Parvovirus B19 infection in sickle cell disease: An analysis from the Centers for Disease Control haemoglobinopathy blood surveillance project.

OBJECTIVE: In the multicentre Haemoglobinopathy Blood Surveillance Project, to evaluate the seroprevalence of parvovirus B19 and DNA viral load in sickle cell disease (SCD). BACKGROUND: Although the epidemiology of parvovirus B19 seropositivity in SCD has been well documented, there are few studies that have assessed possible persistent parvovirus DNAemia and associated risk factors including blood transfusion. METHODS: A qualitative analysis of parvovirus B19 serology using ELISA and quantitative parvovirus B19 DNA by RT-PCR was performed in patients with SCD. RESULTS: Of 322 patients, 113 (35%) were parvovirus IgG positive and 119 (37%) were IgM positive at enrolment. The prevalence of IgG positivity increased with age. 71/322 (22%) were parvovirus DNA positive at enrolment with a mean viral load of 15 227 ± 55 227 SD. (range 72-329 238 IU/mL). Patients who were positive for parvovirus B19 DNA received a significantly higher red blood cell transfusion volume in the prior year compared to patients who were negative (mean RBC volume = 8310 mL vs 5435 mL, respectively; P = .0073). Seventy-seven patients had follow-up testing approximately 1 year after enrolment and 11/28 (39%) patients had persistently positive IgM. CONCLUSION: Further studies are needed to better understand the natural history of parvovirus B19 infection in SCD especially in relation to RBC transfusion as a risk factor, as well as disease outcome and severity.

Effects of storage-aged red blood cell transfusions on endothelial function in hospitalized patients.

BACKGROUND: Clinical and animal studies indicate that transfusions of older stored red blood cells (RBCs) impair clinical outcomes as compared to fresh RBC transfusions. It has been suggested that this effect is due to inhibition of nitric oxide (NO)-mediated vasodilation after transfusion of older RBC units. However, to date this effect has not been identified in human transfusion recipients. STUDY DESIGN AND METHODS: Forty-three hospitalized patients with transfusion orders were randomly assigned to receive either fresh (<14 days) or older stored (>21 days) RBC units. Before transfusion, and at selected time points after the start of transfusion, endothelial function was assessed using noninvasive flow-mediated dilation assays. RESULTS: After transfusion of older RBC units, there was a significant reduction in NO-mediated vasodilation at 24 hours after transfusion (p = 0.045), while fresh RBC transfusions had no effect (p = 0.231). CONCLUSIONS: This study suggests for the first time a significant inhibitory effect of transfused RBC units stored more than 21 days on NO-mediated vasodilation in anemic hospitalized patients. This finding lends further support to the hypothesis that deranged NO signaling mediates adverse clinical effects of older RBC transfusions. Future investigations will be necessary to address possible confounding factors and confirm these results.

Endothelium-derived hyperpolarizing factor mediates bradykinin-stimulated tissue plasminogen activator release in humans.

AIMS: Bradykinin (BK) stimulates tissue plasminogen activator (t-PA) release from human endothelium. Although BK stimulates both nitric oxide and endothelium-derived hyperpolarizing factor (EDHF) release, the role of EDHF in t-PA release remains unexplored. This study sought to determine the mechanisms of BK-stimulated t-PA release in the forearm vasculature of healthy human subjects. METHODS: In 33 healthy subjects (age 40.3 ± 1.9 years), forearm blood flow (FBF) and t-PA release were measured at rest and after intra-arterial infusions of BK (400 ng/min) and sodium nitroprusside (3.2 mg/min). Measurements were repeated after intra-arterial infusion of tetraethylammonium chloride (TEA; 1 µmol/min), fluconazole (0.4 µmol·min(-1)·l(-1)), and N(G)-monomethyl-L-arginine (L-NMMA, 8 µmol/min) to block nitric oxide, and their combination in separate studies. RESULTS: BK significantly increased net t-PA release across the forearm (p < 0.0001). Fluconazole attenuated both BK-mediated vasodilation (-23.3 ± 2.7% FBF, p < 0.0001) and t-PA release (from 50.9 ± 9.0 to 21.3 ± 8.9 ng/min/100 ml, p = 0.02). TEA attenuated FBF (-14.7 ± 3.2%, p = 0.002) and abolished BK-stimulated t-PA release (from 22.9 ± 5.7 to -0.8 ± 3.6 ng/min/100 ml, p = 0.0002). L-NMMA attenuated FBF (p < 0.0001), but did not inhibit BK-induced t-PA release (nonsignificant). CONCLUSION: BK-stimulated t-PA release is partly due to cytochrome P450-derived epoxides and is inhibited by K(+)Ca channel blockade. Thus, BK stimulates both EDHF-dependent vasodilation and t-PA release.

