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F Ten Hoor

Publications and source records attributed to F Ten Hoor.

18 recordsLinked to original sources
PubMed1992

Diet-induced thermogenesis and cumulative food intake curves as a function of familiarity with food and dietary restraint in humans.

Cumulative food intake curves and diet-induced thermogenesis were recorded in women during four-course solid-food lunches, consisting of familiar and unfamiliar food, offered in ad lib or restricted portions, in order to assess a possible relation between eating behaviour on the one hand and a reflection of internal processes and subject characteristics on the other. The subjects were characterized as normal weight restrained, normal weight unrestrained, and overweight restrained. A negative relation was found between degree of restraint and deceleration of the cumulative food intake curve during the ad lib courses of any menu, and between degree of restraint and diet-induced thermogenesis (p less than 0.001). Consequently, a positive relation was found between deceleration of the cumulative food intake curves during the ad lib courses of any menu and diet-induced thermogenesis (p less than 0.001). Diet-induced thermogenesis during the first serving of a meal consisting of unfamiliar food was significantly higher in all groups than during the other two times, when meals consisting of more familiar food were served (+0.98%; 0.71%, p less than 0.05).

Adult↗
PubMed1992

Long-term effect of physical activity on energy balance and body composition.

We studied the effect of an increase in physical activity on energy balance and body composition without interfering with energy intake (EI). Sixteen women and sixteen men, aged 28-41 years, body mass index 19.4-26.4 kg/m2, not participating in any sport before the start of the experiment, prepared to run a half-marathon competition after 44 weeks. Measurements of body composition, EI and energy expenditure (EE) were performed before (0 weeks), and 8, 20, and 40 weeks after the start of training. Body composition was measured with hydrodensitometry and isotope dilution, and EI with a 7 d dietary record. EE was measured overnight in a respiration chamber (sleeping metabolic rate (SMR)) and in a number of subjects over 2-week intervals with doubly-labelled water (average daily metabolic rate (ADMR)). ADMR showed an average increase of 30% in both sexes from the start of training onwards while SMR tended to decrease. EI showed a tendency to drop from week 20 to week 40 in the men and a tendency to increase from week 20 to week 40 in the women. Body mass (BM) did not change in both sexes until the observation at 40 weeks when the median value of the change in men was -1.0 kg (P < 0.01; Wilcoxon signed-rank) while the corresponding change of -0.9 kg in the women was not statistically significant. Body composition changes were most pronounced in men as well. Based on changes in BM, body volume and total body water, men lost 3.8 kg fat mass (FM) (P < 0.001; Wilcoxon signed-rank) and gained 1.6 kg protein mass (P < 0.01; Wilcoxon signed-rank) while the corresponding changes in women were 2.0 kg (P < 0.05; Wilcoxon signed-rank) and 1.2 kg (P < 0.05; Wilcoxon signed-rank). In men the loss of FM was positively correlated with the initial percentage body fat (Pearson r 0.92, P < 0.001). In conclusion, body fat can be reduced by physical activity although women tend to compensate for the increased EE with an increased EI, resulting in a smaller effect on BM and FM compared with men.

Adult↗
PubMed1992

Effects of butylated hydroxyanisole on arachidonic acid and linoleic acid metabolism in relation to gastrointestinal cell proliferation in the rat.

In order to determine the effect of oral administration of 2(3)-tert-butyl-4-hydroxyanisole (BHA; dose-level: 1.5% BHA of the diet) on arachidonic acid (AA) and linoleic acid (LA) metabolism in correlation with changes in gastrointestinal cell kinetics, we coadministered two inhibitors of prostaglandin H synthase, acetylsalicylic acid (ASA) and indomethacin (IM), to rats. Coadministration of ASA (0.2%) and IM (0.002%) in the drinking water, resulted in a significant reduction of the BHA-induced enhancement of cell proliferation in forestomach and glandular stomach. ASA completely counteracted the effect of BHA on labeling indices in colon/rectum whereas IM exhibited no effect in this organ. Both inhibitors had no direct effect on cell kinetics in the control groups. ASA, and to a lesser degree IM, inhibited prostaglandin E2 release in all tissues examined. Whereas ASA did inhibit lipoxygenase-mediated metabolism of AA in forestomach tissue, ASA did not affect the release of AA- and LA-derived hydroxy fatty acids in glandular stomach and colon/rectum. IM did not affect lipoxygenase production. BHA, however, appeared to be a strong inhibitor of both routes of AA metabolism. While ASA nor IM affected LA metabolism, BHA inhibited both prostaglandin H synthase-mediated and lipoxygenase-mediated metabolism of AA and LA. A causal role of AA or LA metabolites in the process of cell proliferation enhancement induced by BHA, can therefore be excluded. Prostaglandin H synthase may, however, be involved in BHA activation by converting the hydroquinone metabolite of BHA to the corresponding quinone by redox cycling, which is probably accompanied by reactive intermediate production.

