Van Wiechen Research Articles

Prematuur geboren kinderen en het Van Wiechen-ontwikkelingsonderzoek

Inleiding: Het Van Wiechen-ontwikkelingsonderzoek (VWO) wordt door jeugd- en kinderartsen gebruikt om de ontwikkeling van alle kinderen, ook van prematuren, zorgvuldig te volgen. Voor prematuren is niet bekend hoe hun ontwikkelingstraject verloopt volgens het Van Wiechen-ontwikkelingsonderzoek. Methode: Wij hebben dit onderzocht in het Pinkeltje-cohort, bestaande uit 625 à terme geborenen, 1.079 matig prematuren en 617 vroeg prematuren die zijn geboren in 2002–2003. We hebben de Van Wiechen-gegevens opgedeeld in drie domeinen: ‘sociaal-emotioneel’, ‘fijne motoriek’ en ‘grove motoriek’. Per zwangerschapsduurgroep bepaalden we hoeveel kinderen de ontwikkelingskenmerken op tijd behaalden, wat betreft hun kalenderleeftijd. Resultaten: Matig en vroeg prematuren behaalden ontwikkelingskenmerken gemiddeld minder vaak tijdig dan à terme kinderen: in het sociaal-emotionele domein behaalden 96%, 90% en 79% van respectievelijk de à terme geborenen, de matig en vroeg prematuren de kenmerken tijdig. Voor de grove motoriek waren de percentages respectievelijk 89%, 84% en 70%, en voor de fijne motoriek respectievelijk 89%, 84% en 84%. In alle domeinen bestond aanzienlijke variatie in het behalen van de verschillende kenmerken. Conclusie: Het behalen van ontwikkelingskenmerken in de eerste levensjaren is sterk afhankelijk van de zwangerschapsduur. Nader onderzoek is gewenst naar de aanpassing en toepassing van het Van Wiechen-ontwikkelingsonderzoek voor à termen en prematuren.

LInking EDCs in maternal Nutrition to Child health (LINC study) - protocol for prospective cohort to study early life exposure to environmental chemicals and child health.

BackgroundThe presence of chemicals in the environment is ubiquitous. Human biomonitoring studies have shown that various chemicals can be detected in the majority of the population, including pregnant women. These compounds may pass the placenta, and reach the fetus. This early life exposure in particular may be detrimental as some chemicals may disrupt the endocrine system, which is involved in various processes during development. The LINC study is a prospective birth cohort designed to study associations between early life environmental exposures and child health, including growth and neurodevelopment. The purpose of this paper is to give an overview of this cohort.Methods and designRecruitment for this cohort has started in 2011 in three Dutch areas and is still ongoing. To date over 300 mother-child pairs have been included. Women are preferably included during the first trimester of pregnancy. Major congenital anomalies and twin births are reasons for exclusion. To assess exposure to environmental chemicals, cord blood, placenta, meconium and vernix are collected. Parents collect urine of the child shortly after birth and breast milk in the second month of life. Exposure to a broad range of environmental chemicals are determined in cord plasma and breast milk. Furthermore various hormones, including leptin and cortisone, are determined in cord plasma, and in heel prick blood spots (thyroxine). Data on anthropometry of the child is collected through midwives and youth health care centres on various time points until the child is 18 months of age. Furthermore cognitive development is monitored by means of the van Wiechen scheme, and information on behavioral development is collected by means of the infant behavior questionnaire and the child behavior checklist. When the child is 12 months of age, a house visit is scheduled to assess various housing characteristics, as well as hand-to-mouth behavior of the child. At this visit exposure of the child to flame retardants (with endocrine disrupting properties) in house dust is determined by means of body wipes. They are furthermore also measured in a saliva sample of the child. Next to these measurements, women receive questionnaires each trimester regarding amongst others lifestyle of the parents, general health of the parents and the child, and mental state of the mother.DiscussionThis study was approved by the medical ethics committee of the VU University Medical Centre. Consent for the infant is given by the mother, who is specifically required to give consent for both herself as well as her child. Results will be published regardless of the findings of this study, and will be widely disseminated among related medical stakeholders (e.g. midwives and pediatricians), policy makers, and the general public.

