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Biomedical subjects

R Derom

Publications and source records attributed to R Derom.

At least 37 records · Page 2Linked to original sources
PubMed1994

Cardiovascular reactivity in isometric exercise and mental arithmetic in children.

In children, we studied noninvasively the cardiovascular stress responses, including changes over time of systolic blood pressure (SBP), heart rate (HR), and stroke volume (SV) in isometric handgrip (IHG) and mental arithmetic. Specifically, we asked whether 1) these cardiovascular stress responses were different for the two stress conditions in children, 2) these responses differed in boys and girls, and 3) the anthropometric variables related to these stress responses. SV differed significantly between IHG and mental arithmetic over the entire stress period. This may reflect higher systemic vascular resistance during IHG. HR in boys was lower than in girls over the entire period of stress in both stress tests. This observation cannot be attributed to differences in conditioning, because this should not influence responses to isometric or mental stress. A larger left ventricular mass was related to higher SVs. A marked relationship was found between HR and SBP and between HR and SV. No relationship was found between SBP and SV.

Blood Pressure↗
PubMed1994

X chromosome inactivation patterns correlate with fetal-placental anatomy in monozygotic twin pairs: implications for immune relatedness and concordance for autoimmunity.

BACKGROUND: Monozygotic (MZ) twinning is a poorly understood phenomenon that may result in subtle biologic differences between twins, despite their identical inheritance. These differences may in part account for discordant expression of disease in MZ twin pairs. Due to their stochastic nature, differences in X chromosome inactivation patterns are one source of such variation in female MZ twins. MATERIALS AND METHODS: We investigated X chromosome inactivation patterns in the blood of 41 MZ twin pairs based on methylation of the androgen receptor gene using a Hpa II-PCR assay. Twenty-six female MZ twin pairs with autoimmune disease (rheumatoid arthritis or multiple sclerosis) were studied. In addition, we studied 15 newborn female MZ twin pairs who were characterized at birth with respect to the anatomy of chorionic membranes (dichorionic versus monochorionic). RESULTS: We found a strong correlation between dichorionic fetal anatomy and differences in X chromosome inactivation patterns between members of an MZ twin pair. In contrast, all monochorionic twin pairs had closely correlated patterns of X chromosome inactivation. X chromosome inactivation patterns did not distinguish between MZ twin pairs who were concordant or discordant for autoimmune disease. CONCLUSIONS: The highly similar patterns of X chromosome inactivation among monochorionic twin pairs may result from their shared placental blood supply during intrauterine life. Alternatively, these patterns may indicate that X chromosome inactivation occurs before the twinning event in this anatomic subgroup of MZ twins. The data further suggest that these factors do not make a major contribution to the high discordance rates for autoimmune disease in MZ twin pairs.

Autoimmune Diseases↗
PubMed1993

Iatrogenic multiple pregnancies in East Flanders, Belgium.

OBJECTIVE: To evaluate the specific contribution of artificial induction of ovulation to the increasing number of multiple gestations in East Flanders and the effects of this treatment on the frequencies of monozygotic and dizygotic twinning. DESIGN: Since 1976 the East Flanders Prospective Twin Study has collected data on artificial induction of ovulation for all the multiple births listed in its registry. SETTING: East Flanders Prospective Twin Survey. PATIENTS: Between 1976 and 1992, 458 twin and 78 triplet pregnancies resulting from artificial induction of ovulation were analyzed. MAIN OUTCOME MEASURES: Zygosity and frequency of iatrogenic multiple births. RESULTS: Since 1985 there is an explosive increase in twin and triplet births in East Flanders. This increase has been caused mainly by the sole use of fertility-enhancing drugs and in the last few years by resorting to other technologies of assisted reproduction, such as IVF-ET, GIFT, or zygote intrafallopian transfer. CONCLUSION: In view of the elevated risk inherent to multiple pregnancies in terms of perinatal mortality and morbidity, the over enthusiastic or improper use of fertility drugs should be curtailed.

Belgium↗
PubMed1991

Genotyping of macerated stillborn fetuses.

It is generally impossible to collect blood or to culture tissue from a macerated stillborn fetus. Accurate genotyping of such a fetus may, however, be critical for the diagnosis of genetic diseases and appropriate genetic counseling. In the East Flanders Prospective Twin Study, placental tissue of twin and triplet sets, in some of which one or both members were stillborn and macerated, has been stored at -20 degrees C. Of all these fetuses, sex and zygosity could be determined accurately on the placental deoxyribonucleic acid. We tested the possibility of nongenetic changes in deoxyribonucleic acid that result from maceration or tissue degradation over time in storage on placental samples from monochorionic twins in which only one member was stillborn and macerated. The deoxyribonucleic acid variants in these monozygotic twins were identical whether or not either cotwin was macerated. Thus deoxyribonucleic acid variants can be determined accurately on the placental tissue of macerated fetuses, even after prolonged freezing.

DNA↗
PubMed1991

Social differences in low birthweight and preterm deliveries in twins.

The relationship between low social class and low birthweight or preterm deliveries is well established in singletons but not in twins. We present a study using all twin deliveries registered in Belgium in 1983 and in Aberdeen between 1951 and 1983. No significant relationship was found between social class and low birthweight, very low birthweight or preterm deliveries in the Belgian sample. In Aberdeen, we found significantly higher rates of low birthweight twins in low social classes. This increase of low birthweight twins in low social classes occurred in Aberdeen during the period 1951-1968, but not in the more recent data.

