Abdominal obesity is associated with an impaired fibrinolytic activity and elevated plasminogen activator inhibitor-1

Associations of haemostatic variables with body mass index: a community-based study

Obesity is a risk factor for venous and arterial thrombosis. We examined relationships between body mass index (BMI) and a number of haemostatic and inflammatory variables in a community-based study of 150 adults (73 male, 77 female; age range, 23-80 years). Associations with BMI were sought after adjustment for age, smoking and diurnal variation. There were significant interactions of gender on the associations of BMI with fibrinogen (P = 0.002) and C-reactive protein (P = 0.02). In women, there were strong positive associations of BMI with fibrinogen (r = 0.57, P < 0.0001) and C-reactive protein (r = 0.40, P = 0.001). In men, these associations were non-significantly inverse. For all other variables there were no sex differences, so results for men and women were combined. Significant positive associations with BMI were seen for factor VIIc, activated factor XII, antithrombin activity, protein C activity and plasminogen activator inhibitor-1 activity. Inverse associations with BMI were seen for tissue plasminogen activator activity and activated protein C ratio. Increasing BMI is associated with elevation of certain coagulation factors, inhibitors of fibrinolysis, and inhibitors of coagulation, the latter potentially reflecting a compensatory response. Gender influences the association of certain inflammatory variables with BMI so the sexes should be considered separately in studies of inflammation and obesity.

Beneficial effects of metformin on haemostasis and vascular function in man

Type 2 diabetes is characterised by insulin resistance in association with clustering of atherothrombotic risk factors (dysglycaemia, hyperinsulinaemia, hypertension, raised triglyceride, low HDL cholesterol and increased levels of plasminogen activator inhibitor-1 (PAI-1) and clotting factor VII). There is a 3-5 fold increase in risk of myocardial infarction rising to 10-20 fold in the presence of microalbuminuria and overall around 70-75% of subjects with type 2 diabetes die of cardiovascular disease. However, classical risk factors which associate with insulin resistance do not account for all the increased burden of vascular disease in diabetic subjects. Metformin is a biguanide compound which is antihyperglycaemic, reduces insulin resistance and has cardioprotective effects on lipids, thrombosis and blood flow. Metformin has a weight neutral/weight lowering effect and reduces hypertriglyceridaemia, elevated levels of PAI-1, factor VII and C-reactive protein. In addition recent studies indicate that metformin has direct effects on fibrin structure/function and stabilises platelets, two important components of arterial thrombus. The United Kingdom Prospective Diabetes Study (UKPDS) reported that metformin was associated with a 32% reduction in any diabetes related endpoint (p<0.002), a 39% reduction in myocardial infarction (p<0.01) and a non-significant 29% fall in microvascular complications. The figures for macrovascular complications compare favourably for those described for other cardioprotective agents such as ACE inhibitors and statins. These findings confirm metformin as first line therapy in the management of obese insulin resistant type 2 diabetes and in the prevention of the vascular complications of this common condition.

The genetics of atherothrombotic disorders: a clinician's view

The development of coronary artery disease is dependent on the interaction of multiple biochemical pathways that lead to the development of plaque in the arterial wall and ultimately plaque instability, plaque rupture and thrombosis. The latter stages lead to vascular obstruction, tissue death and the final phenotype of myocardial infarction. Hemostasis gene association studies of atherothrombotic disorders have been unrewarding, with largely underpowered studies reporting inconsistent results. Clinical studies such as the Multiple Risk Factor Intervention Trial clearly indicate that clustering of classical risk increases the likelihood of myocardial infarction, and the addition of diabetes mellitus to the risk profile exponentially increases the risk of a vascular event. The development of insulin resistance is considered to be a pivotal event in vascular risk with associated clustering of dysglycemia, hyperinsulinemia, systolic hypertension, raised triglyceride and low high-density lipoprotein cholesterol. Additionally, elevated levels of plasminogen activator inhibitor-1, factor (F)VII, FXII, fibrinogen and tissue plasminogen activator occur with insulin resistance to create an atherothrombotic risk cluster. Heritability studies of insulin resistance and the vascular risk profile demonstrate genetic pleitropy between diabetes and vascular risk, which indicate that common genes have an important role. Increasingly, it is felt that inflammation underpins both diabetes and cardiovascular disease and that the expression of the final phenotype(s) may depend on complex gene-environment interactions with regulatory genes, including those for nuclear transcription factors and RNA-binding proteins. The complexity of coronary artery disease and the risk factor interactions make it unlikely that genetic epidemiology will identify genes involved in these processes without a better understanding of environmental influences.

Promoter (4G/5G) plasminogen activator inhibitor-1 genotype and plasminogen activator inhibitor-1 levels in blacks, Hispanics, and non-Hispanic whites: the Insulin Resistance Atherosclerosis Study

BACKGROUND

The 4G/5G polymorphism of the plasminogen activator inhibitor-1 (PAI-1) gene has been related to cardiovascular disease.

METHODS AND RESULTS

Insulin resistance was measured with a frequently sampled intravenous glucose tolerance test in the Insulin Resistance Atherosclerosis Study (IRAS), and PAI-1 4G/5G promoter genotype was established by allele-specific polymerase chain reaction amplification of genomic DNA. There were 287 subjects with the 4G/4G genotype (18.4%), 691 heterozygote subjects (44.2%), and 586 carriers of the 5G/5G genotype (37.5%). The genotype distribution was different across the 3 ethnic groups (P=0.001). PAI-1 levels were lower in blacks than in non-Hispanic whites and Hispanics and lower in non-Hispanic whites than in Hispanics (all P=0.0001). Subjects homozygous for the 4G allele had the highest plasma PAI-1, heterozygote subjects were intermediate, and 5G homozygotes had the lowest levels of PAI-1. These patterns remained unaffected by adjustments for age, gender, clinical center, glucose tolerance status, body mass index, waist, triglycerides, and insulin resistance. Multiple linear regression analyses showed that the 4G/5G genotype explained very little of the variation in PAI-1 levels (0.63% in non-Hispanic whites, 0.99% in Hispanics, and 2.37% in blacks), and interaction analyses revealed no significant differences in the relation of circulating PAI-1 levels to the 4G/5G genotype by ethnicity (P=0.4).

CONCLUSIONS

We have shown ethnic differences in the PAI-1 4G/5G polymorphism along with corresponding differences in circulating PAI-1 levels. The association of the genotype with PAI-1 levels was seen consistently among all 3 ethnic groups and was unaffected by metabolic covariates, including insulin resistance.

Hemostatic variables, carbohydrate metabolism and lipid profile in women with low body mass index

The aim of this study was to evaluate hemostatic variables in women according to different body mass index (BMI) values, and then correlate them with some metabolic parameters - fasting insulin and glucose, total cholesterol, high-density lipoprotein (HDL)-cholesterol, low-density lipoprotein (LDL)-cholesterol and triglycerides. Eighty-four female patients aged 18-39 years were recruited, and agreed to participate in the study. The study group was divided into three subgroups according to BMI: low BMI (BMI < 18.5 kg/m2; n = 43), normal-weight (control) (BMI 18.5-24.99 kg/m2; n = 21) and overweight/obese (BMI > 25 kg/m2; n = 20). BMI was calculated, and the following measurements were taken: International Normalized Ratio, antithrombin III, tissue plasminogen activator (t-PA) activity, t-PA-antigen, plasma fibrinogen level, factor VII, Plasminogen activator inhibitor (PAI)-1 activity and antigen and metabolic parameters: fasting insulin and glucose, total cholesterol, HDL-cholesterol, LDL-cholesterol and triglycerides. The results were statistically analyzed. In the low BMI group, a negative correlation between fasting insulin and PAI-1 activity, and a positive correlation between fasting glucose and PAI-1 antigen were observed. Also, a strong negative correlation between PAI-1 activity and insulin/glucose index was found. Plasma insulin levels were significantly lower in the low-BMI women than in the overweight/obese group (p < 0.001) and with no difference compared to the control group. We did not find any difference in fasting glucose level between all groups. HDL-cholesterol showed the highest levels in the normal BMI group and was significantly higher than in the low BMI and obese groups (p < 0.05 and p < 0.01, respectively). PAI-1 activity in the low BMI women revealed increased activity in comparison to control and overweight/obese women (p < 0.001 and p < 0.05, respectively). Lower antigen levels were also shown as compared to both these groups (p < 0.001 and p < 0.001, respectively). Similar results were obtained with t-PA antigen levels (p < 0.001 and p < 0.001, respectively). There were no differences in activity of t-PA in all groups. Obese women showed significantly higher fibrinogen levels than other BMI groups (p < 0.001 and p < 0.001 respectively). Analysis of hemostatic variables in women with a low BMI testify to the impaired fibrinolysis in this group, also showing a strong correlation with carbohydrate metabolism.

