Hemostatic function in young subjects with central obesity: relationship with left ventricular function

Reduced fibrinogen, fibrinolytic biomarkers, and physical parameters after a weight-loss program in obese subjects

Background:

Obese subjects are at risk of multiple comorbidities including stroke and coronary heart disease (CHD), which is partly due to disturbances in the hemostatic system.

Aims:

The aims of the present study were to determine the effects of a weight-loss program on fibrinogen and fibrinolytic markers.

Materials and Methods:

Twenty-eight obese subjects were involved in a weight-loss program consisted of exercise and nutritional education for 12-weeks duration. Physical parameters were documented and blood specimen was tested at pre and post-intervention for fibrinogen, tissue plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1), and thrombin activatable fibrinolysis inhibitor (TAFI). Paired t-test was used for statistical analysis.

Results:

There was a significant decline in the levels of t-PA, PAI-I, TAFI and fibrinogen following the weight-loss program (P < 0.01 for each). A significant positive correlation between tPA levels and body weight, body mass index (BMI), waist circumference, and fat-free mass were found. There was also a significant correlation betwen BMI and other blood parameters.

Conclusion:

Reduced fibrinogen, fibrinolytic, and physical parameters were demonstrated in obese subjects following the weight reduction program. These findings suggest the possible beneficial effects of this program on the hemostatic burden particularly on the fibrinolytic biomarkers.

Increased coagulation in childhood obesity

OBJECTIVE

This study aims to explore the relation between childhood obesity and procoagulant and anticoagulant systems.

METHOD

Fifty-one obese children and 32 normal-weighted children with similar age and gender distribution and between ages of 5 and 16 years were recruited to the study. Antropometric measures of all subjects, existence of any accompanying disease, and medication histories had been recorded. Full blood count, procoagulant, and anticoagulant coagulation tests were run for all subjects.

RESULTS

When hematologic variables of obese children were compared with those of healthy controls, it was found that average erythrocyte hemoglobin concentration, erythrocyte distribution width, and platelet count of obese children are significantly higher than healthy control group. It was also found that fibrinogen, thrombin time, factor (F) VIII, FIX, FX, and von Willebrand factor levels of obese children are higher than healthy control group. By contrast, antithrombin levels of obese children are found to be lower.

CONCLUSION

In our study, we found that there is a procoagulant increase in the coagulation system activity of obese children compared to non-obese healthy children, whereas there is a significant decrease in anticoagulant system. These changes occurred in obese patients, especially higher levels of plasma procoagulant factors such as fibrinogen, FVIII, FIX, and von Willebrand factor, lead us to think that there is an activity in these patients at endothelial level. Further studies are needed on endothelial activity of obese children.

Inflammatory and prothrombotic parameters in normotensive non-diabetic obese women: effect of weight loss obtained by gastric banding

Hypertension and diabetes are known risk factors for obesity-related thrombosis, but several studies have shown that obesity is characterised by a potentially prothrombotic inflammatory state because of activated coagulation and impaired fibrinolysis. In order to verify if obese patients-unaffected by hypertension, diabetes, dyslipidemia, cigarette smoking or inflammatory diseases-show increased prothrombotic markers and whether the weight loss induced by gastric banding normalises such parameters. Plasma levels of C reactive protein (CRP), fibrinogen, plasminogen activator inhibitor-1 (PAI-1), von Willebrand factor (VWF) and factor VII (FVII) were measured in 25 women with isolated obesity prior to, as well as 3, 6 and 12 months subsequent to gastric banding. Twenty-five healthy women served as a baseline control group. The obese women had higher CRP (p = 0.0001), fibrinogen (p = 0.014), PAI-1 (p = 0.003), VWF (p = 0.004) and FVII levels (p = 0.0001) than the normal controls, and their body mass index (BMI) positively correlated with CRP (r = 0.462, p = 0.02), fibrinogen (r = 0.426, p = 0.04) and PAI-1 (r = 0.468, p = 0.02). Twelve months after gastric banding, the median BMI had decreased from 40.0 to 34.9 (p = 0.0001); CRP from 4.18 to 1.69 μg/ml (p = 0.01); fibrinogen from 389 to 318 mg/dl (p = 0.0001); PAI-1 from 32.1 to 12.0 UI/ml (p = 0.003); VWF from 144 to 120% (p = 0.0001); and FVII from 134 to 112% (p = 0.002). Even in the absence of major cardiovascular risk factors, obese patients are characterised by a prothrombotic state. The weight loss induced by gastric banding decreases the parameters of inflammation, coagulation and impaired fibrinolysis, thus potentially reducing the thrombotic risk.

