Biomedical subjects

A Nadeau

Publications and source records attributed to A Nadeau.

At least 73 records · Page 4Linked to original sources

PubMed1996

Cell-specific expression of the ZPK gene in adult mouse tissues.

ZPK is a recently identified human putative protein kinase gene that encodes an unusual serine/threonine kinase containing two potential leucine zipper motifs similar to those found in transcription factors as well as in members of the newly discovered mixed-lineage family of protein kinases. To study the normal biological function of ZPK, we have isolated a mouse ZPK cDNA and examined the pattern of ZPK mRNA expression in adult mouse tissues by Northern blot and in situ hybridization analyses. The predicted open reading frame of this cDNA encodes an 888-amino-acid protein that shares 95% overall identity with its human counterpart. By Northern blot analysis, we detected expression of ZPK mRNA in the brain of adult mice, but not in any other tissue tested. In situ hybridization analysis of mouse brain sections revealed specific association of ZPK mRNA with neuronal cell populations, primarily in the hippocampus, the cerebral cortex, and the Purkinje cell layer of the cerebellum. Interestingly, a remarkable pattern of cell-type-specific expression was also found in the epithelial compartment of various organ systems, including stomach, small intestine, liver, and pancreas, as well as in the seminiferous tubules of mature testes. Taken together, these observations suggest that ZPK could play a role in development, function, and maintenance of a variety of specialized cells.

Amino Acid Sequence↗

PubMed1996

Insulin sensitivity and hemodynamic responses to insulin in Wistar-Kyoto and spontaneously hypertensive rats.

The insulin-mediated vasodilator effect has been proposed as an important physiological determinant of insulin action on glucose disposal in normotensive humans. The present study was designed to further examine the acute regional hemodynamic effects of insulin in different vascular beds and to explore the relationships between insulin vascular effects and insulin sensitivity during euglycemic hyperinsulinemic clamps in conscious normotensive Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR). The rats were instrumented with intravascular catheters and pulsed Doppler flow probes to measure blood pressure, heart rate, and regional blood flows. In WKY rats, the euglycemic infusion of insulin (4 and 16 mU.kg-1.min-1) causes vasodilations in renal and hindquarter vascular beds but no changes in mean blood pressure, heart rate, or superior mesenteric vascular conductance. In contrast, in SHR, the same doses of insulin produce vasoconstrictions in superior mesenteric and hindquarter vascular beds and, at high doses, increase blood pressure. Moreover, at the lower dose of insulin tested, we found a reduction in the insulin sensitivity index in the SHR compared with the WKY rats. The present findings provide further evidence for an association between insulin sensitivity and insulin-mediated hemodynamic responses.

Animals↗

PubMed1996

The apoB-100 gene EcoRI polymorphism influences the relationship between features of the insulin resistance syndrome and the hyper-apoB and dense LDL phenotype in men.

The aim of this study was to investigate whether the EcoRI polymorphism of the apolipoprotein B (apoB) gene influences the relationships between features of the insulin resistance syndrome and the dense LDL phenotype and apoB concentrations. A sample of 65 men was divided into two groups on the basis of the EcoRI genotype. Forty-four subjects were (+/+) homozygotes for the presence of the EcoRI restriction site that is associated with a glutamic acid at codon 4154. Twenty-one men were (+/-) heterozygotes for the absence of the restriction site resulting from a glutamic acid to a lysine substitution at codon 4154. In the (+/-) group, fasting plasma FFA levels were positively correlated with plasma apoB, LDL-apoB, and the LDL particle score that was calculated from the migration distances of LDL subspecies and their relative band intensities, reflecting the proportion of small dense LDL particles. However, these associations were not found among (+/+) subjects. The two genotypic groups were further divided into two subgroups on the basis of fasting FFA concentrations, and the LDL particle score and the LDL-apoB levels were compared. High FFA levels were associated with a higher proportion of small dense LDL particles, as reflected by a higher mean LDL particle score, irrespective of the genotype. However, the apoB-EcoRI polymorphism appeared to influence the association between high FFA levels and LDL-apoB concentrations because (+/-) heterozygotes with high FFA levels had higher LDL-apoB concentrations than (+/-) heterozygotes with low FFA levels. In addition, the integrated area under the curve of plasma insulin concentrations, measured in response to a 75-g oral glucose challenge, and the amount of visceral adipose tissue, measured by computed tomography, were positively associated with the LDL particle score only in (+/-) heterozygotes. When subjects were divided on the basis of insulin area (low vs. high) or visceral adipose tissue (low vs. high), (+/-) heterozygotes with high insulin area or with high levels of visceral adipose tissue had a higher mean LDL particle score than (+/-) heterozygotes with low insulin area or low visceral adipose tissue. However, among (+/+) homozygotes, low or high levels of insulin or visceral adipose tissue could not discriminate between men with large or small LDL particles. Therefore, (+/-) heterozygotes may be more susceptible to develop the dense LDL phenotype in presence of hyperinsulinemia and visceral obesity. Results of the present study suggest that the apoB-EcoRI polymorphism may exacerbate the alterations in the LDL particle (size and concentration) found among visceral obese-hyperinsulinemic men.