Association of plasminogen activator inhibitor-1 with insulin resistance in Japan where obesity is rare

The association between plasminogen activator inhibitor-1 (PAI-1) and insulin resistance is established in western countries. The major component of this association is obesity. Accordingly, we examined this association in Japan where the prevalence of obesity is low. Data for fasting PAI-1 levels of 404 subjects were obtained from a general population in a farming area. We measured body mass index (BMI), systolic and diastolic blood pressure, high-density lipoprotein (HDL)-cholesterol, triglycerides, fasting plasma glucose (FPG), insulin, creatinine, and uric acid. The use of alcohol was ascertained by a questionnaire. The formula for the homeostasis model assessment (HOMA) score was used as an index of insulin resistance. Uni- and multivariate analyses were applied for the determinants of plasma PAI-1. Age and sex did not affect plasma PAI-1. The average BMI was 23.0 +/- 3.2 kg/m(2). Thus, most of the subjects were not obese. Because, even in this population, BMI (P <.001) was the strongest determinant for PAI-1 after univariate analysis, we performed multiple linear regression analyses after adjustment for BMI. The significance of triglycerides, FPG, insulin, and the HOMA score still remained. PAI-1 levels were linearly related to the HOMA score. From the subanalysis of the non-obese subjects (BMI < 25; n = 298), waist-hip ratio, triglycerides, FPG, and HOMA scores were significant determinants of PAI-1. This is the first demonstration that increased PAI-1 levels were significantly related to insulin resistance in a Japanese general population. PAI-1 levels are associated with insulin resistance, irrespective of obesity.

The effect of fiber-rich carbohydrates on features of Syndrome X

There has been much debate among nutritionists and scientists regarding the optimal dietary approach for the treatment of the Insulin Resistance Syndrome, also called Syndrome X. This condition, which may affect as many as 47 million individuals in the United States, significantly increases risk of coronary heart disease and stroke. Major health organizations have historically recommended high-carbohydrate, low-fat (HCLF) diets to reduce chronic disease risk. However, there is evidence that a high intake of carbohydrates may adversely affect one or more of the abnormalities associated with this syndrome. Studies in this area have often had limitations. For example, some studies showing adverse effects of an HCLF diet have not taken into account the dietary fiber content of the diet. This article describes abnormalities often associated with Syndrome X, reviews the beneficial effects of fiber-rich carbohydrates, discusses the effect of fiber-rich carbohydrates on features of this syndrome, and concludes with applications of these findings for those involved in treating individuals with features of this disorder. This review indicates that an HCLF dietary pattern such as that used in the DASH trial, with a level of dietary fiber consistent with the recommendations of the American Dietetic Association (eg, 20-35g/day), containing from 3 to 10 g soluble fiber/day, may be beneficial for treating those with Syndrome X.

The obesity epidemic: pathophysiology and consequences of obesity

Obesity has reached epidemic proportions in the United States: more than 20% of adults are clinically obese as defined by a body mass index of 30 kg/m(2) or higher, and an additional 30% are overweight. Environmental, behavioral, and genetic factors have been shown to contribute to the development of obesity. Elevated body mass index, particularly caused by abdominal or upper-body obesity, has been associated with a number of diseases and metabolic abnormalities, many of which have high morbidity and mortality. These include hyperinsulinemia, insulin resistance, type 2 diabetes, hypertension, dyslipidemia, coronary heart disease, gallbladder disease, and certain malignancies. This underscores the importance of identifying people at risk for obesity and its related disease states.

Effects of moderate weight loss on anginal symptoms and indices of coagulation and fibrinolysis in overweight patients with angina pectoris

OBJECTIVE

To evaluate the effects of moderate weight loss, in overweight patients with angina, on plasma coagulation, fibrinolytic indicies and pain frequency.

DESIGN

Single-stranded 12-week dietary intervention, an individualised eating plan with quantitative advice delivered by a dietitian. Target weight loss of 0.5 kg per week.

SETTING

Outpatient research clinic.

SUBJECTS

Fifty-four volunteers with angina pectoris were recruited. Five subjects withdrew, so 27 males, 22 females, mean body mass index (BMI) 29.3 (s.d. 4.3) kg/m(2) and age 60.3 (s.d. 6.5) y completed the intervention.

MEASUREMENTS

Body weight and frequency of anginal pain. Plasma fibrinogen, red cell aggregation (RCA), viscosity, factor VII activity, plasminogen activator inhibitor (PAI) activity, tissue plasminogen activator antigen (t-PA), plasma cholesterol, triglyceride and insulin.

RESULTS

After the 12-week dietary intervention period, mean body weight fell by 3.5 (s.d. 2.6) kg or 4.3% (P=0.0001), range -11.7 to +1.7 kg. Mean angina frequency fell by 1.8 (s.d. 3.6) from 3.2 to 1.4 episodes/week (P=0.009) and plasma cholesterol by 0.4 (s.d. 0.7) from 6.3 to 5.9 mmol/l (P=0.0001). HDL cholesterol and triglyceride were unchanged. Of the coagulation and fibrinolytic factors, factor VII activity and RCA were significantly reduced by 5 (s.d. 20), IU/dl (P=0.04) and 1.3 (s.d. 1.3) arbitrary units (P=0.014), respectively.

CONCLUSIONS

A conventional dietetic intervention, resulting in 4% weight loss, offers the potential to reduce atherosclerotic and thrombotic risk, and to reduce pain frequency, in angina patients. Given the importance of this result in a public health context, these results indicate that this may be a fruitful area for future nutrition research.

Tissue factor pathway inhibitor and other endothelium-dependent hemostatic factors in elderly individuals with normal or impaired glucose tolerance and type 2 diabetes

OBJECTIVE

Impaired glucose tolerance (IGT) is believed to be a prediabetic phase that precedes the development of type 2 diabetes. In elderly subjects, IGT and diabetes are both independently associated with the occurrence of cardiovascular disease. Endothelial damage precedes atherosclerotic changes of the vascular wall. Therefore, several markers of endothelial dysfunction were examined in elderly subjects with IGT and elderly patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Von Willebrand factor (vWF), tissue plasminogen activator (t-PA), plasminogen activator inhibitor type-1 (PAI-1), and thrombomodulin were studied as markers of endothelial dysfunction in a population-based study of elderly subjects with normal glucose tolerance (NGT) or IGT and type 2 diabetes. In addition to these endothelium-dependent factors, we also investigated tissue factor pathway inhibitor (TFPI) activity in relation to metabolic parameters and cardiovascular risk factors.

RESULTS

All data were adjusted for age. Increased levels of vWF antigen, t-PA antigen, and PAI-1 activity were seen in the IGT and diabetic group compared with the NGT group. TFPI activity and thrombomodulin levels were increased in all elderly subjects, and no differences were seen between the groups. There was a positive association between HbA(1c) and TFPI activity and vWF antigen. Fasting blood glucose levels correlated with vWF antigen, t-PA antigen, and PAI-1 activity, whereas urine albumin excretion correlated with TFPI activity, vWF antigen, and PAI-1 activity. Serum insulin levels correlated strongly not only with vWF antigen and t-PA antigen but also with PAI-1 activity. This correlation did not change after further adjustment for serum glucose and HbA(1c), which may suggest that in the elderly subjects, impaired fibrinolysis is probably associated with insulin resistance. There were no associations between the endothelium-dependent hemostatic factors and lipids, except for a negative correlation between HDL cholesterol and thrombomodulin.

CONCLUSIONS

In elderly subjects with IGT, several endothelium-dependent hemostatic factors are already consistently increased, indicating endothelial damage in this stage.

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.

Chronic graft dysfunction in renal transplant patients: potential role of plasminogen activator inhibitor type 1

BACKGROUND

Chronic allograft nephropathy is the main cause of long-term kidney graft loss. The plasminogen activator inhibitor type 1 (PAI-1) is a potential fibrogenic molecule whose secretion is regulated by several metabolic, inflammatory, and genetic factors. We aimed to determine whether PAI-1 secretion in renal transplant patients is correlated with the decline in renal function after transplantation.

METHODS

Renal transplant patients (145 male/71 female) were included in the study 1-27 years after transplantation (median of follow-up: 7.35 years). At inclusion, routine clinical and biological data were collected, the 4G/5G polymorphism of the recipient PAI-1 gene was determined, and the PAI-1 plasma level was measured.

RESULTS

The mean rate of decline in renal function was -4.26+/-0.30 ml/min/year. By multiple linear regression analysis, the rate of decline in renal function was significantly correlated with proteinuria (P=0.0176), occurrence of late acute rejection episodes (P=0.0001), and PAI-1 plasma level (P=0.0051). In addition, PAI-1 plasma level was also significantly correlated with body mass index (P=0.038), insulin (P<0.0001), platelet count (P<0.0001), and fibrinogen (P=0.024). The PAI-1 gene polymorphism tested did not influence the rate of decline in renal function after transplantation nor the plasma level of PAI-1 antigen.

CONCLUSION

We conclude that PAI-1, whose secretion is determined in large part by metabolic and inflammatory factors, may be implicated in the rate of decline in renal function after transplantation.

Gut microbial ecology in critical illness: is there a role for prebiotics, probiotics, and synbiotics?