Nontraditional risk factors and biomarkers for cardiovascular disease: mechanistic, research, and clinical considerations for youth: a scientific statement from the American Heart Association

The rapid increase in the prevalence and severity of obesity in children is likely to lower the age of onset and increase the incidence of cardiovascular disease worldwide. Understanding the pathophysiology and improving the clinical management of cardiovascular disease involve a knowledge of novel risk factors and biomarkers. The clinical and mechanistic roles of these novel biological factors during childhood are currently being investigated. The goals of this scientific statement are to present the existing knowledge and theoretical framework of nontraditional risk factors for cardiovascular disease as they relate to children and adolescents, to describe the relevance and weight of available experimental and clinical evidence and the therapeutic implications pertaining to nontraditional risk factors in the pediatric population, and to stimulate further research with a goal of developing valid and reliable approaches to identify and validate novel risk factors that will aid in the clinical evaluation and perhaps prediction of cardiovascular disease in the pediatric population. Although several biomarkers are promising, substantial research is required before nontraditional risk factors can be used to identify and reduce cardiovascular disease risk in children and adolescents.

Visceral obesity and metabolic syndrome: two faces of the same medal?

In this review, we have analyzed the role of visceral obesity in the occurrence of metabolic syndrome (MetS). MetS is a common metabolic disorder that has been related recently to the increasing prevalence of obesity. The disorder is defined in various ways, but in the near future a new definition(s) should be applicable worldwide. The pathophysiology has been largely attributed, in the past years, to insulin resistance, although several epidemiological and pathophysiological data now indicate visceral obesity as a main factor in the occurrence of all the components of MetS. In view of this, relationships among visceral obesity, free fatty acids, dyslipidemia and insulin resistance have been reported. In addition, the effects of some adipocytokines and other proinflammatory factors produced by fat accumulation on the occurrence of MetS have been also emphasized. Accordingly, the "hypoadiponectinemia hypothesis" has been proposed as the most interesting to explain the pathophysiology of MetS. The epidemiologic, pathophysiologic and clinical data reported seem to indicate that MetS might be considered a fatal consequence of visceral obesity.

Diet and haemostatic processes

Diet plays an important role in the primary and secondary prevention of cardiovascular disease. The growing perception that abnormal haemostatic processes of coagulation, platelet aggregation and fibrinolysis contribute to cardiovascular disease aetiology motivated this review on the relationships of diet, specific foods and nutrients with haemostatic function. Functional endpoints that reflect the function and status of some of these processes and which can be measured in dietary trials are identified. The effects of energy intake and expenditure, alcohol, total fat and specific fatty acids, non-starch polysaccharides (dietary fibre), antioxidant nutrients and some foods on a variety of haemostatic markers are reviewed. The results indicate that the prudent low-fat, high-fibre diet and maintenance of ideal body weight recommended to protect against and treat hyperlipidaemia and coronary heart disease will also benefit haemostatic profiles. It is concluded that more research on specific effects is needed for improved recommendations on a population level for prevention of cardiovascular disease.

Leptin repletion restores depressed {beta}-adrenergic contractility in ob/ob mice independently of cardiac hypertrophy

Impaired leptin signalling in obesity is increasingly implicated in cardiovascular pathophysiology. To explore mechanisms for leptin activity in the heart, we hypothesized that physiological leptin signalling participates in maintaining cardiac beta-adrenergic regulation of excitation-contraction coupling. We studied 10-week-old (before development of cardiac hypertrophy) leptin-deficient (ob/ob, n=12) and C57Bl/6 (wild-type (WT), n=15) mice at baseline and after recombinant leptin infusion (0.3 mg kg-1 day-1 for 28 days, n=6 in each group). Ob/ob-isolated myocytes had attenuated sarcomere shortening and calcium transients ([Ca2+]i) versus WT (P<0.01 for both) following stimulation of the beta-receptor (with isoproterenol (isoprenaline)) or at the post-receptor level (with forskolin and dibutryl-cAMP). In addition, sarcoplasmic reticulum (SR) Ca2+ stores were depressed. Leptin replenishment in ob/ob mice restored each of these abnormalities towards normal without affecting gross (wall thickness) or microscopic (cell size) measures of cardiac architecture. Immunoblots revealed alterations of several proteins involved in excitation-contraction coupling in the ob/ob mice, including decreased abundance of Gsalpha-52 kDa, as well as alterations in the expression of Ca2+ cycling proteins (increased SR Ca2+-ATPase, and depressed phosphorylated phospholamban). In addition, protein kinase A (PKA) activity in ob/ob mice was depressed at baseline and correctable towards the activity found in WT with leptin repletion, a finding that could account for impaired beta-adrenergic responsiveness. Taken together, these data reveal a novel link between the leptin signalling pathway and normal cardiac function and suggest a mechanism by which leptin deficiency or resistance may lead to cardiac depression.

