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Biomedical subjects

A Astrup

Publications and source records attributed to A Astrup.

At least 145 records · Page 8Linked to original sources
PubMed1994

Plasma adrenaline concentration is lower in post-obese than in never-obese women in the basal state, in response to sham-feeding and after food intake.

1. Plasma pancreatic polypeptide, plasma catecholamine, blood glucose, plasma insulin and plasma peptide YY concentrations were studied to assess differences between eight formerly obese and eight never-obese control women during 25 min of sham-feeding (with the sight and smell of an English breakfast) and for 5 h after they had ingested the meal (3514 kJ, 50% fat, 35% carbohydrate). The post-obese women had maintained their normal body weight for at least 3 months before the study. 2. The plasma noradrenaline concentration was not different between the groups either during fasting (post-obese women 0.08 +/- 0.01 ng/ml versus control women 0.10 +/- 0.01 ng/ml) or in the significant postprandial increase (P < 0.001). The plasma adrenaline concentration increased significantly during sham-feeding in the control group from 0.024 +/- 0.004 ng/ml to 0.033 +/- 0.004 ng/ml (P = 0.02) in contrast with the post-obese women, who had significantly lower plasma concentrations of adrenaline in the fasting state (post-obese 0.016 +/- 0.003 ng/ml versus control women 0.024 +/- 0.004 ng/ml, P = 0.003), during sham-feeding (post-obese women 0.018 +/- 0.002 ng/ml versus control women 0.033 +/- 0.004 ng/ml, P = 0.003) and in the postprandial increase (P = 0.003). The maximal postprandial response concentrations recorded 5 h after the meal were 0.025 +/- 0.003 ng/ml in post-obese women and 0.035 +/- 0.004 ng/ml in control subjects (P = 0.04). There were no significant differences in plasma pancreatic polypeptide, plasma peptide YY, plasma insulin, or blood glucose concentrations between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Insulin sensitivity in post-obese women.

1. Both increased and decreased sensitivity to insulin has been proposed to precede the development of obesity. Therefore, insulin sensitivity was measured during a 2 h hyperinsulinaemia (100 m-units min-1 m-2) euglycaemic (4.5 mmol/l) glucose clamp combined with indirect calorimetry in nine weight-stable post-obese women and in nine matched control women preceded by 12 h fasting after 48 h on a standardized diet. 2. Both glucose disposal rate (post-obese women, 9.5 +/- 2.2 mg min-1 kg-1, control women, 11.2 +/- 1.4 mg min-1 kg-1, not significant) and glucose oxidation (3.6 +/- 0.5 mg min-1 kg-1 versus 4.0 +/- 0.7 mg min-1 kg-1, not significant) were similar in the two groups during the last 30 min of the clamp. Lipid oxidation also decreased similarly during the clamp in the post-obese women (from 30.4 +/- 12 to 2.0 +/- 7 J min-1 kg-1) and in the control women (from 33.6 +/- 11 to 5.4 +/- 8 J min-1 kg-1, not significant). Basal plasma concentrations of free fatty acids were similar, but at the end of the clamp free fatty acids were lower in the post-obese women than in the control women (139 +/- 19 and 276 +/- 48 mumol/l, P = 0.02). 3. We conclude that the insulin sensitivity of glucose metabolism is unaltered in the post-obese state. The study, however, points to an increased antilipolytic insulin action in post-obese subjects, which may favour fat storage and lower lipid oxidation rate postprandially.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Twenty-four-hour energy expenditure and substrate utilization in body builders.

Twenty-four--hour energy expenditure (EE) was measured by indirect calorimetry in 10 body builders and 10 lean control subjects of the same sex with similar age, height, and percent body fat. The study was performed to elucidate possible effects of strength training on energy metabolism and substrate utilization. Twenty-four--hour EE was higher in the body builders than in control subjects but was similar when adjusted for differences in fat-free mass. A higher 24-h nonprotein respiratory quotient (RQ) was found in the body builders. Because both groups were in energy balance, the higher RQ in the body builders can be attributed to a different habitual diet or may be explained by physiological differences.

Adult↗
PubMed1994

Obesity as an adaptation to a high-fat diet: evidence from a cross-sectional study.