Approximately 70% of the immune system is localized in the gastrointestinal tract: its glands, mucosa, and mucosa-associated lymphoid system. The system influences health conditions because it produces large amounts of important gastrointestinal secretions as rich as breast milk in health-supporting and disease-preventing factors, and because of its rich gastrointestinal flora. The intestine normally contains 10 times more microbes than there are eukaryotic cells in the entire body. The optimal function of these microbes depends on the supply of food destined for the colonic bacteria (fermentable fibers, complex proteins, gastrointestinal secretions). The consideration of these functions influences outcome. Unfortunately, the conditions (supply of drugs-especially antibiotics, and reduced supply of food-especially fruits and vegetables) in the modern ICU are extremely poor both for optimal gastrointestinal secretion and for flora and need more attention. To improve treatment, a supply of new and effective flora (probiotics) and food for the flora (prebiotics) is needed, from which numerous health-supporting products (synbiotics) will be produced and absorbed at the level of the mucosa, mainly in the lower gastrointestinal tract.

Elevated plasma activator inhibitor 1 is not related to insulin resistance and to gene polymorphism in healthy centenarians

Previous studies demonstrated a relationship between the degree of insulin resistance and plasma plasminogen activator inhibitor type-1 (PAI-1) levels. We aim at investigating the relationship between the degree of insulin resistance and plasma PAI-1 levels in aged subjects (n=83) and in healthy centenarians (n=42). In all subjects the degree of insulin resistance was assessed by HOMA method. Our data demonstrated that healthy centenarians have higher plasma PAI-1 levels (73.1+/-13.9 vs 23.7+/-14.7 ng/ml, P<0.001) and lower degree of insulin resistance (1.4+/-0.5 vs 3.3+/-1.3, P<0.001) than aged subjects. In aged subjects plasma PAI-1 levels correlated with the degree of insulin resistance (r=0.61, P<0.001), fasting plasma triglycerides (r=0.74, P<0.001) and age (r=0.33, P<0.001). All such associations were lost in centenarians. Plasma PAI-1 Ag levels were also similar in aged subjects and centenarians even after categorization for PAI gene polymorphism. In multivariate analysis, a model made by age, sex, body mass index, fasting plasma triglycerides, HOMA and PAI-1 gene explained 65 and 50% of plasma PAI-1 level variations in aged subjects and centenarians, respectively. Nevertheless, HOMA (P<0.001) was significantly and independently associated with plasma PAI-1 levels only in aged subjects. In conclusion, our data demonstrates that in healthy centenarians, plasma PAI-1 were not associated with the degree of insulin resistance as in aged subjects. Frequency of PAI-1 genotype does not provide an explanation for such differences between aged subjects and centenarians.

Adipose tissue and the insulin resistance syndrome

Obesity is associated with insulin resistance. Insulin resistance underlies a constellation of adverse metabolic and physiological changes (the insulin resistance syndrome) which is a strong risk factor for development of type 2 diabetes and CHD. The present article discusses how accumulation of triacylglycerol in adipocytes can lead to deterioration of the responsiveness of glucose metabolism in other tissues. Lipodystrophy, lack of adipose tissue, is also associated with insulin resistance. Any plausible explanation for the link between excess adipose tissue and insulin resistance needs to be able to account for this observation. Adipose tissue in obesity becomes refractory to suppression of fat mobilization by insulin, and also to the normal acute stimulatory effect of insulin on activation of lipoprotein lipase (involved in fat storage). The net effect is as though adipocytes are 'full up' and resisting further fat storage. Thus, in the postprandial period especially, there is an excess flux of circulating lipid metabolites that would normally have been 'absorbed' by adipose tissue. This situation leads to fat deposition in other tissues. Accumulation of triacylglycerol in skeletal muscles and in liver is associated with insulin resistance. In lipodystrophy there is insufficient adipose tissue to absorb the postprandial influx of fatty acids, so these fatty acids will again be directed to other tissues. This view of the link between adipose tissue and insulin resistance emphasises the important role of adipose tissue in 'buffering' the daily influx of dietary fat entering the circulation and preventing excessive exposure of other tissues to this influx.

Plasminogen activator inhibitor-1 and haemostasis in obesity

The connection between obesity and disordered haemostasis is well established, but incompletely understood. There is a strong link between inhibition of fibrinolysis and obesity, and elevation of the plasma inhibitor, plasminogen activator inhibitor-1 (PAI-1), is regarded as a central factor. Here we explore the increased risk of atherothrombotic disorders in obese subjects, and the evidence for metabolic and genetic causes. There is a clear relationship between plasma PAI-1 and obesity, and adipose tissue synthesises PAI-1, as has been shown in mouse and rat models, and more recently in human material. This tissue also produces several effector molecules that can up regulate PAI-1. These molecules include transforming growth factor beta, tumour necrosis factor alpha, angiotensin II and interleukin 6, all of which up regulate PAI-1 in various cell types. The issue of whether adipose tissue directly contributes to plasma PAI-1, or whether it primarily contributes indirectly, its products stimulating other cells to produce PAI-1 that feeds into the plasma pool, is not yet resolved. Finally, we briefly examine other proteins of haemostasis that are products of adipose tissue. Further studies are needed to define the regulation of these proteins, in adipose tissue itself and in other cells influenced by its products, in order to extend recent insights into the links between obesity and haemostasis.

Similar PAI-1 expression in visceral and subcutaneous fat of postmenopausal women

Recent studies showed that intraabdominal visceral fat located in the mesenterium and omentum may significantly influence the circulating plasminogen activator inhibitor type 1 (PAI-1). To substantiate this link, we performed analysis of PAI-1 expression in human visceral and subcutaneous adipose tissues in peri- and postmenopausal women. The samples of both visceral and subcutaneous fat from 28 generally healthy women (aged 45-69 years) with a wide range of body mass index (BMI; 22.30-38.67 kg/m2), who underwent surgical operation due to benign ovary and uterine tumours, were obtained. In these samples, expression of mRNAs for PAI-1, tumour necrosis factor alpha (TNFalpha), acyl-CoA synthetase (ACS), and glucose transporter (GLUT-4) was analysed by relative quantitative RT PCR and correlated with plasma PAI-1 antigen. In addition, visceral fat area was measured with computer tomography. Both types of fat tissues contained similar quantities of PAI-1 mRNA, and there was no correlation between plasma PAI-1, measured both by antigen and activity, with either visceral or subcutaneous fat PAI-1 mRNA. Furthermore, there was no significant association between the expression of PAI-1 mRNA and TNFalpha mRNA in tested fat samples. PAI-1 mRNA in both fat tissues was significantly correlated with plasma levels of estradiol (positive correlation) and follicle-stimulating hormone (FSH; negative correlation). Finally, the expression of PAI-1 mRNA was negatively correlated with mRNA of ACS present in both fat tissues. In summary, this study directly indicates that PAI-1 mRNA is similarly expressed in both subcutaneous and visceral fat of peri- and postmenopausal women and its expression strongly depends upon lipid metabolism.

Obesity and coronary heart disease

Obesity is commonly cited as a risk factor for the development of coronary heart disease (CHD). Epidemiologic studies tend to support this contention, particularly those focusing on patients with central obesity. Such studies however, are imprecise and prone to misclassification bias. Angiographic and post mortem studies have demonstrated little or no correlation of total fat mass and coronary atherosclerosis except in those with abdominal obesity. There is a strong association of obesity, particularly central obesity, and traditional risk factors for CHD such as hypertension, type II diabetes mellitus, and dyslipidemia. There may also be an association between obesity and several nontraditional risk factors such as hyperhomocystinemia, elevated Lp(a) levels and factors that increase thrombogenesis. Obesity may also alter endothelial function. Weight loss, although associated with favorable modification of multiple risk factors for CHD, has not been shown to independently and definitively reduce CHD risk.

Diabetes and endothelial dysfunction: a clinical perspective

The main etiology for mortality and a great percent of morbidity in patients with diabetes mellitus is atherosclerosis. A hypothesis for the initial lesion of atherosclerosis is endothelial dysfunction, defined pragmatically as changes in the concentration of the chemical messengers produced by the endothelial cell and/or by blunting of the nitric oxide-dependent vasodilatory response to acetylcholine or hyperemia. Endothelial dysfunction has been documented in patients with diabetes and in individuals with insulin resistance or at high risk for developing type 2 diabetes. Factors associated with endothelial dysfunction in diabetes include activation of protein kinase C, overexpression of growth factors and/or cytokines, and oxidative stress. Several therapeutic interventions have been tested in clinical trials aimed at improving endothelial function in patients with diabetes. Insulin sensitizers may have a beneficial effect in the short term, but the virtual absence of trials with cardiovascular end-points preclude any definitive conclusion. Two trials offer optimism that treatment with ACE inhibitors may have a positive impact on the progression of atherosclerosis. Although widely used, the effect of hypolipidemic agents on endothelial function in diabetes is not clear. The role of antioxidant therapy is controversial. No data have been published regarding the effects of hormonal replacement therapy on endothelial dysfunction in postmenopausal women with type 2 diabetes.