Effect of meditation on endothelial function in Black Americans with metabolic syndrome: a randomized trial.

OBJECTIVES: Psychological stress may play a role in metabolic syndrome. A consequence of metabolic syndrome is endothelial dysfunction, which is also influenced by psychological stress. We sought to compare the effect of consciously resting meditation (CRM), a sound based meditation, with a control intervention of health education (HE) on endothelial function in the setting of metabolic syndrome. METHODS: Sixty-eight black Americans with metabolic syndrome risk factors (age, 30-65 years) were randomized to either CRM (n = 33) or HE (n = 35); interventions were matched for frequency and duration of sessions and lasted 12 months. Endothelial function was assessed by brachial artery flow-mediated dilation at baseline and at 6 and 12 months. Arterial elasticity, metabolic risk factors, and psychosocial and behavioral variables were secondary end points. RESULTS: Although flow-mediated dilation improved in the CRM group for 12 months, this increase was not significantly higher than that in the HE group (p = .51 for the interaction between group and time). Non-endothelium-dependent dilation and arterial elasticity did not change in either group. Most metabolic syndrome risk factors showed beneficial trends in the CRM group only. A risk factor score counting the number of metabolic syndrome components decreased in the CRM group only (p = .049 for the interaction between treatment group and time). CONCLUSIONS: Among black Americans with metabolic syndrome risk factors, CRM, did not improve endothelial function significantly more than a control intervention of HE. CRM resulted in favorable trends in metabolic syndrome risk factors, which were examined as secondary outcomes.

Evidence for the transmission of parvovirus B19 in patients with bleeding disorders treated with plasma-derived factor concentrates in the era of nucleic acid test screening.

BACKGROUND: Parvovirus B19 (B19V) is a small, nonenveloped virus that typically causes a benign flu-like illness that occurs most frequently in childhood. The virus is resistant to current viral inactivation steps used in the manufacture of antihemophilic factor concentrates and B19V transmission through these products has been documented. Since 2000, B19V nucleic acid test (NAT) screening of plasma pools has been implemented to further decrease the viral burden in these products, but no study has examined populations using these products to assess the impact of the screening on B19V transmission. STUDY DESIGN AND METHODS: Blood specimens obtained from participants of a surveillance system established in federally supported specialized bleeding disorders clinics were used in a B19V seroprevalence study. RESULTS: A total of 1643 specimens from 1043 participants age 2 to 7 years born after B19V NAT screening was implemented were tested. Age-specific prevalence rates were generally higher for subjects exposed to either plasma-derived products alone or in combination with other products compared to subjects with no exposure to antihemophilic products. Overall, compared to participants unexposed to blood or blood products, those exposed to plasma-derived products alone were 1.7 times more likely to have antibodies to B19V (p = 0.002). CONCLUSION: These results are consistent with continued B19V transmission through plasma-derived factor concentrates. Effective viral inactivation and detection processes are needed to protect users of these products from infection with B19V or other new or emerging viruses.

Accumulation of retained nonfunctional arteriovenous grafts correlates with severity of inflammation in asymptomatic ESRD patients.

