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Biomedical subjects

J Madsen

Publications and source records attributed to J Madsen.

At least 73 records · Page 4Linked to original sources
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

Diving physiology and pathophysiology.

Divers have worked at 500 m depth in the sea and have reached 700 m in simulated chamber dives. A prerequisite for this has been extensive physiological studies of the body's reactions to pressure and pressure changes. This paper reviews such physiological and pathophysiological studies with emphasis on recent developments.

Decompression Sickness↗
PubMed1994

Adipose tissue metabolism in humans determined by vein catheterization and microdialysis techniques.

A technique for catheterization of a vein draining abdominal subcutaneous tissue and a microdialysis technique that allows measurements of intercellular water concentrations in adipose tissue in humans have recently been described. In the present study, we compare the two techniques during an oral glucose load. In addition a technique using microdialysis for measurement of tissue oxygen and carbon dioxide tensions is described. Microdialysis and vein catheterization were performed in the same region on the abdomen, and the subcutaneous adipose tissue blood flow was measured by the local 133Xe washout method. The results show that subcutaneous adipose tissue gas tensions are on level with gas tensions measured in abdominal venous blood. Comparison of metabolite concentrations measured in the venous blood and venous blood concentrations calculated from microdialysis data shows that there is good agreement between the concentrations obtained by the two techniques with respect to glucose and glycerol, whereas lactate concentrations are very different. With regard to substrate fluxes calculated by Fick's principle, the catheterization technique is probably the most reliable, considering the numerous assumptions on which calculations of venous concentrations from microdialysis data are based. Advantages and disadvantages of the two techniques are discussed.

Abdomen↗
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

Effect of air, heliox, and oxygen breathing on air bubbles in aqueous tissues in the rat.

Our purpose was to examine the behavior of air bubbles in three non-lipid tissues (skeletal muscle, tendon, and the anterior chamber of the eye) during breathing of air, helium-oxygen (heliox, 80:20), or oxygen. Air bubbles were injected into skeletal muscle or tendon in rats after decompression from a 1-h air exposure at 3.5 atm abs (355 kPa) or into the anterior chamber of the rat eye without any previous pressure exposure. The bubbles were studied by photomicroscopy at 1 atm abs (101 kPa) during either air breathing or during air breathing followed by heliox or O2 breathing. Muscle: during air breathing, all bubbles initially increased in size for a period of 55-100 min after decompression and then started to shrink. Both heliox and O2 breathing increased the shrinking rate as compared to air. Bubble size decreased more rapidly during O2 than heliox breathing. Tendon: during air breathing, bubble size decreased at a constant rate; in one bubble the decrease was preceded by a small increase. During heliox breathing most bubbles decreased faster than during breathing of air. O2 breathing caused a short-term increase in bubble size in 4 out of 10 bubbles. Otherwise, the shrinkage rate was increased in six bubbles and uninfluenced in four bubbles during breathing of O2. Rat eye: during air breathing all bubbles shrank in the observation period. When heliox breathing was started, all bubbles transiently grew for 10-35 min, after which they began shrinking faster than during air breathing. When O2 breathing was started, five out of seven bubbles initially grew or stopped shrinking for 5-15 min, after which they decreased in size faster than during both air and heliox breathing. We conclude that breathing of either heliox or O2 will cause air bubbles in aqueous tissues to disappear faster than during breathing of air. Since heliox breathing promoted bubble shrinking in both muscle and tendon, gas exchange was probably not primarily limited by extravascular diffusion in these aqueous tissues. The present experiments suggest that heliox breathing at 1 atm abs may not exacerbate limb bends.

Air↗
PubMed1994

Protective effect of oxygen and heliox breathing during development of spinal decompression sickness.

A rat model of spinal decompression sickness (DCS) allows study of spinal cord function for at least 3 h after decompression to 1 atm abs (101 kPa) after an exposure to air at 3.8 atm abs (385 kPa) for 1 h. During these 3 h, spinal evoked potentials (SEPs) elicited by peroneal nerve stimulation may be reduced or disappear, and histologic lesions in the spinal cord are observed. Three groups of animals were given either air, oxygen, or heliox (80/20) to breathe at 1 atm abs for 3 h after decompression. Both oxygen and heliox breathing impeded the development of DCS significantly as judged by the mortality of the animals and disappearance of the SEPs. The effect of heliox seemed to be superior to that of oxygen. The latency time from stimulation to the first SEP peak increased significantly during both air and oxygen breathing, whereas no significant increase was seen during heliox breathing. Histologic examination of the spinal cords of animals breathing air, oxygen, or heliox (80/20) showed focal lesions in the white and gray matter. In the white matter, degenerated myelin sheaths as well as expanded extracellular spaces compatible with bubble formation were seen. In the gray matter, perikaryal degeneration was observed. The extracellular space in the white matter was increased in all decompressed animals compared with controls (P < 0.01). Oxygen and heliox breathing caused a smaller increase in extracellular space as compared with air-breathing animals (P < 0.05) and (0.10 > P > 0.05), respectively. It is concluded that breathing of oxygen or heliox (80/20) at 1 atm abs has a preventive effect on the development of DCS when compared with air breathing; the effect of heliox seems to be superior to that of oxygen.

Air↗
PubMed1993

Relationship between self-monitoring of diet and exercise change and subsequent risk factor changes in children and adults.