Close relationship of tissue plasminogen activator-plasminogen activator inhibitor-1 complex with multiple organ dysfunction syndrome investigated by means of the artificial pancreas

BACKGROUND

Glucose tolerance (GT) has not been taken into consideration in investigations concerning relationships between coagulopathy and multiple organ dysfunction syndrome (MODS), and endothelial cell activation/endothelial cell injury (ECA/ECI) in septic patients, although coagulopathy is known to be influenced by blood glucose level. We investigated those relationships under strict blood glucose control and evaluation of GT with the glucose clamp method by means of the artificial pancreas in nine septic patients with glucose intolerance. The relationships between GT and blood stress related hormone levels (SRH) were also investigated.

METHODS

The amount of metabolized glucose (M value), as the parameter of GT, was measured by the euglycemic hyperinsulinemic glucose clamp method, in which the blood glucose level was clamped at 80 mg/dl under a continuous insulin infusion rate of 1.12 mU/kg per min, using the artificial pancreas, STG-22. Multiple organ failure (MOF) score was calculated using the MOF criteria of Japanese Association for Critical Care Medicine. Regarding coagulopathy, the following parameters were used: disseminated intravascular coagulation (DIC) score (calculated from the DIC criteria of the Ministry of Health and Welfare of Japan) and the parameters used for calculating DIC score, protein-C, protein-S, plasminogen, antithrombin III (AT-III), plasminogen activator inhibitor-1 (PAI-1), and tissue plasminogen activator-PAI-1 (tPA-PAI-1) complex. Thrombomodulin (TM) was measured as the indicator of ECI.

RESULTS

There were no significant correlations between M value and SRH, parameters indicating coagulopathy and the MOF score. The MOF score and blood TM levels were positively correlated with DIC score, thrombin-AT-III complex and tPA-PAI-1 complex, and negatively correlated with blood platelet count.

CONCLUSIONS

GT was not significantly related to SRH, coagulopathy and MODS under strict blood glucose control. Hypercoagulability was closely related to MODS and ECI. Among the parameters indicating coagulopathy, tPA-PAI-1 complex, which is considered to originate from ECA, seemed to be a sensitive parameter of MODS and ECI, and might be a predictive marker of MODS. The treatment for reducing hypercoagulability and ECA/ECI were thought to be justified as one of the therapies for acutely ill septic patients.

Clustering of procoagulation, inflammation, and fibrinolysis variables with metabolic factors in insulin resistance syndrome

The known metabolic cardiovascular disease risk factors associated with insulin resistance syndrome (IRS) do not adequately explain the excess cardiovascular disease risk attributed to this syndrome, and abnormalities in hemostatic variables may contribute to this excess risk. Using data from 322 nondiabetic elderly men and women (aged 65-100 years) participating in the Cardiovascular Health Study during 1989-1990, the authors performed factor analysis on 10 metabolic risk factors associated with IRS and 11 procoagulation, inflammation, and fibrinolysis variables to examine the clustering of the metabolic and hemostatic risk markers. Factor analysis of the metabolic variables confirmed four uncorrelated factors: body mass, insulin/glucose, lipids, and blood pressure. Adding the hemostatic variables yielded three new factors interpreted as inflammation, vitamin K-dependent proteins, and procoagulant activity. Plasminogen activator inhibitor-1 clustered with the body mass factor, supporting the hypothesis that obesity is related to impaired fibrinolysis. Fibrinogen clustered with the inflammation summary factor rather than procoagulant activity, supporting the position that fibrinogen principally reflects underlying inflammation rather than procoagulant potential. The authors conclude that should hemostatic variables be shown to contribute to IRS-related cardiovascular disease, apart from plasminogen activator inhibitor-1, they may do so independently of the established metabolic abnormalities.

Determinants of haemostatic risk factors for coronary heart disease in obese children and adolescents

OBJECTIVE

To investigate the contribution of serum lipids, parameters of glucose metabolism, body composition and cardiovascular fitness to the variance of several haemostatic risk factors for coronary heart disease (CHD) in obese children and adolescents.

SUBJECTS AND MEASUREMENTS

Forty-two healthy, obese children and adolescents (20 male, 22 female, age 12.6 +/- 3.2y; body mass index (BMI), 30.4 +/- 5.3 kg/m2), were screened for haemostatic and metabolic risk factors for CHD. Thirty-five of the participants (18 male, age 13.5 +/- 2.9y; BMI, 29.9 +/-4.5kg/m2; 17 female, age 12.8+/-2.1 y, BMI, 31.1 +/- 5.3 kg/m2) were assessed for cardiovascular fitness by means of incremental cycle ergometer exercise.

RESULTS

After adjustment for age, fat mass correlated significantly with plasminogen activator inhibitor-1 antigen (PAI-1-Ag) in boys and girls and factor VIIc only in girls. Children with lower power output (< or = 2.77W/kg) showed significantly higher values for factor VIIc, fibrinogen and tissue-type plasminogen activator antigen (tPA-Ag). Neither body composition nor cardiovascular fitness contributed independently to the variance of the determined haemostatic risk factors, except PAI-1-Ag, which has been shown to be determined by fat mass. In multiple linear regression analysis, triglycerides and PAI-1-Ag explained significant independent proportions of the variance of tPA-Ag. Factor VIIc was explained by C-peptide, insulin and fibrinogen. Von Willebrand factor antigen (vWF-Ag) was significantly related to glucose and insulin.

CONCLUSION

The results suggest that in obese children and adolescents the haemostatic risk factors factor VIIc, vWF-Ag and tPA-Ag are mainly determinated by plasma insulin and triglyceride concentrations, but are primarily independent of body composition and cardiovascular fitness.

How deadly is the "deadly quartet"? A post-CABG evaluation

OBJECTIVES

The aim of the study was to determine the value of a cluster of metabolic risk factors in predicting mortality after coronary artery bypass surgery (CABG).

BACKGROUND

The "deadly quartet" of metabolic risk factors (i.e., obesity, diabetes, hypertension, and hypertriglyceridemia) has been associated with coronary heart disease in healthy population studies. The expected influence of the cluster on survival in secondary prevention remains untested overall as well as by gender.

METHODS

Patients with lipid profiles undergoing primary isolated CABG (n = 6,428) between 1987 and 1992 were followed a median of eight years. Cox models were used to evaluate all-cause mortality. Metabolic risk factors were incorporated as the sum of deadly quartet risk factors present in each patient (0 to 4). The role of gender as it relates to survival and metabolic risk clusters was also examined.

RESULTS

The sum of deadly quartet risk factors showed a significant relationship to mortality as the hazard ratio increased from 1.64 (confidence interval [CI] = 1.34-2.01) for one risk factor to 3.95 (2.73-5.69) for four risk factors. Annualized mortality ranged from 1% per year in patients with no risk factors to 3.3% per year in patients with all four risk factors. Within gender, the hazard ratio associated with four risk factors was 2.58 for men and 13.39 for women. The expected clustering of risk factors was 8% compared to the observed clustering of 10% in men and 21% in women.

CONCLUSIONS

This cohort showed risk factor clustering beyond that expected due to chance, particularly in women. Even after revascularization, survival is diminished for patients with members of a family of metabolic risk factors at the time of surgery.

Implications of cardiovascular risk in patients with type 2 diabetes who have abnormal lipid profiles: is lower enough?

Patients with type 2 diabetes are at high risk for coronary heart disease (CHD); frequently, these patients have abnormal lipid profiles, placing them at even greater risk. A syndrome of insulin resistance, hyperinsulinaemia, hypertension, and high levels of fibrinogen and plasminogen activator inhibitor contributes to cardiovascular risk, which is not sufficiently decreased by glycaemic control alone. In several large interventional trials, CHD risk in patients with diabetes was substantially reduced by aggressive lipid-lowering therapy. In patients with diabetes, CHD, low high-density lipoprotein levels, and normal low-density lipoprotein levels, gemfibrozil reduced fatal and non-fatal CHD events. For lipid-lowering in patients with diabetes and CHD, pravastatin and simvastatin are the only HMG-CoA reductase inhibitors shown to reduce fatal and non-fatal CHD events. Of these, pravastatin has less potential for drug-drug interactions and may be safer to use, particularly for combination therapy with fibric acid derivatives, as may now be important for CHD prevention in mixed dyslipidaemias.

Chronic subclinical inflammation as part of the insulin resistance syndrome: the Insulin Resistance Atherosclerosis Study (IRAS)

BACKGROUND

Inflammation has been suggested as a risk factor for the development of atherosclerosis. Recently, some components of the insulin resistance syndrome (IRS) have been related to inflammatory markers. We hypothesized that insulin insensitivity, as directly measured, may be associated with inflammation in nondiabetic subjects.