Hemostatic risk factors and insulin sensitivity, regional body fat distribution, and the metabolic syndrome

Disturbances in the thrombotic and fibrinolytic systems are a feature of insulin resistance, obesity, and the metabolic syndrome. However, there are few studies in which these relationships have been explored in mainly asymptomatic individuals using sophisticated measures of insulin sensitivity and regional adiposity. Variables of the hemostatic system were measured in 106 men (aged 32-68 yr; body mass index, 20-34 kg/m(2)). Insulin sensitivity was measured by minimal model analysis and regional adiposity by dual energy x-ray absorptiometry. Clustering of intercorrelated variables was assessed by the statistical technique of factor analysis. Plasma levels of procoagulant factors VII and X, anticoagulant proteins C and S, and plasminogen activator inhibitor-1 correlated positively with total and percent central body fat (r = 0.25-0.38; P < 0.05) and negatively with insulin sensitivity (except protein S; r = -0.24 to -0.35; P < 0.05). On factor analysis, procoagulant factors VII and X, proteins C and S, and plasminogen activator inhibitor-1 were components of the cluster of variables that explained the greatest proportion of the variance in the data (39.2%). Other variables included in this cluster were those typical of the metabolic syndrome and also serum gamma-glutamyl transferase activity. These results suggest that factors VII and X and proteins C and S are features of the intercorrelated disturbances of the metabolic syndrome. Associations with adiposity and liver enzyme activity suggest the involvement of hepatic fat deposition.

Obesity and cardiovascular risk: the new public health problem of worldwide proportions

Obesity could be considered a new global health epidemic above all others, especially when it is characterized by central fat distribution. This is illustrated by dramatic provisional data, indicating a continuous increase in the trend of overweight and obese individuals in several countries, including the USA and countries in Europe. Several epidemiological, pathophysiological and clinical studies clearly indicate that two of the major independent risk factors for cardiovascular disease or events are being overweight, and obesity. Accordingly, weight loss and prevention of weight gain has to be considered one of the most important strategies to reduce the incidence of cardiovascular disease.

Alterations in left ventricular structure and function in young healthy obese women: assessment by echocardiography and tissue Doppler imaging

OBJECTIVES

This study was designed to determine the effects of obesity on left ventricular (LV) structure and function in young obese women.

BACKGROUND

Severe prolonged obesity in older adults results in increased plasma volume, eccentric LV hypertrophy, and systolic and diastolic dysfunction. Obese women are at increased risk for the development of heart failure. However, the effects of the obesity on cardiac structure and function in young, otherwise-healthy women are controversial.

METHODS

Fifty-one women were evaluated: 20 were obese (body mass index [BMI] > or =30 kg/m(2)) and 31 were non-obese (BMI <30 kg/m(2)). Left ventricular structure and systolic and diastolic function were assessed by two-dimensional echocardiography and tissue Doppler imaging, including the load-independent systolic myocardial velocity (Sm global) and early diastolic myocardial velocity (Em global), respectively. The effects of BMI on LV structure and function were assessed using multivariate regression analyses.

RESULTS

Obese women had higher end-diastolic septal and posterior wall thickness, LV mass, and relative wall thickness than non-obese women; BMI values showed significant correlations with these variables (r = 0.58, p < 0.0001; r = 0.50, p < 0.0002; r = 0.52, p < 0.0001, and r = 0.40, p < 0.005, respectively). The Sm global and Em global were lower in obese women, suggesting systolic and diastolic function are decreased; both were negatively correlated with BMI (r = -0.43, p <. 002 and r = -0.61, p < 0.0001, respectively). Multivariate analysis showed BMI was the only independent predictor of relative wall thickness, Sm global, and Em global.

CONCLUSIONS

Obesity in young otherwise-healthy women is associated with concentric LV remodeling and decreased systolic and diastolic function. These early abnormalities in LV structure and function may have important implications for explaining the myocardial dysfunction that is associated with increased cardiovascular morbidity and mortality caused by obesity.

Weight loss reduces tissue factor in morbidly obese patients

OBJECTIVE

To investigate the tissue factor (TF) pathway in clinical obesity and associated metabolic syndrome.

RESEARCH METHODS AND PROCEDURES

Thirty-seven morbidly obese patients (4 men; BMI, 48 +/- 7 kg/m(2); range, 42 to 53 kg/m(2)), undergoing elective gastroplasty for the induction of weight loss, were examined for hemostatic, metabolic, and inflammatory parameters at baseline and 14 +/- 5 months postoperatively.