Adipose Tissue↗

PubMed1996

The dense LDL phenotype. Association with plasma lipoprotein levels, visceral obesity, and hyperinsulinemia in men.

OBJECTIVE: To investigate the potential relationship between the cluster of metabolic abnormalities found in visceral obesity and the small dense LDL phenotype. RESEARCH DESIGN AND METHODS: We have estimated LDL peak particle size by nondenaturing 2-16% gradient gel electrophoresis in a sample of 79 men. Glucose tolerance and fasting plasma insulin and lipoprotein levels were also measured. RESULTS: The LDL particle score, calculated from migration, distances and relative band intensities and reflecting the proportion of small dense LDL particles, was positively correlated with plasma triglyceride (TG) (r = 0.60, P < 0.0001) and negatively correlated with HDL cholesterol (r = -0.56, P < 0.0001) levels. Although the LDL particle score was not associated with variations in plasma LDL cholesterol or LDL apolipoprotein (apo) B concentrations, it was significantly correlated with the LDL apo B-to-LDL cholesterol ratio (r = 0.60, P < 0.0001). Fasting plasma insulin and visceral adipose tissue (AT) areas measured by computed tomography were weakly but significantly correlated with the LDL particle score (r = 0.23 and 0.29, respectively, P < 0.05). LDL peak particle size showed similar but inverse correlations with anthropometric and metabolic variables. Subjects classified as having small dense LDL particles (by comparing subjects in the highest tertile versus those in the lowest tertile of the LDL particle score distribution) were characterized by increased plasma TG, reduced HDL cholesterol, higher fasting insulin levels, and elevated visceral AT accumulation. However, multiple regression analyses revealed that visceral AT accumulation was not an independent predictor of the dense LDL phenotype after inclusion of TG and HDL cholesterol levels and lipoprotein ratios in the model. CONCLUSIONS: It thus appears that the high TG-low HDL cholesterol dyslipidemia frequently found in visceral obesity and in a hyperinsulinemic state is a strong correlate of the small dense LDL phenotype. Although associated with the dense LDL phenotype, visceral obesity and hyperinsulinemia were not independent predictors of an increased proportion of small dense LDL particles after controlling for TG and HDL cholesterol levels.

Adipose Tissue↗

PubMed1996

Seven-year changes in body fat and visceral adipose tissue in women. Association with indexes of plasma glucose-insulin homeostasis.

OBJECTIVE: To study the associations between changes in body fatness, visceral adipose tissue (AT), and indexes of plasma glucose-insulin homeostasis over a 7-year follow-up period. RESEARCH DESIGN AND METHODS: A sample of 30 nondiabetic women aged 35.2 +/- 5.6 (SD) years at baseline was studied. RESULTS: Changes in visceral AT and in subcutaneous AT (measured by computed tomography) as well as changes in body fat mass (obtained by hydrostatic weighting) were significantly related to changes in fasting plasma insulin levels and in plasma insulin area measured after a 75-g oral glucose load (0.47 < or = r < or = 0.62; P < 0.01). Changes in visceral AT but not in body fat mass or in subcutaneous AT area were significantly associated with changes in plasma glucose area (r = 0.37; P < 0.05). When two subgroups of women with similar mean increases in body fat mass but with either small or large increases in visceral AT were compared, the subgroup with the largest gain in visceral AT showed the greatest deterioration in indexes of plasma glucose-insulin homeostasis. On the other hand, when two subgroups with similar mean increases in visceral AT but with different changes in body fat mass were compared, both subgroups showed similar changes in plasma glucose and insulin concentrations. CONCLUSIONS: Results of this 7-year follow-up study in women suggest that changes in indexes of plasma glucose-insulin homeostasis are significantly associated with changes in visceral AT, even after control for changes in body fat mass.

