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Biomedical subjects

V Stich

Publications and source records attributed to V Stich.

At least 37 records · Page 2Linked to original sources
PubMed2001

A twin study of weight loss and metabolic efficiency.

OBJECTIVE: To assess the genetic contribution to determinants of therapeutic weight loss in obese female identical twins. DESIGN: Subjects were studied for 40 days on an inpatient unit in three phases: 7 baseline days; 28 days of weight reduction by a very low calorie diet (1.6 MJ per day); and 5 days after weight reduction. SUBJECTS: Fourteen pairs of premenopausal obese female identical twins (age: 39.0+/-1.7 y; body weight (BW): 93.9+/-21.2 kg; body mass index (BMI): 34.2+/-7.8 kg/m2). MEASUREMENTS: : Body composition by hydrodensitometry and resting metabolic rate by indirect calorimetry were assessed before and after weight loss. RESULTS: : There was great variability among pairs in loss of weight (5.9-12.4 kg) and body fat (3.1-12.4 kg). By contrast, the intraclass correlation (ICC) within twin pairs was 0.85, P<0.001 for weight and 0.88, P<0.001 for body fat. A measure of metabolic efficiency, calculated as the difference between 'estimated' and 'measured' energy deficit showed high intrapair correlation (ICC=0.77; P<0.001). CONCLUSIONS: The high correlation in metabolic efficiency within twin pairs in response to therapeutic weight loss suggests a strong genetic contribution.

Adult↗
PubMed2001

The within-pair resemblance in serum levels of androgens, sex-hormone binding globulin and cortisol in female obese identical twins - effect of negative energy balance induced by very low-calorie diet.

The first aim of the present study was to evaluate the changes in serum levels of cortisol, testosterone, dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulphate (DHEA-S) and sex hormone-binding globulin (SHBG) in response to weight loss induced by one month of treatment with a very low-calorie diet (VLCD) in twelve pairs of female obese monozygotic twins. The second aim of the study was to investigate any within-pair resemblance in serum levels of steroids and SHBG before and after a negative balance protocol, as well as the resemblance in changes in response to therapeutic weight loss. VLCD-induced weight loss of 8.7+2.9 kg was associated with significant increases in serum testosterone (p<0.05) and SHBG (p<0.001) levels, whereas no significant changes in serum levels of cortisol, DHEA and DHEA-S were observed. Significant within-pair resemblances for both pre-treatment and post-treatment concentrations were revealed for DHEA-S (pre-treatment ICC = 0.795, p < 0.01, post-treatment ICC = 0.712, p < 0.01) and for testosterone (pre-treatment ICC = 0.594, p <0.05, post-treatment ICC = 0.735, p < 0.01). The baseline within-twin-pair resemblance in serum cortisol level at 7 a.m. (ICC=0.747, p < 0.05) was lost with VLCD treatment, while its concentration at 9 p.m. developed a within-pair similarity with weight loss (ICC = 0.824, p < 0.001). Similarly, VLCD treatment led to a significant within-pair resemblance in post-treatment level of DHEA (ICC = 0.755, p < 0.01), while no within-twin-pair resemblance was shown for either pre-treatment or post-treatment SHBG levels. None of the hormones measured exhibited any within-pair resemblance in response to VLCD-induced energy deficit, except for serum cortisol levels. A significant within-twin-pair resemblance in the changes in serum cortisol levels at 7 a. m. (ICC = 0.789, F = 8.5, p < 0.001), at 1 p.m. (ICC = 0.660, F = 4.9, p <0.01) and at 9 p.m. (ICC = 0.795, F = 8.8, p <0.001) were demonstrated even after adjustment for fat mass loss. An absence of any within-pair similarity was observed in both pretreatment and post-treatment levels of SHBG, while a significant within-pair resemblance in SHBG response to VLCD treatment (ICC = 0.658, p < 0.05) was recorded. We conclude that the significant within-twin-pair resemblance demonstrated for androgens and cortisol might suggest an important role for genetic factors in the regulation of their serum levels. Our results also suggest that the mechanisms controlling baseline levels of cortisol and SHBG differ from those influencing their responses to energy deficit induced by VLCD.

