PubMed Health⌕ Search

Biomedical subjects

K R Westerterp

Publications and source records attributed to K R Westerterp.

At least 19 recordsLinked to original sources
PubMed2006

PPARgamma activity in subcutaneous abdominal fat tissue and fat mass gain during short-term overfeeding.

OBJECTIVE: As the peroxisome proliferator-activated receptor gamma (PPARgamma) plays a central role in fat mass regulation, we investigated whether initial subcutaneous PPARgamma activity is related to fat mass generation during overfeeding. SUBJECTS: Fourteen healthy female subjects (age 25 +/- 4 years, BMI 22.1 +/- 2.3 kg/m2). DESIGN AND MEASUREMENTS: Subjects were overfed with a diet supplying 50% more energy than baseline energy requirements for 14 days. Fasting blood samples were analyzed for leptin, insulin and glucose. Fasting subcutaneous abdominal fat biopsies were obtained for analysis of PPARgamma1, PPARgamma2, aP2 and UCP2 mRNAs. RESULTS: Initial PPARgamma1 and 2, aP2 and UCP2 mRNAs were not related to fat gain (P > 0.12). However, PPARgamma1, PPARgamma2 and aP2 mRNA changes were positively related to changes in plasma leptin (P < 0.05) and, except aP2 (P = 0.06), to fat gain (P < 0.05). PPARgamma and aP2 mRNA changes were positively related (P<0.01), indicating that PPARgamma mRNA levels reflected PPARgamma activity. CONCLUSION: These data suggest that the ability to increase PPARgamma activity might be involved in the susceptibility to gain weight during a positive energy balance.

Adipogenesis↗
PubMed2005

Assessment of body composition and breast milk volume in lactating mothers in pastoral communities in Pokot, Kenya, using deuterium oxide.

BACKGROUND: In sub-Saharan Africa, the practice of breast-feeding infants is common. Records documenting the intake of breast milk amongst infants are limited. This study evaluated the association between maternal body composition and the intake of breast milk in infants from the pastoral communities within Pokot, Kenya. METHODS: The study was conducted in 10 lactating mothers who were participating in a longitudinal study aimed at determining maternal body composition, iron stores and vitamin A status during the third trimester pregnancy and four months after they had given birth. Maternal and infant anthropometric measurements were made, and maternal blood samples were taken to determine serum retinol and ferritin levels. Infant milk intake and maternal fat-free mass (FFM) and percent body fat (% BF) were measured using 'the dose to the mother method'. A measured deuterium oxide ((2)H(2)O) dose was given to the mother. Urine and breast milk from the mother, and saliva samples from the infant, were collected on days 1, 8 and 14 after dosing. RESULTS: The mean (+/- SD) maternal mid upper arm circumference (MUAC) and body mass index (BMI) were 21.8 (0.9) cm and 18.6 (1.0) kg/height (m(2)), respectively. Infant weight and weight/age Z score were 4.956 (0.874) kg and -1.750 (0.77), respectively. Throughout the study, the infants gained 20 (4) g/day in body weight and had a milk intake of 555 (22) ml/day. The energy intake of the infant was 1,602 (148) kJ/day and was lower (p < 0.05) than the 2,404 (423) kJ/day estimated requirement by the FAO/WHO/UNU. The maternal FFM, %BF, Hb, Hct, ferritin and retinol were 32.8 (3.1) kg, 17.24 (7.0), 11.5 (1.3) g/dl, 33.9 (4.9), 16.2 (0.1) microg/l and 0.894 (0.16) micromol/l, respectively. Infant milk intake was significantly and positively correlated to maternal pregnancy triceps (r = 0.679) p < 0.05) and pregnancy MUAC (r = 0.725) p < 0.05). Maternal pregnancy MUAC was an important predictor of infant breast milk intake. CONCLUSION: Data on volume of breast milk consumed by the infants suggests, at least for this group of infants, that adequate growth may not be achieved. There is a possibility that lactating mothers practicing exclusive breast-feeding and living under harsh conditions may experience periods of low breast milk volume. Body composition and biochemical findings among this group of Pokot mothers indicate dietary inadequacies that require nutritional intervention.