Belgium↗
PubMed1989

Genetic and environmental variation in the birth weight of twins.

Two novel approaches to the analysis of twin data are illustrated with data from birth weight in twins. First, two possible covariates of birth weight are fitted to the data simultaneously, allowing for linear effects of these variables, and their correlation. Second, information on chorionicity is used to estimate the effects of chorion type on birth weight. The data were collected from a large sample of twins born in East Flanders, Belgium. Variation and covariation in twins were considered as a function of sex, chorionicity, maternal age, gestational age, and genotype. No evidence for sex differences in causes of variation was found. As expected, the largest source of variation in bith weight was associated with gestational age. Other common environmental influences were non-significant. Heritability was significant, constituting approximately 40% of variation not associated with maternal and gestational age. A small but significant effect of chorionicity was found, such that dichorionic twins show a greater similarity than monochorionic.

Birth Weight↗
PubMed1989

Perinatal health in Belgium: an introduction.

The objectives of this special issue are reviewed. The principle aim is to discuss the relatively high perinatal mortality rate observed in Belgium. Belgian perinatal mortality is higher than that of Japan and very close to that of the USA, even though Belgium has fewer low-birthweight newborns and teenage pregnancies than the USA. This introduction also briefly describes the general organization of the Belgian health care system.

Adolescent↗
PubMed1989

Organization of obstetrical care in Belgium.

Belgium, with its pluralistic health care system, has many small-sized maternity units staffed almost exclusively with obstetricians. The maternal and perinatal mortality and morbidity rates are still higher than in some of the neighboring countries. The new regulations with regard to the accreditation of maternity units might improve the figures. Other measures must be taken, however, to ensure that only low-risk patients are taken into small maternity units and that all high-risk cases and all those developing complications are cared for in large, well-equipped and well-staffed hospitals. Some form of peer review would also be beneficial.

Belgium↗
PubMed1989

Frequency of cesarean deliveries in Belgium.

Belgium has not been spared the increase in the rates of cesarean section (CS) observed in other Western countries. In contrast with some of these countries, however, rate increases have been rather modest, both nationally and in most Belgian hospitals. Casuistic data suggest that the indications explaining the increase of CS rates in Belgium are by and large comparable to those pinpointed elsewhere. Ways to reduce rates of abdominal delivery are suggested.

Belgium↗
PubMed1989

Clinical experience with an ethinyl estradiol-desogestrel oral contraceptive.

Desogestrel (150 micrograms), a potent progestogen virtually devoid of androgenic activity, was used in combination with 30 micrograms ethinyl estradiol as an oral contraceptive preparation (Marvelon). 219 women completed a total of 4074 cycles, and the use-effectiveness was 0.58 Pearl Units. Serious side effects were not observed. The drug-related discontinuation index was 12.8% in six months.

Adult↗
PubMed1988

The validity of Weinberg's rule in the East Flanders Prospective Twin Survey (EFPTS).

Most population studies of twins estimate the number of monozygotic (MZ) and dizygotic (DZ) pairs by Weinberg's differential rule. This rule assumes that within the DZ twins the numbers of unlike-sexed (U) and like-sexed (L) twins are equal. The literature on the validity of Weinberg's rule is still controversial. In this prospective population-based study (EFPTS) of 2,589 twin pairs, of whom 2,577 were of known zygosity and placentation, the estimates of Weinberg's rule agree well with the results of direct zygosity determination.

Belgium↗
PubMed1988

The European Multiple Birth Study (EMBS).

The more that twin and other multiple pregnancies are investigated, the more it becomes mandatory that collaborative studies are set up in order to attain the critical number of cases needed to achieve meaningful and reliable results. The European Multiple Birth Study (EMBS) aims to study two aspects of twin and multiple pregnancy: 1) management of pregnancy and labour, with emphasis on the prevention of preterm delivery; 2) accurate determination of zygosity, a prerequisite for the proper use of the twin method in a variety of fields, eg, congenital malformations, genetics, clinical investigations, etc. The rationale, the methods and the organisation of the study are described and discussed.

Data Collection↗
PubMed1988

Is the quality of care in twins and in singletons related?

We investigated if it is possible to use the data collected in twins to identify areas with high rates of operative deliveries, preterm deliveries and low birthweight infants in singletons. Our data correspond to all deliveries registered in Belgium in 1983. A significant correlation was found between the rates of cesarean sections in twins and in singletons. A significant correlation was also found between the rate of deliveries at a gestational age of less than 32 weeks in twins and the rate of deliveries at less than 37 weeks in singletons. However, correlations between other preterm rates, low birthweight rates and vacuum extraction or forceps rates, were nonsignificant. We conclude that the use of twins as tracers of the quality of care in singletons is of limited value.

Belgium↗
PubMed1988

Triplet and higher-order births: what is the optimal delivery route?

Data concerning 16 triplet and higher-order deliveries (resulting in a total of 56 infants) are reviewed. The vaginal delivery rate was 81%. Maternal morbidity was more serious after abdominal delivery. Prematurity (less than 36 weeks gestation) rate amounted to 68%. Overall perinatal and neonatal mortalities for infants born after 28 weeks gestation and weighing at least 1000 g were 7% and 3%, respectively. We doubt that neonatal outcome could have been markedly improved by performing more cesareans. The importance of antenatal care is stressed.

Birth Weight↗