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C De Graaf

Publications and source records attributed to C De Graaf.

16 recordsLinked to original sources
PubMed2006

Metabolism of N-substituted 7-methoxy-4-(aminomethyl) -coumarins by cytochrome P450 2D6 mutants and the indication of additional substrate interaction points.

Previous studies have shown the critical roles residues F120 and F483 play in the oxidative metabolism of 7-methoxy-4-(aminomethyl)-coumarin (MAMC) by cytochrome P450 2D6 (CYP2D6). In the present study, a series of N-alkyl-7-methoxy-4-(aminomethyl)-coumarins (MAMC analogues) were used as substrates for the F120A and F483A mutants in order to probe the CYP2D6 active site. The F120A and F483A mutants of CYP2D6 displayed significant activity towards the MAMC analogues. Automated docking studies of the MAMC analogues in a CYP2D6 homology model suggested a distal hydrophobic active site binding cleft for the substrate N-alkyl chains, consisting of the residues L213 and V308.

Alkylation↗
PubMed2000

Short- and long-term effects of changes in pleasantness on food intake.

This study concerns the effects of pleasantness on ad libitum food intake, liking and appetite over 5 successive days. Pleasantness was manipulated by varying the salt level in bread. Thirty-five students consumed ad libitum sandwiches for lunch, made with bread individually perceived as low, medium or high in pleasantness, in a balanced cross-over design. Pleasantness and desire-to-eat the sandwich were rated at first bite, after the consumption of each sandwich and at the end of the lunch. Fullness was rated just before and at several intervals after lunch. On the first day, the students ate less of the least pleasant bread than of the medium and most pleasant bread. On the fifth day, however, consumption of all breads was similar. For the least pleasant bread, energy intake at lunch, desire-to-eat and fullness, all increased over days, whereas these variables remained constant for the medium and most pleasant bread. Mean pleasantness ratings for all breads remained unaltered across the days. We conclude that, with repeated exposure, the desire-to-eat, fullness and intake of a less preferred food can increase over time. Thus, the relationship between pleasantness and food intake changes over this period.

Adult↗
PubMed1999

Palatability affects satiation but not satiety.

The present study was designed to investigate the effect of the pleasantness of a food on satiation (meal termination) and satiety. It was also studied whether or not the subsequent availability of other attractive foods affected the effect of palatability on intake. In a within-subjects repeated-measures design, 35 (26 female and 9 male) young healthy nonrestrained subjects consumed at lunchtime a preload consisting of tomato soup, and a buffet/test meal consisting of many attractive food items. Three factors were manipulated. The palatability of the preload was manipulated by varying the citric acid concentration of the soup at three levels: 0 (pleasant), 7.5 (less pleasant), and 15 (unpleasant) g citric acid/kg soup. Intake of the soup was either ad lib (for investigation of satiation), or standardized (350 g for women, and 500 g for men; for investigation of satiety). The third factor was the availability of other foods, manipulated by the amount of time between start of preload and start of the test meal (intermeal interval = IMI), which was set at two levels: 15 and 90 min. Subjects rated hunger and satiety feelings, before the preload, and in between preload and test meal. The results showed that the ad lib intakes of the less pleasant and unpleasant soups were about 65 and 40% of the intake of the pleasant soup. Subjects ingested about 20% more soup when the subjects had to wait for the test meal about 90 min, compared to the 15 min IMI condition. The availability of other foods had no effect on the effect of pleasantness on ad lib intake. There was also no effect of the pleasantness on subsequent satiety: hunger ratings and test meal intake were similar after the three standardized soups. One conclusion is that pleasantness of foods has an effect on satiation but not on subsequent satiety. A second conclusion is that people eat more of a food when they know that they have no access to other foods for a particular amount of time.

Adolescent↗
PubMed1999

Sweetness intensity and pleasantness in children, adolescents, and adults.

