagulation system. This alters both coagulation and fibrinolytic processes,increasing bleeding and thrombosis risks. Particularly, critically ill cirrhotic patients represent a diagnostic challenge since they have multiple comorbidities making the thrombotic and bleeding risks unpredictable. The prevalence of bleeding and thrombosis in this subset of patients remains poorly described. The main aim of this article is to describe the prevalence of thrombotic and hemorrhagic complications in cirrhotic patients admitted between 2007 and 2012 at Médica Sur Clinic and Foundation ICU.Material and methods. We performed a five years retrospective study including every cirrhotic patient admitted to ICU between January 2007 and December 2012.Results. The incidence of hemorrhage was 48.5%, the overall incidence of thrombotic complications was 13.66%. Variceal bleeding was the most prevalent hemorrhagic event and portal vein thrombosis the most common thrombotic event. Factors associated with presenting a bleeding episode included kidney injury, infection an thrombosis. Factors associated with increased thrombotic risk included ascitis,infection and bleeding.Conclusion. Critically ill cirrhotic patients have an high risk for both thrombotic and bleeding episodes. The association between the presence of bleeding and thrombotic events was statistically significant.     

A Simple Two-step Isolation Procedure for Human and Bovine Antithrombin II/III (Heparin Cofactor): a Comparison of Two Methods

Human and bovine antithrombin II/III have been isolated by a simple procedure essentially using only affinity chromatography on heparin-agarose and polyethylene glycol precipitation. An additional ammonium sulphate step removes polyethylene glycol and trace contaminants. The final preparation is homogeneous by SDS-, disc- and agar slide electrophoresis. End group analysis of human antithrombin II/III shows histidine as the N-terminal amino acid. The pure preparation showed both progressive antithrombin activity and heparin cofactor activity.     

The DYSlipidemia International Study (DYSIS)-Egypt: A report on the prevalence of lipid abnormalities in Egyptian patients on chronic statin treatment

Introduction and objectivesCardiovascular disease and its associated comorbidities, including diabetes mellitus, obesity and dyslipidemia, represent a significant socioeconomic burden, particularly in low- to middle-income countries. Pharmacological intervention with statins, which reduce low-density lipoprotein–cholesterol levels, has been demonstrated to reduce cardiovascular risk. This study assessed the prevalence of lipid abnormalities as well as risk factors for dyslipidemia in Egyptian patients on chronic statin treatment.MethodsDYSIS is a cross-sectional, observational, multinational study. Key eligibility criteria were age of at least 45 years and stable statin treatment for at least three months. In the Egyptian DYSIS cohort, a total of 1466 patients, 920 men and 532 women, were enrolled in 24 different centers. Patient characteristics and lipid measurements were documented, and multivariate regression modeling was used to assess factors associated with dyslipidemia.ResultsMost patients (85%) were defined as being at very-high risk of cardiovascular disease. Gender-specific differences included higher rates of tobacco smoking and metabolic syndrome in men and women, respectively. Goal LDL–C levels were not achieved by 67.2% of the population, rising to 72% in both high- and very-high risk patients. Factors independently associated with LDL–C levels not being at goal included diabetes mellitus, ischemic heart disease, and high blood pressure.ConclusionsDespite chronic statin treatment, two-thirds of patients in the DYSIS-Egypt study had elevated LDL–C levels. A dual strategy, comprising modification of lifestyle factors together with novel treatment options, appears to be necessary to combat the rise in cardiovascular-related morbidity and mortality.     

An alarmingly high prevalence of diabetic nephropathy in Asian type 2 diabetic patients: the MicroAlbuminuria Prevalence (MAP) Study

