M. Cigolini

Visceral Fat Accumulation and Its Relation to Plasma Hemostatic Factors in Healthy Men

The associations between abdominal visceral fat and the plasma hemostatic system were examined in 38-year-old healthy men (n=52) with a wide range of fatness and fat distribution. Plasma hemostatic factors and metabolic parameters, including glucose tolerance, were measured, and body fatness and adipose tissue distribution were assessed by using computed tomography. The men with more visceral fat (ie, higher than the median value [n=26]) had a less favorable metabolic profile than the men with less visceral fat (n=26). They also had significantly (P<.05) higher plasma fibrinogen, factor VIII clotting activity, tissue-type plasminogen activator antigen, and plasminogen activator inhibitor-1 (PAI-1) activity (19.2+/-2.4 versus 8.5+/-1.6 AU/mL, P<.001) and lower basal tissue-type plasminogen activator activity. After adjustment for plasma insulin, the men with larger abdominal visceral fat area still had significantly higher plasma PAI-1 activity, but no difference was found in any of the other hemostatic factors. In multiple linear regression analysis, abdominal visceral fat area was a positive predictor of plasma PAI-1 activity, but it failed to show any significant association with other hemostatic factors after controlling for plasma insulin. These results suggest the presence of relationships between abdominal visceral fat and several plasma hemostatic factors that are largely mediated by concomitant alterations in plasma insulin concentration. In addition, our results suggest that abdominal accumulation of visceral fat is an independent predictor of plasma PAI-1 activity.

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

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.

Body fat distribution in relation to serum lipids and blood pressure in 38-year-old European men: the European fat distribution study.

A study on 512 38-year-old European men selected from 6 different towns was conducted. There were significant differences between the centers in averages of anthropometric variables (except for thigh circumference), serum lipids (except for LDL-cholesterol), and blood pressure. In the pooled material, body mass index (BMI) as well as waist circumference, waist/hip ratio and waist/thigh ratio and subscapular skinfold were positively correlated to serum triglycerides, total cholesterol, LDL-cholesterol, and blood pressure and negatively with HDL-cholesterol. After adjustment for BMI, waist, waist/hip, and waist/thigh were all still significantly correlated with serum triglycerides (P less than 0.001). In addition, waist/hip and waist/thigh ratio showed significant partial correlations with total cholesterol (r = 0.16, P less than 0.001, r = 0.10, P less than 0.05 respectively), and diastolic blood pressure (r = 0.10, P less than 0.05, r = 0.09, P less than 0.05 respectively). In addition, waist/hip was, independently of BMI, correlated to LDL-cholesterol (r = 0.12, P less than 0.01), and waist/thigh ratio with HDL-cholesterol (r = -0.12, P less than 0.01). The partial association between waist/thigh with HDL cholesterol became insignificant after adjustment for smoking habits and physical activity. Adjustment for differences in anthropometric measurements did not explain the differences in serum lipids and blood pressure between the centers. The authors conclude that indicators of body fat distribution are associated with unfavorable risk profiles for cardiovascular disease in European men covering a large geographical and cultural variety and a wide range of body measurements and cardiovascular risk factors.

The white blood cell count: its relationship to plasma insulin and other cardiovascular risk factors in healthy male individuals

Targher G, Seidell JC, Tonoli M, Muggeo M, De Sandre G, Cigolini M (Division of Endocrinology and Metabolic Diseases, Institute of Clinical Medicine, University of Verona, Italy; and Department of Chronic Diseases and Environmental Epidemiology‐RIVM, Bilthoven, The Netherlands). The white blood cell count: relationship to plasma insulin and other cardiovascular risk factors in healthy males. J Intern Med 1996; 239: 435–41.

Fat distribution and gender differences in serum lipids in men and women from four European communities

We studied male/female differences in serum lipids in randomly selected 38-year-old men (n = 337) and women (n = 342) from various cities in The Netherlands, Sweden, Italy, and Poland. Overall, men had higher triglycerides and total cholesterol levels and lower HDL-levels compared to women (P less than 0.001). Adjustment for smoking habits, city, and body mass index did not remove the gender difference. Further adjustments for waist circumference alone and waist/hip and waist/thigh circumference ratio removed the gender differences in serum triglycerides and total cholesterol. Only adjustment for waist/thigh ratio removed the gender difference in HDL-cholesterol but linear relationships were different in men and women. The average male/female difference in serum lipids, particularly for total and LDL-cholesterol varied considerably among centers. In analyses of the data from the separate centers we found that sex differences in serum triglycerides and HDL-cholesterol in all 4 centers disappeared when adjusted for waist circumference alone and for waist/hip and waist/thigh ratio. For total and LDL-cholesterol, however, adjustment for circumference ratios tended to increase the male/female difference in 2 of the 4 centers. It is concluded that, in European men and women, fat distribution may be responsible for male/female differences in serum triglycerides but that such conclusions are less clear for HDL-, total- and LDL-cholesterol.

Androgenicity in relation to body fat distribution and metabolism in 38-year old women - the European fat distribution study.