In the present study we investigated the perceived sweetness intensity and pleasantness of sucrose in water, and sucrose in orange lemonade, in 30 children (9-10 years), 30 adolescents (14-16 years), and 30 adults (20-25 years) by means of direct (five-point category scales) and by means of indirect scaling (rank ordering) methods. Concentrations for determination of perceived sweetness intensity and pleasantness were 1, 4.8, 6.9, 14.4, 20.8, and 30.0 g sucrose/100 mL solute (0.03, 0.14, 0.20, 0.29, 0.42, 0.61, and 0.88 mol/L). Concentrations used to test discriminatory ability were 7.6, 8.7, 10.0, 11.5, and 13.2 g sucrose/100 mL solute (0.22, 0.25, 0.29, 0.34, and 0.39 mol/L). The results of the direct and indirect scaling methods concurred with each other. Children had a lower slope of the psychophysical function of the perceived sweetness intensity of sucrose, and were less well able to discriminate between the different sucrose concentrations than the adolescents, and the adolescents showed a lower sensitivity towards sucrose than the adults. Children had higher optimal preferred sucrose concentrations than the adolescents, and the adolescents had higher optimal preferred sucrose concentrations than adults. The age effects were similar for sucrose in water and sucrose in lemonade.

Adolescent↗
PubMed1999

Determinants of salt use in cooked meals in The Netherlands: attitudes and practices of food preparers.

OBJECTIVE: To assess current habits of using salt and other seasonings in food preparation, and to investigate the psychosocial determinants of salt use. In addition we examined differences in salt consumption and psychosocial determinants with respect to stages of change and socio-economic classes. SUBJECTS AND METHODS: 400 adults were interviewed to determine: 1) use of salt and other seasonings in food preparation; 2) added table salt; 3) consumption of foods with high salt content; and 4) psychosocial determinants of salt consumption. Subjects were divided into 5 stages of change for salt content of the cooked meal: precontemplation, contemplation, decision, action and maintenance. RESULTS: Salt appeared to be the type of seasoning mostly added in food preparation. Frequently used seasonings containing no added salt were pepper, onion, nutmeg, garlic, curry, sweet pepper powder, parsley, and bay-leaf. Spearman correlation coefficients between added cooking salt and taste attitude, health attitude, social influence and self-efficacy were 0.51, 0.14, 0.36, and 0.32 respectively. Correlations between consumption of foods with high salt content and convenience attitude, taste attitude, health attitude and self-efficacy were 0.41, 0.27, 0.18 and 0.21 respectively. Subjects in maintenance of low salt consumption, used less salt than subjects in precontemplation. Socio-economic status only showed an effect on the use of foods with high salt content. CONCLUSION AND PRACTICAL IMPLICATIONS: Health aspects did not play a major role in salt intake, whereas taste attitude was an important predictor of added cooking salt. Attempts to reduce cooking salt should be directed at satisfying taste. Nutrition education tailored to stages of change may be very helpful in decreasing salt consumption.

Adult↗
PubMed1997

Energy and fat compensation during long-term consumption of reduced fat products.

The objective of this study was to investigate the behavioral response to the long term realistic consumption of reduced fat products. During six months, a control group of 103 subjects had free access to about 45 commercially available full-fat products, and a reduced-fat group of 117 subjects had access to the reduced fat equivalents. These experimental products covered about 37% of total energy intake in the control group and 30% of energy intake in the reduced fat group. Other non-experimental food products were bought in regular shops. The results showed that, compared to a baseline measurement before the start of the study, energy intake increased from 10.4 MJ/day to 11.2 MJ/d in the control group, whereas it remained constant at 10.2 MJ/d in the reduced fat group. Fat intake in the control group increased from 99 g/d (35.6en%) to 123g/d (40.6en%), whereas fat intake in the reduced fat group decreased from 95 g/d (34.en%) to 90 g/d (32.7en%). The energy and fat intake from experimental products was lower in the reduced fat group (3.1 MJ/d, 37 g fat/d) than in the control group (4.2 MJ/d, 71 g fat/d). There was some compensatory response in the consumption of experimental products: the ingested amount of experimental products was about 10% higher in the reduced fat group (447 g/d) than in the control group (399 g/d)[t = 2.6; p < 0.01]. There was no compensatory response in the consumption of non-experimental products. Both the control and reduced fat group consumed about 7.1 MJ/d and 53 g fat/d from non-experimental products. It is concluded that long term consumption of reduced fat products leads to a lower energy and fat intake, compared to the consumption of full-fat products.

Adult↗
PubMed1996

Effect of sucrose in breakfast items on pleasantness and food intake in the elderly.

