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K de Meer

Publications and source records attributed to K de Meer.

48 records · Page 3Linked to original sources
PubMed1997

Reference values for maximum work capacity in relation to body composition in healthy Dutch children.

Exercise performance is associated with physical development. For sick children, there is a need for parameters reflecting exercise performance, which should be easy to measure and should take their nutritional state into account. The aim of this study was to investigate the relationship between maximum work-load (Wmax) and body weight (BW) as well as fat-free mass (FFM) in healthy children performing an incremental maximum exercise test on a bicycle ergometer, and to develop reference values for Wmax corrected for nutritional state. A random sample of 158 children (77 boys and 81 girls), aged 12-18 yrs, underwent an incremental maximum exercise test on a bicycle ergometer. BW and FFM were also measured. Correlation analysis showed a significant association (p < 0.001) between BW and Wmax (boys: r = 0.82; girls: r = 0.73), and between FFM and Wmax (boys: r = 0.89; girls: r = 0.79). Two-way analysis of variance showed a significant effect of gender on variance of Wmax/BW ratio as well as Wmax/FFM ratio. The influence of age was significant for Wmax/FFM (p = 0.003), but not for Wmax/BW. The maximum workload/body weight ratio and the maximum workload/fat-free mass ratio are useful parameters of work capacity in bicycle exercise testing in children. The reference values (mean, SD, median, and percentiles) for boys and girls aged 12-18 years can be used to predict workload corrected for body composition in healthy and sick children.

Adipose Tissue↗
PubMed1996

The six-minute walking test in children with cystic fibrosis: reliability and validity.

There is a need to judge general exercise tolerance in children with cystic fibrosis (CF) under normal daily activity conditions and -when more extensive testing is required-in an exercise laboratory in a specialized center. We investigated the reproducibility, validity, and criterion for a 6-minute walking test, which simulates normal childhood activities. In Part A, we evaluated the reproducibility of a 6-minute walking test in 23 children (12 girls and 11 boys; ages 11.1 +/- 2.2 years; range, 8.2 15.6 years) with mild symptoms of CF [forced expiratory volume in 1 second (FEV1) 94.4 +/- 16.5% of predicted values (range, 60.6-129.7); body weight Z-score -0.71 +/- 0.81 (range, -1.73-0.93)]. The subjects performed two standardized 6-minute walking tests with 1 week between tests. There was no significant difference between the two walking distances reached (737 +/- 85 versus 742 +/- 90 meters; P = 0.56), and there was a strong correlation between the two walking distances reached by the individuals (r = 0.90, P < 0.0001). In Part B, the validity of the walking test was evaluated in 15 children (6 girls and 9 boys; ages 14.5 +/- 2.0 years; range, 10.2-16.9 years) with moderate symptoms of CF [FEV1 = 58 +/- 16.0% of predicted values, (range, 41.1-89.4); RV/TLC ratio = 46.3 +/- 6.5% (range, 31.6-57.2); body weight Z-score: -1.29 +/- 0.60 (range, -2.20-0.14)]. They underwent standardized maximum incremental exercise testing on a cycle ergometer and a 6-minute walking test. Postexertional lactate values exceeded threshold values (as described in the literature) in all patients but one. Correlation analysis (Pearson) showed a significant correlation between the walking distance reached (WD = 697 +/- 104 meters), and the maximum workload (Wmax = 118 +/- 44 watt; r = 0.76, P < 0.001) or the maximum oxygen uptake (1,688 +/- 495 ml; r = 0.76, P < 0.001), the latter two being determined on a cycle ergometer, RV/TLC% showed a significant negative correlation (r = -0.72, P < 0.01) with WD. Stepwise multiple regression analysis showed a multiple regression coefficient of R = 0.84 (P < 0.001) for Wmax and RV/TLC % as the independent variables vs. WD as the dependent variable. We conclude that the 6-minute walking test is a valid and useful test in children with mild to moderate symptoms of CF to assess their exercise tolerance and endurance. Exercise test results correlated negatively with pulmonary hyperinflation expressed by the RV/TLC ratio.