RESULTS

Weight loss significantly reduced circulating plasma TF (314 +/- 181 vs. 235 +/- 113 pg/mL, p = 0.04), coagulation factor VII (130 +/- 22% vs. 113 +/- 19%, p = 0.023), and prothrombin fragment F1.2 (2.4 +/- 3.4 vs. 1.14 +/- 1.1 nM, p = 0.04) and normalized glucose metabolism in 50% of obese patients preoperatively classified as diabetic or of impaired glucose tolerance. The postoperative decrease in plasma TF correlated with the decrease of F1.2 (r = 0.56; p = 0.005), a marker of in vivo thrombin formation. In subgroup analysis stratified by preoperative glucose tolerance, baseline circulating TF (402.6 +/- 141.6 vs. 176.2 +/- 58.2, p < 0.001) and TF decrease after gastroplasty (DeltaTF: 164.7 +/- 51.4 vs. -81 +/- 31 pg/mL, p = 0.02) were significantly higher in obese patients with impaired glucose tolerance than in patients with normal glucose tolerance.

DISCUSSION

Procoagulant TF is significantly reduced with weight loss and may contribute to a reduction in cardiovascular risk associated with obesity.

Relationship between circulating E-selectin, DD genotype of angiotensin-converting-enzyme, and cardiovascular damage in central obese subjects

Fifty-six young central obese patients were investigated to evaluate relationships between soluble E-selectin (sE-S), angiotensin-converting enzyme (ACE) gene polymorphism, left ventricular function and structure, and carotid morphology by determination of sE-S and ACE genotypes. Our results indicated that central obese subjects with concomitant higher levels of sE-S and ACE DD genotype may be characterized by early cardiovascular alterations and then considered a particular subset of subjects at higher risk of cardiovascular disease.

Risk factor clustering in the insulin resistance syndrome and its relationship to cardiovascular disease in postmenopausal white, black, hispanic, and Asian/Pacific Islander women

The aim of this study was to examine how major components of the insulin resistance (IR) syndrome relate to each other and to cardiovascular disease (CVD) in postmenopausal women in 4 ethnic groups. Baseline data from the Women's Health Initiative (WHI) on 3,083 50- to 79-year-old women (1,635 white, 802 black, 390 Hispanic, and 256 Asian/Pacific Islander) were examined. Participants underwent a personal interview and a physical examination, blood samples were drawn, and a detailed cardiovascular history was ascertained. Factor analysis was used to assess the clustering and interdependence of groups of CVD-related IR syndrome variables. Four factors were identified. An obesity factor included IR in all groups and had a significant association with CVD in white (P =.0001) and Hispanic (P =.0024) women. A dyslipidemia factor (high-density lipoprotein [HDL], triglycerides, and HDL2: total HDL ratio) also included insulin and IR and was significantly correlated with CVD in black (P=.0006) and Hispanic (P =.0217) women and had a borderline association in white women (P =.068). Total and low-density lipoprotein (LDL) cholesterol did not relate to CVD in any group. Blood pressure was related weakly to CVD in white women (P =.0434) and strongly in black women (P =.0095). Components of the IR syndrome appear to be associated with CVD in postmenopausal women, although the magnitude of these relationships differed by ethnicity.

Obesity and cardiovascular disease

Obesity is a major contributor to the prevalence of cardiovascular disease in the developed world, and yet has only recently been afforded the same level of attention as other risk factors of coronary artery disease. Obesity is a chronic metabolic disorder associated with cardiovascular disease and increased morbidity and mortality. It is apparent that a variety of adaptations/alterations in cardiac structure and function occur as excessive adipose tissue accumulates, even in the absence of comorbidities. Shifts toward a less physically demanding lifestyle are observed today throughout different populations, and this scourge associated with obesity implicates a corresponding increase in the number of individuals afflicted with the metabolic syndrome, which defines the obese patient as being "at risk." Adipose tissue is not simply a passive storehouse for fat, but an endocrine organ that is capable of synthesizing and releasing into the bloodstream a variety of molecules that may impact unfavorably the risk factor profile of a patient. Indeed, obesity may affect atherosclerosis through unrecognized variables and risk factors for coronary artery disease such as dyslipidemia, hypertension, glucose intolerance, inflammatory markers, and the prothrombotic state. By favorably modifying lipids, decreasing blood pressure, and decreasing levels of glycemia, proinflammatory cytokines, and adhesion molecules, weight loss may prevent the progression of atherosclerosis or the occurrence of acute coronary syndrome events in the obese high-risk population.

