Relationship between fat cell size and number and fatty acid composition in adipose tissue from different fat depots in overweight/obese humans

OBJECTIVE

To evaluate the body fat distribution and fat cell size and number in an overweight/obese population from both genders, and to determine the possible relationship between fat cell data from three different adipose tissue localizations (subcutaneous (SA), perivisceral and omental) and adipose tissue composition and dietary fatty acid.

DESIGN

The sample consisted of 84 overweight/obese patients (29 men and 55 women) who have undergone abdominal surgery. The adipocyte size and total fat cell number was studied. Fat cell data were related with anthropometric, adipose tissue and subject's habitual diet fatty acid composition.

MEASUREMENTS

Fat cell size was measured according to a Sjöström method from the three adipose depots. Total fat cell number was also calculated. The fatty acid composition of adipose tissue was examined by gas chromatography. The subjects diet was studied by a 7 days dietary record.

RESULTS

Our data showed a negative relationship between the adipocyte size and the n-6 and n-3 fatty acids content of the SA adipose tissue (r=-0.286, P=0,040; r=-0.300, P=0.030) respectively, and the n-6 in the omental depots (r=-0.407, P=0.049) in the total population. Positive associations with the total of saturated (r=0.357, P=0.045) and negative (r=-0.544, P=0.001) with the n-9 fatty acids were observed when the relationship between the adipocyte number and the fatty acid composition of the different anatomical fat regions was studied. Dietary fatty acids composition positively correlated with fat cell size for the myristic acid (14:0) in men in the visceral depot (r=0.822, P=0.023), and for the saturated fatty acids (SFAs) in women in the omental depot (r=0.486, P=0.035).

CONCLUSION

In the present study, for the first time in humans we found that n-3 and n-6 fatty acids are related to a reduced adipocyte size according to the depot localization. In contrast, adipose tissue and dietary SFAs significantly correlated with an increase in fat cell size and number. No significant associations were found between n-9 acids content and adipocyte size. However, n-9 adipose tissue fatty acids content was inversely associated with fat cell number showing that this type of fatty acid could limit hyperplasia in obese populations. The differences observed in the three different regions, perivisceral, omental and SA fat, indicate that this population adipose tissue have depot-specific differences.

Adiposity and dietary intake in cardiovascular risk in an obese population from a Mediterranean area

The aim of the study was to determine the particular relevance of android fat distribution and dietary intake in cardiovascular risk in an obese Mediterranean population with high intake of monounsaturated fatty acids (MUFA) and to compare the findings with those from normal-weight subjects. For the study, 193 subjects aged 25-60 were selected: 118 obese (BMI > or = 27 kg/m2), and 75 normal-weight (BMI < 25 kg/m2). Cardiovascular risk factors including hypertension, dyslipidaemia, glucose intolerance and insulin resistance were assessed. Nutrient intake and body fat distribution were determined. Results show that MUFA were highly consumed in the total population (21% of total energy). The obese population was normolipidemic and normoinsulinemic. However, cardiovascular risk factors (CVRF) were significantly higher than in normal-weight (P < 0.05). Obese subjects derived a greater percentage of their energy intake from total fat and lower from carbohydrates and saturated fats (P < 0.05). BMI and waist-hip ratio positively correlated with fat percentage of total energy intake and with MUFA (g/100 g fatty acids) in men, indicating that the excess of fat intake in obesity is due to a larger consumption of olive oil. CVRF were significantly and positively associated to waist circumference and WHR, both in obese and in normal-weight subjects. In conclusion, not only obesity but also android fat in normal-weight subjects are important factors in cardiovascular disease even in the Mediterranean population, with a high intake of MUFA, where these factors seem to be more relevant to cardiovascular risk than dietary composition.

Interrelationship between serum lipid profile, serum hormones and other components of the metabolic syndrome