Adipose Tissue↗

PubMed1996

Insulin and glucagon responses to adrenaline infusion in abdominal obese men.

OBJECTIVE: To investigate the hormonal, cardiovascular and metabolic responses of visceral vs subcutaneous obese men to infused adrenaline. DESIGN: Intervention study of an hour adrenaline infusion (0.01 micrograms/kg fat-free mass/min). SUBJECTS: Eighteen moderately obese men (age: 30-40 y, BMI: 28-34 kg/m2) divided according to their degree (low vs high) of visceral adipose tissue (AT) accumulation. MEASUREMENTS: Various fatness and fat distribution variables (computed tomography and anthropometry), heart rate and blood pressure, plasma concentrations of gluco-regulatory hormones, glucose, glycerol and free fatty acids (FFA). RESULTS: Similar increases were noted in heart rate, plasma adrenaline, FFA and glycerol levels in both low and high visceral AT groups after hormonal infusion. There was a tendency for plasma glucagon responses to be higher in men with high amounts of visceral fat (p = 0.07). Plasma glucose levels increased in both groups, but significantly more in men with low levels of visceral AT (p < 0.05), whereas plasma insulin concentrations increased significantly only in men with high amounts of visceral AT in response to adrenaline infusion (p < 0.01). In the overall sample of obese men, visceral AT accumulation (but not the fat mass) was positively correlated with plasma insulin (r = 0.70) and glucagon responses (r = 0.63) to the hormone infusion (p < 0.01). These metabolic responses were not related to the achieved catecholamine concentration. CONCLUSION: These results suggest that some of the impairments in plasma glucose-insulin homeostasis noted in visceral obesity may be related to an abnormal metabolic response to an adrenaline challenge.

Abdomen↗

PubMed1995

Plasma glucose, insulin, and glucagon before and after long-term overfeeding in identical twins.

Plasma glucose, insulin, and glucagon levels were measured before and after long-term overfeeding (4.2 MJ/d during a 100-day period) in 24 lean adults (12 pairs of monozygotic twins). Fasting plasma glucose, insulin, and glucagon were significantly increased by overfeeding. During a 75-g oral glucose tolerance test (OGTT), no major alteration in glucose tolerance was observed and insulin area under the curve was increased. During a meal test, insulin and glucagon areas under the curve were increased. The pre-overfeeding values for glucose, insulin, and glucagon (fasting and areas) were not correlated with the gains in body weight and in fat mass. However, fasting glucagon before overfeeding was positively correlated with the gains in abdominal visceral fat and in femoral fat. The changes with overfeeding in insulin area during the OGTT were positively correlated with the changes in total subcutaneous fat, even after adjustment for total body fat gain. Significant twin intrapair similarity was observed for fasting plasma glucagon before overfeeding and for the changes in fasting insulin and glucagon with overfeeding. These results indicate that (1) in response to long-term overfeeding, both fasting insulin and glucagon are increased; (2) initial levels of glucose, insulin, and glucagon do not predict the gains in body weight and total body fat during overfeeding, but are related to changes in indicators of fat topography; (3) the changes in total subcutaneous fat represent an important correlate of insulin changes with overfeeding; and (4) the genotype could be an important determinant of insulin and glucagon responses to a prolonged positive-energy-balance period.

Adipose Tissue↗

PubMed1995

Hyperinsulinemia and regulation of energy balance.

Recent data suggest that hyperinsulinemia with euglycemia may favor the restoration of energy balance when one gains body weight. To test the validity of this concept in humans, the data of 24 young men who had been exposed to a 353-MJ overfeeding protocol for 100 d and who were remeasured after a 4-mo follow-up were analyzed. The sample was subdivided in two groups on the basis of the overfeeding-induced change in postprandial plasma insulin. The increase in postprandial energy expenditure induced by overfeeding was significantly greater in high than in low postprandial insulin responders (P < 0.05) but not after body fat gain was controlled for. After the overfeeding protocol, the loss of subcutaneous adiposity was greater in high than in low postprandial insulin responders. However, this difference was no more significant after the gain in fat mass was controlled for. There was no difference between the two groups in post-overfeeding loss of body weight, fat mass, or fat-free mass. These results partly agree with the idea that hyperinsulinemia resulting from a long-term positive energy balance and its associated fat gain exert a regulatory role promoting the restoration of energy balance.