Aim/hypothesis Microalbuminuria represents the earliest clinical evidence of diabetic nephropathy and is a marker of increased cardiovascular morbidity and mortality. Its early detection allows the implementation of individualised and aggressive intervention programmes to reduce cardiovascular risk factors. There is limited information on the prevalence of microalbuminuria among hypertensive type 2 diabetic patients in Asia.Methods This cross-sectional epidemiological study aimed to assess the prevalence of microalbuminuria and macroalbuminuria among consecutively screened hypertensive type 2 diabetic adult patients in 103 centres in 10 Asian countries or regions. Predictive factors for microalbuminuria and macroalbuminuria were characterised using a stepwise logistic regression model.Results A total of 6,801 patients were enrolled and 5,549 patients constituted the per-protocol population (patients with bacteriuria and haematuria were excluded). The prevalence of microalbuminuria was 39.8% (39.2–40.5; 95% CI) and the prevalence of macroalbuminuria was 18.8% (18.2–19.3; 95% CI). Only 11.6% of the patients had systolic and diastolic blood pressure below the 130/80 mm Hg target. In the multivariate analyses, the predictive factors for the presence of microalbuminuria were age, BMI, systolic blood pressure and ethnic origin. The highlighted predictive factors for the presence of macroalbuminuria were age, sex, ethnic origin, BMI, duration of diabetes, presence of diabetic complications, intake of diuretics, intake of calcium channel blockers, diastolic and systolic blood pressure.Conclusions/interpretation The high prevalence (58.6%) of micro or macroalbuminuria observed in these patients is alarming and indicates an impending pandemic of diabetic cardiovascular and renal diseases in Asia with its potential economic consequences.A.Y.T. Wu, F.A. de Leon and M.R. Weir received honoraria for speaking engagements and A. Rouillon is employed by Sanofi-Synthelabo Groupe.     

Citrate 4% versus Heparin and the Reduction of Thrombosis Study (CHARTS)

Background and objectives: Citrate 4% has antithrombotic and antibacterial properties, which makes it a potentially superior alternative to heparin as an indwelling intraluminal locking agent.Design, setting, participants, and measurements: Sixty-one prevalent hemodialysis (HD) patients dialyzing with a tunneled cuffed HD catheter were randomized in a pilot study to receive either heparin 5000 U/ml or citrate 4% as a locking agent after HD. The primary outcomes were the development of catheter dysfunction (defined as a blood pump speed <250 ml/min or the use of tissue plasminogen activator) and catheter-associated bacteremia. The secondary outcomes were the development of an exit-site infection or bleeding complications (either local or systemic).Results: Citrate had comparable catheter dysfunction episodes to heparin (13/32 [41%] cases versus 12/29 [41%] cases, respectively). There were no differences in the development of catheter-associated bacteremia (2.2/1000 catheter days citrate versus 3.3/1000 catheter days heparin group; P = 0.607) or exit-site infection (2.2/1000 catheter days for both groups).Conclusions: The preliminary findings from our pilot study demonstrate that 4% citrate is effective in maintaining catheter patency and does not appear to have any increased incidence of infections. Because citrate is significantly cheaper and has a more favorable side effect profile than heparin, it can be considered a potentially better locking agent in HD catheters.Catheter use among hemodialysis (HD) patients continues to be high; in fact, recent data indicates that up to 33% of patients in Canada are dialyzing with a catheter (1). Complications of catheters are well known and include catheter dysfunction (CD), infection, and central vein stenosis. The burden of catheter-associated infections contributes to morbidity and subsequent mortality in HD patients. Catheter-related infections may start with bacterial colonization of the catheter hub or exit site and lead to subsequent exit-site infection (ESI) with or without bacteremia.The use of a catheter and all of its associated complications significantly increases the cost of care in these patients as compared with a native arteriovenous fistula (2). There is a renewed interest in citrate as an alternate to heparin as a locking solution in HD catheters because of its antithrombotic and antibacterial properties and the reduced costs relative to heparin. Furthermore, complications of heparin include local and systemic bleeding events as well as the potential for thrombocytopenia (3). Citrate may be a useful alternative to heparin because it is not known to produce the complications of thrombocytopenia or bleeding.Despite the use of citrate 4% in many HD units there is only one published randomized trial that compares citrate 4% and heparin in the HD catheter population (4). This study allocated 30 patients with temporary catheters to citrate 4%, heparin 5000 U/ml or polygeline (4). Unfortunately this study was not designed to compare outcomes of infection or thrombosis and the main outcome (i.e., visible clot formation in the catheter) is of questionable clinical relevance. Two prospective observational trials (5,6) recently examined the rate of catheter exchange, tissue plasminogen activator (TPA) use, and bacteremias in a HD population who were converted from heparin to citrate 4%. These studies gave conflicting results, with Lok et al. demonstrating significant reductions in catheter exchange rates, TPA use, and bacteremias in the citrate group whereas Grudzinski et al. found no reduction in catheter exchanges or bacteremias.Weijmer et al. performed a randomized trial involving 210 patients (98 tunneled cuffed catheters and 193 uncuffed catheters) who received either heparin 5000 U/ml or citrate 43% (7). There was a significant reduction in catheter-associated bacteremia (CAB): 1.1/1000 catheter days for citrate and 4.1 catheter days in the heparin group (P < 0.01) but no difference in the CD episodes.Initial studies of citrate were halted because of cardiac toxicity of 43% solutions (8); recent advances have demonstrated that 4% solutions are safe and effective, but direct comparisons of citrate to heparin are limited and have been performed in variable populations with different outcomes (9,10). We conducted a pilot study using a randomized design to compare the effect of citrate 4% and 5000 U/ml heparin in terms of CAB, ESI, and thrombotic episodes in a Canadian cohort of prevalent dialysis patients with cuffed catheters. The purpose of this pilot study is to assess the feasibility of pursuing a large, multicenter, quasi-randomized trial by exploring the resources and recruitment methods required.     

