Association of Blood Pressure With Blood Viscosity in American Indians

Assessment of Red Blood Cell Aggregation in Preeclampsia by Microfluidic Image Flow Analysis-Impact of Oxidative Stress on Disease Severity

Preeclampsia (PE) is a hypertensive disease characterized by proteinuria, endothelial dysfunction, and placental hypoxia. Reduced placental blood flow causes changes in red blood cell (RBC) rheological characteristics. Herein, we used microfluidics techniques and new image flow analysis to evaluate RBC aggregation in preeclamptic and normotensive pregnant women. The results demonstrate that RBC aggregation depends on the disease severity and was higher in patients with preterm birth and low birth weight. The RBC aggregation indices (EAI) at low shear rates were higher for non-severe (0.107 ± 0.01) and severe PE (0.149 ± 0.05) versus controls (0.085 ± 0.01; p < 0.05). The significantly more undispersed RBC aggregates were found at high shear rates for non-severe (18.1 ± 5.5) and severe PE (25.7 ± 5.8) versus controls (14.4 ± 4.1; p < 0.05). The model experiment with in-vitro-induced oxidative stress in RBCs demonstrated that the elevated aggregation in PE RBCs can be partially due to the effect of oxidation. The results revealed that RBCs from PE patients become significantly more adhesive, forming large, branched aggregates at a low shear rate. Significantly more undispersed RBC aggregates at high shear rates indicate the formation of stable RBC clusters, drastically more pronounced in patients with severe PE. Our findings demonstrate that altered RBC aggregation contributes to preeclampsia severity.

Relationship between blood viscosity and thrombus burden in ST-segment elevation myocardial infarction

BACKGROUND

İncreased whole blood viscosity (WBV) is associated with increased infarct area, impaired microvascular circulation and mortality in patients with ST-elevation myocardial infarction (STEMI).

OBJECTIVES

We aimed to analyze the association between the WBV and thrombus burden (TB) in STEMI patients.

METHODS

This cross-sectional study included 167 STEMI patients who received primary percutaneous coronary intervention. WBV values were assessed using hematocrit and total protein values, and low shear rate(LSR) and high shear rate(HSR) were calculated. Angiographic TB was assessed according to the definition of the Thrombolysis in Myocardial Infarction (TIMI) study group. The cases were dichotomized into low TB (grade 1-3) (n = 87) and high TB (grade 4-5) (n = 80) groups.

RESULTS

The mean HSR and LSR values of the high TB group were significantly increased compared to the low TB group (p < 0.001, for each). In ROC analysis,for prediction of TB, a cut-off value of 3.83 WBV for HSR had a 71% sensitivity and a 60.7% specificity, and a cut-off value of 21 WBV for LSR had a 70% sensitivity and 59.9% specificity (p < 0.001,for each). Multivariate regression analysis showed that both HSR (OR = 2.408;p=0.020) and LSR (OR = 1.055;p=0.021) were independent predictors for high TB.

CONCLUSION

İncreased WBV was an independent predictor for the presence of high TB in patients with STEMI.

Increased whole blood viscosity is associated with primary idiopathic complete atrioventricular block and poor clinical outcomes in these patients

BACKGROUND

Complete atrioventricular block is most commonly caused by age-related degeneration and fibrosis in the cardiac conduction system and is called primary idiopathic complete atrioventricular (iCAVB). Although many factors affect this situation, which increases with age in the cardiac conduction system, the relationship between whole blood viscosity (WBV) and iCAVB has not been clarified until now. In this study, we aim to reveal the relationship between iCAVB and WBV.

METHODS AND RESULTS

141 patients with dual-chamber permanent pacemaker implanted for iCAVB and 140 age- and sex-matched subjects were included in this study. The WBV values of the study groups were compared in both high shear rate (HSR) and low shear rate (LSR). Both WBV at HSR and WBV at LSR were significantly higher in the iCAVB group compared to the control group (16.11 [15.14-16.89] vs 14.40 [13.62-15.58]; 39.82 [17.43-55.23] vs 1.38 [-13.14-26.73]; p < 0.001, respectively). The patient population was followed up for an median of 38 months for all-cause mortality. Higher mortality rates were found in higher WBV at HSR and WBV at LSR (p < 0.001,for both).

CONCLUSIONS

In this study, WBV was found to be an independent predictor for iCAVB, and in these patients WBV was associated with poor clinical outcomes.

The predictive value of MAPH score for determining thrombus burden in patients with non-ST segment elevation myocardial infarction

Background

A high thrombus burden has been connected with poor clinical events in patients with non-ST segment elevation myocardial infarction (NSTEMI). In patients with STEMI, a high MAPH score has been associated with a large thrombus burden. However, the predictive value of the MAPH score in determining the thrombus burden in patients with NSTEMI is unclear. The present report aimed to evaluate the prognostic role of the MAPH score in the estimating coronary thrombus burden in NSTEMI patients. The study patients were split into two groups according to their thrombus grade. The low shear rate (LSR) and high shear rate (HSR) were estimated by haematocrit levels and serum total protein levels. The MAPH score was calculated by adding mean platelet volume (MPV) levels and age, in addition to total protein and haematocrit.

Results

The patients with a high thrombus burden (HTB) had a higher LSR, higher HSR and higher MAPH score compared to patients with low thrombus burden. MAPH score was found to be an independent predictors of HTB in Model 1 (OR: 1.124, 95% CI: 1.011–1.536; p = 0.039) and Model 2 (OR: 1.236; 95% CI: 1.002–1.525; p = 0.047). The cut-off value of the MAPH score for predicting HTB was 2 based on the Youden index.

Conclusions

The MAPH score, which calculated by adding MPV levels and age, in addition to total protein and haematocrit, is a novel, easily accessible score. The MAPH score at both LSR and HSR was an independent predictor of HTB.

The effect of whole blood viscosity on contrast-induced nephropathy development in patients undergoing percutaneous coronary intervention

OBJECTIVE

In our study, we aimed to investigate how whole blood viscosity (WBV) affects the development of contrast-induced nephropathy (CIN) in patients undergoing percutaneous coronary intervention (PCI).

METHODS

In our study, 500 patients who applied to the cardiology clinic and underwent PCI for elective procedure, ST segment elevation myocardial infarction (STEMI), and non-STEMI were prospectively included. Before the procedure, we calculated WBV using the formula [(0.12× hematocrit) + (0.17×(total protein - 2.07)]. We defined CIN as the absolute (≥0.5 mg/dl) or relative increase (≥25%) in serum creatinine 48-72 h after exposure to a contrast agent compared with baseline serum creatinine values.