Obesity, haemostasis and the fibrinolytic system

Obese patients are at risk for the development of cardiovascular diseases, which can in part be explained by disturbances in the haemostatic and fibrinolytic systems. Indeed, obese subjects tend to have higher values of fibrinogen, factor VII, factor VIII, von Willebrand factor and plasminogen activator inhibitor compared to non-obese subjects. Abdominal obesity, in particular, has been shown to be associated with disturbances in fibrinogen, factor VIII and von Willebrand factor, while less consistent results have been found for factor VII. Recently it has been demonstrated that the adipocyte itself is able to produce plasminogen activator inhibitor-1, possibly explaining the high levels found in obesity. Different studies have investigated the association between haemostatic and fibrinolytic parameters and the insulin resistance syndrome, often present in obese subjects. Fibrinogen has been found to be related to insulin, but it has been suggested that this relationship is not independent of the accompanying inflammatory reaction. Results from studies on the relationship between insulin resistance and factor VII, factor VIII and von Willebrand factor levels are inconsistent. In contrast, plasminogen activator inhibitor-1 has been found to correlate with all components of the insulin resistance syndrome, and can be considered as a true component of this metabolic syndrome. Weight loss seems to have a beneficial effect on factor VII--probably mediated through a reduction in triglycerides. Data on factor VIII and von Willebrand factor are scarce but weight loss does not seem to have an effect. Fibrinogen does not seem to be reduced by modest weight loss and a more substantial weight loss seems necessary to lower fibrinogen levels. In contrast, both modest and substantial weight loss have been found to significantly reduce plasminogen activator inhibitor-1 levels. In conclusion, the increased cardiovascular risk observed in obesity could in part be explained by the association between insulin resistance and components of the fibrinolytic and haemostatic systems. Whether this relationship is truly causal or indirect needs to be elucidated further.

Increased synthesis rate of fibrinogen as a basis for its elevated plasma levels in obese female adolescents

Increased concentrations of plasma fibrinogen, an independent risk factor for cardiovascular disease (CVD), in obese children have been reported. The underlying mechanism for this, however, remains to be defined. In the current study, we measured the fractional synthesis rates (FSR) of plasma fibrinogen in six healthy postpubertal obese girls [body mass index (BMI) 36.6 +/- 1.8 kg/m(2); age 16.6 +/- 0.5 yr] and six age-matched lean normal control girls (BMI 20.8 +/- 0.7 kg/m(2); age 16.4 +/- 0.4 yr) during a primed, continuous infusion of L-[1-(13)C]leucine in the postabsorptive state. The method involved purification of plasma fibrinogen by use of immunoaffinity chromatography followed by measurement of [(13)C]leucine enrichment using gas chromatography-combustion-isotope ratio mass spectrometry. The FSR of fibrinogen in obese girls (35.06 +/- 2.61%/day) was almost double that in lean girls (17.02 +/- 1.43%/day), and this increase was associated with a relative increase in plasma concentration of fibrinogen as well as BMI in the subjects studied. Obese subjects had high fasting insulin levels (138 +/- 47 pmol/l) compared with lean subjects (54 +/- 11 pmol/l), whereas their glucose concentrations were similar (4.5 +/- 0.3 mmol/l in obese and 4.4 +/- 0.4 mmol/l in lean subjects), suggesting insulin resistance. The doubling of the FSR of fibrinogen provides novel insight into the mechanism of elevated levels of plasma fibrinogen and suggests a primary role for increased synthesis in producing the hyperfibrinogenemia associated with obesity. This finding may have important implications in the design of therapies for modulating plasma fibrinogen levels in obesity and/or CVD in childhood.

Regulation of tissue factor gene expression in obesity

Altered expression of proteins of the fibrinolytic and coagulation cascades in obesity may contribute to the cardiovascular risk associated with this condition. In spite of this, the zymogenic nature of some of the molecules and the presence of variable amounts of activators, inhibitors, and cofactors that alter their activity have made it difficult to accurately monitor changes in the activities of these proteins in tissues where they are synthesized. Thus, as a first approach to determine whether tissue factor (TF) expression is altered in obesity, this study examined changes in TF mRNA in various tissues from lean and obese (ob/ob and db/db) mice. TF gene expression was elevated in the brain, lung, kidney, heart, liver, and adipose tissues of both ob/ob and db/db mice compared with their lean counterparts. In situ hybridization analysis indicated that TF mRNA was elevated in bronchial epithelial cells in the lung, in myocytes in the heart, and in adventitial cells lining the arteries including the aortic wall. Obesity is associated with insulin resistance and hyperinsulinemia, and administration of insulin to lean mice induced TF mRNA in the kidney, brain, lung, and adipose tissue. These observations suggest that the hyperinsulinemia associated with insulin-resistant states, such as obesity and noninsulin-dependent diabetes mellitus, may induce local TF gene expression in multiple tissues. The elevated TF may contribute to the increased risk of atherothrombotic disease that accompanies these conditions.