Arm↗
PubMed2005

Vitamin a deficiency and anaemia in young children living in a malaria endemic district of western Kenya.

BACKGROUND: Vitamin A deficiency makes children vulnerable to infections and influences the outcome of various infections. In 1993 vitamin A deficiency was found to be a public health problem in Bungoma district of western Kenya. OBJECTIVE: To determine the prevalence of vitamin A deficiency, anaemia and malaria parasitaemia and to correlate these with haemoglobin, ferritin and acute phase response. DESIGN: A cross-sectional study. SETTING: Bungoma district of western Kenya. SUBJECTS: Three hundred and three children aged one to three years were studied. MAIN OUTCOME MEASURES: Serum retinol, haemoglobin, serum ferritin, alpha-1 acid glycoprotein, C-reactive protein and malaria parasite density. RESULTS: Twentynine percent of the children had severe vitamin A deficiency, 92% had anaemia (haemoglobin less than 10 g/dl) 24(7%) of these were severely anaemic while 76% had malaria parasitaemia. There was no significant difference in the retinol levels of children with malaria parasitaemia and those without malaria parasitaemia (P = 0.6). Retinol levels were significantly lower among children with high C-reactive protein (P < 0.001). Malaria parasitaemia negatively correlated with haemoglobin (r = -0.13, P < 0.05) and C-reactive protein (r = 0.21, P < 0.01). There was no difference in haemoglobin level of children with normal serum retinol and those with low serum retinol (P = 0.16). Ferritin did not differ significantly among children with normal haemoglobin and those with low haemoglobin (P = 0.13). CONCLUSION: Vitamin A deficiency and anaemia are a public health problem among the children studied. The high prevalence of vitamin A deficiency may have resulted from acute phase response induced by infections.

Age Factors↗
PubMed2004

Seasonal changes in metabolic and temperature responses to cold air in humans.

The metabolic and temperature response to mild cold were investigated in summer and winter in a moderate oceanic climate. Subjects were 10 women and 10 men, aged 19-36 years and BMI 17-32 kg/m2. Metabolic rate (MR) and body temperatures were measured continuously in a climate chamber with an ambient temperature of 22 degrees C for 1 h and subsequently 3 h of 15 degrees C. The average metabolic response during cold exposure, measured as the increase in kJ/min over time, was significantly higher in winter (11.5%) compared to summer (7.0%, P < .05). The temperature response was comparable in both seasons. The metabolic response in winter was significantly related to the response in summer (r2 = .47, P < .001). Total heat production during cold exposure was inversely related to the temperature response in both seasons (summer, r2 = .39, P < .01; winter r2 = .32, P < .05). In conclusion, the observed higher metabolic response in winter compared to summer indicates cold adaptation. The magnitude of the cold response varies, but the relative contribution of metabolic and temperature response was subject specific and consistent throughout the seasons, which can have implications for energy balance and body composition.

Acclimatization↗
PubMed2004

Physical activity pattern of children assessed by triaxial accelerometry.

OBJECTIVES: Accelerometry was used to assess the relationship between the physical activity level (PAL) and time spent on activities of various intensities in children. DESIGN: A total of 20 children aged 8.6+/-3.3 y wore a triaxial accelerometer (Tracmor2) for 2 weeks. PAL was calculated with Tracmor2 output data. The fraction of time spent on activities with a given level of intensity (low, moderate, high) was calculated. The fractions of time spent on activities of different intensities were compared with previously obtained data for young adults and elderly persons. RESULTS: PAL showed an inverse relation with the percentage of time spent on low-intensity activities (r = -0.76; P < 0.0001) and a positive relation with the percentage of time spent on high-intensity activities (r = 0.93; P < 0.0001). The fraction of time spent on low-intensity activities was smaller in children than in young adults (P < 0.05) and elderly persons (P < 0.0001), while the fraction spent on high-intensity activities (P < 0.0001) was larger. CONCLUSIONS: The present data are important for a better understanding of physical activity in children, which is necessary for education and prevention about physical (in)activity in childhood. Our observations suggest that to obtain a higher PAL in children, they should be given the opportunities to perform high-intensity activities.