Adipose Tissue↗
PubMed2001

In vitro and in vivo impairment of alpha2-adrenergic receptor-dependent antilipolysis by fatty acids in human adipose tissue.

The aim of the present study was to study the influence of fatty acids on the adrenergic control of lipolysis both in vitro and in vivo. Human subcutaneous adipose tissue explants were cultured for 48 h in the presence of 100 microM bromopalmitate (BrPal), and lipolysis was measured in isolated adipocytes. In control conditions, beta-AR-dependent activation of lipolysis by epinephrine was almost undetectable, and could be fully restored by pharmacological blockade of alpha2-AR-dependent antilipolysis. After BrPal treatment, epinephrine became fully lipolytic and was no longer influenced by alpha2-AR-blockade. Radioligand binding analysis revealed that BrPal treatment led to a significant reduction in the coupling of alpha2-AR to G proteins. In parallel, a chronic and significant increase in plasma fatty acids resulting from a 4-day high-fat diet (HFD) was accompanied by an impairment of the amplifying effect of the alpha2-AR antagonist phentolamine on exercise-induced lipolysis (measured in the subcutaneous adipose tissue with the use of a microdialysis probe) normally observed after a low-fat diet. In conclusion, in vitro and in vivo studies showed that fatty acids impair alpha2-AR-dependent antilipolysis.

Adipocytes↗
PubMed2001

A single bout of exercise induces beta-adrenergic desensitization in human adipose tissue.

This study was designed to assess whether physiological activation of the sympathetic nervous system induced by exercise changes adipose tissue responsiveness to catecholamines in humans. Lipid mobilization in abdominal subcutaneous adipose tissue was studied with the use of a microdialysis method in 11 nontrained men (age: 22. 3 +/- 1.5 yr; body mass index: 23.0 +/- 1.6). Adipose tissue adrenergic sensitivity was explored with norepinephrine, dobutamine (beta(1)-agonist), or terbutaline (beta(2)-agonist) perfused during 30 min through probes before and after 60-min exercise (50% of the maximal aerobic power). The increase in extracellular glycerol concentration during infusion was significantly lower after the exercise when compared with the increase observed before the exercise (P < 0.05, P < 0.02, and P < 0.01, respectively, for norepinephrine, dobutamine, and terbutaline). In a control experiment realized without exercise, no difference in norepinephrine-induced glycerol increase between the two infusions was observed. To assess the involvement of catecholamines in the blunted beta-adrenergic-induced lipolytic response after exercise, adipose tissue adrenergic sensitivity was explored with two 60-min infusions of norepinephrine or epinephrine separated by a 60-min interval. With both catecholamines, the increase in glycerol was significantly lower during the second infusion (P < 0.05). The findings suggest that aerobic exercise, which increased adrenergic activity, induces a desensitization in beta(1)- and beta(2)-adrenergic lipolytic pathways in human subcutaneous adipose tissue.

Adipose Tissue↗
PubMed2001

Lack of alpha(2)-adrenergic antilipolytic effect during exercise in subcutaneous adipose tissue of trained men.

The aim of this study was to investigate the involvement of the antilipolytic alpha(2)-adrenergic receptor pathway in the regulation of lipolysis during exercise in subcutaneous abdominal adipose tissue (SCAAT). Seven trained men and 15 untrained men were studied. With the use of microdialysis, the extracellular glycerol concentration was measured in SCAAT at rest and during 60 min of exercise at 50% of maximal oxygen consumption. One microdialysis probe was perfused with Ringer solution; the other was supplemented with phentolamine (alpha(2)-adrenergic receptor antagonist). No differences in baseline extracellular or plasma glycerol concentrations were found between the two groups. The exercise-induced extracellular and plasma glycerol increase was higher in trained compared with untrained subjects (P < 0.05). Addition of phentolamine to the perfusate enhanced the exercise-induced response of extracellular glycerol in untrained subjects but not in trained subjects. The exercise-induced increase in plasma norepinephrine and epinephrine concentrations and the decrease in plasma insulin were not different in the two groups. These in vivo findings demonstrate higher exercise-induced lipolysis in trained compared with untrained subjects and show that, in trained subjects, the alpha(2)-mediated antilipolytic action is not involved in the regulation of lipolysis in SCAAT during exercise.