High plasma levels of soluble P-selectin are predictive of venous thromboembolism in cancer patients: results from the Vienna Cancer and Thrombosis Study (CATS)

Cancer patients are at high risk for venous thromboembolism (VTE). Laboratory parameters with a predictive value for VTE could help stratify patients into high- or low-risk groups. The cell adhesion molecule P-selectin was recently identified as risk factor for VTE. To investigate soluble P-selectin (sP-selectin) in cancer patients as risk predictor for VTE, we performed a prospective cohort study of 687 cancer patients and followed them for a median (IQR) of 415 (221-722) days. Main tumor entities were malignancies of the breast (n = 125), lung (n = 86), gastrointestinal tract (n = 130), pancreas (n = 42), kidney (n = 19), prostate (n = 72), and brain (n = 80); 91 had hematologic malignancies; 42 had other tumors. VTE occurred in 44 (6.4%) patients. In multivariable analysis, elevated sP-selectin (cutoff level, 53.1 ng/mL, 75th percentile of study population) was a statistically significant risk factor for VTE after adjustment for age, sex, surgery, chemotherapy, and radiotherapy (hazard ratio = 2.6, 95% confidence interval, 1.4-4.9, P = .003). The cumulative probability of VTE after 6 months was 11.9% in patients with sP-selectin above and 3.7% in those below the 75th percentile (P = .002). High sP-selectin plasma levels independently predict VTE in cancer patients. Measurement of sP-selectin at diagnosis of cancer could help identify patients at increased risk for VTE.     

Clinical update: the role of angiotensin II receptor blockers in patients with left ventricular dysfunction (Part II of II)

Almost 5 million individuals in the United States have chronic heart failure (HF), which is increasing in prevalence. Angiotensin-converting enzyme (ACE) inhibitors are standard therapies for HF, although more than 10% of patients with HF are unable to tolerate these agents. Furthermore, ACE inhibitors may not provide complete blockade of the renin-angiotensin system (RAS) in the long term. Because angiotensin II receptor blockers (ARBs) may block the RAS more completely than ACE inhibitors and are better tolerated, several large-scale ARB trials have been performed exploring their potential role in treating patients with symptomatic HF and left ventricular systolic dysfunction. The Losartan Heart Failure Survival Study (ELITE II) demonstrated no significant differences in morbidity and mortality between the ARB losartan and the ACE inhibitor captopril among elderly patients with HF. The Valsartan Heart Failure Trial (Val-HeFT) demonstrated reductions in hospitalizations for HF with the ARB valsartan when added to standard HF therapy, with no effect on mortality. Both trials suggested a potential negative interaction between ARB and beta-blocker therapy. The Candesartan in Heart failure-Assessment of Reduction in Mortality and morbidity (CHARM) program demonstrated significant reductions in morbidity and mortality with the ARB candesartan in patients with HF due to systolic dysfunction, with or without ACE inhibitors and with or without beta blockers. Thus, the addition of ARBs to the treatment regimen of patients with symptomatic HF should be strongly considered.     

