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Biomedical subjects

C van den Berg

Publications and source records attributed to C van den Berg.

At least 19 recordsLinked to original sources
PubMed2006

Towards a VR trainer for EVAR treatment.

Endovascular repair of aortic abdominal aneurysms (AAA) is more and more becoming part of clinical practice. Up to approximately 30 clinical procedures however are necessary to obtain the surgical skills to make the procedure reliable and safe. The current study aims to generate a VR trainer to speed up the training process of experienced vascular surgeons to become experienced EVAR (endovascular AAA repair) surgeons by introducing a VR environment. This manuscript describes the contents and validation of the first step in the VREST - EVAR trainer, i.e. the proper definition of the knowledge and skills that need to be transferred.

Aortic Aneurysm, Abdominal↗
PubMed2001

Follow-up investigations in uncultured amniotic fluid cells after uncertain cytogenetic results.

Fluorescence in situ hybridization (FISH) on uncultured amniotic fluid (AF) cells is a widespread technique for the rapid prenatal detection of specific chromosome aberrations. During a 6-year period (1993-1998) we used FISH for quick follow-up investigations in uncultured AF cells after finding an uncertain chromosome aberration in a first chorionic villus (CV) or AF sample in 79 cases. These FISH results were compared with conventional cytogenetic results of the AF cell cultures in all cases. We found discrepant FISH and cytogenetic results in four instances. In general, FISH on uncultured AF cells proved to be a reliable technique for the rapid differentiation between confined placental mosaicism and true fetal mosaicism, and between pseudomosaicism and true mosaicism, respectively. Uncultured cells may sometimes even better reflect chromosomal mosaicism than cultured cells, since they are not subject to culture induced selection mechanisms. However, we found evidence that exceptional cases of tissue confined mosaicism may go undetected in uncultured cells.

Amniocentesis↗
PubMed2000

Case of 45,X/46,XY mosaicism with non-mosaic discordance between short-term villi (45,X) and cultured villi (46,XY).

We report on a prenatally detected case of discordant non-mosaic karyotypes following chorionic villus sampling. A 45,X karyotype was found in cytotrophoblast cells and a 46,XY karyotype in mesenchymal core cells. A subsequent amniocentesis showed a true 45,X/46,XY mosaicism. Confirmatory studies, including fluorescence in situ hybridization (FISH) in various fetal and placental tissues as well as in the original villi preparations changed the presumed condition of generalized mosaicism with culture confined normality to that of generalized mosaicism with absolute concordance. This case underscores the importance of the investigation of both short-term and cultured villi preparations, the implementation of prenatal FISH studies, and the need for thorough follow-up investigation in cases of discrepant results.

Chorionic Villi Sampling↗
PubMed2000

Coordination disorders in patients with Parkinson's disease: a study of paced rhythmic forearm movements.

Whereas the consequences of Parkinson's disease (PD) for the performance of single-limb movements are well documented (i.e., bradykinesia, akinesia, rigidity, and tremor), fairly little is known about its implications for the coordination between limb movements. To help resolve this situation an experiment was conducted in which 11 PD patients and 11 control subjects performed rhythmic forearm movements at a comfortable amplitude in the in-phase, antiphase, and single-arm mode at pacing frequencies ranging from 0.5 to 3 Hz. The PD group displayed marked coordination problems over and above the known clinical motor symptoms of PD. The performance of both the in-phase and antiphase modes was significantly affected in the PD group compared to the control group; furthermore, the variability of relative phase was significantly increased in this group. These observations were not caused by problems to synchronize the movements with the external pacing signal. In addition to the bimanual coordination problems, involuntary mirror movements (MM) were observed in the single-arm control trials that were significantly larger in the PD group (4.4% of the amplitude of the moving arm) than in the control group (2.3%), suggesting a reduced ability to suppress a basic in-phase coupling of the arms. In the PD group, MM were largest during movements of the least-affected arm. These parkinsonian coordination problems are interpreted in terms of recent evidence on the neural organization of bimanual coordination, suggesting that they are due to cortical rather than callosal dysfunction.

Aged↗
PubMed2000

Accuracy of abnormal karyotypes after the analysis of both short- and long-term culture of chorionic villi.