Adipose Tissue↗
PubMed2001

[Effect of nutrition on adipose tissue metabolism in humans].

Lipolysis in adipose tissue and balance between energy intake and expenditure are involved in the regulation of adipose tissue mass. Several recent findings suggest that alterations in the regulation of lipolysis and/or energy balance might contribute to the development of obesity. Hormone-sensitive lipase and uncoupling proteins play important role in regulation of lipolysis in adipose tissue as well as in the regulation of energy balance of various tissues. Mechanisms of the control of expression of genes coding synthesis of these proteins are poorly known. A brief overview of the present knowledge of the effects of nutritional intervention on the regulation of lipolysis in adipose tissue and on the expression of genes of hormone-sensitive lipase and that of uncoupling proteins is given in this article. Results of the authors' studies on the effect of calorie restriction on gene expression in adipose tissue are presented.

Adipose Tissue↗
PubMed2000

Intrapair resemblance in very low calorie diet-induced weight loss in female obese identical twins.

OBJECTIVE: To assess intrapair resemblance in changes of body weight, total body fat, fat distribution, resting metabolic rate, fasting respiratory quotient and cardiovascular disease risk factors in response to therapeutic weight loss in female obese identical twins. DESIGN: Patients stayed for 40 days on an inpatient metabolic unit under careful supervision. The stay was divided into three parts: an initial period of 7 days for adjustment to the hospital environment and for baseline measurements, 28 days of the weight reduction regimen when negative energy balance was achieved mainly by a very low calorie diet (1.6 MJ per day) and 5 days of testing after weight reduction. SUBJECTS: Fourteen pairs of premenopausal female obese identical twins (age: 39.0+/-1.7 y; body weight (BW): 93.9+/-21.2 kg; body mass index (BMI): 34.2+/-7.8 kg/m2) participated in the study. MEASUREMENTS: Before and after weight loss, the following measurements were made: body composition by anthropometry and hydrodensitometry, intra-abdominal fat by ultrasonography, resting metabolic rate by indirect calorimetry. Total cholesterol, high-density lipoprotein-cholesterol, triglycerides and uric acid were determined by standard laboratory procedures. Blood pressure was measured in the morning in the recumbent position. RESULTS: Subjects lost 8.8+/-1.9 kg of weight, from 93.9+/-21.2 to 85.1+/-10.9 kg (P<0.0001) and 6.5+/-2.3 kg of body fat (P<0.001). Weight losses varied widely among subjects, with a high correlation between losses of members of twin pairs for body weight (r=0.85; P<0.001) and for body fat (r=0.88; P<0.0001). Changes in uric acid resulting from weight loss were also correlated among members of twin pairs whereas changes in blood pressure, cholesterol and triglycerides were not. CONCLUSION: The great intrapair resemblance observed in very low calorie diet-induced weight and fat losses in female obese identical twins suggests an important role of genetic factors in response to the weight reduction regimen.

Adipose Tissue↗
PubMed2000

Recent developments on lipolysis regulation in humans and discovery of a new lipolytic pathway.

In man, the major hormones controlling the lipolytic function are insulin (inhibition of lipolysis) and catecholamines (stimulation of lipolysis). Catecholamines are of major importance for the regulation of lipid mobilization in human adipose tissue and for the increase of non-esterified fatty acid supply to the working muscle. In vitro studies have shown that there are differences in the catecholaminergic control of fat cells from various fat deposits and a number of physiological and pathological alterations of catecholamine-induced lipolysis have been reported. Lipolytic resistance to catecholamines has been reported in subcutaneous adipose tissue, the major fat depot in obese subjects. Multiple alterations in catecholamine signal transduction pathways have been reported. In situ microdialysis allows a physiological exploration of adipose tissue biology. Recent data obtained on the catecholaminergic regulation of lipolysis and lipid mobilization, using microdialysis in humans, will be analysed. A potent lipolytic and lipomobilizing effect of atrial natriuretic peptide has recently been discovered; the mechanisms of action and physiological relevance will also be discussed.