Adipose Tissue↗

PubMed1995

The lipoprotein lipase HindIII polymorphism modulates plasma triglyceride levels in visceral obesity.

The aim of this study was to investigate the potential interaction between the lipoprotein lipase (LPL) HindIII polymorphism and visceral adipose tissue (AT) accumulation in the modulation of triglyceride levels in visceral obesity. The LPL-HindIII genotype was determined by polymerase chain reaction in 52 min. Twenty-three subjects were heterozygous (+/-) and 28 were homozygous (+/+) for the presence of the restriction site. One subject who was homozygous for the--allele was excluded from analysis. Body mass index (BMI), fasting insulin level, and visceral AT area as measured by computed tomography were positively correlated with triglyceride levels only in subjects homozygous for the + allele. Furthermore, whereas these variables were negatively correlated with plasma HDL2 cholesterol concentrations in the +/+ group, these associations were not found in +/- heterozygotes, with the exception of BMI. To further investigate the interaction of the LPL-HindIII polymorphism with visceral obesity and hyperinsulinemia, the two genotype groups were further subdivided on the basis of BMI (low versus high), fasting insulin level (low versus high), and visceral AT area (low versus high), and their lipoprotein profiles were compared. Elevated levels of abdominal visceral AT were significantly associated with increased triglyceride concentrations in +/+ homozygous men, suggesting that visceral obesity may lead to hypertriglyceridemia in the presence of the +/+ genotype. In the +/- group, variation in the amount of visceral AT was not associated with differences in triglyceride concentration. However, hypertriglyceridemia and an increased cholesterol-to-HDL cholesterol ratio were observed in the hyperinsulinemic state irrespective of LPL-HindIII genotype status.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗

PubMed1995

Effects of different training intensities on the cardiopulmonary baroreflex control of forearm vascular resistance in hypertensive subjects.

We recently reported that ambulatory blood pressure decreased during the awake period after training at low intensity but not after training at moderate intensity in subjects with mild to moderate hypertension. The reasons for the failure of moderate-intensity training to reduce blood pressure are not clear. In the present article, we report the effects of different training intensities on cardiopulmonary baroreflex control of forearm vascular resistance, left ventricular function, vascular reactivity, and resistive vessel structure. After moderate-intensity training, the cardiopulmonary baroreflex control of forearm vascular resistance was significantly attenuated, left ventricular performance was enhanced, and vascular reactivity and resistive vessel wall thickness in the calf were reduced compared with values after the control sedentary period. No significant changes in these indexes were found after low-intensity training compared with sedentary values. These results indicate that attenuation of the cardiopulmonary baroreflex control of skeletal muscle vascular resistance after training at moderate intensity may contribute to the lack of antihypertensive effects, as seen from unchanged ambulatory blood pressure levels during the awake period, after training at this intensity. A decreased vascular smooth muscle response to sympathetic nervous stimulation appears to be partly involved in the alteration in the baroreflex control of forearm vascular resistance after moderate-intensity training. Although these findings should be confirmed in a greater number of subjects, the present results point to a key mechanism that might explain why moderate endurance exercise training fails to lower arterial blood pressure in hypertensive subjects.

Adult↗

PubMed1995

Relation of steroid hormones to glucose tolerance and plasma insulin levels in men. Importance of visceral adipose tissue.