RESULTS

CIN was developed in 69 (13.6%) of the 500 patients in the study. PCI was performed in 206 patients (41.2%) electively, 175 (35%) due to non-STEMI, and 119 (23%) due to STEMI. CIN was observed in 20.2% of the STEMI group, 13.7% of the non-STEMI group, and 10.2% of the elective PCI group. Multivariate logistic regression analysis results show that the independent predictors of CIN are low ejection fraction [OR:0.95 (95% CI:0.92-0.97); p < 0.001], low glomerular filtration rate [OR:0.96 (95% CI:0.95-0.98); p < 0.001], and increased amount of contrast agent [OR:1.008 (95% CI:1.004-1.01); p < 0.001]. When all patients were examined, no significant relationship was found between WBV and CIN. However, in the subgroup evaluation, it was concluded that low WBV was an independent predictor in elective PCI patients [OR:0.60 (95% CI:0.36-0.99); p = 0.04] for CIN.

CONCLUSION

We found that low WBV was an independent predictor of CIN in patients undergoing elective PCI(NCT04703049).

Association of whole blood viscosity with thrombus presence in patients undergoing transoesophageal echocardiography

Whole blood viscosity (WBV) is considered as a reasonable proxy measure of blood flow, and it has been investigated in different cohort settings, including in patients with deep venous thrombosis, arterial thrombosis, acute stent thrombosis, and left ventricular apical thrombus formation following acute coronary syndrome. To determine the association between WBV and the presence of thrombus in the left atrium (LA) or left atrial appendage (LAA) in individuals who had transoesophageal echocardiography (TEE). The clinical data from 262 consecutive patients who had TEE at our facility were included in this retrospective cohort study. WBV was determined at both a high shear rate (HSR) and low shear rate (LSR) using hematocrit and total protein levels. In 22 cases (8.3%), the thrombus was detected. According to multivariable analyses, WBV at HSR and LSR were independently linked with thrombus detection in TEE. In a receiver operating characteristic (ROC) analysis, the area under curve (AUC) values of WBV at HSR and LSR were 0.77 and 0.76, respectively. To predict the presence of thrombus in TEE; the ideal value of WBV at HSR was > 16.6 with 81% sensitivity and 69% specificity and the ideal value of WBV at LSR was > 51.4 with 81% sensitivity and 70% specificity. This was the first study to indicate that significantly higher levels of WBV at both the HSR and LSR were linked to the presence of thrombus in the LA and LAA in cases who underwent TEE.

Age variation in blood pressure: Rural-urban and sex differences among the Hmar adults of Manipur, Northeast India

BACKGROUND

Increase in blood pressure (BP) is thought to be an unavoidable consequence of ageing but in secluded communities and in rural areas this is not the case.

AIMS

The present study aims to examine blood pressure response with age across place of residence and sex; the prevalence of hypertension in relation to place of residence and sex; and to find out the relative importance of biological and behavioural factors as risk factors for hypertension among the Hmar adults (17 to 70 years of age) of Manipur, Northeast India.

MATERIALS AND METHODS

A cross-sectional sample was collected on 1207 Hmars adults residing in rural and urban settings in Manipur, Northeast India. Demographic data, blood pressure, height, weight and behavioural factors were collected.

RESULTS

Blood pressure significantly increases with an increasing age and this trend is more pronounced in urban settings compared to rural settings. The overall prevalence of hypertension in the present study is about 21 per cent. Urban Hmar males, rural and urban Hmar females who are ≥ 45 years of age show significantly higher risk of developing hypertension compared to their counterparts who are < 45 years of age, but the same is not observed in Hmar males from rural areas. Males show significantly higher odds of developing hypertension compared to females in both the settings. Obesity is the strongest predictor of hypertension in both the place of residence and sexes.

DISCUSSION AND CONCLUSION

The present study confirms that population blood pressure does not show a marked increase with increasing age in traditional/rural areas which is clearly perceptible in Hmar men. It also strengthen the case that urban residence, men, increasing age and overweight and/or obese significantly increases the odds of developing hypertension.

The Fibrinogen-to-Albumin Ratio Is Associated With Outcomes in Patients With Coronary Artery Disease Who Underwent Percutaneous Coronary Intervention

Coronary artery disease (CAD) is a systemic chronic inflammatory disease, and serum fibrinogen and albumin are 2 important factors in systemic inflammation. We aimed to investigate the relationship between the fibrinogen–albumin ratio (FAR) and outcomes in patients with CAD who underwent percutaneous coronary intervention (PCI). All patients were from the Clinical Outcomes and Risk Factors of Patients with Coronary Heart Disease after PCI (CORFCHD-PCI) study, which is a retrospective cohort study (Identifier: ChiCTR-ORC-16010153) that includes a total of 6050 patients with CAD after PCI from January 2008 to December 2016. A total of 5829 patients with CAD after PCI were recruited in the present study. They were divided into 2 groups according to the FAR cutoff value, which was calculated using a receiver operating characteristic curve, a low group (FAR < 0.095, n = 3811), and a high group (FAR ≥ 0.095, n = 2018). The average follow-up time was 35.9 ± 22.6 months. The multivariate Cox proportional hazards model showed that FAR was independently correlated with all-cause mortality (adjusted hazard ratio [HR] = 1.432 [1.134-1.808], P = .003), cardiac mortality (adjusted HR = 1.579 [1.218-2.047], P = .001), major adverse cardiac and cerebrovascular events (adjusted HR = 1.296 [1.125-1.494], P < .001), major adverse cardiac events (adjusted HR = 1.357 [1.170-1.572], P < .001), and heart failure (adjusted HR = 1.540 [1.135-2.091], P = .006). The present study indicated that the FAR was associated with adverse outcomes in patients with CAD who underwent PCI.

Whole blood viscosity in the evaluation of thrombogenic milieu in mitral stenosis

Aim: We aimed to assess the association of whole blood with thromboembolic milieu in significant mitral stenosis patients. Methodology & results: We included 122 patients and classified patients into two groups as having thrombogenic milieu, thrombogenic milieu (+), otherwise patients without thrombogenic milieu, thrombogenic milieu (-). Whole blood viscosity (WBV) in both shear rates were higher in thrombogenic milieu (+) group comparing with thrombogenic milieu (-). WBV at high shear rate and WBV at low shear rate parameters were moderately correlated with grade of spontaneous echo contrast. Adjusted with other parameters, WBV parameters at both shear rates were associated with presence of thrombogenic milieu. Discussion & conclusion: We found that extrapolated WBV at both shear rates was significantly associated with the thrombogenic milieu in mitral stenosis. This easily available parameter may provide additional perspective about thrombogenic diathesis.