This study was designed to determine the differences between young and elderly people on the perceived intensity and pleasantness of sucrose in foods, in relation to their food intake. First, a group of 35 young subjects (mean age: 22 +/- 2 years) and 29 elderly subjects (mean age: 79 +/- 6 years) judged the intensity and the pleasantness of 5 series of breakfast items: orange lemonade, strawberry jam, strawberry yoghurt, chocolate paste, and grain porridge, each with 5 geometrically spaced sucrose concentration levels. On average, the elderly people had a lower slope of the sucrose psychophysical function. Optimal preferred sucrose concentrations were higher for the elderly compared to the young. The second phase in the study concerned the effects of the different optimal sucrose concentrations in foods on food intake. The second experiment dealt with 2 different optimal preferred sucrose concentrations (elderly vs. young subjects) in the food items: orange lemonade, strawberry and blueberry jam, and strawberry and blueberry yoghurt, served during breakfast. A group of 33 young people (mean age: 23 +/- 2 years) and 25 elderly subjects (mean age: 82 +/- 5 years) participated in a crossover study of 2 5-day (breakfast) treatments. Subjects are ad lib from these foods and other items such as bread, coffee, and tea. The results showed that the sucrose concentration had no effect on the absolute amount consumed, although total energy intake of the breakfast increased with the higher sucrose foods. No clear difference was found in pleasantness between the 2 breakfasts with the different sucrose concentrations. These findings indicate that a flavor concentration evaluated as being most pleasant by the elderly with the help of small amounts of stimuli (in a lab setting) does not necessarily predict the pleasantness and the food intake behaviour in realistic settings.

Adult↗
PubMed1996

Nonabsorbable fat (sucrose polyester) and the regulation of energy intake and body weight.

A substantial number of people have difficulties in controlling their body weight and energy/fat intake. Fat substitutes may be helpful in solving these problems. We here report the first study on the longer-term effects of the nonabsorbable fat sucrose polyester (SPE) on energy intake in normal-weight subjects. We studied the longer-term (12 days) effects of the consumption of warm meals with normal dietary fat (5.0 MJ, 1,195 kcal) or meals in which 52 g of fat were replaced by the fat replacer SPE (3.1 MJ, 740 kcal) on spontaneous food intake (measured by dietary records), body weight, and gastrointestinal complaints in healthy volunteers in two studies. In the first study the 48 subjects were unaware of the treatment, whereas in the second study the 47 subjects were informed of what they received. In both studies men and women consumed less energy per day during the SPE (11.2 MJ) compared with the fat treatment (12.7 MJ) (P values < 0.0001) for the whole 12-day period. This was accompanied by equivalent changes in body weight. The percentage of energy from fat decreased from 43% during the fat treatment to 32% during the SPE treatment. During the SPE treatment, more gastrointestinal complaints and a higher frequency of defecation were reported. Information about the treatment did not affect. the outcomes. It is concluded that the use of a fat replacer such as SPE helps in reducing fat and energy intake in normal-weight people.

Adult↗
PubMed1996

Nutrition knowledge and attitudes towards high-fat foods and low-fat alternatives in three generations of women.

OBJECTIVES: To assess family resemblance in food habits in three generations of maternally related family members. DESIGN AND SUBJECTS: Ninety-seven adult women, their mothers and grandmothers were asked about nutrition knowledge, attitudes and fat intake. Nutrition knowledge and attitudes were determined by means of a self-administered questionnaire. A food frequency questionnaire was used to assess fat intake. RESULTS: Mean percentage energy derived from fat was 39% for the younger generation, and 40% for their mothers and grandmothers. Generations differed in their nutrition knowledge score (P <0.0001), the grandmothers having a lower nutrition knowledge than the other generations. Correlations of nutrition knowledge scores were 0.30 (95% confidence limits (c.l.) 0.10 and 0.48) between the younger and middle generations, 0.35 (95% c.l. 0.16 and 0.52) between the middle and older generations, and 0.14 (95% c.l. -0.06 and 0.34) between the younger generation and their grandmothers. For attitudes towards high-fat foods and their low-fat alternatives these figures were 0.27 (95% c.l. 0.07 and 0.45), 0.22 (95% c.l. 0.01 and 0.41), and 0.17 (95% c.l. - 0.03 and 0.36), respectively, while for energy percentage of fat intake the correlations were only 0.19 (95% c.l. -0.01 and 0.37), -0.02 (95% c.l. -0.22 and 0.18), and 0.12 (95% c.l. limits - 0.08 and 0.31), respectively. Within generations the correlations between attitudes and nutrition knowledge or percentage energy derived from fat were found to be higher in the middle generation than in other generations. No statistically significant correlations were found between nutrition knowledge and percentage energy derived from fat. CONCLUSIONS: From this study it can be concluded that mothers and their adult daughters resemble each other in nutrition knowledge and attitudes.