Adipose Tissue↗
PubMed2000

Activation of alpha(2)-adrenergic receptors impairs exercise-induced lipolysis in SCAT of obese subjects.

With the use of the microdialysis method, exercise-induced lipolysis was investigated in subcutaneous adipose tissue (SCAT) in obese subjects and compared with lean ones, and the effect of blockade of alpha(2)-adrenergic receptors (ARs) on lipolysis during exercise was explored. Changes in extracellular glycerol concentrations and blood flow were measured in SCAT in a control microdialysis probe at rest and during 60-min exercise bouts (50% of heart rate reserve) and in a probe supplemented with the alpha(2)-AR antagonist phentolamine. At rest and during exercise, plasma norepinephrine and epinephrine concentrations were not different in obese compared with lean men. In the basal state, plasma and extracellular glycerol concentrations were higher, whereas blood flow was lower in SCAT of obese subjects. During exercise, the increase of plasma glycerol was higher in obese subjects (115 +/- 35 vs. 65 +/- 21 micromol/l). Oppositely, the exercise-induced increase in extracellular glycerol concentrations in SCAT was five- to sixfold lower in obese than in lean subjects (50 +/- 14 vs. 318 +/- 53 micromol/l). The exercise-induced increase in extracellular glycerol concentration was not significantly modified by phentolamine infusion in lean subjects but was strongly enhanced in the obese subjects and reached the concentrations found in lean sujects (297 +/- 46 micromol/l). These findings demonstrate that the physiological stimulation of SCAT adipocyte alpha(2)-ARs during exercice-induced sympathetic nervous system activation contributes to the blunted lipolysis noted in obese men.

Adipose Tissue↗
PubMed2000

Adipose tissue lipolysis is increased during a repeated bout of aerobic exercise.

The goal of the study was to examine whether lipid mobilization from adipose tissue undergoes changes during repeated bouts of prolonged aerobic exercise. Microdialysis of the subcutaneous adipose tissue was used for the assessment of lipolysis; glycerol concentration was measured in the dialysate leaving the adipose tissue. Seven male subjects performed two repeated bouts of 60-min exercise at 50% of their maximal aerobic power, separated by a 60-min recovery period. The exercise-induced increases in extracellular glycerol concentrations in adipose tissue and in plasma glycerol concentrations were significantly higher during the second exercise bout compared with the first (P < 0.05). The responses of plasma nonesterified fatty acids and plasma epinephrine were higher during the second exercise bout, whereas the response of norepinephrine was unchanged and that of growth hormone lower. Plasma insulin levels were lower during the second exercise bout. The results suggest that adipose tissue lipolysis during aerobic exercise of moderate intensity is enhanced when an exercise bout is preceded by exercise of the same intensity and duration performed 1 h before. This response pattern is associated with an increase in the exercise-induced rise of epinephrine and with lower plasma insulin values during the repeated exercise bout.

Adipose Tissue↗
PubMed2000

Respiratory quotient in obesity: its association with an ability to retain weight loss and with parental obesity.

A high fasting respiratory quotient (RQ) was observed during the treatment by very low calorie diet (VLCD) in obese patients who regained weight at two-year follow-up (weight regainers) or in those who exhibited repeated cycles of weight loss with a subsequent weight regain (weight cyclers). In contrast obese patients who succeeded to retain the weight loss achieved initially by the VLCD at 2-yr follow-up (weight losers) or those who did not exhibit weight fluctuations (weight noncyclers) were characterized by a significantly lower RQ. Therefore a high fasting RQ during the VLCD treatment should be considered predictive of body weight gain. Resting metabolic rate (RMR) expressed per kg fat free mass (FFM) did not influence body weight changes. A high RQ revealed in obese subjects reporting parental obesity and a low fasting RQ observed in those obese without family history of obesity suggest a role of hereditary factors in the ability to oxidize fat in severely obese subjects. In contrast, parental history of obesity did not affect RMR in severely obese individuals.