BACKGROUND: The contribution of multiple retained nonfunctional arteriovenous grafts (AVGs) to the burden of chronic inflammation in chronic hemodialysis patients has not been well studied. Here, we sought to evaluate the association between plasma levels of C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-alpha) and albumin and the number of retained nonfunctional AVGs. METHODS: This cross-sectional study enrolled 91 prevalent patients undergoing in-center hemodialysis without evidence of infection or inflammation. A baseline blood sample was obtained at study enrollment. A general linear model (GLM) was used to compare levels of biomarkers of systemic inflammation across groups defined by the number of retained, nonfunctional AVGs. RESULTS: A total of 43 patients had one or more retained thrombosed AVG and had significantly greater plasma log-CRP levels compared with patients without a previous AVG (P= 0.036), regardless of the current AV access type. Using a GLM, we found that for every additional retained thrombosed AVG, plasma log-CRP, log-IL-6 and TNF-alpha concentrations increased significantly by 0.30 mg/L (P= 0.011), 0.18 pg/mL (P= 0.046) and 0.72 pg/mL (P= 0.046), respectively, following adjustment. CONCLUSIONS: Hence, the severity of inflammation increases with the number of retained nonfunctional AVG's, suggesting that AVG accumulation may contribute to the cardiovascular morbidity and mortality associated with chronic inflammation in asymptomatic end-stage renal disease (ESRD) patients. Further study is indicated to determine whether patients with one or more thrombosed, retained AVG may benefit from periodic screening with CRP monitoring to identify those patients who may benefit from AVG resection.

Elevated C-reactive protein is associated with severe periodic leg movements of sleep in patients with restless legs syndrome.

BACKGROUND: Restless legs syndrome (RLS) is a common sleep disorder in which urges to move the legs are felt during rest, are felt at night, and are improved by leg movement. RLS has been implicated in the development of cardiovascular disease. Periodic leg movements (PLMs) may be a mediator of this relationship. We evaluated systemic inflammation and PLMs in RLS patients to further assess cardiovascular risk. METHODS: 137 RLS patients had PLM measurements taken while unmedicated for RLS. Banked plasma was assayed for high sensitivity C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-alpha). RESULTS: Mean (SD) PLM index was 19.3 (22.0). PLMs were unrelated to TNF-a and IL-6, but were modestly correlated with logCRP (r(129)=0.19, p=0.03). Those patients with at least 45PLMs/h had an odds ratio of 3.56 (95% CI 1.26-10.03, p=0.02, df=1) for having elevated CRP compared to those with fewer than 45PLMs/h. After adjustment for age, race, gender, diabetes, hypertension, hyperlipidemia, inflammatory disorders, CRP-lowering medications, and body mass index, the OR for those with ≥ 45PLMs/h was 8.60 (95% CI 1.23 to 60.17, p=0.03, df=10). CONCLUSIONS: PLMs are associated with increased inflammation, such that those RLS patients with at least 45PLMs/h had more than triple the odds of elevated CRP than those with fewer PLMs. Further investigation into PLMs and inflammation is warranted.

Association between depression and inflammation--differences by race and sex: the META-Health study.

OBJECTIVE: To test whether the association between depression and inflammation differs by race and sex. Depressive symptoms have been associated with higher levels of C-reactive protein (CRP). However, few studies have examined this association in samples including a significant number of African Americans, or examined whether the association differs by race and sex. METHODS: Depressive symptoms and CRP were assessed in 512 African American and white participants, age 30 to 65 years, as part of the community-based Morehouse and Emory Team up to Eliminate Health Disparities (META-Health) Study. Depression was determined by responses to the Beck Depression Inventory II (BDI-II). Multivariable linear regression models were used to adjust for demographic and metabolic risk factors. RESULTS: African American men had higher total BDI-II scores than white men (p = .03), whereas there was no difference in women. There was a significant race-sex-depression interaction in predicting CRP levels (p = .02). White women with mild to severe depressive symptoms had higher levels of CRP compared with those with minimal to no depressive symptoms (p < .05). There were no differences in levels of CRP by severity of depressive symptoms in white men or African Americans of either sex. Higher BDI-II scores were related to higher CRP levels in white women after adjusting for age and level of education (ß = 0.227, p = .006). However, the association was eliminated after further adjustment for metabolic risk factors (ß = 0.077, p = .35). CONCLUSIONS: Although depressive symptoms are associated with inflammation, the association varies by race and sex.