Thrombosis and survival in essential thrombocythemia: A regional study of 1,144 patients

To identify prognostic factors affecting thrombosis‐free survival (TFS) and overall survival (OS), we report the experience of a Regional cooperative group in a real‐life cohort of 1,144 patients with essential thrombocythemia (ET) diagnosed from January 1979 to December 2010. There were 107 thrombotic events (9.4%) during follow‐up [60 (5.3%) arterial and 47 (4.1%) venous thromboses]. At univariate analysis, risk factors for a shorter TFS were: age >60 years (P < 0.0054, 95% CI 1.18–2.6), previous thrombosis (P < 0.0001, 95% CI 1.58–4.52) and the presence of at least one cardiovascular risk factor (P = 0.036, 95% CI 1.15–3.13). Patients with a previous thrombosis occurred ≥24 months before ET diagnosis had a shorter TFS compared to patients with a previous thrombosis occurred <24 months (P = 0.0029, 95% CI 1.5–6.1); furthermore, patients with previous thrombosis occurred <24 months did not show a shorter TFS compared with patients without previous thrombosis (P = 0.303, 95% CI 0.64–3.21). At multivariate analysis for TFS, only the occurrence of a previous thrombosis maintained its prognostic impact (P = 0.0004, 95% CI 1.48–3.79, RR 2.36). The 10‐year OS was 89.9% (95% CI 87.3–92.5): at multivariate analysis for OS, age >60 years (P < 0.0001), anemia (P < 0.0001), male gender (P = 0.0019), previous thromboses (P = 0.0344), and white blood cell >15 × 10⁹/l (P = 0.0370) were independent risk factors. Previous thrombotic events in ET patients are crucial for TFS but their importance seems related not to the occurrence per se but mainly to the interval between the event and the diagnosis. Am. J. Hematol. 89:542–546, 2014. © 2014 Wiley Periodicals, Inc.     

Insulin-like growth factor I gene promoter polymorphism, collagen type II alpha1 (COL2A1) gene, and the prevalence of radiographic osteoarthritis: the Rotterdam Study

OBJECTIVE: To examine the role of an IGF-I gene promoter polymorphism in the prevalence of radiographic osteoarthritis (ROA), and study its interaction with the COL2A1 gene. METHODS: Individuals genotyped for IGF-I (n = 1546) and COL2A1 gene polymorphisms (n = 808) were selected from a random sample (n = 1583) derived from the Rotterdam study. The presence of ROA was defined as a Kellgren score of 2 or more in at least one of four joints (knee, hip, hand, and spine). Genotype specific odds ratios (OR) were adjusted for age, sex, body mass index, and bone mineral density using logistic regression. Interaction with the COL2A1 genotype was tested. RESULTS: Overall, no association was found between the IGF-I polymorphism and ROA. In subjects aged 65 years or younger (n = 971), the prevalence of ROA increased with the absence of the 192 base pair (bp) allele (p for trend = 0.03). Compared with homozygotes for the 192 bp allele, the prevalence of ROA was 1.4 times higher in heterozygotes (95% confidence interval, 1.0 to 1.8) and 1.9 times higher in non-carriers (1.1 to 3.3). There was evidence of interaction between the IGF-I and COL2A1 genes. Individuals with the risk genotype of both genes had an increased prevalence of ROA (OR 3.4 (1.1 to 10.7)). No effect was observed in subjects older than 65 years. CONCLUSIONS: SUBJECTS: with genetically determined low IGF-I expression (non-carriers of the 192 bp allele) may be at increased risk of ROA before the age of 65 years. Furthermore, an interaction between the IGF-I and COL2A1 genes is suggested.     