OBJECTIVE: Low plasma testosterone levels are associated with hyperinsulinemia and glucose intolerance in men. However, it is unclear whether these abnormalities are related to the concomitant alteration in regional adipose tissue (AT) accumulation associated with reduced androgen levels. RESEARCH DESIGN AND METHODS: We measured plasma steroid levels in a sample of 79 men, ranging from lean to obese (aged 29-42 years), for whom an oral glucose tolerance test (OGTT), anthropometric and computed tomography (CT) measurements of body fatness, and AT distribution were performed. Sex hormone binding globulin (SHBG) and the following steroids were measured after extraction from plasma and chromatography: dehydroepiandrosterone, androstenedione, androst-5-ene-3 beta,17 beta-diol, testosterone, estrone, and estradiol (E2). RESULTS: Several significant negative correlations were found between adrenal C19 steroid precursors, testosterone, SHBG, and fasting insulin levels, as well as between plasma glucose and insulin concentrations measured during the OGTT (-0.25 < or = r < or = -0.35, 0.05 > or = P > or = 0.001). The best steroid correlate of plasma glucose and insulin homeostasis indexes was the E2: testosterone ratio (0.34 < or = r < or = 0.42, 0.005 > or = P > or = 0.001). However, after correction of steroid levels for either fat mass, body mass index (BMI), or visceral AT area, as measured by CT, no significant residual associations were noted between testosterone, adrenal C19 steroid, SHBG, and estrogen levels and indexes of plasma glucose-insulin homeostasis, although the positive association between the E2: testosterone ratio and glucose area remained significant after adjustment for total body fat mass and BMI. Furthermore, 15 pairs of obese subjects, matched for visceral AT area, showing either low or high levels of the steroids studied, did not differ in fasting insulin and postglucose plasma insulin levels or in glucose tolerance. CONCLUSIONS: These results suggest that the previously reported relationships between androgen levels and indexes of plasma glucose-insulin homeostasis are mediated, to a large extent, by concomitant alterations in levels of total body fat and visceral AT in men.

Adipose Tissue↗

PubMed1995

Regional variation in adipose tissue metabolism of severely obese premenopausal women.

Lipolytic and lipoprotein lipase (LPL) activities were studied in isolated human adipocytes obtained from two intraabdominal depots (round ligament and omental) and from the subcutaneous abdominal region of nine severely obese premenopausal women (with body mass indices ranging from 37 to 51 kg/m2), aged 36 +/- 3 yr, undergoing gastrointestinal surgery. Both fat cell weight and LPL activity were significantly greater in round ligament adipose cells than in subcutaneous abdominal or in omental adipocytes (P < 0.05). The antilipolytic effect of insulin and the sensitivity to this hormone were also higher in round ligament adipose cells than in omental adipocytes (P < 0.05). Although epinephrine initiated a similar biphasic profile of response in all cell types, the catecholamine promoted a weaker inhibition of lipolysis in omental adipocytes than in subcutaneous abdominal adipose cells (P < 0.05). In addition, a lack of regional variation was found in the maximal antilipolysis initiated by UK 14304 and the alpha 2-adrenoceptors was higher in both subcutaneous abdominal and round ligament fat cells than in omental adipocytes. Moreover, the maximal lipolytic response to isoproterenol or to agents acting at post-receptor levels was not different among fat depots. Finally, a lower beta-adrenergic lipolytic sensitivity associated with a reduced beta-adrenoceptor density was observed in round ligament as compared to omental adipose cells. These data suggest that in massively obese premenopausal women, omental and round ligament adipose tissues show distinct metabolic properties that may contribute to limit the impact of intraabdominal obesity.

Adipocytes↗

PubMed1994

Waist circumference and abdominal sagittal diameter: best simple anthropometric indexes of abdominal visceral adipose tissue accumulation and related cardiovascular risk in men and women.

The amount of abdominal visceral adipose tissue measured by computed tomography is a critical correlate of the potentially "atherogenic" metabolic disturbances associated with abdominal obesity. In this study conducted in samples of 81 men and 70 women, data are presented on the anthropometric correlates of abdominal visceral adipose tissue accumulation and related cardiovascular disease risk factors (triglyceride and high-density lipoprotein cholesterol levels, fasting and postglucose insulin and glucose levels). Results indicate that the waist circumference and the abdominal sagittal diameter are better correlates of abdominal visceral adipose tissue accumulation than the commonly used waist-to-hip ratio (WHR). In women, the waist circumference and the abdominal sagittal diameter also appeared more closely related to the metabolic variables than the WHR. When the samples were divided into quintiles of waist circumference, WHR or abdominal sagittal diameter, it was noted that increasing values of waist circumference and abdominal sagittal diameter were more consistently associated with increases in fasting and postglucose insulin levels than increasing values of WHR, especially in women. These findings suggest that the waist circumference or the abdominal sagittal diameter, rather than the WHR, should be used as indexes of abdominal visceral adipose tissue deposition and in the assessment of cardiovascular risk. It is suggested from these data that waist circumference values above approximately 100 cm, or abdominal sagittal diameter values > 25 cm are most likely to be associated with potentially "atherogenic" metabolic disturbances.