Whole blood viscosity predicts nondipping circadian pattern in essential hypertension

Aim: We aimed to investigate the association between whole blood viscosity (WBV) and nondipping pattern in patients with essential hypertension. Materials & methods: A total of consecutive 530 patients who had been evaluated by ambulatory blood pressure monitoring were included. WBV was estimated by using hematocrit and plasma total protein levels for both WBV in low shear rate (0.5 s-1) and WBV in high shear rate (208 s-1) according to the de Simone’s formula. Results: In the multivariate analysis, low shear rate and high shear rate of WBV were associated independently with nondipping pattern in patients with essential hypertension. Conclusion: As a simple, inexpensive and noninvasive tool, WBV seems to be a significant predictor of nondipping hypertension.

Usefulness of whole blood viscosity estimated by de Simeone's formula to predict left ventricular thrombus formation within one year following acute anterior myocardial infarction

BACKGROUND

Despite improvements in treatment of ST-segment myocardial infarction (STEMI), thrombus formation in the left ventricle is still a concerning complication that may lead to systemic thromboembolism and stroke.

OBJECTIVES

To evaluate the predictive value of estimated whole blood viscosity (WBV) for left ventricular thrombus development in patients surviving an acute anterior myocardial infarction (AAMI).MATERIALS \& METHODS:Seven hundred eighty AAMI patients who were treated percutaneously were enrolled consecutively. Serial echocardiographic examinations were performed within 24h of admission, before hospital discharge, and at 1, 3, 6 and 12 months following hospital discharge. WBV was calculated according to de Simones formula.

RESULTS

One hundred patients (12.8%) developed thrombus formation within one year following AAMI. Patients with left ventricular thrombus (LVT) had significantly higher WBV values. Supramedian values of WBV at both low (0.5 sec-1) and high (208 sec-1) shear rates were found to be an independent predictor of LVT development.

CONCLUSION

As an easily accessible parameter, WBV might be a useful predictor of LVT formation within one year following acute anterior myocardial infarction.

Whole blood viscosity in microvascular angina and coronary artery disease: Significance and utility

INTRODUCTION AND OBJECTIVES

Whole blood viscosity (WBV) is the intrinsic resistance of blood flow in vessels, and when elevated induces endothelial shear stress and endothelial inflammation and can accelerate the atherosclerotic process. This study aims to compare WBV levels in patients with microvascular angina (MVA), patients with coronary artery disease (CAD), and normal controls, and to identify the relationship between WBV and high-sensitivity C-reactive protein as a marker of inflammation in MVA and CAD.

METHODS

A total of 573 patients were studied. The MVA group consisted of 189 subjects, the CAD group consisted of 203 subjects, and the control group consisted of 181 age- and gender-matched individuals. WBV was calculated from hematocrit and plasma protein concentration at a low shear rate (0.5 s^-1) and high shear rate (208 s^-1) by a validated equation.

RESULTS

Patients with CAD and MVA had significantly higher WBV at both low and high shear rates compared to the control group. Correlation analysis revealed a significant relationship between high-sensitivity C-reactive protein and WBV at low (r=0.556; p<0.001) and high shear rates (r=0.562) in the CAD group and at low (r=0.475) and high shear rates (r=0.493) in the MVA group.

CONCLUSIONS

Overall, this study demonstrated a significant and independent association between blood viscosity and the existence of endothelial inflammation and the atherosclerotic process.

Relationship between apical thrombus formation and blood viscosity in acute anterior myocardial infarction patients

Aim: This study sought to investigate the predictive value of whole blood viscosity (WBV) to identify high-risk patients who will develop an apical thrombus during the acute phase of anterior transmural infarction. Materials & methods: Consecutive 1726 patients with first acute anterior myocardial infarction were evaluated. WBV was calculated according to the Simone’s formula. Results: Patients with an apical thrombus had prolonged pain to balloon time, higher rate of post-PCI thrombolysis in myocardial infarction flow ≤1 and significantly higher mean WBV values at both shear rates than those without an apical thrombus. Conclusion: WBV values at both shear rates were found to be significant and independent predictors for early LV apical thrombus formation complicating a first-ever anterior wall myocardial infarction.

Usefulness of the whole blood viscosity to predict stent thrombosis in ST-elevation myocardial infarction

Aim: This study sought to investigate the predictive value of estimated whole blood viscosity (WBV) for stent thrombosis (ST) in ST-elevation myocardial infarction (STEMI) patients who underwent percutaneous coronary intervention. Materials & methods: A total of 1720 STEMI patients treated with primary percutaneous coronary intervention were followed up for median 36.0 months. WBV was calculated according to the Simone's formula. Results: During follow-up period, 119 patients were diagnosed as 'definite' ST. The rate of ST was significantly higher in the high WBV group. In multivariate analysis, adjusted for other factors, higher WBV significantly increased risk of ST at both shear rates. Conclusion: Being an easily accessible and costless parameter, WBV seems to be an emerging predictor of ST in patients with STEMI.

GWAS and PheWAS of red blood cell components in a Northern Nevadan cohort

In this study, we perform a full genome-wide association study (GWAS) to identify statistically significantly associated single nucleotide polymorphisms (SNPs) with three red blood cell (RBC) components and follow it with two independent PheWASs to examine associations between phenotypic data (case-control status of diagnoses or disease), significant SNPs, and RBC component levels. We first identified associations between the three RBC components: mean platelet volume (MPV), mean corpuscular volume (MCV), and platelet counts (PC), and the genotypes of approximately 500,000 SNPs on the Illumina Infimum DNA Human OmniExpress-24 BeadChip using a single cohort of 4,673 Northern Nevadans. Twenty-one SNPs in five major genomic regions were found to be statistically significantly associated with MPV, two regions with MCV, and one region with PC, with p<5x10^-8. Twenty-nine SNPs and nine chromosomal regions were identified in 30 previous GWASs, with effect sizes of similar magnitude and direction as found in our cohort. The two strongest associations were SNP rs1354034 with MPV (p = 2.4x10^-13) and rs855791 with MCV (p = 5.2x10^-12). We then examined possible associations between these significant SNPs and incidence of 1,488 phenotype groups mapped from International Classification of Disease version 9 and 10 (ICD9 and ICD10) codes collected in the extensive electronic health record (EHR) database associated with Healthy Nevada Project consented participants. Further leveraging data collected in the EHR, we performed an additional PheWAS to identify associations between continuous red blood cell (RBC) component measures and incidence of specific diagnoses. The first PheWAS illuminated whether SNPs associated with RBC components in our cohort were linked with other hematologic phenotypic diagnoses or diagnoses of other nature. Although no SNPs from our GWAS were identified as strongly associated to other phenotypic components, a number of associations were identified with p-values ranging between 1x10^-3 and 1x10^-4 with traits such as respiratory failure, sleep disorders, hypoglycemia, hyperglyceridemia, GERD and IBS. The second PheWAS examined possible phenotypic predictors of abnormal RBC component measures: a number of hematologic phenotypes such as thrombocytopenia, anemias, hemoglobinopathies and pancytopenia were found to be strongly associated to RBC component measures; additional phenotypes such as (morbid) obesity, malaise and fatigue, alcoholism, and cirrhosis were also identified to be possible predictors of RBC component measures.