The aim of the present study was to investigate the association between the serum lipid profile and components of the metabolic syndrome, such as central obesity (anthropometric, computed tomography and fat cell data), insulin, sex-hormone-binding-globulin (SHBG) and different hormones influencing this important syndrome, e.g. sex steroids, leptin and tumor necrosis factor-alpha (TNF-alpha). The sample consisted of 85 obese patients (30 men and 55 women) who had undergone abdominal surgery. Fasting serum lipids were analysed, as well as anthropometric and computed tomography data, perivisceral and subcutaneous fat cell size and serum glucose and hormones. Abdominal fat revealed itself as an important correlator of the adverse changes in plasma lipoprotein levels, the waist-to-hip-ratio and waist-to-thigh-ratio being the best morphological correlators in men and women, respectively. Intra-abdominal fat (VA) correlated significantly and positively to perivisceral fat cell size in women, while no correlation was found between subcutaneous fat accumulation (SA) and adipocyte size in both genders. Perivisceral fat cell size showed the greatest number of correlations with the adverse plasma lipid profile compared to that in the subcutaneous depot. SHBG and sex steroids showed a negative correlation with serum lipids considered a cardiovascular risk. In contrast, TNF-alpha and C-peptide were inversely correlated with potential protector lipids. In conclusion, abdominal obesity, adipocyte hypertrophy from visceral fat, serum TNF-alpha and C-peptide seem to be the best correlators of the lipoprotein disturbance characteristic of the metabolic syndrome, whereas SHBG and sex steroids could play a protective role regarding the lipid profile associated to this syndrome.

Site-specific differences in the fatty acid composition of abdominal adipose tissue in an obese population from a Mediterranean area: relation with dietary fatty acids, plasma lipid profile, serum insulin, and central obesity

BACKGROUND

Abdominal obesity is associated with coronary risk, although causality is not well established.

OBJECTIVE

In an obese Mediterranean population, we measured the fatty acid composition of adipose tissue, its relation with dietary fatty acids and central fat deposition, and its influence on plasma lipids and insulin.

DESIGN

Adipose tissue samples were obtained from 84 obese patients (29 men, 55 women) aged 30-70 y (body mass index, in kg/m(2): 27-35). We measured concentrations of insulin and lipids in plasma and fatty acids in subcutaneous, omental, and perivisceral fat. Dietary fatty acid intake was assessed with a 7-d diet record.

RESULTS

The population studied was normolipidemic and normoinsulinemic. There were important differences in fatty acid composition between tissue sites: saturated fatty acids were higher and monounsaturated fatty acids were lower in perivisceral than in subcutaneous fat (P < 0.05). Significant correlations were found for oleic, linoleic, alpha-linolenic, and total n-6 polyunsaturated fatty acids between the subject's habitual diet and adipose tissue composition. Oleic and n-3 fatty acids from adipose regions were negatively correlated with apolipoprotein B and triacylglycerols; adipose tissue 22:1n-9, 20:2n-6, stearic acid, and eicosapentaenoic acid were positively correlated with HDL and apolipoprotein A; and adipose tissue myristic acid was negatively correlated with apolipoprotein A (P < 0.05). Central obesity was positively associated with n-6 polyunsaturated fatty acids and inversely associated with monounsaturated fatty acids and n-3 polyunsaturated fatty acids in adipose tissue (P < 0.05).

CONCLUSION

The differences found in the composition and metabolism of perivisceral, omental, and subcutaneous fats may indicate that their atherogenic capacities also differ.

Endocrine, metabolic and nutritional factors in obesity and their relative significance as studied by factor analysis

OBJECTIVE

To evaluate different aspects of obesity, such as body fat distribution, plasma hormone and lipid profiles, adipose tissue composition and dietary intake in an obese population in order to identify the most important factors that contribute to obesity.

DESIGN

Eighty-five obese subjects, 30 men and 55 women (age, 30-70 y; body mass index (BMI), 27-35 kg/m2), were studied using anthropometric measurements, computed tomography, adipose tissue composition, serum hormone and lipid profiles and nutritional evaluations. To determine to what extent individual factors contributed to the general process of obesity, the data were subjected to a factor analysis.

RESULTS

Three patterns of anthropometric and computed tomography data emerged that accounted for 69% of the variance. Factor 1 defined abdominal obesity and explained 30% of the total variance, factor 2 (gynoid obesity) accounted for 26%; and factor 3 (subcutaneous fat) explained 13% of the total variance. When other factors associated with obesity, such as lipid profile, hormonal profile and fat composition, were introduced, obesity itself, especially abdominal obesity, remained the principal factor, accounting for 23% of total variability. All factors were of secondary importance when dietary characteristics were introduced. In the overall factor analysis, more than 40% of the variability in obesity was related to dietary habits, particularly fat intake, followed by energy and saturated fatty acids intake.

CONCLUSION

Even though obesity is a multifactorial phenomenon, the results suggest that dietary intake, especially fat intake, is the most important factor contributing to obesity. Secondary factors include endocrine and metabolic factors.