Bleeding events are associated with an increase in markers of inflammation in acute coronary syndromes: an ACUITY trial substudy.

Bleeding events have been associated with adverse early and late outcomes in virtually all clinical settings. The mechanism behind this observation remains poorly understood. We sought to determine if the reason might be the provocation of an inflammatory response by bleeding events. In a formal substudy of the ACUITY trial, plasma samples of a range of biomarkers were collected at baseline, discharge, 30 days, and 1 year from 192 patients with acute coronary syndromes (ACS) and were analyzed in a central core laboratory. Temporal changes in biomarker levels were assessed in patients who experienced in-hospital hemorrhagic events, recurrent ischemic events, or neither. Sixteen patients were excluded from the study (7 with incomplete samples, 5 undergoing coronary artery bypass grafting (CABG) during index hospitalization; 1 had both bleeding and ischemic events). Median high sensitivity C-reactive protein (hs-CRP) levels (mg/l) increased significantly more from admission to discharge among the 9 patients who experienced an in-hospital major bleed compared to either the 9 patients who had a recurrent ischemic event (+6.0 vs. +0.70, P = 0.04) or the 151 patients who had no event (+6.0 vs. +0.60, P = 0.003). Compared to patients with no in-hospital events, median interleukin-6 (IL-6) levels (pg/ml) increased from admission to hospital discharge non-significantly in those with a bleeding event (+0.92 vs. +2.46, P = 0.55) and in those who experienced an in-hospital recurrent ischemic event (+0.92 vs. +3.60, P = 0.09). These data suggest that major bleeding is associated with development of a pro-inflammatory state. If confirmed, this mechanism may in part explain the poor prognosis of patients experiencing an acute hemorrhagic event.

25-hydroxyvitamin D concentration is inversely associated with serum MMP-9 in a cross-sectional study of African American ESRD patients.

BACKGROUND: Circulating 25-hydroxyvitamin D [25(OH)D] concentration is inversely associated with peripheral arterial disease and hypertension. Vascular remodeling may play a role in this association, however, data relating vitamin D level to specific remodeling biomarkers among ESRD patients is sparse. We tested whether 25(OH)D concentration is associated with markers of vascular remodeling and inflammation in African American ESRD patients. METHODS: We conducted a cross-sectional study among ESRD patients receiving maintenance hemodialysis within Emory University-affiliated outpatient hemodialysis units. Demographic, clinical and dialysis treatment data were collected via direct patient interview and review of patients records at the time of enrollment, and each patient gave blood samples. Associations between 25(OH)D and biomarker concentrations were estimated in univariate analyses using Pearson's correlation coefficients and in multivariate analyses using linear regression models. 25(OH) D concentration was entered in multivariate linear regression models as a continuous variable and binary variable (<15 ng/ml and ≥15 ng/ml). Adjusted estimate concentrations of biomarkers were compared between 25(OH) D groups using analysis of variance (ANOVA). Finally, results were stratified by vascular access type. RESULTS: Among 91 patients, mean (standard deviation) 25(OH)D concentration was 18.8 (9.6) ng/ml, and was low (<15 ng/ml) in 43% of patients. In univariate analyses, low 25(OH) D was associated with lower serum calcium, higher serum phosphorus, and higher LDL concentrations. 25(OH) D concentration was inversely correlated with MMP-9 concentration (r = -0.29, p = 0.004). In multivariate analyses, MMP-9 concentration remained negatively associated with 25(OH) D concentration (P = 0.03) and anti-inflammatory IL-10 concentration positively correlated with 25(OH) D concentration (P = 0.04). CONCLUSIONS: Plasma MMP-9 and circulating 25(OH) D concentrations are significantly and inversely associated among ESRD patients. This finding may suggest a potential mechanism by which low circulating 25(OH) D functions as a cardiovascular risk factor.

