Search PubMed⌕ Search

Biomedical subjects

R A Mullaart

Publications and source records attributed to R A Mullaart.

At least 19 recordsLinked to original sources
PubMed2006

Histological evaluation of acute covering of an experimental neural tube defect with biomatrices in fetal sheep.

OBJECTIVE: The aim of the study was to determine the histological effect on the neural tissue of in utero covering of an experimental neural tube defect in fetal lambs, with the use of two different biomatrices. MATERIALS AND METHODS: In 23 fetal sheep, surgery was performed at 79 days' gestation. In 19 of these, a neural tube defect was created, while 4 fetuses served as sham-operated controls. In 7 of the 19 operated fetuses the defect was left uncovered. In the remaining 12 animals the defect was covered either with a collagen biomatrix (4 animals), skin (3 animals), or small intestinal submucosa biomatrix (5 animals). The lambs were sacrificed at 1 week of age and histological examination was performed. RESULTS: All lambs with an uncovered neural tube defect showed histological damage of the spinal cord. In lambs in which the neural tube defect was covered, one half showed a normal architecture of the spinal cord while minor histological damage was present in the other half. Between the three groups in which the defect was covered, the histological outcome was comparable. CONCLUSIONS: Acute covering of an experimental neural tube defect in fetal lambs prevents severe histological damage to the spinal cord independent of the two biomatrices used in this study.

Animals↗
PubMed2005

Influenza-associated encephalopathy: no evidence for neuroinvasion by influenza virus nor for reactivation of human herpesvirus 6 or 7.

During 2 consecutive influenza seasons we investigated the presence of influenza virus, human herpesvirus (HHV) type 6, and HHV-7 in cerebrospinal fluid samples from 9 white children suffering from influenza-associated encephalopathy. We conclude that it is unlikely that neuroinvasion by influenza virus or reactivation of either HHV-6 or HHV-7 is involved.

Brain Diseases↗
PubMed2004

Educational career and predictors of type of education in young adults with spina bifida.

Children with spina bifida (SB) often require special education. To date, little information is available about the educational career of these children. This study focuses on educational career and predictors of attending special education of young adults with SB, using a cross-sectional study including 178 young Dutch adults with SB aged from 16-25. The main outcome was attending regular versus special education. For searching predictive power we selected age, gender, type of SB, level of lesion, hydrocephalus (HC), number of surgical interventions, ambulation, continence and cognitive functioning. Chi-square tests and binary logistic regression were used in the data analysis. Participants with HC attended special primary education more often (59%) than participants without HC (17%). For those participants with HC, the necessity of special primary education was associated with below average intelligence (75% versus 35%), wheelchair dependence (82% versus 39%) and surgical interventions (74% versus 44%). Only half of the participants with HC followed regular secondary education, whereas for participants with SB without HC, the outcome in secondary education was similar to that of the general population (92%). Intelligence was the main predictor of attending special secondary education (odds 5.1:1), but HC (odds 4.3:1) and wheelchair dependence (odds 2.6:1) were also a significant. Other variables were not significant predictors of special secondary education.

Adolescent↗
PubMed2002

MECP2 mutation in a boy with severe neonatal encephalopathy: clinical, neuropathological and molecular findings.

We describe the clinical and neuropathological presentation of a male with an MECP2 mutation whose sister has Rett syndrome (RS). He presented with severe neonatal encephalopathy and died at the age of 13 months. Mutation analysis of the MECP2 gene demonstrated a 488 - 489 del mutation in his and his sister's copies of the gene. Post mortem examination revealed bilateral polymicrogyria in the perisylvian region. This malformation was visibly more severe than previously described in females with RS and another male with an MECP2 mutation. As bilateral polymicrogyria was described in congenital perisylvian syndrome, the presented patient could be regarded as having suffered from a severe form of this syndrome. We conclude that MECP2 screening should be considered in males with severe neonatal encephalopathy and in males and females with a bilateral polymicrogyria syndrome.

Brain Diseases↗
PubMed2001

[Development and the developmental disorders of human brain. I. Early development of the cerebrum].