Adult↗
PubMed1999

Endurance training increases the beta-adrenergic lipolytic response in subcutaneous adipose tissue in obese subjects.

OBJECTIVE: The aim of this study was to assess, by longitudinal follow-up, the influence of aerobic training on the in vivo lipolytic activity of adipose tissue in obese male subjects. SUBJECTS: Eleven obese non-diabetic males, aged 41.5+/-5.77 (range 27-49 y) with body mass index (BMI) 36.5+/-4.5 kg/m2 (range 29.4-47.1 kg/m2) participated in the study. DESIGN: Subjects took part in a 12-week aerobic training program. Before and after training, microdialysis of abdominal subcutaneous adipose tissue (SCAT) was carried out, using perfusion with graded doses of the beta-adrenergic agonist isoprenaline and a single dose of the phosphodiesterase inhibitor theophylline. In addition, the response of plasma glycerol and free fatty acids (FFAs) to intravenous infusion of graded doses of isoprenaline was tested. RESULTS: The training did not induce significant weight loss and promoted an increase in maximum aerobic capacity (P<0.05). The increase of extracellular glycerol in SCAT in response to isoprenaline perfusion was enhanced after the training (P<0.05), while no change in the response of interstitial glycerol to theophylline action was observed. The training did not elicit a change in the isoprenaline-induced changes of blood flow in adipose tissue. The increases of plasma FFAs and glycerol in response to intravenous isoprenaline infusion, were significantly enhanced after training. CONCLUSION: The present study shows that aerobic training induced an increase in the response of plasma and subcutaneous adipose tissue concentration of glycerol to beta-adrenergic stimulation. The effect of an agent acting at the post-receptor level (theophylline) in SCAT was not modified by training.

Adipose Tissue↗
PubMed1999

Activation of antilipolytic alpha(2)-adrenergic receptors by epinephrine during exercise in human adipose tissue.

The involvement of the antilipolytic alpha(2)-adrenergic pathway and the specific role of epinephrine in the control of lipolysis during exercise in adipose tissue (AT) were investigated in healthy male subjects (age: 24.1 +/- 2.2 yr; body mass index: 23.0 +/- 1.6). An in vitro study carried out on isolated adipocytes showed that the weak lipolytic effect of epinephrine was potentiated after blockade of alpha(2)-adrenergic receptor (AR) by an alpha(2)-AR antagonist and reached that of isoproterenol, a beta-AR agonist. The effect of the nonselective alpha(2)-AR antagonist phentolamine on the response of the extracellular glycerol concentration (EGC) in AT during two successive bouts of aerobic exercise (50% maximum O(2) uptake, 60 min duration) was evaluated using the microdialysis method. The metabolic responses measured in perfused probes with Ringer solution were compared with those obtained in perfused probes with Ringer plus 0.1 mmol/l phentolamine. Plasma norepinephrine level was not different during the two exercise bouts, whereas that of epinephrine was 2.5-fold higher during the second exercise. EGC in AT was twofold higher in the second compared with the first exercise, and the same response pattern was found for plasma glycerol. The exercise-induced increase in EGC was higher in the probe perfused with phentolamine compared with the control probe in both bouts of exercise. However, the potentiating effect of phentolamine on EGC was significant during the second exercise bout but did not reach a significant level during the first. These results suggest that epinephrine is involved in the control of lipid mobilization through activation of antilipolytic alpha(2)-AR in human subcutaneous AT during exercise.

Adipocytes↗
PubMed1998

Endurance training changes in lipolytic responsiveness of obese adipose tissue.

The aim of this study was to investigate the effect of aerobic exercise training on the lipolytic response of adipose tissue in obese subjects. Thirteen men (body mass index = 36.9 +/- 1.3 kg/m2) were submitted to aerobic physical training on a cycloergometer (30-45 min, 4 days a wk) for 3 mo. Adipocyte sensitivity to the action of catecholamines and insulin was studied in vitro before and after training. Training induced a decrease in the percentage of fat mass (P < 0.05) without changing the body weight. Basal lipolysis and hormone-sensitive lipase activity were significantly decreased after training (P < 0.05). The lipolytic effects of epinephrine, isoprenaline (beta-adrenoceptor agonist), and dobutamine (beta1-adrenoceptor agonist) were significantly increased (P < 0.05) but not those of procaterol (beta2-adrenoceptor agonist). The antilipolytic effects of alpha2-adrenoceptor and insulin were significantly decreased (P < 0.05). Lipolysis stimulation by agents acting at the postreceptor level was unchanged after training. In conclusion, aerobic physical training in obese male subjects modifies adipose tissue lipolysis through an enhancement of beta-adrenergic response and a concomitant blunting of adipocyte antilipolytic activity.