Exercise in weight management of obesity

Obesity is a chronic metabolic disorder associated with CVD and increased morbidity and mortality. When the BMI is > or = 30 kg/m2, mortality rates from all causes, and especially CVD, are increased by 50% to 100%. There is strong evidence that weight loss in overweight and obese individuals improves risk factors for diabetes and CVD. Additional evidence indicates that weight loss and the associated diuresis reduce blood pressure in both overweight hypertensive and nonhypertensive individuals, reduce serum TG levels, increase high-density lipoprotein cholesterol levels, and may produce some reduction in low-density lipoprotein cholesterol concentrations. Of interest, even if weight loss is minimal, obese individuals showing a good level of cardiorespiratory fitness are at reduced risk for cardiovascular mortality than lean but poorly fit subjects. Insulin and catecholamines have pronounced metabolic effects on human adipose tissue metabolism. Insulin stimulates LPL and inhibits HSL; the opposite is true for catecholamines. There is regional variation in adipocyte TG turnover favoring lipid mobilization in the visceral fat depots and lipid storage in the peripheral subcutaneous sites. The hormonal regulation of adipocyte TG turnover is altered in obesity and is most marked in central obesity. There is resistance to insulin stimulation of LPL; however, LPL activity in fasted obese subjects is increased and remains so following weight reduction. Catecholamine-induced lipolysis is enhanced in visceral fat but decreased in subcutaneous fat. Numerous adaptive responses take place with physical training. These adaptations result in a more efficient system for oxygen transfer to muscle, which is now able to better utilize the unlimited lipid stores instead of the limited carbohydrate reserves available. In addition, the reduced adipose tissue mass represents an important mechanical advantage, allowing better long-term work. Gender differences have been reported in the adaptation of adipose tissue metabolism to aerobic exercise training. Physical training helps counteract the permissive and affluent environment that predisposes reduced-obese subjects to regain weight. An exercise program using weight resistance modalities may also be included safely, and it improved program retention in a multidisciplinary weight management program that was designed for obese children. Thirty to 45 minutes of physical activity of moderate intensity, performed 3 to 5 days a week, should be encouraged. All adults should set a long-term goal to accumulate at least 30 minutes or more of moderate-intensity physical activity on most, and preferably all days. Public health interventions promoting walking are likely to be the most successful. Indeed, walking is unique because of its safety, accessibility, and popularity. It is noteworthy that there is a clear dissociation between the adaptation of cardiorespiratory fitness and the improvements in the metabolic risk profile that can be induced by endurance training programs. It appears that as long as the increase in energy expenditure is sufficient, low-intensity endurance exercise is likely to generate beneficial metabolic effects that would be essentially similar to those produced by high-intensity exercise. The clinician should therefore focus on the improvement of the metabolic profile rather than on weight loss alone. Realistic goals should be set between the clinician and the patient, with a weight loss of approximately of 0.5 to 1 pound per week. It should be kept in mind that since it generally takes years to become overweight or obese, a weight loss pattern of 0.5 or 1 pound per week will require time and perseverance to reach the proposed target. However, the use of physical activity as a method to lose weight seems inversely related to patients' age and BMI and directly related to the level of education. Thus, public health interventions helping these groups to become physically active remain a challenge and further emphasize the importance of the one-on-one interaction between the clinician/health care professional with the obese individual "at risk" of CVD. This notion is critical, as it has been shown that less than half of obese adults have reported being advised to lose weight under the guidance of health care professionals.

Obesity cardiomyopathy: pathophysiology and evolution of the clinical syndrome

Obesity produces an increase in total blood volume and cardiac output because of the high metabolic activity of excessive fat. In moderate to severe cases of obesity, this may lead to left ventricular dilation, increased left ventricular wall stress, compensatory (eccentric) left ventricular hypertrophy, and left ventricular diastolic dysfunction. Left ventricular systolic dysfunction may occur if wall stress remains high because of inadequate hypertrophy. Right ventricular structure and function may be similarly affected by the aforementioned morphologic and hemodynamic alterations and by pulmonary hypertension related to the sleep apnea/ obesity hypoventilation syndrome. The term obesity cardiomyopathy is applied when these cardiac structural and hemodynamic changes result in congestive heart failure. Obesity cardiomyopathy typically occurs in persons with severe and long-standing obesity. The predominant causes of death in those with obesity cardiomyopathy are progressive congestive heart failure and sudden cardiac death.