Abdomen↗

PubMed1994

The response to exercise with constant energy intake in identical twins.

Seven pairs of young adult male identical twins completed a negative energy balance protocol during which they exercised on cycle ergometers twice a day, 9 out of 10 days, over a period of 93 days while being kept on a constant daily energy and nutrient intake. The total energy deficit caused by exercise above the estimated energy cost of body weight maintenance reached 244 +/- 9.8 MJ (Mean +/- SEM). Baseline energy intake was estimated over a period of 17 days preceding the negative energy balance protocol. Mean body weight loss was 5.0 kg (SEM = 0.6) (p < 0.001) and it was entirely accounted for by the loss of fat mass (p < 0.001). Fat-free mass was unchanged. Body energy losses reached 191 MJ (SEM = 24) (p < 0.001) which represented about 78% of the estimated energy deficit. Subcutaneous fat loss was slightly more pronounced on the trunk than on the limbs as estimated from skinfolds, circumferences, and computed tomograply (CT). The reduction in CT-assessed abdominal visceral fat was quite striking, from 81 cm2 (SEM = 5) to 52 cm2 (SEM = 6) (p < 0.001). At the same submaximal power output level, subjects oxidized more lipids than carbohydrates after the program as indicated by the changes in the respiratory exchange ratio (p < or = 0.05). Intrapair resemblance was observed for the changes in body weight (p < 0.05), fat mass (P < 0.01), percent fat (p < 0.01), body energy content (p < 0.01), sum of 10 skinfolds (p < 0.01), abdominal visceral fat (p < 0.01), fasting plasma triglycerides (p < 0.05) and cholesterol (p < 0.05), maximal oxygen uptake (p < 0.05), and respiratory exchange ratio during submaximal work (p < 0.01). We conclude that even though there were large individual differences in response to the negative energy balance and exercise protocol, subjects with the same genotype were more alike in responses than subjects with different genotypes particularly for body fat, body energy, and abdominal visceral fat changes. High lipid oxidizers and low lipid oxidizers during submaximal exercise were also seen despite the fact that all subjects had experienced the same exercise and nutritional conditions for about three months.

Adipose Tissue↗

PubMed1994

The pattern of catecholamine response to burst activity in leopard frogs, Rana pipiens.

It is well known that burst activity causes a rapid breakdown of muscle glycogen and extensive accumulation of lactate in frogs. During recovery, it has been shown that lactate is nearly totally recycled into muscle glycogen. Since catecholamines are likely to play some role in the regulation of postexercise repletion of muscle glycogen, the pattern of catecholamine response was assessed in frogs during intense physical activity and the ensuing recovery period. Chronically cannulated frogs were forced to swim until exhaustion, and serial blood samples were taken at regular time intervals for the measurements of catecholamines. The pattern of changes in plasma and muscle lactate and glucose and muscle glycogen during and after burst activity is similar to that reported in previous studies using noncannulated frogs, a result which indicates that the animals recover well from the surgical trauma associated with cannulation. The concentrations of plasma catecholamines in frogs at rest are comparable to those measured in other amphibians, and the levels of plasma epinephrine in resting frogs are much higher than those of norepinephrine. Burst activity causes a marked increase in plasma catecholamines, with higher levels reached by epinephrine. During recovery, the concentration of plasma catecholamines returns to normal within 30 min. Although this pattern of catecholamine response to intense physical activity may be favorable to the repletion of muscle glycogen postexercise, it remains to be clarified how critical the low levels and fast reduction in plasma catecholamines are for optimum glycogen resynthesis.

Animals↗

PubMed1994

Are gender differences in cardiovascular disease risk factors explained by the level of visceral adipose tissue?