Adipose Tissue↗
PubMed1998

Microdialysis in investigation of adipose tissue metabolism.

Microdialysis--a technique available since more than two decades--has been recently applied in investigation of metabolism of adipose tissue in humans. The technique enables a continuous sampling of metabolites and other small molecules in the extracellular space of subcutaneous adipose tissue and it enables a local exposure of adipose tissue to metabolically active agents. The method has been used to determine the interstitial concentrations of metabolites (glycerol, glucose, lactate etc.) in adipose tissue and to investigate the regulation of lipolysis and of carbohydrate metabolism in situ in subcutaneous adipose tissue. The method has been widely used in clinical research of adipose tissue and it is supposed to be used for continuous monitoring of metabolites in clinical practice.

Adipose Tissue↗
PubMed1998

Clinical guidelines for diagnosis and management of obesity in the Czech Republic.

Guidelines for the management of obesity include recommendation about diet, exercise, behavioral modification, drug therapy and bariatric surgery in the comprehensive management of an obese patient. It is emphasized that the treatment of obesity should be individually tailored according to the age of the patient, degree and phase of obesity, body fat distribution and an expression of risk factors and comorbidities. The new realistic goals in obesity management do not focus on the weight loss per se but mainly on the risk factors reduction which accompanies even modest weight loss. The system of obesity management introduced in the Czech Republic includes obesity management centres attached to major teaching hospitals, obesity out-patient clinics (led by an obesity specialist), primary care physicians and weight reduction clubs. Postgraduate training in obesity management should be recognized by health authorities as a function specialty. A time demanding therapeutic strategy in obesity management should be taken into account by both health policy makers and health insurance companies.

Czech Republic↗
PubMed1998

Long-term treatment of obesity in the obesity unit.

A group of 318 obese patients followed-up at the Obesity Unit in Prague in 1995-1997 was included into a study. Their treatment was based on the standard combination of a weight reduction diet, physical activity and behavioural intervention. In patients with more severe degrees of óbesity VLCD in one daily portion, pharmacotherapy, in-patient regimen lasting 24 days, including VLCD (1,500 kJ/day), exercise and group psychotherapy; or bariatric surgery (mostly laparoscopic gastric banding) were used, if necessary. Patients were divided into two groups according to their compliance to the weight reducing regimen. Group A dropped out before 2 years of follow-up, group B was followed-up 2 years or more. The groups did not differ significantly in their mean age, initial body weight, initial BMI and fat content and in percentage of males and females. Weight, BMI, fat content, essential anthropometric indices (waist circumference, WHR, subscapular and triceps skinfolds) and blood pressure are presented in this study. The maximum weight loss was significantly higher in group B. We did not find any other significant differences between group A and group B. The most significant predictor of compliance expressed as duration of follow-up (evaluated by multiple regression with stepwise variable selection) was the maximum BMI decrease (p < 0.005). The most significant predictors of the weight loss at the end of the follow-up were maximum weight loss and maximum decrease of BMI (p < 0.001). Family history of obesity (obese one or both parents) was significantly more often in group B (p < 0.05). This trend was expressed predominantly in females (p < 0.01), where also family history of obesity in mother was significantly more often in group B (p < 0.05). The frequency of methods used in individual patients was estimated. Standard combination of diet, enhanced physical activity and behavioural intervention was used in all patients. All other methods were used significantly more frequently in group B. In group A in-patient treatment was significantly more often used in men. The in-patient treatment promotes the compliance with the therapeutic regimen in women significantly more effectively than in men.

Adult↗