Obesity and left ventricular diastolic function: noninvasive study in normotensives and newly diagnosed never-treated hypertensives

OBJECTIVE

To evaluate the influence of obesity, per se or associated with hypertension, on left ventricular (LV) diastolic function.

PATIENTS

Thirty-two obese newly-diagnosed never-treated hypertensives; 32 obese normotensives matched for age, sex and BMI with hypertensives; 32 lean newly diagnosed never-treated hypertensives and 32 lean normotensives, matched for age, sex and 24 h blood pressure (BP) with the obese subjects.

METHODS

Twenty-four-hour ambulatory blood pressure monitoring and digitized M-mode LV echocardiograms. PARAMETERS EVALUATED: Twenty-four-hour, day-time and night-time BP and heart rate, percentage nocturnal BP fall; LV end-diastolic diameter index, septal and posterior wall thickness, LV mass index, peak shortening and lengthening rate of LV diameter, peak thinning rate of LV posterior wall.

RESULTS

A main effect was found for obesity on LV diameter and LV mass and for hypertension on LV mass; LV systolic function was normal in all the subjects and similar among the four groups; LV diastolic function was significantly reduced in both obese groups with respect to lean ones. This difference persisted after correction of diastolic parameters for 24 h BP and heart rate, LV diameter and LV mass index and disappeared only after correction for body mass index. This latter was inversely related with diastolic parameters only in the obese groups.

CONCLUSIONS

Obesity is associated with a preclinical impairment of LV diastolic function in both normotensives and hypertensives; the diastolic impairment is independent of haemodynamic factors, such as 24 h BP and heart rate, and bears no relation to LV geometry in normotensives and only little relation in hypertensives, having therefore to be ascribed to obesity itself.

Interleukin-6 as a central mediator of cardiovascular risk associated with chronic inflammation, smoking, diabetes, and visceral obesity: down-regulation with essential fatty acids, ethanol and pentoxifylline

Increased plasma levels of fibrinogen and C-reactive protein (CRP), as well as leukocytosis, are now established as risk factors for the thromboembolic complications of vascular disease. Chronic inflammation or infection associated with an acute-phase response--notably, periodontal disease and smoking-induced lung damage--are likewise known to increase cardiovascular risk. A common etiologic factor in these conditions may be interleukin-6 (IL-6), acting on hepatocytes to induce acute-phase reactants that increase blood viscosity and promote thrombus formation. Recent evidence that hypertrophied adipocytes release IL-6, and that hyperglycemia evokes IL-6 production by endothelium, may explain why plasma fibrinogen is increased in visceral obesity and poorly controlled diabetes. IL-6 is released by a range of tissues in response to stimulation by the monocyte-derived cytokines interleukin-1 and tumor necrosis factor; by suppressing production of these cytokines, fish oil, alpha-linolenic acid, and pentoxifylline can reduce IL-6 synthesis. Moderate ethanol consumption, as well as sex-hormone replacement, also appear to inhibit IL-6 production or activity. These practical protective measures may be of particular value to patients with pre-existing atheroma and elevated plasma levels of acute-phase reactants. Since IL-6 plays a crucial physiological role in osteoclast generation and activation, these measures may also aid preservation of bone density.

Tissue factor gene expression in the adipose tissues of obese mice

Altered expression of proteins of the fibrinolytic and coagulation cascades in obesity may contribute to the cardiovascular risk associated with this condition. We previously reported that plasminogen activator inhibitor 1 (PAI-1) is dramatically up-regulated in the plasma and adipose tissues of genetically obese mice. This change may disturb normal hemostatic balance and create a severe hypofibrinolytic state. Here we show that tissue factor (TF) gene expression also is significantly elevated in the epididymal and subcutaneous fat pads from ob/ob mice compared with their lean counterparts, and that its level of expression in obese mice increases with age and the degree of obesity. Cell fractionation and in situ hybridization analysis of adipose tissues indicate that TF mRNA is increased in adipocytes and in unidentified stromal vascular cells. Transforming growth factor beta (TGF-beta) is known to be elevated in the adipose tissue of obese mice, and administration of TGF-beta increased TF mRNA expression in adipocytes in vivo and in vitro. These observations raise the possibility that TF and TGF-beta may contribute to the increased cardiovascular disease that accompanies obesity and related non-insulin-dependent diabetes mellitus, and that the adipocyte plays a key role in this process. The recent demonstration that TF also influences angiogenesis, cell adhesion, and signaling suggests that its exact role in adipose tissue physiology/pathology, may be complex.