Pertussis in infancy and the association with respiratory and cognitive disorders at toddler age

Pertussis in unvaccinated infants can run a severe course and is often accompanied by complications. In this pilot study, we studied whether there is an association between pertussis hospitalisation in infancy and, respiratory symptoms, growth and cognitive development in early childhood. A group of 89 children aged 13-45 months and hospitalised for laboratory confirmed pertussis within the first six months of their life were compared with 172 children without a history of pertussis. Risk ratios (RR) with 95% confidence intervals (CI) of the association between health outcomes and pertussis in infancy were calculated. Weight-for-length and length-for-age z-scores were calculated to investigate growth. Van Wiechen scores were compared to study cognitive development. Children with a history of pertussis in infancy had a greater chance on "asthma symptoms" (RR 2.8 95%CI 1.1-7.0) on toddler age and were more likely to report "respiratory infections" (RR 3.3 95%CI 1.6-6.6). In addition, children with a history of pertussis in infancy had significantly lower weight-for-height in the first 40 months of life. No significant differences in cognitive development were found. We found an association between severe pertussis in infancy and respiratory symptoms on toddler age. The mechanisms that may underlie this association require further investigation.

Detecting language problems: accuracy of five language screening instruments in preschool children

To identify a simple and effective screening instrument for language delays in 3-year-old children the reliability, validity, and accuracy of five screening instruments were examined. A postal questionnaire sent to parents of 11423 children included the Dutch version of the General Language Screen (GLS), the Van Wiechen (VW) items, the Language Screening Instrument for 3- to 4-year-olds, consisting of a parent form (LSI-PF) and a child test (LSI-CT), and parents' own judgement of their child's language development on a visual analogue scale (VAS). The response rate was 78% or 8877 children. Reliability (internal consistency) was found to be acceptable (alpha=0.67-0.72) for all instruments. Significant correlations between the screening instruments (r=0.29-0.55, p<0.01) indicated good concurrent validity. Accuracy was estimated by the sensitivity, specificity, and receiver operating characteristic (ROC) curves against two reference tests based on parent report and specialists' judgement. If the test would classify approximately 5% of the population as screen-positive, the mean sensitivity was 50%; assigning between 20% and 30% of the population as screen-positive, the mean sensitivity was 77%. The sensitivity was lowest for the LSI-CT (range 43-62%), whereas short instruments like the LSI-PF, VW, and the one-item VAS exhibited high levels of sensitivity (range 50-86%). The area under the ROC curves, ranged from 0.75 to 0.87. Apparently, short and simple parent report instruments like the LSI-PF and the one-item VAS perform remarkably well in detecting language delays in preschool children.

Quality of life of children with language delays

We investigated health-related quality of life (HRQOL) of children with language problems and controls. Data on language development (Language Screening Instrument 3-years-olds, Van Wiechen items) and HRQOL by means of the TNO-AZL Pre-school children Quality of Life-questionnaire (TAPQOL) were collected at age 3 in a population-based cohort by parental questionnaire (n = 8877, response 78%; mean age 39.1 months (SD 2.0), 4347 were girls). Cronbach's alpha (internal consistency) ranged between 0.63 and 0.85. Dependent on the definition of language problem, 131 to 316 children appeared to be language impaired. Receiver Operating Characteristic analyses (ROC-curves) to assess the discriminative ability of six TAPQOL scales revealed that the Communication scale and Social Functioning scale discriminated best between children with language problems and children without these problems. Language-impaired children had significantly lower scores on the Communication scale and Social Functioning scale as compared to children without language problems (p < 0.01). The findings indicate that language problems at age three can have an impact on children's social life. These results provide additional evidence for the importance of monitoring the language development and its consequences during childhood.

Prenatally diagnosed fetal ventriculomegaly: prognosis and outcome

The purpose of the present study was to determine the postnatal outcome and prognostic factors of prenatally diagnosed ventriculomegaly, and to establish the relationship between prenatal sonographic measurements and postnatal psychomotor development. A total of 42 singleton pregnancies with sonographically determined fetal ventriculomegaly at 20-38 weeks' gestation were reviewed, together with follow-up data on postnatal outcome at a mean of 29 months after delivery. Sonographic measurements included head circumference, cerebral lateral ventricular diameter at the anterior and posterior horn level, and hemisphere diameter. Classification of psycho-motor development consisted of assessment of motoric behaviour, speech, communication and social skills ('Van Wiechen' classification). Perinatal mortality rate was 38 per cent, of which half were directly associated with cephalocentesis. Only the ventricle/hemisphere ratio for the anterior and posterior horn of the lateral cerebral ventricles was significantly higher among perinatal deaths than amongst the survivors. Within the subset of survivors (n = 26), psycho-motor development was normal in 46 per cent. Postnatal examination revealed syndrome anomalies in five infants, of which four were associated with psycho-motor retardation. Prenatally diagnosed ventriculomegaly has a poor postnatal outcome with more than 50 per cent of the live-born infants demonstrating abnormal psycho-motor development. The predictive value of fetal biometric measurements is poor. The presence of syndromal anomalies emphasizes the need for genetic counselling in future pregnancies.

Prenatally diagnosed fetal ventriculomegaly; prognosis and outcome.