Adult↗
PubMed1995

Family resemblance in beliefs, attitudes and intentions towards consumption of 20 foods; a study among three generations of women.

Family resemblance in beliefs, attitudes and intentions towards the consumption of 20 foods that contribute to the fat intake was investigated in 97 adult women, their mothers and their grandmothers. Mean correlation for elements from the Fishbein and Ajzen theory of reasoned action between younger and middle generations ranged from 0.09 to 0.17 and between middle and older generations from 0.12 to 0.17. All significant correlations were positive. More statistically significant correlations were found for liking attitudes between the younger and middle generations (p < 0.05 for ten out of 20 correlations) than for other pairs. Between the older and younger generation the number of significant correlations could be due to chance alone. From the relative importance of liking and good/bad attitude on intention it appeared that liking contributed the most to the variance in intention scores. Health related beliefs and attitudes became of increasing importance in the older generations. From this study it can be concluded that mothers and their adult daughters resemble each other in beliefs, food preferences, attitudes and intentions, although resemblance is poor.

Adult↗
PubMed1993

The effects of preloads varying in physical state and fat content on satiety and energy intake.

This study investigated the effect of the physical state and fat content of a preload on feelings of hunger and satiety and subsequent energy intake. Thirty-three normal-weight female subjects each received nine different 550-ml preloads which were served as breakfast. The preloads differed in physical state and fat level. There were three types of physical state (liquid, solid with locust bean gum, and solid with gelatin) combined with three energy levels (0.42, 1.67, and 3.35 MJ). The energy differences were due only to differences in fat content. Subjects were not allowed to eat or drink (except water) for 3.5 h after preload consumption. In this period they rated their feelings of appetite. Subjects recorded their voluntary food intake for the remainder of the study day and the day after the study day. There were no effects of the different amounts of fat or the three different physical states on energy intake during the remainder of the day or the day after. With respect to the appetite ratings, however, it appeared that the solid preloads were more satiating than the liquid preloads and the solid preloads were more satiating with fibre (locust bean gum) than without fibre (gelatin). The high-fat preloads were more satiating than the low-fat preloads.

Adult↗
PubMed1988

Assessment of the taste interaction between two qualitatively similar-tasting substances: a comparison between comparison rules.

The taste interaction between sucrose and fructose was assessed by using three different comparison procedures: the summated response comparison, the factorial plot comparison, and the equimolar comparison rule. The perceived sweetness intensities were obtained on a ratio scale by using a functional measurement approach in combination with a two-stimulus procedure. The conclusions obtained from each of the three comparison rules were identical. The taste interaction between sucrose and fructose could be explained to a large extent, but not completely, by the apparent taste "interactions" within sucrose and fructose as single substances. It is argued that the apparent taste interaction within a large number of single sugars and between two of these sugars in a mixture is somewhat synergistic at low sweetness levels, additive at intermediate sweetness levels, and suppressive at high sweetness levels.

Adolescent↗
PubMedDate not supplied

Effects of learned flavour cues on short-term regulation of food intake in a realistic setting.

The present study examined the effects of repeated midmorning consumption of novel-flavoured low- and high-energy yoghurt drinks on subsequent energy intake at lunch in 69 adults under actual use conditions. Subjects consumed 200 ml of low- and high-energy yoghurt drinks (67 and 273 kcal/200 ml, respectively), with 20 exposures to each drink on alternate days. Analyses focused on the development of compensation for the differences in energy content of the beverages, due to learned satiety. Results revealed incomplete energy compensation for the beverages, both at first exposure and also after 20 exposures. Relative to the no-yoghurt condition, energy intake compensation (+/-S.E.M.) averaged 39+/-36% for the low-energy yoghurt and 17+/-9% for the high-energy version, with no evidence of any change in compensation with repeated exposures. When the flavours of the yoghurt drinks were covertly switched after 20 exposures, subjects increased their energy intake after the high-energy yoghurt drink containing the flavour that was previously coupled with the low-energy yoghurt drink. Vice versa, however, when subjects switched to the low-energy yoghurt drink containing the high-energy flavour, subjects ignored the flavour cue and ate the same lunch size regardless of the energy in the yoghurt drink. We conclude that adults do not readily acquire accurate conditioned adjustments for the energy content in food after repeated experience with the food in free-living natural-eating conditions.

Adolescent↗