The recent discovery of many genes that regulate brain development is revolutionizing our knowledge of neuroembryology and, moreover, our understanding of how gene defects cause human birth defects. The first 8 weeks of the development of the cerebrum can be subdivided into 23 stages, with early development of mostly the spinal cord and the brain stem. Regionalization of the brain has been related to genes that play a part in it. A characteristic developmental disorder for this early phase in the development of the forebrain is holoprosencephaly, a brain patterning disorder. Numerous genes play a part in its occurrence; abnormal function of signal factors as well as of transcription factors may lead to holoprosencephaly.

Brain↗
PubMed1999

Spinal muscular atrophy-like picture, cardiomyopathy, and cytochrome c oxidase deficiency.

The authors report a child with a spinal muscular atrophy (SMA)-like picture, cardiomyopathy, and cytochrome c oxidase (COX) deficiency. Electromyography and muscle biopsy showed findings typical of SMA. However, COX staining of the muscle was negative. DNA analysis did not detect deletions in the survival motor neuron (SMN) gene. The lactate and lactate-to-pyruvate ratios were increased in blood and CSF. COX activity was decreased in muscle and fibroblasts. Western blot analysis showed reduced contents for all COX subunits. Patients with clinical features resembling SMA but with an intact SMN gene should be screened for a mitochondrial disorder.

Blotting, Western↗
PubMed1999

Quantitative ultrasonography of the periventricular white and grey matter of the developing brain.

This study addresses the value of operator-independent computer processing of ultrasonograms of the developing brain. With this aim, routine cranial ultrasonograms obtained from 39 term and preterm infants without clinical or sonographic evidence of brain damage were analyzed by five observers. The procedure, respectively, included: 1. the definition of four regions of interest (ROI), one white matter and one grey matter area on each side of the brain; 2. digitization of the sonogram data within these ROIs; 3. correction for the equipment settings, using data from a tissue-mimicking phantom as a reference; and 4. calculation of four sonogram characteristics (i.e., mean echo level, MEAN, signal-to-noise ratio, SNR, and axial and lateral correlation, CORAX and CORLAT, of the echo level co-occurrence matrix). Significant differences between both sides of the brain or a significant influence of ROI size were not found. The interobserver spread was considerable, but less than the intersubject spread. Two sonogram characteristics seemed strongly correlated in white and grey matter (CORAX and CORLAT) and another only in white matter (SNR with CORAX and CORLAT). MEAN seemed not to be correlated with any other characteristic. Furthermore, it was found that maturation equally decreases white and grey matter MEAN and, thus, hardly affects the ratio between the two. An effect on the other sonogram characteristics was only found in the white matter (i.e., an increase of SNR and a decrease of CORAX and CORLAT). Except for MEAN, the grey matter sonogram characteristics seem hardly affected by maturation. In view of these findings, we conclude that quantitative ultrasonography reveals white and grey matter maturation and, furthermore, provides a conceptional-age-independent reference (MEAN white:grey matter ratio) that might be found to facilitate the detection of pathologic brain alterations.

Age Factors↗
PubMed1997

Cerebral blood flow velocity and pulsation in neonatal respiratory distress syndrome and periventricular hemorrhage.

The present study addressed the hypotheses that cerebral ischemia and/or excessive cerebral blood pulsation contribute to periventricular hemorrhage in preterm newborns with respiratory distress and that the pulse width is a valuable tool to estimate the contribution of cerebral blood pulsation. These hypotheses were tested by following preterm newborns at risk for respiratory distress and periventricular hemorrhage. We monitored for cerebral blood flow velocity (CBFV), cerebral pulse width, and cerebral pulsatility index; for patent ductus arteriosus, capillary Pco2, heart rate (HR) and behavior; and for the occurrence of respiratory distress and periventricular hemorrhage (PVH). The data obtained were analyzed with linear regression with the mode of respiration (spontaneous or supported) and postnatal age as additional covariates. We observed that (a) respiratory distress, either uncomplicated or complicated by PVH, correlates with a low CBFV and a high cerebral pulsatility index; (b) PVH also correlates with a high cerebral pulse width; (c) the increased pulse width precedes the onset of the hemorrhage; and (d) these CBF alterations can be partly attributed to ductal shunting and are ameliorated by mechanical ventilation.