Child↗
PubMed2004

Estimating changes in daily physical activity levels over time: implication for health interventions from a novel approach.

The aim of this study was to use a novel method to examine and compare physical activity levels in four different groups of men to investigate the impact of modernity on activity levels. Physical activity levels of four different groups of men were measured and compared, using a tri-axial accelerometer (Tracmor). The first group (HA = historically active) were actors in a historical theme park who play the part of Australian settlers 150 years ago, the second were sedentary modern-day office workers (MS = modern sedentary), the third men who had successfully lost weight (SWL) in a modern men's weight loss program and the last, men who were unsuccessful (UWL) in the same program. Men who had successfully lost weight in a weight loss program were active at a level similar to that of men performing activity at a level carried out historically. Both of these groups were in turn significantly more active than modern-day sedentary workers (p < 0.05) and men who had not been successful at losing weight (p < 0.01). A linear regression between weekly average activity levels and the degree of waist size loss showed a significant positive association (r = 0.52, p < 0.01). The data suggest that a higher activity level facilitates the maintenance of long-term weight loss and this level is likely to approximate activity levels in the past. For the prevention and treatment of obesity an increase in physical activity is necessary, because (long-term) weight loss or weight maintenance is unlikely to occur when people are as sedentary as most people are today.

Adult↗
PubMed2004

Physical activity as measured by accelerometry in children receiving growth hormone.

AIM: Parents of children treated with growth hormone (GH) frequently report to the paediatrician that their children have become more physically active. In the present study, activity patterns of GH-treated children were measured and compared to those of healthy controls. METHODS: Subjects were 25 children at the start of GH treatment (age 8.4 +/- 2.6 y) and 19 age- and gender-matched controls (age 8.8 +/- 3.2 y). Physical activity was assessed with a tri-axial accelerometer for movement registration over two separate 2-wk intervals, one before the start of GH treatment and one 2 wk after the start of treatment. GH-treated subjects were categorized as poor responders (change in height over 1 y <0.7 SDS, n = 15) or good responders (change in height over 1 y >0.7 SDS, n = 10). RESULTS: Before therapy, good responders showed a significantly lower physical activity compared to healthy controls, spending significantly less time on high-intensity activities. This difference disappeared 2 wk after the start of therapy. Physical activity in poor responders was not significantly different from controls before and after 2 wk of GH therapy. CONCLUSION: Children who respond well to GH therapy (change in height >0.7 SDS) showed a reduced amount of physical activity before therapy, which was normalized after 2 wk of GH therapy.

Arginine↗
PubMed2003

Tracmor system for measuring walking energy expenditure.