METHODS AND RESULTS

We studied the relation of C-reactive protein (CRP), fibrinogen, and white cell count to components of IRS in the nondiabetic population of the Insulin Resistance Atherosclerosis Study (IRAS) (n=1008; age, 40 to 69 years; 33% with impaired glucose tolerance), a multicenter, population-based study. None of the subjects had clinical coronary artery disease. Insulin sensitivity (S(I)) was measured by a frequently sampled intravenous glucose tolerance test, and CRP was measured by a highly sensitive competitive immunoassay. All 3 inflammatory markers were correlated with several components of the IRS. Strong associations were found between CRP and measures of body fat (body mass index, waist circumference), S(I), and fasting insulin and proinsulin (all correlation coefficients >0.3, P<0.0001). The associations were consistent among the 3 ethnic groups of the IRAS. There was a linear increase in CRP levels with an increase in the number of metabolic disorders. Body mass index, systolic blood pressure, and S(I) were related to CRP levels in a multivariate linear regression model.

CONCLUSIONS

We suggest that chronic subclinical inflammation is part of IRS. CRP, a predictor of cardiovascular events in previous reports, was independently related to S(I). These findings suggest potential benefits of anti-inflammatory or insulin-sensitizing treatment strategies in healthy individuals with features of IRS.

Relationship between plasma plasminogen activator inhibitor 1 and insulin resistance

High plasminogen activator inhibitor 1 (PAI-1) levels are associated with an increased cardiovascular risk of atherothrombosis. Furthermore, increased plasma PAI-1 levels are associated with dyslipidemia, hyperinsulinemia and hypertension. This association between PAI-1 and metabolic components of the Metabolic Syndrome could explain the predisposition of insulin resistant patients to atherothrombosis. Recent studies have suggested that visceral adipose tissue might be the link between elevated plasma PAI-1 and insulin resistance in the Metabolic Syndrome. Indeed, visceral adipose tissue was proposed as a potentially important source of PAI-1 in humans. However, in light of recent studies, visceral adipose tissue appears to be involved in the increase of plasma PAI-1 via the metabolic disorders usually associated with central obesity, rather than directly. High plasma PAI-1 levels are undoubtedly related to insulin resistance, and the mechanisms which could explain such an increase in the Metabolic Syndrome appear to be multi-factorial and remain to be elucidated. These mechanisms may involve several metabolic disorders such as hyperinsulinemia, dyslipidemia, impaired glucose tolerance and hypertension, which would favor PAI-1 synthesis and release from different cell types.

Infantile obesity: a situation of atherothrombotic risk?

Obesity is a major risk factor for cardiovascular disease frequently associated with hypertension, dyslipidemia, and diabetes. In recent years, alterations in the hemostatic system have been added to these dysfunctions. We analyzed some of these alterations in coagulation and fibrinolysis in obese children (6 to 9 years old) of both sexes. We studied 61 obese children (mean body mass index [BMI], 22.35 kg/m2; 95% confidence interval [CI], 21.82 to 22.87) and 70 non-obese children (mean BMI, 16.58 kg/m2; 95% CI, 16.24 to 16.93) as a control group. The obese subjects presented significantly elevated values for insulin (P < .001), tissue-plasminogen activator ([t-PA] P < .001), plasminogen activator inhibitor-1 ([PAI-1] P < .001), and fibrinogen (P < .001) with respect to the control group. We found no significant differences in the concentration of glucose and fragment 1 + 2 of prothrombin (F1 + 2). In the obese subjects, insulin, PAI-1, and F1 + 2 were positively correlated with the BMI. On the other hand, t-PA was correlated with insulin and PAI-1 but not with the BMI. Therefore, in the obese children, there was an increment of the risk factors for cardiovascular disease.

Continuation of growth hormone (GH) therapy in GH-deficient patients during transition from childhood to adulthood: impact on insulin sensitivity and substrate metabolism

The appropriate management of GH-deficient patients during transition from childhood to adulthood has not been reported in controlled trials, even though there is evidence to suggest that this phase is associated with specific problems in relation to GH sensitivity. An issue of particular interest is the impact of GH substitution on insulin sensitivity, which normally declines during puberty. We, therefore, evaluated insulin sensitivity (euglycemic glucose clamp) and substrate metabolism in 18 GH-deficient patients (6 females and 12 males; age, 20 +/- 1 yr; body mass index, 25 +/- 1 kg/m2) in a placebo-controlled, parallel study. Measurements were made at baseline, where all patients were on their regular GH replacement, after 12 months of either continued GH (0.018 +/- 0.001 mg/kg day) or placebo, and finally after 12 months of open phase GH therapy (0.016 mg/kg x day). Before study entry GH deficiency was reconfirmed by a stimulation test. During the double-blind phase, insulin sensitivity and fat mass tended to increase in the placebo group [deltaM-value (mg/kg x min), -0.7 +/- 1.1 (GH) vs. 1.3 +/- 0.8 (placebo), P = 0.18; deltaTBF (kg), 0.9 +/- 1.2 (GH) vs. 4.4 +/- 1.6 (placebo), P = 0.1]. Rates of lipid oxidation decreased [delta lipid oxidation (mg/kg x min), 0.02 +/- 0.14 (GH) vs. -0.32 +/- 0.13 (placebo), P < 0.05], whereas glucose oxidation increased in the placebo-treated group (P < 0.05). In the open phase, a decrease in insulin sensitivity was found in the former placebo group, although they lost body fat and increased fat-free mass [M-value (mg/kg x min), 5.1 +/- 0.7 (placebo) vs. 3.4 +/- 1.0 (open), P = 0.09]. In the group randomized to continued GH treatment almost all hormonal and metabolic parameters remained unchanged during the study. In conclusion, 1) discontinuation of GH therapy for 1 yr in adolescent patients induces fat accumulation without compromising insulin sensitivity; and 2) the beneficial effects of continued GH treatment on body composition in terms of decrease in fat mass and increase in fat-free mass does not fully balance the direct insulin antagonistic effects.

Hypoxia induces transcription of the plasminogen activator inhibitor-1 gene through genistein-sensitive tyrosine kinase pathways in vascular endothelial cells

A decline in oxygen concentration perturbs endothelial function, which promotes local thrombosis. In this study, we determined whether hypoxia in the range of that observed in pathophysiological hypoxic states stimulates plasminogen activator inhibitor-1 (PAI-1) production in bovine aortic endothelial cells. PAI-1 production, measured by ELISA, was increased by 4.7-fold (P<0.05 versus normoxic control, n=4) at 12 hours after hypoxic stimulation. Northern blot analysis showed the progressive time-dependent increase in the steady-state level of PAI-1 mRNA expression by hypoxia, which reached a 7.5-fold increase (P<0.05 versus control, n=4) at 12 hours. Deferoxamine, which has been known to bind heme protein and to reproduce the hypoxic response, induced PAI-1 production at both the mRNA and protein levels. The half-life of PAI-1 mRNA, as determined by a standard decay assay, was not affected by hypoxia, suggesting that induction of PAI-1 mRNA was regulated mainly at the transcriptional level. Transient transfection assays of the human PAI-1 promoter-luciferase construct indicates that a hypoxia-responsive region lies between -414 and -107 relative to the transcription start site, where no putative hypoxia response element is found. The hypoxia-mediated increase in PAI-1 mRNA levels was attenuated by the tyrosine kinase inhibitors genistein (50 micromol/L) and herbimycin A (1 micromol/L), whereas PD98059 (50 micromol/L, MEK1 inhibitor), SB203580 (10 micromol/L, p38 mitogen-activated protein kinase inhibitor), and calphostin C (1 micromol/L, protein kinase C inhibitor) had no effect on the induction of PAI-1 expression by hypoxia and deferoxamine. Genistein but not daidzein blocked the production of hypoxia- and deferoxamine-induced PAI-1 protein. Thus, we conclude that hypoxia stimulates PAI-1 gene transcription and protein production through a signaling pathway involving genistein-sensitive tyrosine kinases in vascular endothelial cells.

Visceral fat and insulin resistance--causative or correlative?

The association between abdominal fat accumulation and risk of chronic diseases, including type II diabetes and coronary heart disease, has long been recognized. Insulin resistance may be a key factor in this link. Many studies have pointed to an association between insulin resistance and intra-abdominal fat accumulation (visceral obesity). However there is no clear proof of a causal link between visceral fat accumulation and insulin resistance. In assessing the probability of a causal link, it is useful to consider potential mechanisms. One such potential causal link is the release of non-esterified fatty acids from visceral fat into the portal vein, so that they have direct effects on hepatic metabolism. Visceral fat has been shown in many studies to exhibit a high rate of lipolysis compared with subcutaneous fat depots. However, if the idea that visceral fat releases fatty acids into the portal vein at a high rate is examined critically, a number of difficulties appear. Not least of these is the fact that continued high rates of lipolysis should lead to the disappearance of the visceral fat depot, unless these high rates of fat mobilization are matched by high rates of fat deposition. There is far less evidence for high rates of fat deposition in visceral adipose tissue, and some contrary evidence. Evidence for high rates of visceral lipolysis in vivo from studies involving catheterization of the portal vein is not strong. If this potential link is discounted, then other reasons for the relationship between visceral fat and insulin resistance must be considered. One is that there is no direct causal link, but both co-correlate with some other variable. A possibility is that this other variable is subcutaneous abdominal fat, which usually outweighs intra-abdominal fat several-fold. Subcutaneous fat probably plays the major role in determining systemic plasma non-esterified fatty acid concentrations, which are relevant in determining insulin resistance. In conclusion, there is at present no proof of a causal link between visceral fat accumulation and insulin resistance, or the associated metabolic syndrome. The possibility of co-correlation with some other factor, such as subcutaneous abdominal fat accumulation, must not be forgotten.