Blood Pressure and Haematological Indices in Twelve Communities in Ashanti, Ghana

Hypertension is the most important risk factor for cardiovascular mortality and morbidity in Sub-Saharan Africa. In western populations, high haemoglobin levels are associated with raised BP unlike in Sub-Saharan Africa where there is a paucity of data. Our study examines the association between haematological indices with BP variables. Weight, height, BP, and whole blood indices of viscosity (Hb, haematocrit, RBC count, and MCV) were measured in 921 adults (340 men, 581 women; aged 40-75) in 12 communities in Ghana. Mean values for Hb (12.3 g/dl ± 1.7 SD), haematocrit (36.7% ± 5.2), RBC (4.10 million/μL ± 0.64), and MCV were lower than reference values used in Sub-Saharan Africa. Mean BMI was 21.1 ± 4.1 indicating a lean population. Systolic BP increased by 1.0 mmHg (95% CI 0.5-1.5), p < 0.001, for women and 0.5 (0.1-1.0), p = 0.027, for men per unit increase in haematocrit. Similar relationships were found for Hb and RBC but not for MCV or platelets. The relationships were weaker when adjusted for BMI, 0.7 mmHg (0.2-1.2) in women and 0.5 (0.0-1.0) in men. Findings for diastolic BP were similar. Overall haematological indices were low. We have found a significant, positive relationship between BP, Hb, Haematocrit, and RBC count in our population.

Relationship between Personality Traits and Blood Viscosity

Personality characteristics have been linked to various health outcomes. Personality characteristics and rheological parameters have been found to be independent correlates of cardiovascular diseases. The present study aimed to explore the possible relationship between the two independent factors, personality characteristics (Big Five traits and Type A behaviour pattern) and rheological parameters (blood viscosity, plasma viscosity and red cell rigidity), and it was expected that the factors would be positively correlated to each other. The study was conducted on the sample of 68 healthy young adults. Personality assessments and biomedical analysis of the blood sample of participants were carried out to test the possible correlates. Descriptive statistics and Pearson correlation analysis did not show any significant relationship between the factors. The findings indicate that personality characteristics and changes in rheological factors are independent of each other, and hence rheological parameters do not explain the relationship between personality and cardiovascular disease. Limitation and implications of the study are discussed.

Prognostic significance of whole blood viscosity estimated by de Simone’s formula in ST-elevation myocardial infarction

Background: We assessed the predictive value of estimated whole blood viscosity (WBV) in-hospital and long-term cardiovascular outcomes in patients with ST-elevation myocardial infarction (STEMI). Materials & methods: One thousand eight hundred and thirty-five STEMI patients were followed up for median 34.6 months. WBV was calculated consistent with the de Simone’s formula. Results: In-hospital and long-term major adverse cardiovascular events (MACE) demonstrated an incremental trend in ascending order of WBV tertiles at low and high shear rate. Kaplan–Meier analysis showed a higher occurrence of long-term MACE in third WBV tertiles compared with other tertiles. Conclusion: WBV seems to be a feasible prognostic indicator of short- and long-term cardiovascular adverse events in patients with STEMI. As an easily available parameter, WBV may be utilized in identifying high-risk patients for subsequent MACE.

The Relationship Between Plasma Whole Blood Viscosity and Cardiovascular Events in Patients With Chronic Kidney Disease

BACKGROUND

Plasma levels of estimated whole blood viscosity (eWBV) have been increased by endothelial inflammation. Because there were no consistent data for assessing the eWBV levels for prediction of cardiovascular event (CVE) in patients with chronic kidney disease (CKD). We aimed to investigate the relationship between plasma eWBV levels and CVEs in patients with CKD.

MATERIALS AND METHODS

We conducted a prospective, cross-sectional, long-term follow-up study, assessing the relationship between plasma eWBV levels and CVE (either fatal or nonfatal) in patients with newly diagnosed CKD. We also evaluated estimated glomerular filtration rate (eGFR), pentraxin 3 (PTX3), high-sensitivity C-reactive protein (hsCRP), and flow-mediated dilatation (FMD).

RESULTS

Study patients were divided into 2 groups: patients with CVE and patients without CVE. The eWBV levels were higher in patients with CVE. Additionally, PTX3 and hsCRP were higher, and FMD and eGFR were lower in patients with CVE compared to those without CVE. According to the Cox regression analysis, WBV, plasma asymmetric dimethylarginine levels, FMD, hsCRP, eGFR, systolic blood pressure, calcium, and history of diabetes were independent predictors of CVEs in patients with CKD. Kaplan Meier survival curves were generated to establish the impact of the WBV on the cumulative survival of the cohort. Patients with eWBV values higher than 5.2 centipoise (cP) had lower survival rates when compared to patients with eWBV values lower than 5.2 cP (log rank = 4.49 df = 1 P = .034).

CONCLUSION

In conclusion, plasma eWBV levels may increase the presence of lower eGFR and affect CVE in patients with CKD independent of classical and unconventional risk factors.

Smoking and Intracranial Aneurysm Morphology

BACKGROUND

Smoking is a well-known independent risk factor for both aneurysm formation and rupture. There is mounting evidence that aneurysm morphology beyond size can have a significant role in aneurysm formation and rupture risk by its effects on aneurysmal hemodynamics.

OBJECTIVE

To study the variation in aneurysm morphology between smokers and nonsmokers and delineate how changes in these factors might affect aneurysm formation and rupture.

METHODS

We generated 3-dimensional models of aneurysms and their surrounding vasculature by analyzing preoperative computed tomography angiograms with Slicer software. We then examined the association between smoking status and intrinsic, transitional, and extrinsic aspects of aneurysm morphology in both univariate and multivariate statistical analyses.

RESULTS

From 2005 to 2013, 199 cerebral aneurysms in never smokers and current smokers were evaluated/treated at a single institution with available computed tomography angiograms (102 in never smokers and 97 in current smokers). Multivariate analysis of current smokers vs never smokers demonstrated that aneurysms in current smokers were significantly associated with multiple aneurysms (odds ratio [OR]: 2.15, P = .03), larger daughter vessel diameters (OR: 3.13, P = .01), larger size ratio (OR: 1.78, P = .01), and location at the basilar apex (OR: 6.26, P = .02).