OBJECTIVE: Walking is an important mode of exercise and is likely to represent a major component of nonexercise activity thermogenesis. The question arises, how best to quantify walking-energy expenditure (EE) in free-living individuals. The triaxial accelerometer for movement registration (Tracmor) is a valid measure of body displacement and so we wanted to evaluate this tool for quantifying walking-EE. HYPOTHESIS: In this study, we test the hypothesis that walking-EE, measured in a Room Calorimeter, can be predicted from Tracmor output using a regression equation derived from a brief Tracmor/treadmill/Metabolic Cart protocol. DESIGN: First, 11 healthy subjects completed a 40-min procedure whereby they wore a Tracmor unit and walked on a treadmill at 0, 1, 2 and 3 mph while EE was measured using a Metabolic Cart. This allowed a regression equation to be defined for each subject to convert Tracmor output to EE. Each subject then entered a Room Calorimeter wearing the Tracmor Unit and walked at two self-selected velocities ('slow', 'fast') while EE was measured. 'Tracmor/regression equation' predictions of walking-EE were compared with Room Calorimeter measurements of walking-EE for the two velocities. RESULTS: The 'Tracmor/regression equation' prediction of EE for walking slowly was 6.36+/-1.67 kJ/min, and for walking fast it was 11.0+/-2.60 kJ/min. Room Calorimeter measurements were 6.43+/-1.85 and 10.9+/-3.03 kJ/min, respectively. The intraclass correlation coefficient for slow-paced walking was 0.93 (P<0.001), and for fast-paced walking it was 0.82 (P<0.005). CONCLUSIONS: When combined with laboratory measures of EE, the Tracmor accelerometer provides useful data on walking-EE and is applicable to free-living individuals.

Acceleration↗
PubMed2003

Physical activity levels in children and adolescents.

BACKGROUND: Reference data for physical activity level (PAL) and activity-related energy expenditure (AEE) are needed for a better understanding of the effect of activity on childhood health, growth and development OBJECTIVE: Data from 17 studies measuring TDEE (TDEE) with doubly labelled water DLW were combined to construct a reference line for PAL and AEE as a function of age. DESIGN: A total of 17 studies from the literature were analyzed; 17 on girls and 16 on boys. Children were aged 3-16 y and of Caucasian origin. Weighted least-squares regression was used to obtain reference lines for PAL and AEE as a function of age and gender. The relative numbers of children per study were used as a weighting factor. Basal metabolic rate (BMR) or nonfasted (NF) resting metabolic rate and sex were included in the analysis. RESULTS: Although there was no difference in PAL between boys and girls, a significant difference in AEE was found between the two sexes. PAL: 0.025 x age+1.40. AEE (MJ/day): boys 0.30 x age+0.025; girls 0.21 x age+0.33. If BMR is measured under NF conditions, the obtained value has to be reduced by 0.21 for PAL and 0.75 MJ/day for AEE. No relation was found between AEE/kg and age. CONCLUSIONS: PAL and AEE were found to increase with age, showing the importance of age-dependent recommendations. Recommendations for AEE need to be differentiated for sex. To compare PAL and AEE between studies, the measurement conditions of BMR have to be taken into account. The increase in PAL and AEE values can be attributed to an increase in weight, because there was no relation between AEE/kg and age.

Adolescent↗
PubMed2003

How much physical activity is enough to prevent unhealthy weight gain? Outcome of the IASO 1st Stock Conference and consensus statement.

A consensus meeting was held in Bangkok, 21-23 May 2002, where experts and young scientists in the field of physical activity, energy expenditure and body-weight regulation discussed the different aspects of physical activity in relation to the emerging problem of obesity worldwide. The following consensus statement was accepted unanimously. 'The current physical activity guideline for adults of 30 minutes of moderate intensity activity daily, preferably all days of the week, is of importance for limiting health risks for a number of chronic diseases including coronary heart disease and diabetes. However for preventing weight gain or regain this guideline is likely to be insufficient for many individuals in the current environment. There is compelling evidence that prevention of weight regain in formerly obese individuals requires 60-90 minutes of moderate intensity activity or lesser amounts of vigorous intensity activity. Although definitive data are lacking, it seems likely that moderate intensity activity of approximately 45 to 60 minutes per day, or 1.7 PAL (Physical Activity Level) is required to prevent the transition to overweight or obesity. For children, even more activity time is recommended. A good approach for many individuals to obtain the recommended level of physical activity is to reduce sedentary behaviour by incorporating more incidental and leisure-time activity into the daily routine. Political action is imperative to effect physical and social environmental changes to enable and encourage physical activity. Settings in which these environmental changes can be implemented include the urban and transportation infrastructure, schools, and workplaces.'