The purpose of the present study was to determine the postnatal outcome and prognostic factors of prenatally diagnosed ventriculomegaly, and to establish the relationship between prenatal sonographic measurements and postnatal psychomotor development. A total of 42 singleton pregnancies with sonographically determined fetal ventriculomegaly at 20-38 weeks' gestation were reviewed, together with follow-up data on postnatal outcome at a mean of 29 months after delivery. Sonographic measurements included head circumference, cerebral lateral ventricular diameter at the anterior and posterior horn level, and hemisphere diameter. Classification of psycho-motor development consisted of assessment of motoric behaviour, speech, communication and social skills ('Van Wiechen' classification). Perinatal mortality rate was 38 per cent, of which half were directly associated with cephalocentesis. Only the ventricle/hemisphere ratio for the anterior and posterior horn of the lateral cerebral ventricles was significantly higher among perinatal deaths than amongst the survivors. Within the subset of survivors (n = 26), psycho-motor development was normal in 46 per cent. Postnatal examination revealed syndrome anomalies in five infants, of which four were associated with psycho-motor retardation. Prenatally diagnosed ventriculomegaly has a poor postnatal outcome with more than 50 per cent of the live-born infants demonstrating abnormal psycho-motor development. The predictive value of fetal biometric measurements is poor. The presence of syndromal anomalies emphasizes the need for genetic counselling in future pregnancies.

A maternity waiting home experience in Zimbabwe.

International Journal of Gynecology & ObstetricsVolume 61, Issue 2 p. 179-180 Brief communications A maternity waiting home experience in Zimbabwe W.A Spaans, Corresponding Author W.A Spaans w.a.spaans@amc.uva.nl Department of Obstetrics and Gynecology, Academic Medical Center, Amsterdam, NetherlandsCorresponding author. Tel.: +31 20 5663557; fax: +31 20 6963489; e-mail: w.a.spaans@amc.uva.nlSearch for more papers by this authorJ van Roosmalen, J van Roosmalen Department of Obstetrics, Leiden University Medical Center, Leiden, NetherlandsSearch for more papers by this authorC.M.A.G van Wiechen, C.M.A.G van Wiechen National Institute of Public Health and the Environment, Bilthoven, NetherlandsSearch for more papers by this author W.A Spaans, Corresponding Author W.A Spaans w.a.spaans@amc.uva.nl Department of Obstetrics and Gynecology, Academic Medical Center, Amsterdam, NetherlandsCorresponding author. Tel.: +31 20 5663557; fax: +31 20 6963489; e-mail: w.a.spaans@amc.uva.nlSearch for more papers by this authorJ van Roosmalen, J van Roosmalen Department of Obstetrics, Leiden University Medical Center, Leiden, NetherlandsSearch for more papers by this authorC.M.A.G van Wiechen, C.M.A.G van Wiechen National Institute of Public Health and the Environment, Bilthoven, NetherlandsSearch for more papers by this author First published: 23 February 1999 https://doi.org/10.1016/S0020-7292(98)00027-7Citations: 16Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume61, Issue2May 1998Pages 179-180 RelatedInformation

Linear viscoelastic behavior of the Hookean dumbbell with internal viscosity

The linear viscoelastic modulus G(t) predicted by the analytical formulations of Schieber (1993), Wedgewood (1993), Dasbach et al. (1992), and Booij and van Wiechen (1970) for the free-draining Hookean dumbbell with internal viscosity (IV) are compared with exact analytical results and exact numerical results obtained from Brownian dynamics simulations. All of these analytical formulations employ the Booij and van Wiechen expression for the IV force, thereby eliminating errors associated with linearization of the “deformational” velocity, however the theories differ in the approximations employed to solve configuration moment equations. Comparison with the exact G(t) results provides a means of testing these approximations. The approximate theories all correctly predict the singular part of G(t) at t = 0, providing correct predictions of η′∞, however deviations from the exact G(t) are seen in all cases for t > 0.

LANGUAGE AND SPEECH DELAY AT 1, 2, AND 5 YEARS OF AGE IN VERY PRETERM AND VERY LOW BIRTHWEIGHT INFANTS

Results of language screening in a nationwide collaborative study of a virtually complete year cohort of 1338 infants with a gestational age <32 weeks or with a birthweight of <1500 grams were reported. At the age of 1 and 2 years the language items derived from the Van Wiechen ncurodevelopmental assessment and at 5 years the VTO-language screening test were used, both validated for the Dutch language. Language delay was recorded in 16%, 23%, and 24% respectively at 1, 2, and 5 years of age (corrected for preterm birth). In a multiple logistic regression analysis a relationship of language delay at 5 years was found with perinatal risk factors: level of parental education, multiple pregnancy, birthweight, male sex, and neurological status at discharge. Both language delay at 1 year and at 2 years were predictors for delay at the age of 5 (OR 2.2 and OR 2.9). Disability not due to language delay at 5 years of age was related to language delay (OR 3.2). Particularly disabilities of mental development and neuromotor function and to a lesser extent disabilities of visual function and hearing loss were involved. At 5 years 12% is already attending special education. As language delay is a strong predictor of school failure in the coming years a considerable increase of this percentage is expected.