Self-monitoring is often used in health behaviour change programs; but it is not known to what extent self-monitoring data are valid and useful in predicting changes in cardiovascular disease (CVD) risk. Subjects included 72 Anglo adults, 68 Anglo children, 80 Mexican-American adults and 94 Mexican-American children. Subjects were families with fifth and sixth grade children who participated in an 18-session family-based diet and exercise change program designed to reduce CVD risk. During the intervention, each participant self-monitored diet and aerobic physical activity. Families were measured at baseline, 3, 12, and 24 months. For adults, self-monitored changes in diet correlated with changes in body mass index, systolic blood pressure, total cholesterol and LDL 1 and 2 years later. Correlations between self-monitored diet and diet-related risk factor changes were not observed among children. Correlations between self-monitored exercise and subsequent risk factor changes were not observed among adults. For children, self monitored changes in aerobic physical activity correlated significantly with changes in VO2Max and HDL/LDL ratio 1 and 2 years later. Thus, this study provides some support for the predictive validity of diet self-monitoring in adults and exercise self-monitoring in children.

Adult↗
PubMed1993

Process variables as predictors of risk factor changes in a family health behavior change program.

The purpose of the present study was to determine the extent to which intervention process measures are useful in predicting changes in cardiovascular disease (CVD) risk factors among subjects exposed to interventions. Subjects were 99 adult and 105 children who participated in an 18 session, family-based diet and exercise change program. During the intervention, each participant self-monitored diet and exercise for 12 weeks. Additionally, attendance, session evaluation, confidence to achieve goals and goal achievement data were collected each week. The intervention was successful in changing diet, blood pressure and cholesterol levels, but did not produce significant changes in exercise or body mass index. Stepwise multiple regression analyses were conducted for each outcome variable at the 1 and 2 year follow-ups. Ethnicity and sex were first forced into each regression. None of the process measures consistently predicted multiple outcomes in adults and children. The pattern of results provides limited support for the hypothesis that intervention process variables such as attendance, adherence to self-monitoring, achievement of goals and attitude toward sessions partially mediate intervention effects. It is concluded that process measures should be collected in health behavior change programs so that process-outcome relationships can be further explored.

Adolescent↗
PubMed1993

Glucose-induced thermogenesis in patients with small cell lung carcinoma. Before and after inhibition of tumour growth by chemotherapy.

Seven weight-losing patients with histologically verified small cell lung carcinoma were given an oral glucose load of 75 g before and at least 3 weeks after the end of chemotherapy to examine the effect of glucose on whole body and skeletal muscle thermogenesis before and after reduction of tumour. Whole body energy expenditure was measured by the open circuit ventilated hood system. Forearm blood flow was measured by venous-occlusion strain-gauge plethysmography. The uptake of oxygen in skeletal muscle was calculated as the product of the forearm blood flow and the difference in a-v oxygen concentration. Whole body resting energy expenditure (REE) did not increase, it was 4.4 +/- 0.3 kJ min-1 (mean +/- SE) before chemotherapy and 4.4 +/- 0.2 kJ min-1 after chemotherapy. The glucose-induced thermogenesis in the 180 min following the glucose load was 93.6 +/- 9.9 kJ 180 min-1 before chemotherapy. This is significantly increased compared to that found in a healthy control group (74.7 +/- 4.8 kJ 180 min-1, P < 0.02). The glucose-induced thermogenesis was significantly reduced to 47.7 +/- 10.2 kJ 180 min-1 (P < 0.05) after chemotherapy. The oxygen uptake in resting skeletal muscles was 6.9 +/- 0.3 mumol 100 g-1 min-1 before chemotherapy and 7.0 +/- 0.7 mumol 100 g-1 min-1 after chemotherapy. This did not increase during the first 90 min following the glucose load in either investigations. In the period 90-180 min following the glucose load, the oxygen uptake was significantly increased before chemotherapy as compared to after chemotherapy, which suggests that the reduced whole body thermogenesis after chemotherapy in part was due to reduced skeletal muscle thermogenesis.

Adult↗
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↗
PubMed1992

Metabolic changes during treatment with valproate in humans: implication for untoward weight gain.

This study was initiated to elucidate the mechanisms behind valproate-induced weight gain. Eight patients with epilepsy were studied with identical examination programs before and during the end of the first month of treatment with sodium valproate (VPA). The measurements included registration of food intake, indirect calorimetry, and determination of pancreatic and thyroid hormones, catecholamines, albumin, electrolytes, glycerol, and free fatty acids. Measurements were performed both at the basal condition and during a 3-hour oral glucose tolerance test (OGTT). After the start of VPA treatment, the mean levels during the OGTT of plasma glucose and catecholamines were significantly decreased by 7% and 25%, respectively (P less than .05). The mean ratio of insulin to glucagon decreased by 37% (P less than .01). During the glucose load, the decreases in free fatty acids were less pronounced after the start of VPA treatment, whereas the mean levels of glycerol were found to be unchanged. We detected no differences between the two periods with regard to total energy intake or macronutrient selection, energy expenditure, or thyroid hormones. As VPA is known to affect the concentration of carnitine in humans, it is hypothesized that a possible VPA-induced deficiency of the beta-oxidation of fatty acids is important for the development of obesity in epileptic patients in long-term treatment with VPA, but changes in catecholamines or other hormones might also be of importance.

Adult↗