Anthropometric, computed tomography and fat cell data in an obese population: relationship with insulin, leptin, tumor necrosis factor-alpha, sex hormone-binding globulin and sex hormones

OBJECTIVE

To correlate anthropometric, computed tomography and fat cell data from abdominal regions with the levels of serum insulin, C-peptide, leptin, tumor necrosis factor-alpha (TNF-alpha), testosterone, 17beta-estradiol, androstenedione, dehydroepiandrosterone sulphate (DHEA-S) and sex hormone-binding globulin (SHBG).

DESIGN AND METHODS

The sample consisted of 84 obese patients (29 men, 22 premenopausal women and 33 postmenopausal women) who had undergone abdominal surgery. Weight, height, percentage of body fat by skinfolds, waist, hip and thigh circumferences, sagittal and coronal diameters, visceral and subcutaneous area, serum hormones and fat cell data were studied.

RESULTS AND CONCLUSIONS

Premenopausal women showed the lowest values in most abdominal distribution parameters, although, depending on the waist circumference criteria at the umbilicus level perimeter (W1) or midway between lower rib margin and iliac crest perimeter (W2), the population was classified differently, as gynoid or android. Although there were no differences in fat cell size between genders, gynoid women had smaller and more numerous fat cells than the android type. Perivisceral fat cell size was significantly smaller than subcutaneous fat cell size. In women, central obesity was significantly correlated with an increase in serum insulin, leptin, TNF-alpha, testosterone and androstenedione levels, and a decrease in 17beta-estradiol and DHEA-S, while in men significant correlations were positive with insulin and negative with testosterone and androstenedione. Fat cell size was positively correlated with serum levels of leptin, insulin, DHEA-S, androstenedione and inversely correlated with SHBG. These data indicate that hormones seem to interact not only with body fat distribution but also with fat cell size. This interaction differs between genders and between the different abdominal adipose tissue regions.

Papillary thyroid carcinoma: prognostic index for survival including the histological variety

BACKGROUND

Numerous prognostic factors have been studied for survival in patients with papillary thyroid carcinoma (PTC), although there are few multivariate studies that include the histological variety of PTC.

HYPOTHESIS

There are prognostic factors that influence survival in a series of patients with PTC, including the histological variety, and a new prognostic index (PI) for survival can be formulated by accounting for these factors.

DESIGN

A retrospective study.

SETTING

A university hospital department of surgery.

PATIENTS

Between January 1970 and December 1995, 200 patients undergoing surgery for PTC were observed (mean follow-up, 8 years).

MAIN OUTCOME MEASURES

A univariate analysis was done for survival rates using the Kaplan-Meier estimation method. The possible prognostic factors were evaluated using a multivariate analysis according to the Cox model. We formulated a PI and defined 3 risk groups (low, medium, and high) for mortality.

RESULTS

Of the 200 patients, 175 (87.5%) are still alive. Of the 25 deaths, 19 (9.5%) were due to the tumor. The survival was 97.5% at 1 year, 92.8% at 5, 89.5% at 10, and 83.9% at 15 and 20 years. The prognostic factors obtained after the multivariate analysis were age, tumor size, extrathyroid spread, and histological variant of the PTC. The PI is calculated as follows: PI = (2 x size) + (6 x spread) + (2 x variant) + (3 x age). As for the risk groups, the low-risk group showed a mortality of 0%; the medium-risk group, 17.1%; and the high-risk group, 76.5%.

CONCLUSIONS

The histological variety of PTC has prognostic value for survival in patients with PTC. As risk factors for PTC mortality, we consider an age of 50 years or older, a tumor larger than 4 cm, the existence of extrathyroid spread, and a certain histological subtype of PTC. With these risk factors, it is possible to formulate a PI and classify patients into low-, medium-, and high-risk groups for mortality.

Differences between sporadic and multiple endocrine neoplasia type 2A phaeochromocytoma

OBJECTIVES

Phaeochromocytoma may be either sporadic or part of a familial cancer syndrome. We have investigated whether there are differences between sporadic and MEN 2A phaeochromocytomas.

DESIGN

A retrospective study. We analysed age at presentation, sex, mode of presentation, clinical data, laboratory and imaging techniques, treatment, pathology and follow-up.

PATIENTS

Forty-six patients diagnosed with phaeochromocytoma between 1979 and 1995 (23 sporadic and 23 familial) at the Hospital Universitario Virgen de la Arrixaca (Murcia, Spain), a tertiary referral centre.