Biomarker profile in stable Fontan patients.

BACKGROUND: As the population of adults with congenital heart disease (CHD) grows, cardiologists continue to encounter patients with complex anatomies that challenge the standard treatment of care. Single ventricle Fontan palliated patients are the most complex within CHD, with a high morbidity and mortality burden. Factors driving this early demise are largely unknown. METHODS AND RESULTS: We analyzed biomarker expression in 44 stable Fontan outpatients (29.2 ± 10.7 years, 68.2% female) seen in the outpatient Emory Adult Congenital Heart Center and compared them to 32 age, gender and race matched controls. In comparison to controls, Fontan patients had elevated levels of multiple cytokines within the inflammatory pathway including Tumor Necrosis Factor-α (TNF-α) (p < 0.001), Interleukin-6 (IL-6) (p < 0.011), Growth Derived Factor-15 (GDF-15) (p < 0.0001), ß2-macroglobulin, (p = 0.0006), stem cell mobilization: Stromal Derived Factor-1∝ (SDF-1α) (p = 0.006), extracellular matrix turnover: Collagen IV (p < 0.0001), neurohormonal activation: Renin (p < 0.0001), renal dysfunction: Cystatin C (p < 0.0001) and Urokinase Receptor (uPAR) (p = 0.022), cardiac injury: Troponin-I (p < 0.0004) and metabolism: Adiponectin (p = 0.0037). Within 1 year of enrollment 50% of Fontan patients had hospitalizations, arrhythmias or worsening hepatic function. GDF-15 was significantly increased in Fontan patients with clinical events (p < 0.0001). In addition, GDF-15 moderately correlated with longer duration of Fontan (r = 0.55, p = 0.01) and was elevated in atriopulmonary (AP) Fontan circulation. Finally, in a multivariate model, VEGF-D and Collagen IV levels were found to be associated with a change in MELDXI, a marker of liver dysfunction. CONCLUSION: Multiple clinical and molecular biomarkers are upregulated in Fontan patients, suggesting a state of chronic systemic dysregulation.

The lack of association between four point mutations in the promoter region of the toll-like 4 receptor gene and myocardial infarction.

The toll-like receptor 4 gene product (TLR4) has been implicated in the pathogen recognition response mechanism because it plays a central role in the transcriptional activation of the host defense system. Activation of TLR4 initiates an intracellular signaling cascade, via the adapter protein MyD88 (myeloid differentiation factor 88), which leads to the activation of NF-kappaB transcriptional factor, and ultimately to the induction of a pro-inflammatory response. This inflammatory response has been increasingly associated with atherosclerosis. Recent analyses on two polymorphisms of TLR4, which affect the extracellular domain of the receptor, have been shown to give rise to an attenuated innate immune defense which may contribute to disease susceptibility. We have investigated the significance of four new substitutions found by re-sequencing in the 5'-proximal promoter region of the TLR4 gene in a case-control study of acute myocardial infarction. Our results found no statistically significant association between these genetic variants and MI.

Elevated factor VII as a risk factor for recurrent fetal loss. Relationship to factor VII gene polymorphisms.