Expansion of the fat stores has been proposed as a prerequisite for increasing fat oxidation in response to a high-fat diet in individuals with a predisposition to obesity. In a cross-sectional design we measured 24-h substrate oxidations on a standardized diet in 38 overweight or obese and 35 nonobese women. Fat oxidation (g/d) was mainly a function of total energy requirements (r = 0.71, P < 0.0001). To account for this we used for further analysis oxidative fat energy (%), a counterpart to dietary fat energy (%). After differences in fat energy of consumed food (%), age, and 24-h energy balance were adjusted for, obese women had higher oxidative fat energy than did nonobese women [40.2% (37.8-42.6) vs 36.0% (33.6-38.5), P < 0.02]. Adjusted oxidative fat energy (%) increased with increasing size of fat mass (r = 0.31, P < 0.01). This relation suggests that a 10-kg change in fat mass may be caused by a change in dietary fat energy of > or = 1.6% (0.4-2.7%). The study supports the concept that in susceptible individuals the expansion of fat stores is a prerequisite to increase the oxidative fat energy to an amount commensurate with a high percentage of dietary fat energy.

Adipose Tissue↗
PubMed1994

Decreased postprandial thermogenesis and fat oxidation but increased fullness after a high-fiber meal compared with a low-fiber meal.

The effect of a high-fiber (4.7 g/MJ) and an isoenergetic low-fiber (1.7 g/MJ) meal on 6-h postprandial thermogenesis, substrate metabolism, hormones, and satiety was investigated in 10 healthy, normal-weight male subjects. Diet-induced thermogenesis (DIT) was significantly reduced after the high-fiber meal (416.4 +/- 28.6 kJ/6 h) compared with the low-fiber meal (498.5 +/- 23.1 kJ/6 h; ANOVA: P < 0.0001), as was postprandial fat oxidation (P < 0.0001). The difference in DIT was correlated with the different palatability of the test meal (r = 0.89, P < 0.01). No differences were observed in plasma concentrations of glucose, insulin, norepinephrine, epinephrine, or gastrointestinal hormones, but C-peptide increased less (P < 0.05) and nonesterified fatty acids decreased more (P < 0.05) after the high-fiber meal. Finally, fullness was increased and desire to eat decreased after the high-fiber meal (P < 0.0001). In conclusion, a high-fiber meal decreased DIT and fat oxidation but increased fullness compared with a low-fiber meal.

Adult↗
PubMed1994

Resistant starch: the effect on postprandial glycemia, hormonal response, and satiety.

The effect of resistant starch (RS) on postprandial plasma concentrations of glucose, lipids, and hormones, and on subjective satiety and palatability ratings was investigated in 10 healthy, normal-weight, young males. The test meals consisted of 50 g pregelatinized starch (0% RS) (S) or 50 g raw potato starch (54% RS) (R) together with 500 g artificially sweetened syrup. After the R meal postprandial plasma concentrations of glucose, lactate, insulin, gastric inhibitory polypeptide (GIP), glucagon-like peptide-1, and epinephrine were significantly lower compared with after the S meal. Moreover, subjective scores for satiety and fullness were significantly lower after the R meal than after the S meal. Differences in GIP, texture, and palatability may have been involved in these findings. In conclusion, the replacement of digestible starch with RS resulted in significant reductions in postprandial glycemia and insulinemia, and in the subjective sensations of satiety.

Adult↗
PubMed1994

Oxidative DNA damage correlates with oxygen consumption in humans.

Generation of reactive oxygen species from mitochondrial respiration has been proposed as an important determinant of longevity and cumulative cancer risk. Interspecies correlations and animal calorie restriction studies of metabolic rate and oxidative DNA damage support this notion. In the present study we have demonstrated a close association between oxidative DNA damage as assessed by the urinary excretion of 8-oxo-7,8-dihdro-2'-deoxyguanosine (8-oxodG) and oxygen consumption in 33 healthy premenopausal women (r = 0.64; p = 0.00007). In the 12 women who smoked, 8-oxodG excretion was increased by 35%, although oxygen consumption increased only 10% compared with the 21 nonsmoking women. Apparently, the rate of oxidative DNA damage relates to mitochondrial respiration in humans and is aggravated by smoking.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1994

Failure to increase lipid oxidation in response to increasing dietary fat content in formerly obese women.