Increased prevalence of infectious endocarditis in patients with type II diabetes mellitus

BACKGROUND: Patients with diabetes mellitus (DM) are at increased risk of infection. However, there are controversial reports about DM association with infectious endocarditis (IE). We evaluated the occurrence of IE in DM patients compared to a matched control. METHOD: Treatment files of inpatients' admission that contained discharge diagnosis (ICD-9 codes) from Veterans Health Administration hospitals were used for this study. ICD-9 codes for DM (n=293,124) and a control group with ICD-9 codes for hypertension without DM (n=552,623) were utilized for comparison. The prevalence of IE was studied using ICD-9 codes for IE. Multivariate analysis was performed adjusting for chronic and acute renal failure and aortic and mitral valve disease. Continuous variables were analyzed by unpaired t tests. Binary variables were analyzed using the chi-square test and Fisher's Exact Tests. RESULTS: IE was present in 1340 (0.5%) DM patients versus 1412 (0.3%) patients from the control group (relative increase of 40%). Using multivariate analysis adjusting for renal failure and valvular abnormalities, DM remained independently associated with IE (odds ratio=1.9; 95% confidence interval=1.8-2.1; P<.0001). CONCLUSION: Patients with type II DM have significantly higher prevalence of IE independent of renal failure or valvular abnormalities consistent with increased vulnerability of DM patients for infections.     

Thrombosis of anomalous chordae in the right atrium (Chiari's network)

In 1897 Chiari² described eleven cases in which he found a network of fibers in the right atrium of the heart. Since that time such anomalous chordae have commonly carried his name. These fibers are anomalous remnants of the right valve of the sinus venosus, a structure which usually regresses during the fourth fetal month to form only the valves at the orifices of the inferior vena cava and the coronary sinus. In 1936 Yater⁶ found that only twenty-five examples of this structure had been reported since Chiari's original paper, and to this group he added one of his own. Since this review, only two additional cases have appeared in the literature.^3,5     

Sex-specific increase in the prevalence of atrial fibrillation (The Copenhagen City Heart Study)

Atrial fibrillation (AF) is the most frequently encountered cardiac arrhythmia. It is a risk factor for stroke and premature death. We studied the temporal changes in the prevalence of AF from 1976 to 1994 in a random population aged 50 to 89 years. The prevalence of AF, diagnosed from electrocardiograms (ECGs), was determined in 8,606 patients examined in 1976 to 1978, in 8,943 patients examined in 1981 to 1983, and in 6,733 subjecs examined in 1991 to 1994. Changes in prevalence of AF were estimated by logistic regression analysis. In men, the age-standardized prevalence of AF increased from 1.4% in 1976 to 1978 (odds ratio [OR] 1.0, reference) to 1.9% in 1981 to 1983 (OR 1.6, 95% confidence interval [CI] 1.1 to 2.1), and to 3.3% in 1991 to 1994 (OR 2.3, 95% CI 1.6 to 3.4, p <0.001, adjusted for age). In women, the prevalence of AF decreased from 1.5% in 1976 to 1978 (OR 1.0, reference) to 1.0% in 1981 to 1983 (OR 0.7, 95% CI 0.5 to 1.0), and to 1.1% in 1991 to 1994 (OR 0.7, 95% CI 0.5 to 1.0), although the overall decrease was not significant (p = 0.11, adjusted for age). After adjusting for changes in comorbidity, body weight, and height, the increase in the prevalence of AF in men from 1976 to 1978 and from 1991 to 1994 remained significant (OR 1.9, 95% CI 1.3 to 2.8, P = 0.002). Although unchanged in women, the prevalence of AF in men more than doubled from the 1970s to the 1990s. The factors responsible for this gender-specific increase in the prevalence of this common arrhythmia have yet to be identified.     

cis-Dichlorodiamminepltinum(II) in adult patients: Southwest Oncology Group Studies.

In addition to cis-dichlorodiammineplatinum(II) studies in lymphomas and testicular cancer and a broader phase II study of all genitourinary malignancies, the Southwest Oncology Group is currently conducting eight other studies which examine the effectiveness of this drug in adult patients with a variety of tumor types. This report will give preliminary analyses of the five studies for which there are early data, plus briefly describe the design of the three remaining protocols for which there are no data as yet.