CONCLUSION

The differences in aneurysm morphology between smoking and nonsmoking patient populations may elucidate the effects of smoking on aneurysm formation and eventual rupture. We identified several aspects of aneurysm morphology significantly associated with smoking status that may provide the morphological basis for how smoking leads to increased aneurysm rupture.

An overlooked parameter in coronary slow flow phenomenon: whole blood viscosity

Aims: We aimed to assess the relationship between coronary slow flow phenomenon (CSFP) and whole blood viscosity (WBV). Materials & methods: Two hundred patients with CSFP and 200 subjects with normal coronary arteries as control group were enrolled. WBV was calculated from hematocrit and plasma protein concentration at low shear rate (LSR) (0.5 s-1) and high shear rate (HSR) (208 s-1) by a validated equation. Results: CSFP patients had significantly higher WBV for LSR and HSR. The mean corrected TIMI frame count was highest in the highest tertile group for both shear rates. Corrected TIMI frame count revealed a significant relationship with WBV for LSR (r = 0.562) and HSR (r = 0.611). At multivariate analysis, WBV at LSR and HSR were independent predictors of CSFP. Conclusion: WBV seemed to have a significant and an independent predictor of CSFP.

Elevated whole blood viscosity is associated with insulin resistance and non-alcoholic fatty liver

BACKGROUND

Accumulating evidences demonstrate that abnormalities in whole blood viscosity (WBV) have been implicated in insulin resistance which may lead to non-alcoholic fatty liver disease (NAFLD). However, epidemiological studies exploring the association between WBV and NAFLD were not available.

OBJECTIVE

Our objective was to evaluate the association between WBV levels and risk of prevalent NAFLD.

DESIGN

This was a cross-sectional population-based study performed in Shanghai, China.

PATIENTS

A total of 8673 participants aged 40 years or older were included.

MEASUREMENTS

WBV was calculated from haematocrit and plasma protein concentration, at a shear rate of 208(-1) s, by a validated equation. NAFLD was diagnosed by hepatic ultrasound after the exclusion of alcohol abuse and other liver diseases. Insulin resistance (IR) was assessed by homeostasis model assessment (HOMA-IR).

RESULTS

The overall prevalence of NAFLD was 30·2% in this population. With the increase of WBV level, participants have larger waist circumference (WC), more severe insulin resistance and the prevalence of NAFLD increased significantly with elevated WBV quartiles. Compared with those in the lowest quartiles, adults in the highest quartile of WBV levels have higher prevalence of NAFLD (adjusted odds ratio 1·77, 95% confidence interval [CI] 1·48-2·13) and IR (2·72, 95% CI 2·26-3·27).

CONCLUSIONS

Elevated WBV is associated with prevalence of NAFLD and IR in middle-aged and elderly Chinese population.

Coronary slow flow phenomenon: Not only low in flow rate but also in myocardial energy expenditure

BACKGROUND AND AIM

Coronary slow flow phenomenon (CSFP) is a miscellaneous clinical entity leading to angina-like symptoms, and electrocardiographic and scintigraphic evidence of ischemia. The impact of this syndrome on myocardial performance has not been comprehensively evaluated. In this study, we sought to evaluate the myocardial energy expenditure (MEE) in patients with CSFP and its relationship with exercise capacity.

METHODS AND RESULTS

A total of 64 patients (64.1% male, mean age 53.2 ± 10.3 years) with CSFP and 64 patients (60.9% male, mean age 52.2 ± 10.9 years) with normal coronary artery as control group were included. MEE was calculated by a validated formula that uses transthoracic echocardiography (TTE) parameters, including left ventricular circumferential end-systolic stress, stroke volume, and ejection time CSFP patients had significantly lower MEE (0.79 cal/systole ± 0.15 vs. 0.91 cal/systole ± 0.09, p < 0.001). In correlation analysis, MEE had a significant negative correlation with mean corrected TIMI frame count (mTFC) (β = -0.523; p < 0.001) and positive correlations with metabolic equivalents (METs) (β = 0.560; p < 0.001), rate pressure product (β = 0.649; p < 0.001), and exercise duration (β = 0.408; p < 0.001). At multivariate analysis, MEE was demonstrated as an independent predictor of CSFP (OR 1.863, CI 95% 1.485-2.338 p < 0.001).

CONCLUSION

Myocardial energy consumption, as a calculation obtained from TTE parameters, was reduced in patients with CSFP, and it had a significant relationship with exercise capacity. Considering its significant correlation with exercise capacity, myocardial energy consumption seemed to use evaluation of myocardial performance and functional status in another cardiovascular disease.

The distribution of whole blood viscosity, its determinants and relationship with arterial blood pressure in the community: cross-sectional analysis from the Gutenberg Health Study

Background:

Blood viscosity has a role in modulating cardiovascular homeostasis; changes in this parameter have been associated with cardiovascular mortality and morbidity. However, it remains unclear whether these changes are (1) involved in the pathophysiology of disease, (2) an epiphenomenon, or (3) the expression of counterregulatory mechanisms. We report data on the normal values of blood viscosity and its association with cardiovascular risk factors, prevalent cardiovascular disease, and blood pressure in a large population-based cohort study.

Methods and results:

Viscosity was calculated using validated formulae and its associations were explored in 15,010 participants (mean 55.0, min–max: 35–74 years old; 49.5% women) from the Gutenberg Health Study as well as in a subgroup of 3223 subjects (61.1% women, mean age 49.2, min–max 35–74 years old) without risk factors or self-reported cardiovascular disease. Age- and gender-adjusted mean values for viscosity were defined. Regression models showed a relationship between classical risk factors and blood viscosity measures; the overall R2 of the multiple linear regression model was however as low as 0.067 and 0.049 for high and low shear stress viscosity, respectively. After correction for cardiovascular risk factors, there was a very mild association between viscosity and prevalent coronary artery disease and heart failure. Systolic, mean and diastolic blood pressure increased with increasing blood viscosity after correction for age and gender.

Conclusions:

We provide reference values for viscosity in a population-based cohort. Blood viscosity decreases in older subjects and shows a very mild association with cardiovascular risk factors and prevalent disease in our cohort. There is a linear positive association between viscosity and blood pressure.

The Forgotten Variable of Shear Stress in Mitral Annular Calcification: Whole Blood Viscosity

OBJECTIVE

The aim of this research was to assess the relationship between mitral annular calcification (MAC) and whole blood viscosity (WBV).