It has been suggested that the lower prevalence of cardiovascular disease in women before menopause in comparison with men may be explained by differences in body fat distribution, plasma lipoprotein levels and indices of plasma glucose-insulin homeostasis. Thus, gender differences in visceral adipose tissue accumulation measured by computed tomography and metabolic variables were studied in 80 men and 69 pre-menopausal women, aged 23-50 years. Despite the fact that women had higher levels of total body fat (p < 0.0001), they displayed lower areas of abdominal visceral adipose tissue (p < 0.06) and a lower ratio of abdominal visceral to mid-thigh adipose tissue areas than men (p < 0.0001). After adjustment for body fat mass, women generally displayed a more favourable risk profile than men which included higher plasma HDL2-cholesterol and lower plasma insulin, apolipoprotein B and triglyceride levels (p < 0.01). Metabolic variables adjusted for body fat mass were then compared between genders after control for differences in abdominal visceral adipose tissue area. After such controls, variables related to plasma glucose-insulin homeostasis were no longer significantly different between men and women. Gender differences for plasma concentrations of triglyceride, apolipoprotein B and the ratio of HDL2-cholesterol/HDL3-cholesterol also disappeared, whereas plasma concentrations of HDL-cholesterol, HDL2-cholesterol as well as the ratio of HDL-cholesterol/total cholesterol remained significantly higher in women than in men (p < 0.01). These results suggest that abdominal visceral adipose tissue is an important correlate of gender differences in cardiovascular disease risk. However, additional factors are likely to be involved in gender differences in plasma HDL-cholesterol levels.

Adipose Tissue↗

PubMed1994

Systolic blood pressure during submaximal exercise: an important correlate of cardiovascular disease risk factors in normotensive obese women.

Body fatness, plasma lipids, lipoproteins, indicators of glucose metabolism, and resting as well as submaximal treadmill exercise systolic blood pressures (BPs) were measured in a sample of 25 normotensive obese premenopausal women. No association was observed between body fatness, risk factors for cardiovascular disease, and resting BP. However, body fatness and plasma cholesterol, low-density lipoprotein cholesterol (LDL-CHOL), LDL apolipoprotein B (apo B), and apo B concentrations, as well as the high-density lipoprotein cholesterol to cholesterol (HDL-CHOL/CHOL) ratio, showed significant correlations with systolic BP measured during submaximal exercise. In addition, fasting plasma insulin concentrations and the glucose and insulin areas under the oral glucose tolerance test (OGTT) curve were both significantly associated with systolic BP during submaximal exercise. Partial correlation analyses revealed that the associations between submaximal exercise systolic BP and plasma apo B and LDL apo B levels were in part independent from the level of obesity. These results indicate that plasma concentrations of lipoproteins and insulin are important correlates of the systolic BP during submaximal exercise in obese premenopausal women. Further analyses performed on two subgroups indicated that women with high exercise systolic BP values exhibited significant differences in their metabolic profile in comparison to women with low BP during exercise. These results suggest that the absolute systolic BP recorded during submaximal exercise may be useful in the early detection of individuals at risk for the development of cardiovascular disease in resting normotensive obese women.

Adult↗

PubMed1994

Diminished diabetogenic effect of streptozotocin in adrenodemedullated rats.

Although stress is suspected to play a role in the development of diabetes mellitus, no direct experimental evidence for involvement of the adrenal medullae in onset of the disease has yet been found. We recently observed that, in comparison with sham-operated rats, fewer adrenodemedullated rats become diabetic after an i.v. injection of streptozotocin (STZ); thus, the present study examined the role of the adrenal medullae in the development of experimental diabetes. Male Wistar rats were surgically adrenodemedullated (ADM) or sham-operated (SHAM). After a 3-week recovery period, they were injected with 40 mg STZ/kg freshly dissolved in citrate buffer or buffer alone. A 1-mL arterial blood sample was withdrawn 12 days later in previously cannulated animals; then the rats were killed and their pancreas was removed. The plasma glucose levels were lower in ADM rats injected with buffer alone than in their SHAM counterparts (7.7 +/- 0.1 vs. 8.5 +/- 0.1 mmol/L; p < 0.05). The glucose levels were higher (p < 0.001) in both groups of STZ-treated rats, with values 28% lower in ADM than in SHAM rats (14.7 +/- 1.6 vs. 18.8 +/- 1.2 mmol/L; p < 0.03). Whereas plasma insulin levels did not differ between ADM and SHAM rats injected with buffer alone (431 +/- 38 vs. 428 +/- 35 pmol/L; p > 0.05), they were diminished in SHAM animals injected with STZ (292 +/- 37 vs. 428 +/- 35 pmol/L; p < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Medulla↗