The effect of an increase in dietary fat content on fat and carbohydrate balances and energy expenditure (EE) was studied in nine formerly obese women with genetic predisposition to obesity (postobese) and a closely matched control group. Isocaloric low- (20% fat energy) and high-fat diets (50%) were consumed for 3 days preceding and during a 24-h respiratory chamber stay, whereas a medium-fat diet (30%) was consumed only on the day of measurement. After adjustment for 24-h energy intake to equal 24-h EE, 24-h fat balance was increased when the dietary fat content increased (P < 0.0002). No differences in macronutrient balances were found on the low-fat and medium-fat diets, but on the high-fat diet the postobese women failed to increase ratio of fat to carbohydrate oxidation appropriately (0.59 g/g, 95% confidence interval 0.47-0.67 vs. controls 1.02 g/g, 0.88-1.12; P = 0.002). This caused a positive adjusted fat balance (+11.0 g/day, 2.3-19.6 vs. controls -8.9 g/day, -17.5 to -0.2; P < 0.001) and a negative carbohydrate balance (-41.8 g/day, -69.5 to -14.0 vs. controls +23.2 g/day, -4.6 to +50.9; P < 0.001). Decreasing the dietary fat content increased 24-h EE in the postobese women (P = 0.02), whereas it was unaffected in the control group. Independent of energy balance, an increase in dietary fat content to 50% fat energy results in preferential fat storage, impaired suppression of carbohydrate oxidation, and reduction of 24-h EE in postobese women.

Adult↗
PubMed1994

Evidence for an abnormal postprandial response to a high-fat meal in women predisposed to obesity.

The present study was undertaken to investigate fat metabolism after a high-fat meal [50 energy percent (E%) fat] in formerly obese subjects with a familial history of obesity. Twelve normal-weight postobese women (PO) and 12 closely matched controls were given the test meal after a 2-day carbohydrate-rich weight-maintenance diet (58 E% carbohydrate). Whereas the thermic effect of the meals was similar in the two groups, postprandial fat oxidation was 2.5 times more suppressed in PO compared with controls (P < 0.05). A similarly enhanced suppression of arterialized plasma concentrations of nonesterified fatty acids was seen postprandially in PO (P < 0.05), possibly due to a more marked suppression of epinephrine and a reduced glucagon response in PO than in controls. Moreover, the postprandial plasma triglyceride response was attenuated and only amounted to 43% of that in controls (P < 0.05). This may be explained by a more pronounced increase in gastric inhibitory polypeptide in PO, giving rise to a higher adipose tissue lipoprotein lipase activity. No other differences were found in plasma substrates and hormones or in subjective appetite scores. In conclusion, a metabolic and hormonal pattern favoring lipid storage was observed in postobese subjects after a high-fat meal.

Adult↗
PubMed1994

The effect of ephedrine plus caffeine on plasma lipids and lipoproteins during a 4.2 MJ/day diet.

The effect of treatment with a combination of ephedrine and caffeine during eight weeks' energy restriction (4.2 MJ/day) on the fasting plasma lipid profile was studied in obese women. Thirty-two women were randomly assigned to either ephedrine 20 mg plus caffeine 200 mg (EC) or placebo three times per day. Weight loss (7.8 +/- 0.63 kg) and loss of fat mass (6.2 +/- 0.49 kg) did not differ significantly between the two groups. Total cholesterol concentration declined from baseline to week 8 (0.58 +/- 0.13 mmol/l) with no significant difference between the two groups. HDL-cholesterol concentration was decreased by 0.14 +/- 0.03 mmol/l at week 4 and week 8 in the placebo group (P < 0.05) but remained unchanged in the EC group. No effect of dieting was seen on plasma triglyceride concentration in the placebo group but a decrease was observed in the EC group at week 8. It is suggested that EC combinations abolish the decline in HDL-cholesterol during active weight loss due to the beta-agonistic properties of ephedrine.

Body Composition↗
PubMed1993

Localization of thermogenesis induced by single infusion of ephedrine in dog.

The localization of the thermogenic effect of ephedrine (1 mg.kg-1 infused intravenously over 10 min.) was studied in 6 fasted dogs anaesthetized with etorfin-acepromazin-N2O. Three experiments were performed in each animal to determine the effect of ephedrine on a) splanchnic oxygen uptake, b) lower leg oxygen uptake and c) the work of the heart. In all experiments whole body oxygen uptake was monitored. Following ephedrine administration the following significant changes were seen as whole body oxygen uptake increased 16%, and splanchnic and lower leg oxygen uptakes increased respectively from 38.4 to 42.3 and from 7.3 to 12.1% of the whole body control oxygen uptake. The pressure-volume work of the heart more than doubled. Significant changes were also seen in mean arterial blood pressure, pulse rate, cardiac output, splanchnic blood flow, and haematocrit and haemoglobin concentration. Plasma glycerol and free fatty acid concentrations increased after ephedrine, and the effects were not elicited by circulating catecholamines.

Animals↗
PubMed1993

Local forearm and whole-body respiratory quotient in humans after an oral glucose load: methodological problems.