Animals↗
PubMed1991

Plate waste producing situations on nursing wards.

This study examines the existence of a positive correlation of interferences during mealtime and the amount of plate waste. Textbooks prescribe a quiet and relaxed atmosphere. With an exploratory research design, data about the patient, his environment and plate waste were collected on a medical unit of an academic teaching hospital. Mealtime environmental conditions by no means met prescribed demands. The amount of plate waste correlated with movements made by laboratory and housekeeping personnel, visitors and physicians. Loss of appetite as well as related environmental factors are further discussed and elaborated.

Appetite↗
PubMed1991

Daily variation in gastric emptying when using the double sampling technique.

The purpose of this study was to establish the intra-individual variation in the rate of gastric emptying (GE) by using the double sampling technique of George. Eight healthy male volunteers, all familiar with gastric intubation and testing, participated in four GE tests, using an isotonic fluid as a test meal. Conditions were kept constant during all four tests, and each test was separated by at least 48 h. The within-subjects coefficient of variation proved to be 29%. The findings demonstrate that, given standard conditions, GE is reproducible from day to day.

Adult↗
PubMed1988

Assessment of mutagenic activity of repeatedly used deep-frying fats.

Mutagenic activity of repeatedly used deep-frying fats was evaluated in relation to chemical characteristics. Deep-frying fat samples were collected from local restaurants and snack bars after sensory indication of abuse. A total of 20 deep-frying fat samples and 2 unused control fat samples was tested. Fat samples were fractionated into non-polar and polar compounds by column chromatography. Amounts of polar compounds obtained ranged from 2% (by weight) for unused fat to 44% for used deep-frying fat. Levels of di- and polymeric triglycerides (DPTG) were determined using gel-permeation chromatography. DPTG concentrations of 13 used deep-frying fat samples exceeded the threshold level of 10% above which fats are rejected for use. In addition thiobarbituric acid-reactive substances (TBA-RS) were measured. Amounts of TBA-RS were just above detection levels for most fat samples. Five used fat samples, however, contained relatively high concentrations of TBA-RS, ranging from 82 to 177 nmoles malondialdehyde/g. Non-polar and polar fractions were screened for mutagenic activity using the Ames mutagenicity assay. Mutagenic activity was found predominantly in polar fractions at doses higher than 1 mg/plate in strains TA97, TA100 and TA104, variously with and without metabolic activation. The highest number of mutagenic samples was detected by strain TA97, which appeared to be most sensitive. Some samples exhibited toxic effects. Chromatography blanks, consisting of solvents processed according to the same procedures as used for fat samples, were not mutagenic. Mutagenic activity was also detected in polar material obtained from unused frying fat. Non-polar fractions of unused frying fats showed no mutagenicity. A frying experiment carried out under laboratory conditions indicated that during repeated and prolonged use of deep-frying fat mutagenic polar substances were formed. Fat samples taken after 20 and 40 h of frying contained increasing amounts of polar compounds. Mutagenic activity was highest after 20 h of frying but was slightly decreased after 40 h of frying. At this stage, however, mutagens also appeared in the non-polar fraction. Mutagenic activity of polar fractions of used deep-frying fats in strain TA97 was positively correlated with levels of TBA-RS, which may indicate the involvement of lipid oxidation products in mutagenicity of used deep-frying fats. No significant correlations were found with other chemical characteristics. In the process of deep-fat frying numerous degradation products are formed, which may include mutagenic heterocyclic amines and other pyrolysates.(ABSTRACT TRUNCATED AT 400 WORDS)

Fats↗
PubMed1988

Determination of total gastric volume, gastric secretion and residual meal using the double sampling technique of George.