We report in detail the cytogenetic results of 1838 consecutive chorionic villus samples with the availability of both short-term culture (STC-villi) and long-term culture (LTC-villi) preparations in 1561 cases (84.9%). A high degree of laboratory success (99.5%) and diagnostic accuracy (99.8%) was observed; in four cases of low mosaicism, all four associated with the final birth of a normal child, a small risk of uncertainty was accepted. The combined analysis of STC- and LTC-villi reduced follow-up amniocenteses by one-third in comparison with the analysis of STC-villi alone. We believe that the desired level of quality and accuracy of prenatal cytogenetics in chorionic villi can only be achieved when both STC- and LTC-villi are available. We conclude that CVS might then be the mode of prenatal diagnosis of first choice in pregnancies with a high (cytogenetic) risk.

Amniocentesis↗
PubMed1999

Prenatal detection of trisomy 18 caused by isochromosome 18p and 18q formation.

We report on the prenatal detection and further genetic studies in a case of trisomy 18 caused by isochromosome 18p [i(18p)] and 18q [i(18q)] formation. The diagnosis was made by standard cytogenetic techniques in amniotic fluid cells and confirmed by fluorescence in situ hybridization. The formation of the isochromosomes cannot be explained by a single model; centromere misdivision and meiosis II nondisjunction without recombination or mitotic misdivision are the most likely mechanisms of formation as indicated by DNA analysis.

Adult↗
PubMed1999

Amniocentesis or chorionic villus sampling in multiple gestations? Experience with 500 cases.

500 women with multiple pregnancies underwent amniocentesis or chorionic villus (CV) sampling at our department between January 1988 and July 1997. The aim of this retrospective study was to evaluate the laboratory aspects and the consequences of discordant results in these pregnancies in relation to the method of sampling. Uncertain results in one or both samples, requiring further investigation were more frequent in CV samples (eight times in 163 paired samples, 5 per cent) than in amniotic fluid (AF) samples (once in 298 paired samples, 0.3 per cent). Sampling one fetus twice (erroneous sampling) was seen only once among 163 pregnancies with two CV samples in our study. Cross contamination due to mixed sampling was discovered in two of seven pregnancies that underwent DNA diagnosis in CV and might be a rather regular occuring phenomenon. In none of the 500 pregnancies mixed sampling caused diagnostic dilemmas. A third sampling problem, maternal cell contamination caused a diagnostic problem once among the AF samples. Selective fetal reduction appeared safer after CV sampling than after amniocentesis. Subsequently, CV sampling instead of amniocentesis has become the method of choice for prenatal diagnosis in multiple pregnancies in our department.

Amniocentesis↗
PubMed1998

Abnormal karyotypes in semi-direct chorionic villus preparations of women with different cytogenetic risks.

Among 3499 cytogenetically investigated semi-direct chorionic villus samples, 219 (6.3 per cent) abnormal karyotypes were encountered. The karyotypes were considered certainly abnormal (generalized abnormal with high probability) in 109 cases (3.1 per cent), and in 110 cases (3.1 per cent) uncertainly abnormal (potentially confined to the placenta), requiring further investigation. Of these 110 uncertain abnormalities, the cytogenetic result turned out to be finally abnormal representing generalized abnormality in 36 cases (32.7 per cent), finally normal representing confined placental mosaicism (CPM) in 69 cases (62.7 per cent), and remained undetermined in 5 instances (4.5 per cent). The rate of the numbers of certainly abnormal and all (certainly + uncertainly) abnormal results, the certainty rate, and that of generalized abnormalities and all abnormalities (generalized abnormalities + CPM cases), the predictive value, are strongly correlated with the cytogenetic risk. Therefore, we advise chorionic villus sampling for cytogenetic investigation only in women with a cytogenetic risk equal to or exceeding that of a 40-year-old pregnant woman. Because of the high rate of prenatal follow-up investigations after the finding of uncertain results in semi-direct villi, semi-direct and cultured villi should be karyotyped simultaneously.

Adult↗
PubMed1998

Cell fate and cell differentiation status in the Arabidopsis root.

Post-embryonic development in plants is mainly achieved by its meristems. Within the Arabidopsis root meristem, both the fate and origin of its cells can be predicted with high accuracy. Mutants defective in the determination of root cell fates show that the corresponding genes are first required during embryogenesis. The sub-specification of cell fates, such as during epidermal root hair formation, involves transcription factors and phytohormones. In the Arabidopsis root, initial cell fate specification events must be followed by position-dependent reinforcement of cellular identity. A major question remains as to whether the signals that are involved in initiating the cellular pattern are the same or different from the signals used to reinforce it. The integrity of the root meristem is kept by balancing cell proliferation and cell differentiation, and differentiation-inhibiting signals originating from the quiescent centre are involved.