Haemostatic abnormalities can be detected in a portion of the women who have recurrent fetal loss. We measured factor VII coagulant activity (FVII:C) in 65 women with 3 or more fetal losses (recurrent cases), 31 women with one 2nd or 3rd trimester loss (late loss cases), and 81 women with only live births (controls). FVII:C was greater than 2 standard deviations above the mean for controls in 9 recurrent cases (13.8%) and 2 controls (2.5%) for an odds ratio of 6.35 (95% CI 1.32-30.52, p=0.012). In recurrent cases, mean levels were significantly higher than controls for FVII:C (p=0.003), FVII antigen (p=0.024), and FVIIa (p=0.001). Late loss cases had an odds ratio of 4.23 (95% CI 0.67-26.67, p=0.098) with FVII:C, FVII antigen, and FVIIa not significantly different from the controls. DNA was examined for the presence of mutations or polymorphisms in the promoter region of the FVII gene, using denaturing HPLC. Abnormal patterns were confirmed with direct sequencing. A previously reported polymorphism, -402 G>A, was found to be present in 11/14 subjects with elevated FVII:C (79%) and 43% of those with normal levels (p=0.029). FVII:C, FVII antigen and FVIIa varied significantly with genotype; however, genotype frequencies did not differ between controls and either case group. No other promoter polymorphisms were identified. This is the first report of a significant elevation of FVII in a population with recurrent fetal loss. These data suggest the need for further investigation of this potential risk factor.

Plasma stromal cell-derived factor 1α/CXCL12 level predicts long-term adverse cardiovascular outcomes in patients with coronary artery disease.

OBJECTIVE: Stromal derived factor-1α/CXCL12 is a chemoattractant responsible for homing of progenitor cells to ischemic tissues. We aimed to investigate the association of plasma CXCL12 with long-term cardiovascular outcomes in patients with coronary artery disease (CAD). METHODS: 785 patients aged: 63 ± 12 undergoing coronary angiography were independently enrolled into discovery (N = 186) and replication (N = 599) cohorts. Baseline levels of plasma CXCL12 were measured using Quantikine CXCL12 ELISA assay (R&D systems). Patients were followed for cardiovascular death and/or myocardial infarction (MI) for a mean of 2.6 yrs. Cox proportional hazard was used to determine independent predictors of cardiovascular death/MI. RESULTS: The incidence of cardiovascular death/MI was 13% (N = 99). High CXCL12 level based on best discriminatory threshold derived from the ROC analysis predicted risk of cardiovascular death/MI (HR = 4.81, p = 1 × 10(-6)) independent of traditional risk factors in the pooled cohort. Addition of CXCL12 to a baseline model was associated with a significant improvement in c-statistic (AUC: 0.67-0.73, p = 0.03). Addition of CXCL12 was associated with correct risk reclassification of 40% of events and 10.5% of non-events. Similarly for the outcome of cardiovascular death, the addition of the CXCL12 to the baseline model was associated with correct reclassification of 20.7% of events and 9% of non-events. These results were replicated in two independent cohorts. CONCLUSION: Plasma CXCL12 level is a strong independent predictor of adverse cardiovascular outcomes in patients with CAD and improves risk reclassification.

Whole blood gene expression profiles distinguish clinical phenotypes of venous thromboembolism.

INTRODUCTION: Recurrent venous thromboembolism (VTE) occurs infrequently following a provoked event but occurs in up to 30% of individuals following an initial unprovoked event. There is limited understanding of the biological mechanisms that predispose patients to recurrent VTE. OBJECTIVES: To identify whole blood gene expression profiles that distinguished patients with clinically distinct patterns of VTE. PATIENTS/METHODS: We studied 107 patients with VTE separated into 3 groups: (1) 'low-risk' patients had one or more provoked VTE; (2) 'moderate-risk' patients had a single unprovoked VTE; (3) 'high-risk' patients had ≥2 unprovoked VTE. Each patient group was also compared to twenty-five individuals with no personal history of VTE. Total RNA from whole blood was isolated and hybridized to Illumina HT-12V4 Beadchips to assay whole genome expression. RESULTS: Using class prediction analysis, we distinguished high-risk patients from low-risk patients and healthy controls with good receiver operating curve characteristics (AUC=0.81 and 0.84, respectively). We also distinguished moderate-risk individuals and low-risk individuals from healthy controls with AUC's of 0.69 and 0.80, respectively. Using differential expression analysis, we identified several genes previously implicated in thrombotic disorders by genetic analyses, including SELP, KLKB1, ANXA5, and CD46. Protein levels for several of the identified genes were not significantly different between the different groups. CONCLUSION: Gene expression profiles are capable of distinguishing patients with different clinical presentations of VTE, and genes relevant to VTE risk are frequently differentially expressed in these comparisons.