The effects of an oral glucose load of 75 g on the local forearm and whole-body energy thermogenesis were measured in normal subjects during the 4 h after the glucose intake. Simultaneous assessment of substrate metabolism in the forearm was performed. Energy expenditure (EE) increased after the glucose load and had not returned to baseline level at the end of the experiment. Whole-body respiratory quotient (RQ) was, on average, 0.80 (SD 0.05) in the baseline condition and increased to a maximum of 0.91 (0.03) and then decreased to baseline level at the end of the experiment. The local forearm oxygen uptake increased 30 min after the glucose intake and remained elevated during the rest of the experiment. The carbon dioxide output from the forearm did not increase before 90 min after the glucose load. Consequently the local forearm RQ decreased significantly from a baseline value of 0.86 (0.17) to 0.63 (0.17) 30 min after the glucose load (P < 0.05). Ninety min after the glucose load RQ increased to a maximum level at 0.95 (0.22) and decreased then gradually to baseline level. The experiments emphasize several methodological problems in the measurement of local forearm RQ. The whole-body RQ and local forearm RQ are not significantly different in the fasting state. The finding of a decrease in local forearm RQ below 0.70 30 min after the glucose load probably indicates a non-steady state in the carbon dioxide exchange. Thus, indirect calorimetry cannot be applied locally during short time periods.

Adult↗
PubMed1993

Dietary composition, substrate balances and body fat in subjects with a predisposition to obesity.

Ecological, cross-sectional and prospective longitudinal studies show that obesity is positively associated with dietary fat energy percentage and negatively with carbohydrate energy percentage. The relationships are concordant with the concept of separately regulated macronutrient balances and the higher satiating effect of carbohydrate than of fat. Dietary records have suggested that obese subjects tend to consume a diet with a higher fat content than normal weight controls. Due to a carry-over effect of the habitual diet on the next day's substrate use, we were able to show that an obese group of women oxidized 40.2% fat energy while a normal weight group oxidized only 36.0% fat energy, although they all consumed a diet with 30% fat energy. Percentage fat oxidation (24 h) was positively correlated with fat mass, which supports the theory that the expansion of fat stores is a prerequisite to an increase in fat oxidation to match a high dietary fat energy percentage. Post-obese subjects did not differ in 24 h macronutrient balances from a control group when consuming diets with 20 and 30% fat energy. In contrast, they failed to increase the ratio of fat to carbohydrate oxidation appropriately when exposed to a high-fat diet (50% fat energy), which resulted in a positive fat balance and a negative carbohydrate balance. The post-obese subjects seem to have normal insulin sensitivity, and preliminary results suggest that exercise-induced stimulation of lipolysis is normal, while fat oxidation is reduced in spite of higher circulating levels of free fatty acids.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1993

Determination of local catecholamine release by microdialysis.

Release of noradrenaline in subcutaneous tissue was measured using a microdialysis technique in combination with an ultrasensitive radio-enzymatic noradrenaline assay. Experiments were performed in conscious dogs with and without tyramine added to the perfusion medium. In the absence of tyramine, the interstitial noradrenaline levels in subcutaneous tissue were similar to arterial blood concentrations provided the former were corrected for recovery. With tyramine added to the perfusion medium, noradrenaline levels in subcutaneous tissue increased tenfold. Arterial noradrenaline concentrations did not change, indicating that noradrenaline was released only locally in the tissue. In four healthy males, the subcutaneous dialysate noradrenaline concentration increased during cold exposure by a factor of 3.5 (Friedman test, P < 0.003). Skin temperature decreased by an average of -12 degrees C +/- 0.6 degrees C during cold exposure. The microdialysis technique in combination with a sensitive radio-enzymatic noradrenaline assay may be useful to assess local subcutaneous noradrenaline release.

Adult↗
PubMed1993

The acute and chronic effects of ephedrine/caffeine mixtures on energy expenditure and glucose metabolism in humans.

This paper describes a 24-week open follow-up trial with reduced obese patients all receiving an ephedrine/caffeine combination (20 mg/200 mg) three times a day. The study was a continuation of a previous 24-week double-blind placebo-controlled study where the ephedrine/caffeine mixture had shown superior weight-reducing properties when compared with either ephedrine alone (20 mg) or caffeine alone (200 mg) three times a day. The medication was stopped between weeks 24-26 in order to evaluate withdrawal symptoms. The follow-up period was from weeks 26 to 50. Of 127 patients included, 99 completed the follow-up treatment, which resulted in an additional weight loss of 1.1 kg (P = 0.02). Adverse drug reactions were all minor and temporary. We conclude that the ephedrine/caffeine combination is safe and effective in long-term treatment in improving and maintaining weight loss. The side-effects are minor and transient and no clinically relevant withdrawal symptoms have been observed.

Adult↗