Plasma plasminogen activator inhibitor 1, insulin resistance and android obesity

Plasma plasminogen activator inhibitor 1 (PAI-1) levels are elevated in insulin-resistant subjects and are associated with increased cardiovascular risk of atherothrombosis. Strong association between PAI-1 and the metabolic components of the insulin resistance syndrome is found in clinical studies, suggesting that insulin resistance may regulate circulating PAI-1. However, the mechanisms underlying increased PAI-1 levels in such conditions are still poorly understood. Several studies have been carried out specifically in patients with central or android obesity, a major characteristic of the insulin resistance syndrome, and have suggested that visceral adipose tissue may be the major component of the relationship between android obesity and PAI-1. Accordingly, adipose tissue PAI-1 production was found to be elevated in obese human subjects, particularly in visceral adipose tissue. The genetic background for having high PAI-1 levels in several populations have been looked for and its role appeared to be weaker than that of the metabolic condition. High plasma PAI-1 levels are then clearly related to android obesity and insulin resistance, but the mechanisms whereby PAI-1 increases in plasma in these diseases remain to be determined.

Plasma plasminogen activator inhibitor-I is associated with plasma leptin irrespective of body mass index, body fat mass, and plasma insulin and metabolic parameters in premenopausal women

Leptin, the satiety hormone expressed almost exclusively in adipose tissue, is a marker of body fat accumulation in humans. Recent studies have shown that plasminogen activator inhibitor-1 (PAI-1), a prothrombotic factor associated with atherosclerosis complications, is also produced in adipose tissue. The objective of the present study was to determine whether PAI-1 antigen plasma concentrations are associated with leptin plasma levels or the body fat mass (FM) independently of the variables known to influence PAI-1 production. Sixty-one nondiabetic women aged 18 to 45 years with a wide range of values for the body mass index ([BMI] 18.1 to 37.7 kg/m2) were evaluated for (1) body FM and fasting plasma levels of (2) PAI-1 antigen, (3) PAI-1 activity, (4) leptin, (5) insulin, (6) blood glucose, and (7) lipids (cholesterol, high-density lipoprotein [HDL]-cholesterol, and triglycerides [TG]). Body FM and fat-free mass (FFM) were estimated during fasting conditions by the bioimpedance analysis (BIA) method using a tetrapolar device. Body fat distribution was evaluated by the waist circumference and the waist to hip ratio (WHR). FM was directly associated with both PAI-1 antigen (r = .585, P < .001) and PAI-1 activity (r = .339, P < .001). Seemingly, leptin was positively related to both PAI-1 antigen (r = .630, P < .001) and PAI-1 activity (r = .497, P < .001). Moreover, both PAI-I antigen and PAI-1 activity were directly correlated with FFM (r = .285, P < .05, and r = .336, P < .01, respectively), BMI (r = .594, P < .001, and r = .458, P < .001, respectively), and WHR (r = .510, P < .001, and r = .391, P < .005, respectively). Insulin was directly related to PAI-1 antigen (r = .540, P < .001), PAI-1 activity (r = .259, P < .05), leptin (r = .447, P < .001), and FM (r = .435, P < .001). The association between PAI-1 antigen (dependent variable) and leptin or FM was tested by a stepwise regression model simultaneously including leptin, FM, BMI, WHR, age, FFM, and fasting insulin, blood glucose, TG, cholesterol, and HDL-cholesterol as independent variables. PAI-1 antigen maintained a significant positive independent relationship only with leptin (t = 2.923, P < .01), insulin (t = 3.489, P < .001), and fasting blood glucose (t = 2.092, P < .05), and a negative independent relationship with HDL-cholesterol (t = -2.634, P < .05). In conclusion, the strong relationship between PAI-1 antigen and leptin irrespective of other variables known to influence these factors seems to indicate that leptin per se may potentially increase PAI-1 plasma concentrations in obese subjects.

Effects of physical training and its cessation on the hemostatic system of obese children

BACKGROUND

Physical training can improve hemostatic function in adults, thereby reducing heart disease risk, but no information is available in children on whether physical training can enhance hemostatic function.

OBJECTIVE

The purpose of this investigation was to examine the effects of a physical training program on hemostatic variables in a biethnic group of obese children.

DESIGN

Children were randomly assigned to 2 groups. Group 1 participated in physical training for 4 mo and then ceased physical training for 4 mo, whereas group 2 did no physical training for the first 4 mo and then participated in physical training for 4 mo. Plasma hemostatic variables [fibrinogen, plasminogen activator inhibitor 1 (PAI-1), and D-dimer) were measured at months 0, 4, and 8.

RESULTS

Analyses of variance revealed no significant group-by-time interactions for the hemostatic variables. When data from both groups were combined there was a significant decrease in D-dimer after 4 mo of physical training (P < 0.05). Factors explaining individual differences in responsiveness to the physical training revealed that individuals with greater percentage fat before physical training showed greater reductions in fibrinogen and D-dimer, and that blacks showed greater reductions in D-dimer than whites (P < 0.05). Stepwise multiple linear regression showed that only higher prephysical training concentrations of fibrinogen, PAI-1, and D-dimer explained significant proportions of the variation in changes in these variables.

CONCLUSIONS

In obese children, 4-mo periods of physical training did not lead to significant changes in hemostatic variables. Children with greater adiposity and concentrations of hemostatic factors before physical training showed greater reductions in hemostatic variables after physical training than did children with lesser values.

Impact of adipose tissue on plasma plasminogen activator inhibitor-1 in dieting obese women

The increased incidence of cardiovascular diseases in obese subjects could be partially attributed to impaired fibrinolysis due to elevated plasma levels of tissue plasminogen activator inhibitor 1 (PAI-1). The associations between changes in plasma PAI-1, metabolic variables, and adipose tissue during weight loss and regain were studied in 52 healthy, premenopausal, obese women participating in a weight reduction program with a hypocaloric diet. PAI-1, insulin, triglyceride, leptin, and adipsin levels were determined at entry, after the first week, after completion of the program, and after 5 months of follow-up. In the 33 obese women who completed the program, decreases in PAI-1 antigen (-54%), PAI activity (-74%), and leptin (-51%), but not of adipsin, were observed. Changes in PAI-1 were associated with changes in body mass index (BMI), body fat, leptin, and insulin. The decreased level of PAI-1 remained low after follow-up in the 14 women who maintained their reduced weight but increased in the 16 women who regained weight. This increase in PAI-1 was correlated with an increase in body fat and leptin. On multivariate analysis, BMI was the major determinant of PAI-1 level. In conclusion, during weight reduction with a hypocaloric diet, the decrease in PAI-1 is more closely related to changes in adipose tissue than to changes in metabolic variables, suggesting a significant role for adipose tissue in regulating plasma levels of PAI-1.

PAI-1 produced ex vivo by human adipose tissue is relevant to PAI-1 blood level

Human adipose tissue has been shown to produce plasminogen activator inhibitor type 1 (PAI-1). However, the importance of adipose tissue in the regulation of the PAI-1 plasma level is not known. The aim of this study was to investigate the relation between the production of PAI-1 by adipose tissue, plasma PAI-1 level, and variables related to the insulin resistance state. The link between the production of PAI-1 inducers such as tumor necrosis factor-alpha and transforming growth factor-beta and the production of PAI-1 by adipose tissue was also evaluated. Blood samples were obtained as soon as possible to the induction of anesthesia from 30 patients undergoing elective abdominoplasty. PAI-1 antigen levels measured in conditioned media after a 19-hour incubation period of adipose tissue explants were significantly correlated with plasma PAI-1 antigen levels (r=0.54, P=0.004) and with systemic lipid parameters such as triglycerides and high density lipoprotein cholesterol (r=0. 46, P=0.014; r=-0.50, P=0.01, respectively) but not with insulinemia and body mass index. PAI-1 production by adipose tissue was correlated with those of TNF-alpha (r=0.5, P=0.01) and TGF-beta (r=0. 53, P=0.007). These results emphasize the role of adipose tissue in determining plasma levels of PAI-1, with a local contribution of TNF-alpha and TGF-beta in PAI-1 production by adipose tissue.

Expression of plasminogen activator inhibitor-1 in human adipose tissue: a role for TNF-alpha?