Mutations in the S4-H2 loop of eIF4E which increase the affinity for m7GTP.

Eukaryotic initiation factor 4E (eIF4E) binds the 5'-cap of eukaryotic mRNAs and overexpression of eIF4E in epithelial cell cancers correlates with the metastases/tissue invasion phenotype. Photolabeling of eIF4E with [gamma-32P]8-azidoguanosine 5'-triphosphate (8-N3GTP) demonstrated cross-linking at Lys-119 in the S4-H2 loop which is distant from the m7GTP binding site [Marcotrigiano et al. (1997) Cell 89, 951-961; Friedland et al. (1997) Protein Sci. 6, 125-131]. Modeling studies indicate that 8-N3GTP cross-linked with Lys-119 because it binds a site that is occupied by the second nucleotide of a bound mRNA. Mutagenesis of the S4-H2 loop produced proteins with a 5-10-fold higher affinity for m7GTP than wild-type eIF4E. These mutants of eIF4E may have uses in selectively purifying mRNAs with intact 5'-ends or in determining how the promyelocytic leukemia protein decreases the affinity of eIF4E for mRNA caps.

The relationship between FV Leiden and pulmonary embolism.

Pulmonary embolism (PE) is one of the leading causes of in-patient hospital deaths. As a consequence, the identification of hemostatic variables that could identify those at risk would be important in reducing mortality. It has previously been thought that deep vein thrombosis and PE are a single disease entity and would, therefore, have the same risk factors. This view is changing, however, with the realization that the prevalence of FV Leiden, a recognized genetic risk factor for deep vein thrombosis, may be a 'milder' genetic risk factor for PE. These observations suggest that PE is not only associated with a different set of risk factors, but may be reflective of a different clot structure.

Venous thromboembolism: implications for gene-based diagnosis and technology development.

Venous thromboembolism is an hypercoagulable state that frequently reflects a complex interplay between inherited, acquired and environmental factors. The overall incidence of venous thromboembolism, which increases with age, is approximately 1:1000 in the US and Western Europe. In addition to known risk factors such as pregnancy and cancer, genetic variants can also increase the venous thromboembolism risk. Once such genetic variant, FV Leiden is characterized by single-point mutation and has been found in approximately 20% of idiopathic venous thromboembolism cases. The discovery of FV Leiden unleashed an increased interest in the genetics of venous thromboembolism as well as other cardiovascular diseases. Because FV Leiden was not only defined by only one common single nucleotide polymorphism but was also widely prevalent, impetus for the development of novel mutation detection methodologies and platforms for DNA analysis in both the clinical and research laboratory was greatly accelerated. An overview of this technology and its relationship to the genetics of venous thromboembolism is reviewed.

The effects of obesity on venous thromboembolism: A review.

Obesity has emerged as a global health issue that is associated with wide spectrum of disorders, including coronary artery disease, diabetes mellitus, hypertension, stroke, and venous thromboembolism (VTE). VTE is one of the most common vascular disorders in the United States and Europe and is associated with significant mortality. Although the association between obesity and VTE appears to be moderate, obesity can interact with other environmental or genetic factors and pose a significantly greater risk of VTE among individuals who are obese and who are exposed simultaneously to several other risk factors for VTE. Therefore, identification of potential interactions between obesity and certain VTE risk factors might offer some critical points for VTE interventions and thus minimize VTE morbidity and mortality among patients who are obese. However, current obesity measurements have limitations and can introduce contradictory results in the outcome of obesity. To overcome these limitations, this review proposes several future directions and suggests some avenues for prevention of VTE associated with obesity as well.