RESULTS

Mean age at presentation was 47 +/- 16 years for sporadic and 38 +/- 11 years for familial phaeochromocytoma (P < 0.05). The most common clinical feature and the presenting feature in cases of isolated phaeochromocytoma was hypertension. Of the MEN 2A patients, 52% were asymptomatic at diagnosis and only 35% presented with hypertension. Levels of adrenaline, noradrenaline, dopamine and metanephrines in a 24-hour urine connection confirmed the diagnosis in 95% of the isolated and 91% of the familial phaeochromocytomas. Computed tomography located 100% of the sporadic and 76% of the familial phaeochromocytomas (P < 0.02). All the MEN 2A phaeochromocytomas were bilateral compared with none of the sporadic phaeochromocytomas (P < 0.001). All the patients with familial phaeochromocytoma underwent bilateral adrenalectomy. The patients with sporadic phaeochromocytoma had the affected gland or the tumour, if extraadrenal, removed.

CONCLUSIONS

In comparing sporadic and MEN 2A phaeochromocytoma we found differences in age at presentation, mode of presentation, clinical data, duration of clinical features, imaging findings bilaterality and type of surgical treatment required.

[Evaluation of food consumption in overweight women before starting voluntary dieting programs]

The dietary intake of 50 premenopausal, overweight women, aged between 18 and 50 years old (31 +/- 9 years), with a mean body mass index of 29.9 +/- 3.1 kg/m2, was evaluated using the 24 hour recall method, the day before the start of a voluntary dietetic treatment. All the women had repeatedly tried losing weight throughout the courses of their lives. Caloric restriction was compared with weight loss after a week of dietetic treatment. Our results indicate that none of the women taking part in the study reported diets balanced in energy and nutrients. Although in 50% of the patients dietary energy intake was insufficient, all of them, when submitted to a diet of 1200 kcal per day, lost more weight (0.8-1.5 kg) than expected. The high fat intake and above all carbohydrate deficiency in these patients, indicate the lack of nutritional knowledge in their weight loss attempts. In our opinion, nutritional education is necessary to help them implement a balanced diet.

Papillary thyroid microcarcinoma: clinical study and prognosis

OBJECTIVE

To study the anatomical and prognostic characteristics of papillary thyroid microcarcinomas (10 mm or less in size).

DESIGN

Retrospective review.

SETTING

Community hospital, Spain.

SUBJECTS

36 patients with papillary microcarcinomas diagnosed over a period of 20 years from a total of 158 papillary carcinomas with complete follow-up.

MAIN OUTCOME MEASURES

Symptoms, treatment, histopathological confirmation and follow-up compared with those of papillary carcinomas more than 10 mm in size.

RESULTS

Six of the patients with microcarcinomas presented with adenopathy, the remaining 30 being admitted for treatment of associated thyroid diseases. In 15 cases the tumour was 5 mm or less in size. Thirty were well-differentiated, 2 were follicular, and 2 showed signs of diffuse sclerosis. Three had recurred after total thyroidectomy, but no patient died. When the results were compared with those of the patients with larger tumours, we found differences in histological type (p = 0.001), the incidence of adenopathy (p = 0.03), TNM stage (p = 0.001) and mortality (p = 0.04).

CONCLUSIONS

There are clinical, histopathological, and prognostic differences between microcarcinomas (which do well) and larger papillary tumours.

[Infections in the diabetic. Comparative study of infections in the foot and other locations]

Given the high morbi-mortality of foot infections among the diabetics and the poor knowledge of their predictive, clinical and evolutive factors, we have retrospectively studied a group of patients with these characteristics, comparing them with infections among diabetics affecting other locations. We studied 66 infections among diabetics: 34 patients with diabetic's foot and 32 with infections at other locations: 20 pyelonephritis and 12 pneumonias. Medical records were obtained in all cases and all patients underwent a complete physical exploration in order to assess their risk factors. We observed as a significant predictive factor of diabetic's foot, diabetes type I, with an evolution longer than 10 years, neuropathy, vasculopathy or retinopathy. From the clinical point of view and compared with the other infections, these patients showed longer hospitalization, greater initial clinical severity, glucemias higher than 200 mgr/l., anemia and high GSR. Ethiologically, the infection of diabetic's foot was polymicrobian in 42.3% of all cases, being S. aureus the microorganism more frequently isolated. On the contrary, in infections at other locations, monomicrobian flora was more frequent, being E. coli the most frequent in pyelonephritis and S. pneumoniae in pneumonias. The evolution was satisfactory in all cases, with a close medical and surgical combined treatment and the appropriate use of antibiotic combinations, mainly clindamicine + tobramicine in the diabetic's foot and cefuroxime in the other locations.