Elevated plasminogen activator inhibitor-1 (PAI-1) plasma levels, responsible for reduced fibrinolysis, are associated with animal and human obesity and with increased cardiovascular disease. The expression of PAI-1 has been found recently in animal and human adipose tissue. Factors and mechanisms regulating such an expression remain to be elucidated. In omental and/or subcutaneous biopsies from obese non-diabetic patients, incubated in Medium 199, we have confirmed that human adipose tissue expresses PAI-1 protein and mRNA; furthermore we have demonstrated that such an expression is clearly evident also in collagenase isolated human adipocytes and that it is stimulated by incubation itself and enhanced by exogenous human tumor necrosis factor-alpha (h-TNF-alpha). Since human adipose tissue produces TNF-alpha, to further characterize the relationship of PAI-1 to TNF-alpha, human fat biopsies were also incubated with Pentoxifylline (PTX) or Genistein, both known to inhibit endogenous TNF-alpha through different mechanisms. PTX caused a dose-dependent decrease of basal PAI-1 protein release, reaching 80% maximal inhibitory effect at 10(-3)M, the same inhibitory effect caused by Genistein at 100 microg/ml. This was associated to a marked inhibition of PAI-1 mRNA and of endogenous TNF-alpha production. Furthermore, when human fat biopsies were incubated in the presence of polyclonal rabbit neutralizing anti-human TNF-alpha antibody (at a concentration able to inhibit 100 UI/ml human TNF-alpha activity), a modest but significant decrease of the incubation induced expression of PAI-1 mRNA was observed (19.8+/-19.0% decrease, P = 0.04, n = 7). In conclusion, the results of this study demonstrate that PAI-I expression is present in human isolated adipocytes and that it is enhanced in human adipose tissue in vitro by exogenous TNF-alpha. Furthermore our data support the possibility of a main role of endogenous TNF-alpha on human adipose tissue PAI-1 expression. This cytokine, produced by human adipose tissue and causing insulin resistance, may be a link in the clinical relationship between insulin-resistance syndrome and increased PAI-1 plasma levels.

Relative contribution of insulin and its precursors to fibrinogen and PAI-1 in a large population with different states of glucose tolerance. The Insulin Resistance Atherosclerosis Study (IRAS)

Hyperinsulinemia is associated with the development of coronary heart disease. However, the underlying mechanisms are still poorly understood. Hypercoagulability and impaired fibrinolysis are possible candidates linking hyperinsulinism with atherosclerotic disease, and it has been suggested that proinsulin rather than insulin is the crucial pathophysiological agent. The aim of this study was to investigate the relationship of insulin and its precursors to markers of coagulation and fibrinolysis in a large triethnic population. A strong and independent relationship between plasminogen activator inhibitor-1 (PAI-1) antigen and insulin and its precursors (proinsulin, 32-33 split proinsulin) was found consistently across varying states of glucose tolerance (PAI-1 versus fasting insulin [proinsulin], r=0.38 [r=0.34] in normal glucose tolerance; r=0.42 [r=0.43] in impaired glucose tolerance; and r=0.38 [r=0.26] in type 2 diabetes; all P<0.001). The relationship remained highly significant even after accounting for insulin sensitivity as measured by a frequently sampled intravenous glucose tolerance test. In a stepwise multiple regression model after adjusting for age, sex, ethnicity, and clinic, both insulin and its precursors were significantly associated with PAI-1 levels. The relationship between fibrinogen and insulin and its precursors was significant in the overall population (r=0.20 for insulin and proinsulin; each P<0.001) but showed a more inconsistent pattern in subgroup analysis and after adjustments for demographic and metabolic variables. Stepwise multiple regression analysis showed that proinsulin (split products) but not fasting insulin significantly contributed to fibrinogen levels after adjustment for age, sex, clinic, and ethnicity. Decreased insulin sensitivity was independently associated with higher PAI-1 and fibrinogen levels. In summary, we were able to demonstrate an independent relationship of 2 crucial factors of hemostasis, fibrinogen and PAI-1, to insulin and its precursors. These findings may have important clinical implications in the risk assessment and prevention of macrovascular disease, not only in patients with overt diabetes but also in nondiabetic subjects who are hyperinsulinemic.

Low-density lipoprotein particle size is inversely related to plasminogen activator inhibitor-1 levels. The Insulin Resistance Atherosclerosis Study

High levels of plasminogen activator inhibitor-1 (PAI-1) and preponderance of small dense low-density lipoproteins (LDL) have both been associated with atherosclerotic disease and with the insulin resistance syndrome (IRS). In vitro studies have shown a stimulatory effect of various lipoproteins on PAI-1 release from different cells, including endothelial cells and adipocytes. The authors sought to investigate the relation of PAI-1 to LDL particle size in a large tri-ethnic population (n=1549) across different states of glucose tolerance. LDL size was determined by gradient gel electrophoresis, and PAI-1 was measured by a 2-site immunoassay, sensitive to free PAI-1. PAI-1 was inversely related to LDL size in the overall population (r=-0.21, P<0.0001), independent of gender and ethnicity. However, the authors found a significant interaction with glucose tolerance status (P=0.035). In univariate analysis, the association between PAI-1 and LDL size was most pronounced in subjects with normal glucose tolerance (NGT, r=-0.22, P<0.0001) and weaker in impaired glucose tolerance (IGT, r=-0.12, P=0.03) and type-2 diabetes (r=-0.10, P=0.02). After adjustment for demographic variables and metabolic variables known to influence PAI-1 levels (triglyceride and insulin sensitivity), a significant inverse relation of LDL size to PAI-1 levels was only present in NGT (P=0. 023). In subjects with IGT or overt diabetes, who usually have elevated PAI-1 levels, additional factors other than LDL size seem to contribute more importantly to PAI-1 levels. The demonstrated inverse relation of LDL size and PAI-1 levels provides one possible explanation for the atherogeneity of small dense LDL particles.

The effect of number of days in culture and plasminogen activator inhibitor-1 (PAI-1) 4G/5G genotype on PAI-1 antigen release by cultured human umbilical vein endothelial cells

An insertion/deletion (4G/5G) polymorphism in what has been shown to be an enhancer/repressor binding site in the promoter region of the PAI-1 gene has been related to plasma PAI-1 activity. Transfection studies demonstrated increased interleukin-1 stimulated PAI-1 synthesis in cells containing the 4G sequence. To study this response in endothelial cells, first passage HUVEC from 26 umbilical cords were stimulated with interleukin-1 and tumor necrosis factor-alpha. PAI-1 antigen was measured in 24-hour conditioned medium and allele-specific PCR utilized to determine genotype at the 4G/5G locus. Analysis of covariance was used to determine whether the effect of a variable time in culture was masking a difference between genotypes. A trend towards higher PAI-1 levels with increasing time in culture was observed. The geometric mean (95% confidence interval) of the basal rate of PAI-1 release was, 4G/4G 9.7 (7.0, 13.5) ng/24 hours (n=11), 4G/5G 9.5 (6.5, 13.9) ng/24 hours (n=9), and 5G/5G 10.9 (7.8, 15.1) ng/24 hours (n=6). In cells of the same cultures, the interleukin-1 stimulated levels were 25.9 (23.1, 29.1), 27.2 (23.6, 31.3), and 23.1 (19.5, 27.3) ng/24 hours, respectively, corresponding to ratios of stimulated to basal levels of 2.68, 2.87, and 2.12. After adjustment for time in culture the basal PAI-1 release was 4G/4G 10.7, 4G/5G 9.1, and 5G/5G 9.7 ng/24 hours. For interleukin-1 stimulated release the adjusted levels were 26.3, 27.0, and 22.7 ng/24 hours, respectively. Adjusted levels in 4G/4G genotype cells were non-significantly greater than those in cells of 5G/5G genotype by a factor of 1.16 (0.95, 4.08). This study did not demonstrate a significant difference in basal or cytokine stimulated PAI-1 release from cells of different PAI-1 promoter (4G/5G) genotypes but does not exclude increased interleukin-1 stimulated PAI-1 release in the 4G/4G compared with the 5G/5G genotype.

Visceral fat accumulation is an important determinant of PAI-1 levels in young, nonobese men and women: modulation by cross-sex hormone administration

Increased plasminogen activator inhibitor type-1 (PAI-1) levels, leading to impaired fibrinolysis, are associated with increased visceral fat in middle-aged and obese subjects. It is unknown, however, whether this association is independent of other disturbances clustered in the insulin resistance syndrome. We analyzed this association in young, nonobese transsexual men and women before and after administration of cross-sex steroids, which potentially influence many elements of the insulin resistance syndrome, including PAI-1 levels and visceral fat accumulation. We assessed the visceral fat area (by MRI); total body fat; insulin sensitivity (with a glucose clamp technique); and plasma levels of PAI-1, insulin, and triglycerides in young (<37 years old), nonobese (body mass index <28 kg/m2), healthy men (n=18) and women (n=15) before and after 12 months of cross-sex hormone administration. Men were treated with ethinyl estradiol 100 microgram/d plus cyproterone acetate 100 mg/d, and women were treated with testosterone esters 250 mg IM every 2 weeks. At baseline, only visceral fat area was significantly correlated with plasma PAI-1 levels in both men (r=0.57, P=0.03) and women (r=0.59, P=0.03). In multivariate linear regression analysis, this association was independent of total body fat, insulin sensitivity, and plasma levels of triglycerides and insulin. After 12 months of cross-sex hormone administration, the plasma PAI-1 levels were no longer correlated with visceral fat (which had increased). We conclude that in young, nonobese men and women, visceral fat area is an important determinant of plasma PAI-1 levels. After cross-sex hormone administration, this association was no longer demonstrable.