Adolescent↗
PubMed1995

Efficiency of oxidative work performance of skeletal muscle in patients with cystic fibrosis.

BACKGROUND: Exercise intolerance in patients with cystic fibrosis is commonly attributed to reduced pulmonary and nutritional status. The possible role of diminished efficiency of mitochondrial oxidative phosphorylation in relation to skeletal muscle performance was investigated in patients with cystic fibrosis. METHODS: In vivo synthesis of ATP in skeletal muscle during submaximal exercise was studied in eight patients with cystic fibrosis aged 12-17 years, and in 19 healthy control subjects aged 8-36 years. The intracellular pH and concentrations of phosphate compounds were calculated at four steady states from phosphorus-31 labelled nuclear magnetic resonance spectroscopy measurements in the forearm muscle during bulb squeezing in an exercise protocol. Normalised power output, expressed as percentage maximal voluntary contraction (Y, in %MVC), was related to the energy force of ATP hydrolysis (X = ln [ATP]/[ADP][Pi]). This relationship provides an in vivo measure of efficiency of oxidative work performance of skeletal muscle. RESULTS: During all workloads (but not at rest) intracellular pH was higher in the patients with cystic fibrosis than in the controls. The linear least square fit for Y = a-bX showed high correlations in both groups; the slope b was 19% lower in the patients than in the controls (11.8% v 14.5% MVC/ln M; 95% confidence interval for difference 0.3 to 5.0). CONCLUSIONS: In patients with cystic fibrosis oxidative work performance of skeletal muscle is reduced. This may be related to secondary pathophysiological changes in skeletal muscle in cystic fibrosis.

Adolescent↗
PubMed1995

Physical adaptation of children to life at high altitude.

Children permanently exposed to hypoxia at altitudes of > 3000 m above sea level show a phenotypical form of adaptation. Under these environmental conditions, oxygen uptake in the lungs is enhanced by increases in ventilation, lung compliance, and pulmonary diffusion. Lung and thorax volumes in children growing up at high altitude are increased. The haemoglobin concentration in highlanders is elevated. With respect to the decreased arterial oxygen tension at high altitude, this seems a useful adaptation. Blood viscosity also increases as a result of the increase in red blood cell concentrations however, and this has potentially negative effects on the microcirculation in the tissues. The decreased partial pressure of oxygen in the lungs of highland children is associated with a higher pulmonary artery pressure. Pulmonary hypertension, high altitude pulmonary oedema, and chronic mountain sickness form part of the pathophysiology afflicting highland dwellers. Birth weight at high altitude is decreased. Decreased postnatal growth has been widely reported in populations at high altitude, particularly in early studies from the Andes. Recent studies taking into account the effects of socio-economic deprivation, suggest that long-term exposure to altitudes of 2500-3900 m is associated with a moderate reduction in linear growth in children.

2,3-Diphosphoglycerate↗
PubMed1993

Differences in physical growth of Aymara and Quechua children living at high altitude in Peru.

Physical growth of Amerindian children living in two Aymara and three Quechua peasant communities in the Andean highlands of southern Peru (altitude 3,810-3,840 m) was studied, taking into account differences in the microclimate, agronomic situation, and sociodemographic variables. Anthropometric measurements were taken in 395 children aged under 14 years of age in a sample of 151 families in these communities, who were surveyed for sociodemographic variables as well. Data on the land system were available for 77 families. In comparison with reference populations from the United States (NCHS) and The Netherlands, stature, weight, head circumference, and midupper arm circumference (but not weight for stature) in the sample children were reduced. Growth retardation increased after the age of 1 year. Stature and weight in the present sample were very similar compared with previously published data on growth of rural Aymara children living near Lake Titicaca in Bolivia. Head circumference, midupper arm circumference, and weight for stature were significantly larger in Aymara children compared with Quechua children. Land was significantly more fragmented in Aymara compared with Quechua families, but amount of land owned was not different. Perinatal and infant mortality was elevated in Aymara vs. Quechua communities. Most families in Aymara communities used protected drinking water. One Quechua community had a severe microclimate, grim economic outlook, and weak social cohesion. Children in this community showed significant reductions in weight and midupper arm circumference compared with their peers in the other communities. We conclude that (presumably nutritionally mediated) intervillage and Aymara-Quechua differences in childhood physical growth existed in this rural high-altitude population in Peru and were associated with microclimate and the village economy, sociodemographic factors, and differences in the land system.