SUBJECTS AND METHODS

A total of 184 patients with MAC and 133 patients without MAC were enrolled in the study. The WBV was calculated with a confirmed formulation using the hematocrit and total plasma protein at a low shear rate (LSR) and high shear rate (HSR). Early diastolic mitral annular velocity (Ea) and late diastolic mitral annular velocity (Aa) were measured using pulse Doppler tissue echocardiography. Pearson's correlation analysis was performed to assess the relationship between WBV and mitral annular motion velocities. The effects of different variables on the occurrence of MAC were assessed in univariate and multivariate logistic regression analysis.

RESULTS

In patients with MAC, WBV values were significantly higher at HSR (18.04 ± 0.84 vs. 17.25 ± 0.96 208 s(-1), p < 0.001) and at LSR (78.0 ± 14.2 vs. 61.9 ± 17.1 0.5 s(-1), p < 0.001). The WBV at HSR and LSR were significantly correlated with Ea (r = -0.477, p < 0.001; r = -0.385, p < 0.001, respectively) and Aa (r = -0.544, p < 0.001; r = -0.323, p < 0.001, respectively). Multivariate analysis showed that WBV of both shear rates was an independent predictor of MAC. Using the ROC curve, a cut-off value of 70.1 for WBV at LSR had a sensitivity of 83.7% and a specificity of 73.7% (AUC 0.785, p < 0.001) and a WBV cut-off value of 17.5 at HSR had a sensitivity of 79.6% and a specificity of 71.4% (AUC 0.761, p < 0.001) for the prediction of MAC.

CONCLUSION

Patients with MAC had significantly higher WBV, which independently predicted the presence of MAC. WBV had an inverse correlation with mitral annular motion velocities, indicating that a higher WBV may lead to greater limitation in annular motion and, thus, more calcification.

Association of hemoglobin levels with blood pressure and hypertension in a large population-based study: the Korea National Health and Nutrition Examination Surveys 2008-2011

BACKGROUND

We investigated the association of hemoglobin (Hb) concentrations with blood pressure (BP) and hypertension in the full range of Hb concentrations, after adjusting for other hypertension risk factors.

METHODS

The study population consisted of a total of 20,076 subjects (8721 men, 11,355 women) aged ≥20 y who participated in the Korea National Health and Nutrition Examination Surveys conducted between 2008 and 2011.

RESULTS

The systolic BP (SBP) and diastolic BP (DBP) increased by 2.6mmHg and 3.2mmHg with 1mmol/l increase in the Hb concentration, respectively, after adjusting for age, body mass index, total cholesterol, alcohol drinking, current smoking, mild renal dysfunction, and diabetes mellitus both in men with Hb concentrations of ≥8.1mmol/l (13.0g/dl) and women with a hemoglobin concentration ≥6.8mmol/l (11.0g/dl). In the multiple logistic regression analysis, the Hb concentration showed significant positive association with hypertension independently of other confounding factors both in men and women.

CONCLUSIONS

Hb concentration was positively associated with SBP and DBP in men with Hb concentrations ≥8.1mmol/l (13.0g/dl) and women with Hb concentrations ≥6.8mmol/l (11.0g/dl) in the general Korean population.

Influence of serological factors and BMI on the blood pressure/hematocrit association in healthy young men and women

The association between mean arterial blood pressure (MAP) and hematocrit (Hct) as a surrogate for blood viscosity was investigated in a young (average 20.0±2.3 years), healthy population of 174 men and 442 women. Health status was assessed by clinical examination and serological evaluation. Individuals with severe anemia or hemoconcentration, prior traumas or major surgical intervention, smokers, and pregnant or lactating women were excluded from the study. The MAP/Hct association was positive and significant (P=0.04) for women and negative, albeit not significantly so, for men. The MAP/Hct association was also evaluated in subgroups of the same population with a progressive step-by-step exclusion of: individuals with cholesterol >200 mg/dL; triglycerides >200 mg/dL; body mass index >25 kg/m(2); and glucose >100 mg/dL. This consecutively reduced the strength of the positive MAP/Hct association in women, which became negative - although not significantly so - when all anomalously high factors were excluded. The same trend was found in men. Our study indicates that previously reported positive trends in the relationship between the MAP and Hct in the population are not present in a young, healthy population of men or women that excludes individuals with the confounding factors of above normal serological values and BMI.

Left ventricular geometry in obesity: Is it what we expect?

Obesity is characterized by the disproportionate growth of the components of body size, including adipose tissue and lean body mass. Left ventricular (LV) hypertrophy often develops, due to the coexistence of hemodynamic (cardiac workload) and non-hemodynamic components (including body composition and activity of visceral fat). While the hypertrophy of cardiomyocytes is produced by the hemodynamic load, through sarcomeric replication, there is a parallel growth of non-muscular myocardial components, including interstitial fat infiltration and accumulation of triglycerides in the contractile elements, which are thought to influence LV geometric pattern. Thus, pure intervention on hemodynamic load is unlikely to result in effective reduction of LV hypertrophy in obese. We review pathophysiology and prevalence of LV hypertrophy in obesity, with specific attention to LV geometric abnormalities and relations with body size.

Genetic variants that confer resistance to malaria are associated with red blood cell traits in African-Americans: an electronic medical record-based genome-wide association study

To identify novel genetic loci influencing interindividual variation in red blood cell (RBC) traits in African-Americans, we conducted a genome-wide association study (GWAS) in 2315 individuals, divided into discovery (n = 1904) and replication (n = 411) cohorts. The traits included hemoglobin concentration (HGB), hematocrit (HCT), RBC count, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC). Patients were participants in the electronic MEdical Records and GEnomics (eMERGE) network and underwent genotyping of ~1.2 million single-nucleotide polymorphisms on the Illumina Human1M-Duo array. Association analyses were performed adjusting for age, sex, site, and population stratification. Three loci previously associated with resistance to malaria—HBB (11p15.4), HBA1/HBA2 (16p13.3), and G6PD (Xq28)—were associated (P ≤ 1 × 10⁻⁶) with RBC traits in the discovery cohort. The loci replicated in the replication cohort (P ≤ 0.02), and were significant at a genome-wide significance level (P < 5 × 10⁻⁸) in the combined cohort. The proportions of variance in RBC traits explained by significant variants at these loci were as follows: rs7120391 (near HBB) 1.3% of MCHC, rs9924561 (near HBA1/A2) 5.5% of MCV, 6.9% of MCH and 2.9% of MCHC, and rs1050828 (in G6PD) 2.4% of RBC count, 2.9% of MCV, and 1.4% of MCH, respectively. We were not able to replicate loci identified by a previous GWAS of RBC traits in a European ancestry cohort of similar sample size, suggesting that the genetic architecture of RBC traits differs by race. In conclusion, genetic variants that confer resistance to malaria are associated with RBC traits in African-Americans.