PPARgamma activators improve glucose homeostasis by stimulating fatty acid uptake in the adipocytes

It is currently thought that the effects of PPARgamma activation on glucose homeostasis may be due to the effect of this nuclear receptor on the production of adipocyte-derived signalling molecules, which affect muscle glucose metabolism. Potential signalling molecules derived from adipocytes and modified by PPARgamma activation include TNFalpha and leptin, which both interfere with glucose homeostasis. In addition to its effects on these proteins, PPARgamma also profoundly affects fatty acid metabolism. Activation of PPARgamma will selectively induce the expression of several genes involved in fatty acid uptake, such as lipoprotein lipase, fatty acid transport protein and acyl-CoA synthetase, in adipose tissue without changing their expression in muscle tissue. This co-ordinate regulation of fatty acid partitioning by PPARgamma results in an adipocyte 'FFA steal' causing a relative depletion of fatty acids in the muscle. Based on the well established interference of muscle fatty acid and glucose metabolism it is hypothesized that reversal of muscle fatty acid accumulation will contribute to the improvement in whole body glucose homeostasis.

Associations between central obesity and indexes of hemostatic, carbohydrate and lipid metabolism. Results of a 1-year intervention from the Oslo Diet and Exercise Study

The relationships of central obesity and physical fitness to indexes of hemostatic, lipid and glucose metabolism both at baseline and after 1 year of diet and exercise intervention were examined in 209 sedentary middle-aged men and women with increased coronary risk factor levels. Central obesity was measured as either waist circumference or waist/hip ratio. Maximal oxygen uptake was used as a measure of physical fitness. The cross-sectional results show that there were significant correlations between waist circumference and euglobuline clot lysis time (r = 0.23), factor VII (r = 0.16), glucose and insulin before and after 1 h glucose load (r ranging from 0.32 to 0.50). The 1-year intervention gave the following associations between changes in waist circumference and changes in: euglobuline clot lysis time (r = 0.27), factor VII (r = 0.19), carbohydrate variables and lipids (magnitude of r ranging from 0.19 to 0.43). Also the other indexes of obesity and physical fitness showed significant correlations to indexes of hemostatic, lipid and glucose variables, both cross-sectionally and for changes after the 1-year intervention. The associations between changes in central obesity and changes in indexes of hemostatic, carbohydrate and lipids were generally stronger during 1 year of diet and exercise intervention than those found at baseline. Multiple regression analyses with waist circumference, waist/hip ratio, percent body fat and Vo2 max as independent variables and indexes of hemostatic, carbohydrate and lipid metabolism as dependent variables showed that waist circumference was a significant predictor for indexes of the hemostatic, carbohydrate and lipid metabolism, mostly independent of physical fitness. The cross-sectional and 1-year change results support each other and therefore underscore the importance of abdominal obesity as an important risk factor for cardiovascular disease.

Physical activity status and adverse age-related differences in coagulation and fibrinolytic factors in women

Adverse changes in coagulation and fibrinolytic factors are thought to contribute to the increased risk of cardiovascular disease and atherothrombosis with age. We tested the hypothesis that such age-related changes in specific coagulation and fibrinolytic factors are absent in physically active women. Resting levels of plasma fibrinogen, tissue-type plasminogen activator (t-PA) antigen and activity, plasminogen activator inhibitor-1 (PAI-1) antigen and activity, and fibrin D-dimer were measured in 24 healthy premenopausal women: 11 sedentary (aged 28+/-1 years; Pre-S) and 13 physically active (aged 30+/-1 years; Pre-PA) and in 27 healthy postmenopausal women: 14 sedentary (aged 61+/-1 years; Post-S) and 13 physically active (aged 58+/-1 years; Post-PA). Post-S had higher (P<.05) fibrinogen, t-PA antigen, PAI-1 antigen, PAI-1 activity, and fibrin D-dimer levels and lower t-PA activity than Pre-S. Post-PA demonstrated lower (P<.01) plasma fibrinogen, t-PA antigen, PAI-1 antigen, and PAI-1 activity and higher (P<.01) t-PA activity levels than Post-S. In addition, plasma fibrin D-dimer levels tended (P=.06) to be lower in Post-PA than in Post-S. Although plasma levels of fibrinogen and fibrin D-dimer in Post-PA were lower than in Post-S, they were higher (P<.05) than in Pre-PA. Importantly, however, the fibrinolytic profile of Post-PA did not differ from that of Pre-PA. The results of the present study demonstrate that the adverse age-associated differences in plasma fibrinogen concentrations and the endogenous fibrinolytic system in sedentary healthy women are either attenuated or absent in highly physically active women. The smaller or absent age-related differences in coagulation and fibrinolytic factors in women who habitually exercise may represent an important mechanism contributing to their lower age-related increase in both cardiovascular disease and atherothrombotic events. Future studies need to determine whether women who are moderately active would demonstrate the same favorable hemostatic profile.

Liposuction in Dercum's disease: impact on haemostatic factors associated with cardiovascular disease and insulin sensitivity

OBJECTIVE

To study the impact of adipose tissue removal by liposuction on factors associated with increased risk of cardiovascular atherosclerotic disease within the coagulation and fibrinolytic system and glucose metabolism.

DESIGN, SETTING AND SUBJECTS

Liposuction was performed in 53 patients with Dercum's disease. The levels of fibrinogen, von Willebrand factor antigen (VWF:Ag) and plasminogen activator inhibitor type 1 activity (PAI-1) were measured preoperatively, and 2 weeks, 4 weeks and 3 months postoperatively. In a subsample of 10 patients, insulin sensitivity was determined before and 2-4 weeks after surgery using the 2-h euglycaemic hyperinsulinaemic clamp technique. The study was performed as a single-centre study.

MAIN OUTCOME MEASURE

Fibrinogen, PAI-1 and VWF:Ag levels, and glucose uptake before and after removal of adipose tissue.

RESULTS

Weight reduction was sustained throughout the follow-up period with a mean decrease from 90.7 to 86.6 kg (P < 0.0001). There was a slight increase in levels of coagulation factors 2 and 4 weeks postoperatively, probably in reaction to the surgical trauma. After 3 months the values had returned to preoperative levels except for PAI-1, which still showed a slight increase (P < 0.05). In the subsample of 10 patients, glucose uptake was improved (P < 0.05) from a short-term perspective after surgery.

CONCLUSION

Surgical removal of adipose tissue, without change in lifestyle, does not seem to improve the levels of coagulation and fibrinolytic factors associated with cardiovascular atherosclerotic disease, whereas glucose takeup may be facilitated and insulin sensitivity increases from a short-term perspective.

Dependence of augmentation of arterial endothelial cell expression of plasminogen activator inhibitor type 1 by insulin on soluble factors released from vascular smooth muscle cells

BACKGROUND

Insulin-resistant states are characterized by accelerated atherosclerosis and are associated with increased plasma concentrations of insulin and plasminogen activator inhibitor type 1 (PAI-1). To determine whether arterial expression of PAI-1 in response to insulin contributes to the increased PAI-1 observed, human and porcine arteries in culture were exposed to insulin, and results were compared with responses of specific arterial cellular constituents maintained in culture and coculture.

METHODS AND RESULTS

Human and porcine arterial segments and cells obtained from arteries were maintained in culture. Insulin increased accumulation of PAI-1 in conditioned medium from arterial segments (ng PAI-1 [1 nmol/L insulin minus control]: human arteries 47+/-17, porcine arteries 3.1+/-1.2, P<.05 for each) and from endothelial cells (ECs) cocultured with smooth muscle cells (SMCs, ng PAI-1 [1 nmol/L insulin minus control]: human cells 43+/-8, porcine cells 0.5+/-0.1, P<.05 for each). Insulin had no effect on EC expression of PAI-1 when not cocultured with SMCs. Increased accumulation of PAI-1 was seen when ECs, in coculture chambers without SMCs, were cultured with medium previously conditioned by SMCs in the presence of insulin. The increased accumulation of PAI-1 in conditioned medium was secondary to both an increased transport of PAI-1 from the basal to the apical surface of ECs as well as an increased production of PAI-1 by ECs.

CONCLUSIONS

Insulin augments arterial expression of PAI-1 by stimulating release of a soluble factor(s) from SMCs. Accordingly, increased arterial elaboration of PAI-1 in response to insulin is likely to account, in part, for the elevated PAI-1 observed in the blood of subjects with insulin-resistant states.