Analysis of Variance↗
PubMed1996

Spina bifida and parental occupation.

To examine the association between parental occupation and spina bifida in offspring, we conducted a multicenter case-referent study in the Netherlands. Cases were children with spina bifida aperta from nine different hospitals throughout the country; the referent group comprised population-based referents who were randomly drawn from municipal birth registries. All children were born between 1980 and 1992. We collected data using postal questionnaires for both parents with questions about occupational title, industry, daily occupational activities, and a number of potential confounders. We were able to include 353 cases and 1,329 referents in the analyses. We found increased risks for maternal agricultural occupations [odds ratio (OR) = 5.6; 95% confidence interval (CI) = 1.8-17.8] and for cleaning women (OR = 1.9; 95% CI = 0.9-3.9). For the fathers, we saw increased odds ratios for welders (OR = 2.1; 95% CI = 0.6-7.0) and transport workers (OR = 1.4; 95% CI = 0.9-2.1).

Case-Control Studies↗
PubMed1995

Intramedullary spinal cord abscess. A case report.

STUDY DESIGN: A case of an intramedullary spinal cord abscess is presented. The literature on this subject is carefully reviewed. OBJECTIVES: To give an overview of clinical presentation, radiographic examination, pathogenesis, treatment, and outcome of intramedullary spinal cord abscesses. Cases presented in the literature are arranged and the findings summarized. SUMMARY OF BACKGROUND DATA: Intramedullary spinal cord abscesses are rare. Most frequently, single cases were reported, followed by a short discussion. All previously reported cases were reviewed. METHODS: After an extensive literature search, all cases of an intramedullary spinal cord abscess (totaling 93 patients), including ours, were reviewed. Incidence, clinical presentation, neuroradiologic investigations, treatment, and pathogenesis are discussed. RESULTS: Intramedullary spinal cord abscesses are rare. The presentation can be very confusing, mimicking thoracic or abdominal diseases. Magnetic resonance imaging is the best diagnostic technique, although the findings are not pathognomonic. Appropriate antibiotic therapy after surgical drainage is warranted. If left untreated, the outcome is bleak. Whereas most cultures remain sterile (38.7%), Staphylococcus or Streptococcus species are involved frequently (23.7% and 17.2%). CONCLUSIONS: Although intramedullary spinal cord abscess is a rare disease, every spine surgeon should have knowledge of its existence because misjudgment and deferring adequate treatment may lead to an unfavorable outcome.

Abscess↗
PubMed1995

Influence of end expiratory pressure on cerebral blood flow in preterm infants.

The effect of interruption of positive and expiratory pressure (PEEP) on cerebral blood flow velocity (CBFV) and CBF fluctuation (CBFF) in the internal carotid arteries and on heart rate, restlessness and wakefulness has been studied in 17 mechanically ventilated neonates with RDS. A decrease in CBFV was found, but no significant change in CBFF. Multiple regression analysis showed that the decrease in CBFV is less pronounced if the PEEP interruption is accompanied by restlessness. It further appeared that the decrease in CBFV is more pronounced if CBFV is high, the ductus arteriosus is patent, or RDS follows a complicated course. These findings indicate that PEEP supports CBF, probably by a decrease in ductal stealing from the brain. Therewith PEEP protects against cerebral hypoperfusion which is one of the major risks in RDS and immaturity. Furthermore, our findings suggest that the decrease in CBF during PEEP interruption is moderated by restlessness and accentuated by brain damage.

Blood Flow Velocity↗
PubMed1995

Asymmetry of the cerebral blood flow: an ultrasound Doppler study in preterm newborns.

The purpose of this study was to investigate whether the preference of periventricular hemorrhage (PVH) for the left hemisphere is due to asymmetry of cerebral blood flow (CBF) and, if so, whether this asymmetry is due to patent ductus arteriosus (PDA). Thirty-three preterm newborns at risk for PVH were followed during their first 5 days after birth. Internal carotid CBF velocity (CBFV) and the flow direction in the common pulmonary artery, both determined by ultrasound Doppler, served as measures of CBF and PDA, respectively. The difference between right and left CBFV was analyzed statistically, with outcome, PDA, capillary PCO2, behavior, heart rate, and the average of right and left CBFV as covariates. Infants who developed PVH (n = 7) exhibited CBFV asymmetry to the disadvantage of the left side. This finding was partially attributable to PDA. Without PVH there was no significant CBFV asymmetry. Because all hemorrhages were bilateral, a relationship with the side of the hemorrhage could not be explored. In conclusion, asymmetry of CBFV is not normal, but is associated with PVH and PDA.