Contribution of blood viscosity in the assessment of flow-mediated dilation and arterial stiffness

Flow-mediated dilation (FMD) is a non-invasive index of endothelial function. In an attempt to standardize FMD for shear stimulus, shear rate (velocity/diameter), rather than shear stress (viscosity*velocity/diameter), is commonly used as a surrogate measure, although it is limited by individual differences in blood viscosity. The purpose of this study was to determine the contribution of whole blood viscosity to FMD and other key measures of vascular function. Blood viscosity, FMD, carotid artery compliance, and carotid-femoral pulse wave velocity (cfPWV) were measured in 98 apparently healthy adults varying widely in age (18-63 years). Whole blood viscosity was not significantly correlated with FMD, cfPWV, or carotid artery compliance. Shear rate was a stronger correlate with FMD than shear stress that takes blood viscosity into account (r = 0.43 vs 0.28). No significant differences were observed between whole blood viscosity and traditional risk factors for cardiovascular disease. Age was positively correlated with cfPWV (r = 0.65, p < 0.001) and negatively correlated with FMD (r = -0.24, p < 0.05) and carotid artery compliance (r = -0.45, p < 0.01). Controlling for viscosity did not reduce the strength of these relations. These results indicate that whole blood viscosity does not significantly impact measures of vascular function and suggests that the common practice to use shear rate, rather than shear stress, in the adjustment of FMD is valid.

Blood pressure and blood viscosity are not correlated in normal healthy subjects

The relationship between blood viscosity, hematocrit (Hct), and mean arterial blood pressure (MAP) was studied in a healthy population of 91 men and 66 women with an average age of 30.6 ± 8.0 years, from the city of Victoria de Durango (1800 m elevation). In women and men, Hct values were 42.4% ± 2.9% and 47.2% ± 2.3%, blood viscosities were 4.5 ± 0.7 and 6.1 ± 1.0 cP, and MAP was 83.0 ± 6.8 and 88.0 ± 6.1 mmHg, respectively. The correlation between blood viscosity and Hct was linear and positive (r² = 0.48) and identical to that of previous studies reported in the literature when men and women are taken as a single group. Separating the data by gender yielded positive, linear correlations (r² = 0.18 and 0.10, respectively) with identical slopes, however blood viscosity for men was 1.2 cP greater than in women (P = 0.02). MAP and blood viscosity (and Hct) were not statistically associated when men and women were analyzed separately and were weakly positively correlated (r² = 0.08, P < 0.02) when treated as a group. The present results suggest that studies that show a positive correlation between MAP and blood viscosity (and Hct) do not differentiate data according to gender, or involve populations that do not compensate for increased blood viscosity and potentially increased shear stress.

Intravenous immunoglobulin increases plasma viscosity without parallel rise in blood pressure

WHAT IS KNOWN AND OBJECTIVE

Intravenous immunoglobulin (IVIg) is a commonly used therapy for autoimmune disease, but may cause chronic hypertension and thrombosis. We determined whether: (i) IVIg systematically affects blood pressure in the short term; (ii) acute changes in plasma viscosity because of IVIg correlate with blood pressure effects; (iii) effects of IVIg on acute blood pressure are related to baseline blood pressure or hypertension status and (iv) IVIg influences plasma markers of inflammation, anticardiolipin antibodies and homocysteine as additional putative prothrombotic risk factors.

METHODS

Twenty adults with autoimmune neurological disease who received a course of IVIg were evaluated immediately before and after each infusion, on every day of the course. Blood pressure, pulse and the following haematological parameters were determined: plasma viscosity, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), haematocrit, fibrinogen, interleukin-6 (IL-6), homocysteine and anticardiolipin positivity.

RESULTS

Intravenous immunoglobulin caused both acute and cumulative rises in plasma viscosity across a treatment course, but no concordant changes in blood pressure. There was also no correlation between individual blood pressure changes and viscosity, baseline blood pressure or hypertension status. Levels of IL-6 rose across the course of therapy, but the acute-phase reactants CRP and fibrinogen did not. One patient developed anticardiolipin antibodies during therapy.

WHAT IS NEW AND CONCLUSION

Individual courses of IVIg do not systematically raise blood pressure. Where IVIg is found to cause hypertension, this does not appear to be due to a direct effect of IVIg on plasma viscosity.

A genome-wide association study of red blood cell traits using the electronic medical record

Background

The Electronic Medical Record (EMR) is a potential source for high throughput phenotyping to conduct genome-wide association studies (GWAS), including those of medically relevant quantitative traits. We describe use of the Mayo Clinic EMR to conduct a GWAS of red blood cell (RBC) traits in a cohort of patients with peripheral arterial disease (PAD) and controls without PAD.

Methodology and Principal Findings

Results for hemoglobin level, hematocrit, RBC count, mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration were extracted from the EMR from January 1994 to September 2009. Out of 35,159 RBC trait values in 3,411 patients, we excluded 12,864 values in 1,165 patients that had been measured during hospitalization or in the setting of hematological disease, malignancy, or use of drugs that affect RBC traits, leaving a final genotyped sample of 3,012, 80% of whom had ≥2 measurements. The median of each RBC trait was used in the genetic analyses, which were conducted using an additive model that adjusted for age, sex, and PAD status. We identified four genomic loci that were associated (P<5×10⁻⁸) with one or more of the RBC traits (HBLS1/MYB on 6q23.3, TMPRSS6 on 22q12.3, HFE on 6p22.1, and SLC17A1 on 6p22.2). Three of these loci (HBLS1/MYB, TMPRSS6, and HFE) had been identified in recent GWAS and the allele frequencies, effect sizes, and the directions of effects of the replicated SNPs were similar to the prior studies.

Conclusions

Our results demonstrate feasibility of using the EMR to conduct high throughput genomic studies of medically relevant quantitative traits.

The variability of blood pressure due to small changes of hematocrit

The hematocrit (Hct) of awake hamsters was lowered to 90% of baseline by isovolemic hemodilution using hamster plasma to determine the acute effect of small changes in Hct and blood viscosity on systemic hemodynamics. Mean arterial blood pressure increased, reaching a maximum of about 10% above baseline (8.6 +/- 5.5 mmHg) when Hct decreased 8.4 +/- 1.9% (P < 0.005). Cardiac output increased continuously with hemodilution. These conditions were reached at approximately 60 min after exchange transfusion and remained stationary for 1 h. Peripheral vascular resistance was approximately constant up to a decrease of Hct of about 10% and then fell continuously with lowering Hct. Vascular hindrance or vascular resistance independent of blood viscosity increased by about 20% and remained at this level up to an Hct decrease of 20%, indicating that the vasculature constricted with the lowered Hct. The results for the initial 2-h period are opposite but continuous with previous findings with small increases in Hct. In conclusion, limited acute anemic conditions increase mean arterial blood pressure during the initial period of 2 h, an effect that is quantitatively similar but opposite to the acute increase of Hct during the same period.