In literature several techniques are described for the measurement of gastric emptying. One of these is the double sampling technique of George which has the advantage that it enables multiple measurements of total gastric volume in one experiment. In order to estimate net gastric emptying, however, it is important to differentiate between the test meal volume present in the stomach and gastric secretion. In the present study George's technique was extended with a calculation procedure to estimate gastric secretion and net test meal outflow. An in vitro experiment was carried out which showed an accuracy of 5-10% for this method. An in vivo comparison was made with Hunt's chloride technique, which is used for estimating gastric secretion. Sixteen subjects participated in a 60 minute test with water as a test meal. Regression analysis showed a high degree of correlation (R2 = 0.99) between Hunt's method and the proposed method. The data obtained indicate that the proposed method gives a reliable estimation of net gastric emptying and is simple to do as no further measurements have to be carried out other than those needed for George's method.

Adult↗
PubMed1988

The work of walking: a calorimetric study.

Experiments were designed to test the traditional assumption that during level walking all of the energy from oxidation of fuel appears as heat and no work is done. Work is force expressed through distance, or energy transferred from a man to the environment, but not as heat. While wearing a suit calorimeter in a respiration chamber, five women and five men walked for 70 to 90 min on a level treadmill at 2.5, 4.6, and 6.7 km.h-1 and pedalled a cycle ergometer for 70 to 90 min against 53 and 92 W loads. They also walked with a weighted backpack and against a horizontal load. During cycling, energy from fuel matched heat loss plus the power measured by the ergometer. During walking, however, energy from fuel exceeded that which appeared as heat, meaning that work was done. The power increased with walking speed; values were 14, 29, and 63 W, which represented 11, 12, and 13% of the incremental cost of fuel above the resting level. Vertical and horizontal loads increased the fuel cost and heat loss of walking but did not alter the power output. This work energy did not re-appear as thermal energy during 18 h of recovery. The most likely explanation of the work done is in the inter-action between the foot and the ground, such as compressing the heel of the shoe and bending the sole. We conclude that work is done in level walking.

Adult↗
PubMed1987

Does exercise give an additional effect in weight reduction regimens?

The effects of dieting and exercise on RMR, body composition and maximal aerobic power were studied in 12 obese women. The subjects were paired on the basis of their body mass index and divided into a diet (D) and a diet + exercise group (DE). The treatment consisted of a 5-week period with a low-energy formula diet of 2.9 MJ and an 8-week period with a mixed diet of 1.7 MJ supplemented with 1.8 MJ normal foodstuffs. DE trained 4 h per week at 50-60 per cent of their maximal aerobic power with aerobics and fitness exercises. Body composition was determined by hydrostatic weighing and RMR was measured from 03.00 to 06.00 hours in a respiration chamber. Maximal aerobic power was measured on a continuously braked ergometer. The measurements were done at week 0, after 4 weeks (week 5), and after 12 weeks (week 13). Weight loss after 4 weeks was 8.2 kg (DE) and 7.9 kg (D) and after 12 weeks 13.2 kg (DE) and 12.2 kg (D). There were no significant differences between the groups. Fat loss was also not statistically different between DE (6.7 and 10.9 kg) and D (6.0 and 9.4 kg). Both groups showed a significant decrease in RMR per kilogram FFM after 12 weeks (DE: 18.2 per cent and D: 26.5 per cent). There was also a significant decrease in RMR for D (19.9 per cent) after 4 weeks but not for DE (12.2 per cent).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1979

Study of the two pathways for arachidonate oxygenation in blood platelets.

During collagen-induced blood platelet aggregation, arachidonic acid is set free from membrane phospholipids and subsequently converted into 12-hydroxyeicosatetraenoic acid by arachidonate lipoxygenase and into thromboxane A2, 12-hydroxyheptadecatrienoic acid (HETE) and malondialdehyde by cyclooxygenase and thromboxane synthase. Lipoxygenase and cyclooxygenase have optimal activity at neutral to basic pH, while the thromboxane synthase is pH-independent between 5 and 9. These enzymes are membrane-bound. The cyclooxygenase is rapidly inactivated upon membrane disruption by nonionic detergents or phospholipid degradation with phospholipase A2. It was found that platelet phospholipase A2 preferentially splits off fatty acid with four double bonds. Eicosatetraynoic acid was used to investigate the physiological function of the arachidonate lipoxygenase during collagen-induced aggregation of rat blood platelets. This fatty acid is a more efficient inhibitor of lipoxygenase than of cyclooxygenase. At an inhibitor concentration of 0.6 microgram/ml, platelet aggreation, 12-hydroxyeicosatetraenoic acid production as well as 15-hydroxytryptamine release are completely inhibited, while there is an apparent stimulation of the cyclooxygenase. These results indicate that arachidonate lipoxygenase is essential for irreversible blood platelet aggregation.

Animals↗