Case-Control Studies↗
PubMed1995

A frameshift mutation in the gene for PAX3 in a girl with spina bifida and mild signs of Waardenburg syndrome.

Neural tube defects (NTD) are among the most prevalent congenital malformations in man. Based on the molecular defect of Splotch, an established mouse model for NTD, and on the clinical association between NTD and Waardenburg syndrome (WS), mutations in the PAX3 gene can be expected to act as factors predisposing to human NTD. To test this hypothesis, 39 patients with familial NTD were screened by SSC analysis for mutations in exons 2 to 6 of the human PAX3 gene. One patient with lumbosacral meningomyelocele was identified with a 5 bp deletion in exon 5 approximately 55 bp upstream of the conserved homeodomain. The deletion causes a frameshift with a stop codon almost immediately after the mutated site. Clinical investigation of the index patient indicated mild signs of WS type I. Varying signs of this syndrome were found to cosegregate with the mutation in the family. Our results support the hypothesis that mutations in the gene for PAX3 can predispose to NTD, but also show that, in general, mutations within or near the conserved domains of the PAX3 protein are only very infrequently involved in familial NTD.

Amino Acid Sequence↗
PubMed1994

Cerebral blood flow fluctuation in neonatal respiratory distress and periventricular haemorrhage.

The relationship of cerebral blood flow fluctuation (CBFF) with periventricular haemorrhage (PVH) and respiratory distress syndrome (RDS) was studied in 35 preterm newborns. CBFF was defined as the interquartile range in the ensemble of pulses of a 20-s Doppler recording of CBF velocity (CBFV) in the internal carotid artery. We found a statistically significant increase in end diastolic CBFF in PVH and RDS. This increase was related to the mode of respiration (spontaneous or mechanically supported), the state of the ductus arteriosus, and the level of end diastolic CBFV. Differences before and after the onset of PVH were not found. In view of this, we conclude that RDS increases CBFF, that this increase is related to pleural pressure fluctuations, that these can be damped by mechanical ventilation, and that their propagation to the CBF is promoted by patency of the ductus arteriosus and foramen ovale. Whether the CBFF increase causes PVH, or is merely an expression of coincident RDS, remains a question that needs further investigation.

Blood Flow Velocity↗
PubMed1992

Cerebral blood flow fluctuation in low-risk preterm newborns.

Cerebral blood flow (CBF) fluctuation was studied by analyzing Doppler internal carotid blood velocity recordings of 13 healthy preterm newborns obtained in the course of their first 5 days of life. As measures of fluctuation we used the interquartile range (IQR) and the coefficient of variation (CV) of the ensemble of heart beats of a 20-s recording. In this way we determined fluctuation of the following velocity curve parameters (VCPs): end diastolic velocity; mean velocity; peak systolic velocity and pulsatility index (PI). The pooled data 5-95% intervals for fluctuation thus measured, were: 93-281% for CV; 0.6-3.7 cm/s for the IQR of the velocities; and 4-19% for the PI-IQR. Multiple regression analysis of IQR revealed significant relationships with: the VCP level; with restlessness; and with patency of the ductus arteriosus. Our findings imply that: (1) CBF has various qualities with different stability, mean velocity being the most stable; (2) for all the VCPs investigated, fluctuation is physiological in the early days after preterm birth; (3) most likely, there exists no age trend; (4) restlessness rather than wakefulness, enhances fluctuation; (5) patent ductus arteriosus destabilizes CBF; and (6) for a proper insight into fluctuation, the level of the VCP in question must be taken into account. We suggest that, the enhancing effect that patent ductus arteriosus has on fluctuation pays a contribution to the pathogenesis of brain damage. Finally, we conclude that the IQR represents fluctuation better than does the more commonly used CV.

Blood Flow Velocity↗