Effects of smoking and hypertension on wall shear stress and oscillatory shear index at the site of intracranial aneurysm formation

OBJECTIVE

The mechanisms by which smoking and hypertension lead to increased incidence of intracranial aneurysm (IA) formation remain poorly understood. The current study investigates the effects of these risk factors on wall shear stress (WSS) and oscillatory shear index (OSI) at the site of IA initiation.

METHODS

Two (n=2) IAs from two patients with history of smoking and hypertension were artificially removed with the help of software @neuFuse (Supercomputing Solutions, Bologna, Italy) and the vessel geometry reconstructed to mimic the condition prior to IA formation. Two computational fluid dynamics (CFD) analyses were performed on each data-set by using in turn the normal physiological values of blood viscosity (BV), and high BV values specific to smoking and hypertension, obtained from literature.

RESULTS

At normal BV, high WSS (>15 Pa) was observed at the site of IA initiation in both patients. When BV values specific to smoking and hypertension were used, both the areas affected by high WSS (>15 Pa) and the maximum WSS were increased whilst the magnitude and distribution of OSI showed no significant change.

CONCLUSIONS

Long-term exposure to high WSS may result in an increased risk of IA development. An incremental increase in areas of high WSS observed secondary to smoking and hypertension may indicate a further increase in the risk of IA initiation. Interestingly, the relationship between BV and the area of increased WSS was not linear, reflecting the need for patient-specific CFD analysis.

Seasonal hematocrit variation and health risks in the adult population of Kinshasa, Democratic Republic of Congo

Hematocrit (Hct) as an indicator of blood viscosity and mean arterial blood pressure (MAP) were assessed according to the season in adult participants of health screenings conducted throughout Kinshasa, Democratic Republic of Congo. Data was collected at the end of summer (April) and the end of winter (August) and identified by gender. Male Hcts in August were significantly higher (P < 0.0001) than in April (48.3% ± 4.2% and 45.7% ± 2.3%, respectively) while male MAP (85.0 ± 8.4 mm Hg) was identical to that recorded in April (85.4 ± 7.7 mm Hg). August female Hcts (41.4% ± 3.1%) were statistically higher than those recorded in April (39.6% ± 1.9%, P = 0.001), MAP being 82.3 ± 7.3 vs 87.9 ± 6.6 mm Hg, respectively (P = 0.0001). Systolic and diastolic blood pressures, heart rate, body mass indices, ages, and personal and familial medical histories of the August and April groups were not significantly different. This study offers further support for the assertion that the relationship between blood viscosity and pressure of a healthy population shows that increased Hct, and therefore increased blood viscosity is associated with lowered MAP, and presumably peripheral vascular resistance.

Multiple loci influence erythrocyte phenotypes in the CHARGE Consortium

Measurements of erythrocytes within the blood are important clinical traits and can indicate various hematological disorders. We report here genome-wide association studies (GWAS) for six erythrocyte traits, including hemoglobin concentration (Hb), hematocrit (Hct), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC) and red blood cell count (RBC). We performed an initial GWAS in cohorts of the CHARGE Consortium totaling 24,167 individuals of European ancestry and replication in additional independent cohorts of the HaemGen Consortium totaling 9,456 individuals. We identified 23 loci significantly associated with these traits in a meta-analysis of the discovery and replication cohorts (combined P values ranging from 5 x 10(-8) to 7 x 10(-86)). Our findings include loci previously associated with these traits (HBS1L-MYB, HFE, TMPRSS6, TFR2, SPTA1) as well as new associations (EPO, TFRC, SH2B3 and 15 other loci). This study has identified new determinants of erythrocyte traits, offering insight into common variants underlying variation in erythrocyte measures.

Hematocrit and mean arterial blood pressure in pre- and postmenopause women

The relationship between mean arterial blood pressure (MAP) and hematocrit (Hct) was studied in pre- and postmenopause women in the city of Durango, Mexico. Premenopause women show a negative trend between parameters that is not statistically significant. MAP and Hct are directly related in postmenopause women (p < 0.01). It is proposed that that this MAP/Hct relationship is in part due to differences in endothelial function where menopause decreases the capacity of the endothelium to respond to increased blood viscosity and shears stress, leading to the increased production of vasodilator mediators to compensate for changes in blood viscosity due to changes in Hct. Comparison with a large group of postmenopause women in the city of Stockholm showed identical trends.

A multiscale model of thrombus development

A two-dimensional multiscale model is introduced for studying formation of a thrombus (clot) in a blood vessel. It involves components for modelling viscous, incompressible blood plasma; non-activated and activated platelets; blood cells; activating chemicals; fibrinogen; and vessel walls and their interactions. The macroscale dynamics of the blood flow is described by the continuum Navier-Stokes equations. The microscale interactions between the activated platelets, the platelets and fibrinogen and the platelets and vessel wall are described through an extended stochastic discrete cellular Potts model. The model is tested for robustness with respect to fluctuations of basic parameters. Simulation results demonstrate the development of an inhomogeneous internal structure of the thrombus, which is confirmed by the preliminary experimental data. We also make predictions about different stages in thrombus development, which can be tested experimentally and suggest specific experiments. Lastly, we demonstrate that the dependence of the thrombus size on the blood flow rate in simulations is close to the one observed experimentally.

Arginine, citrulline and nitrate concentrations in the cerebrospinal fluid from patients with acute hydrocephalus

Citrulline and nitric oxide (NO) are synthesized by NO synthase (NOS) in a 1:1-stoichiometry. In this study, we determined by HPLC arginine and citrulline concentrations by fluorescence detection and nitrate levels by UV absorbance detection in the cerebrospinal fluid (CSF) from patients with acute hydrocephalus that underwent ventricular drainage. We found increased citrulline concentration (50.6+/-17.2 versus 20.9+/-2.0 microM) and decreased arginine/citrulline molar ratio (0.42+/-0.11 versus 1.12+/-0.16) in hydrocephalus patients, while arginine and nitrate concentrations and citrulline/nitrate molar ratio remained with little change. Citrulline has been determined as a marker of NOS activity in some studies, but it remains to be determined the extent at which this statement holds true, since other biochemical pathways also regulate the concentration of this amino acid. Our results suggest that citrulline is primarily synthesized from NOS in acute hydrocephalus. The evaluation of sample deproteinization by addition of methanol for the analysis of amino acids in CSF is also reported.