Adolescent↗
PubMed1993

Socio-cultural determinants of child mortality in southern Peru: including some methodological considerations.

Among Amerindian children living at high altitude in the Andes in southern Peru, high child mortality rates have been reported in the literature, especially in the perinatal and neonatal period. We compared mortality rates in children calculated from retrospective survey data in 86 rural families from 2 Aymara and 3 Quechua peasant communities living at the same level of altitude (3825 m) in southern Peru. Relations between land tenure, socio-cultural factors and child mortality were studied, and methodological considerations in this field of interest are discussed. Checks on consistency of empirical data showed evidence for underreporting of neonatal female deaths with birth order 3 and more. Perinatal (124 vs 34 per 1000 births) and infant mortality (223 vs 111 per 1000 live births) was significantly higher in Aymara compared with Quechua children, but no difference was found after the first year of life. A short pregnancy interval was associated with an elevated perinatal and infant mortality rate, and a similar albeit insignificant association was found with increased maternal age. Amount of land owned and birth order were not related with child mortality. Although levels of maternal education are generally low in both cultures, a consistent decline in infant and child mortality was found with the amount of years mothers had attended school. However, the results suggest a U-shaped relationship between the amount of years of parental education and perinatal mortality in offspring. Late fetal and early neonatal mortality were particularly high in one Aymara community where mothers were found to have more years of education. Infanticide, a known phenomenon in the highlands of the Andes, is discussed in relation with the findings of the study. Although maternal and child health services are utilized by the majority of families in 4 of 5 study communities, 43 of 51 mothers under the age of 45 years reported that they delivered their last baby in the absence of traditional midwives or official medical supervision.

Adult↗
PubMed1989

Blood concentrations after accidental cyclosporin overdose.

Two cases of children are reported with an accidental oral overdose of cyclosporin in whom blood concentrations were monitored. Despite a tenfold oral overdose, the peak blood concentrations of cyclosporin in both patients were only moderately increased above therapeutic levels. Apart from a transient rise in blood pressure in one patient, no toxic effects of cyclosporin were noticed.

Biological Availability↗
PubMed1988

Mortality in children among the Aymara Indians of southern Peru.

During the fieldwork on illness in children in an Aymara peasant community in Southern Peru, data was collected on child mortality. In 35 families surveyed in the village, the total child mortality rate was estimated diachronically at 380 per 1,000 live births. The majority of the child death in these families occurred in the first days after birth. These deaths were also counted as perinatal deaths, and thus the perinatal mortality rate was found to be high as well at 252 per 1,000 total births (99% confidence interval: 181-330 per 1,000). Congenital malformations incompatible with life, neonatal tetanus, and other neonatal disorders did not have an especially high frequency in the village. These disorders seem to explain only a part of the early neonatal deaths responsible for the high mortality rates in children. As perinatal deaths were concentrated in 13 of the 35 families in the survey (especially in those families with many total births and at least two living children), the possibility of infanticide was put forward to explain the high death rates in children in the first days of life. This hypothesis was supported by practices in the village concerning the baptism of dead children by which the cause of death was left unsanctioned. Infanticide could be important to curb recent and future population growth and the resulting pressure on the land.

Adolescent↗