Internal viscosity in polymer kinetic theory: shear flows

The Gaussian closure method and Brownian dynamics simulations have been used to calculate the shear material properties of a dilute solution of Hookean dumbbells with internal viscosity. Results for the zero-shear-rate material properties and small amplitude oscillatory shear material properties have been found analytically, and numerical results for the steady state shear material properties are also presented. Two interpretations of the stress tensor are investigated and results are compared. Brownian dynamics simulations are used to obtain material properties of the Hookean dumbbell with internal viscosity without approximations. These simulation results are compared with the perturbation solution of Booij and van Wiechen as well as with a new Gaussian closure solution. Also presented are the contracted distribution functions as derived from the Gaussian closure method and from Brownian dynamics simulations.

Do internal viscosity models satisfy the fluctuation-dissipation theorem?

The Brownian forces for a Hookean dumbbell model with internal viscosity are characterized using the fluctuation-dissipation theorem and assuming that the momentum and configuration of the chain fluctuate on separate time scales. A Langevin-type approach in the full phase-space of the dumbbell is used to derive the proper stochastic differential equation. By considering both the stochastic differential equation, or equation of motion, and the equivalent Fokker-Planck equation, or diffusion equation, a contraction is made to the configuration space of the dumbbell. The resulting diffusion equation is compared to the models of previous works employing internal viscosity. It is found that some previous models do indeed satisfy the fluctuation-dissipation theorem (Kuhn and Kuhn, Booij and van Wiechen), whereas others do not.

Stress Jump at the Inception of Shear and Elongational Flows of Dilute Polymer Solutions due to Internal Viscosity

All versions of the internal viscosity (IV) model for polymer chain dynamics lead to the prediction that the inception of flow from a rest state is accompanied by a stress jump at t=0. For the general case of long chains (large number of submolecules, N), the jump is predicted here for the onsets of simple shear flow and elongational flow at constant deformational rate. The exact model formulation (i.e., following Booij and van Wiechen) is used, without the need to approximate deformational velocities in the Cerf/Peterlin sense, and rigorous closed‐form solutions are presented. This is apparently the only rheological prediction now available for the large N IV model using the rigorous formulation. Intermediate steps in the analysis demonstrate the extent to which the motions of beads are correlated with those of neighbors at various distances in the linear sequence; the effect is small and depends slightly on φ/f. Final results show that viscosity jumps are independent of deformational rate and depend on both φ and φ/f, where φ is the IV coefficient and f the bead/solvent friction coefficient. Experiments on stress jumps and subsequent transients are thus potentially able to evaluate φ alone, unlike steady‐state experiments which respond only to φ/f. Predictions for shear flow are also compared with those made using the Cerf/Peterlin linearization approximation, showing that the two diverge severely at high values of φ/f.

The energy storage in the Rouse model in an arbitrary flow field

The general solution of the configurational distribution function for the Rouse model of linear flexible macromolecules in solutions subjected to arbitrary flow fields obtained by D. H. King and D. F. James [J. Chem. Phys. 78, 4743 (1983)] is shown to be identical to the one derived by P. H. van Wiechen and H. C. Booij [J. Eng. Math. 5, 89 (1971)]. However, their expression for the energy storage in that model is incorrect. The relevant formula is derived and it appears that a useful approximation of the increase in Helmholz free-energy per unit volume is given by half of the trace of the stress tensor (ΔF≂ 1/2 tr P).

Development in polymer statistics

AbstractA short survey is given of recent developments in polymer statistics. Through the many years since the original conception of the entropy derived from the large number of configurations of macromolecules by Mark and Guth the basic idea has never been subjected to doubt but not much progress has been made in the way of confirmation of quantitative theoretical relations.In quantitative relations quantities appear such as the effective number of chains in a network and also the energy differences between more and less elongated configurations which cannot be determined easily and have to be treated as adaptable parameters.On the other hand the theory of networks has been further developed so as to establish the exact physical meaning of the effective number of chains in a network. The theory of networks has also been extended to entanglement networks in which the entanglements have a finite life time. Based upon the Rouse‐Zimm treatment of viscoelastic dilute solutions on one hand and upon the generalized network model of Duiser and Chömff on the other hand, van Wiechen and Booy have developed a general theory of time dependent elasticity in concentrated polymer systems. This theory is briefly reviewed.