We studied fat distribution and metabolic risk factors in 434 38-year old women selected from population registrars in 5 cities in different parts of Europe. In the present study we focussed on the geographical variation in serum concentrations of free testosterone and its relation to measures of obesity, fat distribution and indicators of cardiovascular risk (serum lipids, insulin, and blood pressure). There were significant differences in free testosterone levels (F = 5.4, p less than 0.001) with lowest levels in Polish women (mean +/- SEM: 1.56 +/- 0.08 pg/ml) and highest in women from Italy (2.07 +/- 0.12 pg/ml). In the pooled data, free testosterone levels were correlated with several anthropometric variables (strongest with subscapular/triceps ratio r = 0.27, with subscapular skinfold and waist/thigh circumference ratio r = 0.25 p-values less than 0.001). In addition, free testosterone was positively correlated with serum total cholesterol (r = 0.11), HDL/total cholesterol fraction (r = 0.12), serum insulin (r = 0.20) and diastolic blood pressure (r = 0.15). These associations remained significant after adjustment for body mass index and waist/thigh ratio (not for diastolic blood pressure) but were no longer significant after further adjustment for insulin levels. There were considerable differences in strength of the associations mentioned between the 5 centers. We conclude that degree of obesity, fat distribution and serum levels of free testosterone all, to a limited degree, contribute to the metabolic profile of randomly selected 38-year old women but that adjustment for such variables increases the differences in metabolic profiles between women from different centers of Europe.

Relationships of plasminogen activator inhibitor-1 to anthropometry, serum insulin, triglycerides and adipose tissue fatty acids in healthy men

Increased plasma levels of plasminogen activator inhibitor-1 (PAI-1), responsible for reduced fibrinolytic activity, have been shown to be an important risk factor for cardiovascular disease. PAI-1 plasma levels are influenced by several factors which have not yet been fully clarified, including dietary fat intake. The relationships of PAI-1 with other cardiovascular risk factors are still not well known. In a random sample of 38-year-old healthy men (n = 94), the association of PAI-1 plasma levels (measured as activity and antigen) with anthropometric parameters, serum lipids, fasting and 2 h insulin and glucose concentration after oral glucose-load was analysed. Furthermore, the fatty acid composition of subcutaneous adipose tissue, as an objective and reliable index of dietary fat intake, was measured. The univariate analysis showed that plasma levels of PAI-1 were significantly associated with body mass index (BMI) (r = 0.37, P < 0.001), waist/hip ratio (WHR) (r = 0.26, P < 0.01), serum triglycerides (r = 0.47, P < 0.0001), HDL/total cholesterol ratio (r = -0.35, P < 0.001), fasting and 2-h insulin (r = 0.27, P < 0.01 and r = 0.34, P < 0.001) and glucose concentrations (r = 0.25, P < 0.05 and r = 0.28, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Human brown adipose cells in culture.

Brown adipose tissue (BAT), obtained from the axillary and perirenal regions of newborns 24-48 h after death, was digested with collagenase and the free cells were cultured. Only the cultures of cells from tissue obtained later than 24 h post mortem were successful. These cells grew slowly to reach confluence. Their typical mitochondria gradually disappeared, being replaced by untypical mitochondria. After confluence, the cells accumulated large amounts of lipid in non-coalescent multivacuolar depots. This model can be useful for the study of the metabolic and morphological features of human brown fat cells.

Fasting serum insulin in relation to fat distribution, serum lipid profile, and blood pressure in European women: The European fat distribution study

Samples of 38-year-old women were randomly selected from five European centers: Ede (The Netherlands), Warsaw (Poland), Gothenburg (Sweden), Verona (northern Italy), and Afragola (Naples-southern Italy). In total, 452 healthy women were studied. Anthropometric measurements were taken by one operator in each country after common training of all operators and blood parameters of all women were determined in one laboratory. Body mass index (BMI) was different among centers, mainly due to the higher values in southern Italy. Women from southern Europe had more central fat distribution than women from north European centers. Fasting serum insulin was higher in women from Poland and The Netherlands than in the other three centers. After adjustment for BMI, fasting insulin was significantly related to subscapular skinfold, subscapular to triceps skinfold ratio, waist circumference, and waist to thigh circumference ratio, although the partial correlations varied somewhat between the centers. In the pooled data, waist circumference showed the highest correlations with fasting serum insulin when adjusted for BMI. Fasting serum insulin showed significant partial correlations, adjusted for BMI, with lipid profile and blood pressure only in women from the two Italian centers. In the pooled data, fasting serum insulin was significantly positively correlated with serum triglycerides and total cholesterol and negatively to high-density lipoprotein (HDL) cholesterol and HDL/total cholesterol, independently of BMI and waist circumference. While blood pressure was not related to insulin in the pooled women, when adjusted for BMI and waist circumference; here as well, there were some differences in relationships between the centers.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma fibrinogen in relation to serum insulin, smoking habits and adipose tissue fatty acids in healthy men

Abstract. Recent prospective studies have reported an independent association between fibrinogen plasma levels and risk of cardiovascular events. Aim of this study was to investigate the relationships between fibrinogen level and conventional cardiovascular risk factors in a random sample of 38 year‐old apparently healthy men (n= 94), and to verify whether the fatty acid composition of the diet might influence those relations. Anthropometric measurements, serum lipids, blood pressure, and smoking habits were evaluated. In addition, fasting and after glucose‐load serum glucose and insulin concentrations were measured. The most significant difference in fibrinogen level was found among the tertiles of fasting serum insulin (Fanova= 4·5; P < 0·01) with the highest plasma fibrinogen values in the third insulin tertile, whereas body mass index (BMI), waist/hip circumference ratio (WHR) and serum triglycerides were more weakly related. The current smokers had substantially higher levels of fibrinogen than subjects who never smoked (P < 0·001). A multivariate regression analysis showed that, among the above reported variables, only serum insulin and smoking were independently associated with plasma fibrinogen. Furthermore, as the possible association between fatty acid composition of the diet and fibrinogen level regards, we have examined the fatty acid composition of adipose tissue, as a good and objective index of quality of the dietary fat intake. It was found that, fibrinogen level was not associated with any adipose tissue fatty acid. In conclusion, this study performed in a random sample of healthy men indicates an independent relationship of fasting insulin and smoking to fibrinogen plasma level.