Adult↗
PubMed2003

Energy expenditure in infants with congenital heart disease, including a meta-analysis.

AIM: To assess energy requirements and body composition in preoperative children with congenital heart disease (CHD). METHODS: In 11 infants with CHD (2-8 mo), total daily energy expenditure (TDEE) and total body water (TBW) were measured with doubly labelled water and compared with historic data from healthy controls. Within the patient group, energy expenditure of infants with versus those without congestive heart failure was compared. Subsequently, the data were pooled with literature data in meta-analyses. RESULTS: CHD patients showed increased TBW (mean +/- SD 66 +/- 3 vs 58 +/- 5% of body weight, p < 0.05) and energy expenditure (381 +/- 42 vs 298 +/- 36 kJ kg(-1) d(-1), p < 0.001). Meta-analyses showed that CHD infants have 35% increased TDEE (376 vs 278 kJ kg(-1) d(-1) , p < 0.00001) and 7% higher TBW (p < 0.0001). Coexistent congestive heart failure (treated with diuretics) had no influence on TDEE (mean difference 14 kJ kg(-1) d(-1) , not significant). In patients with heart failure and growth retardation, an energy balance study showed an average 12% loss of initially ingested energy due to vomiting, increased TDEE and low faecal energy loss, resulting in low energy available for growth, compared with controls (42 +/- 30 vs 96 +/- 61 kJ kg(-1) d(-1) , p < 0.05). CONCLUSION: Many infants with CHD require substantially higher energy intake (at least 100 kJ kg(-1) d(-1) extra) owing to increased TDEE, which is not explained by a higher percentage of body water. Coexistent heart failure does not appear to have an additional influence on TDEE. In infants with CHD and growth failure factors other than elevated TDEE, including vomiting, may explain the disturbed energy balance.

Body Composition↗
PubMed2002

Energy balance, metabolism, hydration, and performance during strenuous hill walking: the effect of age.

We aimed to examine the effect of age on energy balance, metabolism, hydration, and performance during 10 days of strenuous hill walking. Seventeen male subjects were divided into two groups according to their age. The nine subjects in group 1 constituted the younger group (age 24 +/- 3 yr), whereas eight older subjects were in group 2 (age 56 +/- 3 yr). Both groups completed 10 consecutive days of high-intensity hill walking. Mean (range) daily walking distances and ascent were 21 km (10-35 km) and 1,160 m (800-2,540 m), respectively. Energy intake was calculated from weighed food intake, and energy expenditure was measured by the doubly labeled water method. Blood and urine were sampled on alternative days to determine any changes in metabolism and hydration during the 10 days. Subjects also completed a battery of tests that included muscular strength (handgrip), jump performance, cognitive processing time, and flexibility. The younger group remained hydrated, whereas the older group became progressively dehydrated, indicated by a near twofold increase in urine osmolality concentration on day 11. This increased urine osmolality in the older group was highly correlated with impairment in vertical-jump performance (r = -0.86; P < 0.05) and decreased cognitive processing time (r = 0.79; P < 0.05). Despite energy expenditure of approximately 21 MJ/day, body mass was well maintained in both groups. Both groups displayed a marked increase in fat mobilization, reflected in significantly lowered prewalk insulin concentrations and elevated postwalk glycerol and nonesterified fatty acid concentrations. Despite the dehydration and impaired performance in the older group, blood glucose concentrations were well maintained in both groups, probably mediated via the increased mobilization of fat.

Adult↗
PubMed2001

Physical inactivity as a determinant of the physical activity level in the elderly.