Left ventricular function and coagulation activity in healed myocardial infarction

We investigated the plasma levels of molecular markers for the thrombotic and fibrinolytic status in patients with healed myocardial infarction to determine the relation between left ventricular (LV) function and coagulation activity. Our findings demonstrated that the coagulation activity was increased in patients with healed myocardial infarction along with LV dysfunction, suggesting that anticoagulant therapy is considered in patients with severe LV dysfunction to prevent systemic thromboembolism.

Perioperative thromboelastography and sonoclot analysis in morbidly obese patients

PURPOSE

To investigate perioperative coagulation in morbidly obese (MO) patients with the thromboelastograph (TEG) and Sonoclot analyzer.

METHODS

Twenty-six consecutive morbidly obese and 26 consecutive lean patients presenting for elective surgery were enrolled in this prospective, observational study. Blood was sampled for TEG and Sonoclot analysis immediately after anaesthetic induction and at the end of surgery in the MO group, and immediately after anaesthetic induction in the lean group. The R and K times, alpha angle, maximum amplitude and percentage fibrinolysis at 30 and 60 min were recorded from the TEG. The Sonoclot ACT, initial clot rate, peak amplitude and time to peak amplitude were recorded from the Sonoclot.

RESULTS

The TEG in the MO group demonstrated decreased R and K times (8.6 +/- 4.8 vs 11.7 +/- 3.9 mm, and 2.8 +/- 1.2 vs 3.5 +/- 0.9 mm respectively (P < 0.05)), and increased alpha angle (73.7 +/- 6.0 vs 66.7 +/- 6.0 degrees, P < 0.05) and maximum amplitude (72.0 +/- 5.4 vs 67.9 +/- 4.4 mm, P < 0.05), without change in fibrinolysis. Sonoclot variables in the MO group included increased clot rate (37.5 +/- 11.5 vs 23.9 +/- 7.7%, P < 0.05) and decreased time to peak impedance (11.7 +/- 5.0 vs 17.5 +/- 7.2 min, P < 0.05), without change in Sonoclot ACT or peak signature impedance.

CONCLUSION

The MO group demonstrated accelerated fibrin formation, fibrinogen-platelet interaction, and platelet function compared with lean controls but no difference in fibrinolysis. Viscoelastic measures of coagulation may be useful in MO patients, who are at increased risk of thromboembolic events.

Effects of heparin treatment on hemostatic abnormalities in obese non-insulin-dependent diabetic patients

This study was conducted to identify the mechanisms responsible for coagulative and fibrinolytic alterations and to study the effects of a short-term treatment with low-dose heparin on hemostatic abnormalities in obese non-insulin-dependent diabetes mellitus (NIDDM) patients. Four groups of age- and sex-matched patients were studied: (1) lean nondiabetic subjects (n = 30) with a body mass index (BMI) less than 25 kg/m2 (lean control subjects), (2) obese nondiabetic subjects (n = 30) with a BMI greater than 30 kg/m2 (obese control subjects), (3) lean NIDDM patients (n = 30), and (4) obese NIDDM patients (n = 30). All subjects were tested on the following parameters: fibrinogen, factor VII, prothrombin fragment 1 + 2 (F1 + 2), thrombin-antithrombin III complexes (TAT), tissue plasminogen activator (t-PA) antigen (Ag) before and after venous occlusion (VO), and plasminogen activator inhibitor type-1 (PAI-1) activity pre- and post-VO. In addition, all these parameters were evaluated in obese NIDDM patients after 10 days of treatment with a single dose of 12,500-U/d subcutaneous calcium heparin and after a 10-day washout period. At baseline, obese nondiabetic subjects, lean NIDDM patients, and especially obese NIDDM patients displayed significantly (P < .01) higher levels of fibrinogen, factor VII, F1 + 2, TAT, t-PA(Ag) pre-VO, and PAI-1 pre- and post-VO and significantly (P < .01) lower levels of t-PA(Ag) post-VO. In obese NIDDM patients treated with heparin fibrinogen, factor VII, F1 + 2, TAT, t-PA(Ag) pre-VO, and PAI-1 pre- and post-VO levels significantly (P < .01) decreased and t-PA(Ag) post-VO levels significantly (P < .01) increased at the end of treatment. Our findings demonstrate in obese nondiabetic subjects, lean NIDDM patients, and especially obese NIDDM patients the hemostatic abnormalities contributing to an enhanced risk of thrombotic complications. We conclude that in obese NIDDM patients, short-term treatment with heparin may reduce this thrombophilic state and have a potential benefit in the progression of diabetic microvascular and macrovascular disease and needs further investigation.