OBJECTIVE: To assess the relationship between the mean physical activity level (PAL) and the time spent on activities of three different intensity levels in an elderly population. Data was compared with previously obtained data from a group of younger adults. SUBJECTS: Fourteen elderly women and 14 elderly men (61+/-4 y; 27+/-5 kg/m(2); 33+/-7% body fat), and 14 young women and 16 young men (27+/-5 y, 24+/-2 kg/m(2)). MEASUREMENTS: PAL was determined as average daily metabolic rate (ADMR) combined with a measurement of basal metabolic rate (BMR): PAL=ADMR/BMR. ADMR was measured with the doubly labeled water method. BMR was measured with a ventilated hood system. Time spent on activity and activity intensity was measured by using a tri-axial accelerometer (7x2x0.8 cm, 30 g) over a 2 week interval. RESULTS: Mean PAL was 1.65+/-0.14. PAL was inversely related to the percentage of time spent on low-intensity activity (lying, sitting and standing), r= -0.43; P<0.05. Older subjects spent significantly more time at these activities than 20 to 35-y-old subjects (82+/-7% vs 65+/-7%; P<0.0001). A significant relation was not observed between PAL and the percentage of time spent on moderate (walking) or high (household activities, exercise and sports) intensity activity, or activity monitoring time (14.4+/-1.2 h/day). CONCLUSION: In the elderly, spending relatively more time on low-intensity activities affects the mean PAL negatively. To obtain a higher PAL does not necessarily imply high-intensity activities like sports.

Acceleration↗
PubMed2001

Physical activity in daily life in patients with chronic low back pain.

OBJECTIVES: To evaluate disuse (ie, a decreased daily physical activity level) in patients with chronic low back pain (LBP) and to evaluate the construct validity of accelerometry for measuring physical activity in daily life. DESIGN: Case-control study in a cross-sectional design; comparison of accelerometry to the criterion standard (doubly labeled water technique). SETTING: Normal daily living (unrestricted by the measurement devices). PATIENTS: Thirteen patients with chronic nonspecific LBP and 13 age- and gender-matched healthy controls. MAIN OUTCOME MEASURES: Physical activity in daily life, expressed as whole-body acceleration measured with a triaxial accelerometer (Tracmor), and as the ratio between average daily metabolic rate (ADMR), measured by the doubly labeled water technique, and resting metabolic rate (RMR), measured by the ventilated hood. Both techniques were used simultaneously for 14 days. RESULTS: Mean physical activity level in patients and controls did not differ significantly. The correlation between the Tracmor and ADMR and RMR was .72 (p < .01). CONCLUSIONS: Decreased physical activity levels in this sample of chronic LBP patients was not confirmed. The Tracmor is a valid instrument for measuring daily activity in LBP patients.

Activities of Daily Living↗
PubMed2001

Exercise-induced oxidative stress in older adults as measured by antipyrine oxidation.

Aging is associated with increased susceptibility to free radical-mediated tissue damage. Measuring exercise-induced oxidative stress, however, is a major problem in free radical research. We used an exogenous marker (antipyrine) to measure oxidative stress in older adults during submaximal exercise. Antipyrine pharmacokinetics is independent of blood flow to the liver. Furthermore, antipyrine reacts quickly with hydroxyl radicals (10(10)-10(11) L x mol(-1) x s(-1)) to form para- and ortho-hydroxyantipyrine (o-APOH). o-APOH is not formed in man through the mono-oxygenase pathway of cytochrome P450. Thirty-four subjects (62 +/- 1 years) orally ingested 10 mg antipyrine/kg body mass. One hour after ingestion subjects cycled 45 minutes at 50% maximal power output. Exercise significantly increased the ratio of para-hydroxyantipyrine (p-APOH) to native antipyrine in plasma (.0014 +/-.0001 v.0021 +/-.0002; P <.0001). Also, the ratio of o-APOH was significantly increased after exercise (.0014 +/-.0001 v.0019 +/-.0002; P <.0001). Exercise significantly increased plasma levels of plasma malondialdehyde MDA) (.55 +/-.07 v.92 +/-.21 micromol/L; P <.01). In conclusion, in older adults, oxidative stress occurs during cycling at submaximal intensity as measured with free radical reaction products of antipyrine.

Aging↗