Arabidopsis↗
PubMed1998

Uniparental disomy with and without confined placental mosaicism: a model for trisomic zygote rescue.

In the population of children born after prenatal cytogenetic investigation in chorionic villi at our department from 1992 to 1995 (N = 3940), three are known to us with uniparental disomy. One case of maternal heterodisomy 16 was prenatally discovered because of trisomy 16 in direct chorionic villi with subsequently normal amniotic fluid cells. The other two had normal karyotypes in chorionic villi. Maternal heterodisomy 15 was postnatally detected in one of them because of Prader-Willi syndrome. Maternal hetero/isodisomy 16 was accidentally encountered in the other case in the course of prenatal DNA analysis of the tuberous sclerosis complex 2 region at 16p13.3. A model is presented for the understanding of the various combinations of karyotypes in direct chorionic villi, cultured chorionic villi and the fetus in the case of successful and unsuccessful trisomic zygote rescue.

Adult↗
PubMed1997

Short-range control of cell differentiation in the Arabidopsis root meristem.

Meristems are distinctive regions of plants that have capacity for continuous growth. Their developmental activity generates the majority of plant organs. It is currently unknown how cell division and cell differentiation are orchestrated in meristems, although genetic studies have demonstrated the relevance of a proper balance between the two processes. Root meristems contain a distinct central region of mitotically inactive cells, the quiescent centre, the function of which has remained elusive until now. Here we present laser ablation and genetic data that show that in Arabidopsis thaliana the quiescent centre inhibits differentiation of surrounding cells. Differentiation regulation occurs within the range of a single cell, in a manner strikingly similar to examples in animal development, such as during delamination of Drosophila neuroblasts. Our data indicate that pattern formation in the root meristem is controlled by a balance between short-range signals inhibiting differentiation and signals that reinforce cell fate decisions.

Arabidopsis↗
PubMed1996

Ring chromosome 18 in a fetus with only facial anomalies.

We report on a prenatally detected case of ring chromosome 18 [46,XX,r(18)] in amniotic fluid cells of a fetus with an abnormal facial profile on ultrasound as the only malformation. The chromosome 18 origin of the ring chromosome, of a supernumerary marker chromosome in some cells, and of micronuclei was demonstrated by fluorescent in situ hybridization with a whole chromosome 18 paint (Cambio) and 18 centromere probe L1.84. DNA investigations showed deletions of 18p as well as 18q material of r(18), which turned out to be of paternal origin. Autopsy of the fetus after termination of pregnancy at 20 weeks of gestation showed no additional malformations, in agreement with the previous ultrasound findings.

Abortion, Induced↗
PubMed1996

Effect of septicaemia on the plasma levels of biopterin and nitric oxide metabolites in rats and rabbits.

Live Escherichia coli decreased mean arterial blood pressure in rabbits from 67 to 20 mmHg. E. coli did not affect blood pressure in rats but did significantly increase heart rate by 29%. To related the cardiovascular effects with putative relevant biochemical pathways, the plasma levels of nitrate + nitrite (NOx) and biopterin, representing the main metabolites of nitric oxide and tetrahydrobiopterin, respectively, were determined in conscious rats and rabbits after treatment with live E. coli. In rats, E. coli induced a rapid 43% increase in the plasma level of biopterin preceding the 7- to 26-fold increase in NOx level. In rabbits, no increase in the NOx level was observed despite a 3- to 5-fold increase in the biopterin level at 6-10 hr posttreatment. It is concluded that the synthesis of tetrahydrobiopterin precedes nitric oxide synthesis after induction of septicaemia in the rat. After the induction of septicaemia, rabbits show a clear hypotensive response and an increase in biopterin level but no concomitant increase in NOx. Biopterin apparently represents a more appropriate biochemical marker of septic shock than does NOx.

Animals↗
PubMed1995

Cell fate in the Arabidopsis root meristem determined by directional signalling.

Postembryonic development in plants is achieved by apical meristems. Surgical studies and clonal analysis have revealed indirectly that cells in shoot meristems have no predictable destiny and that position is likely to play a role in the acquisition of cell identity. In contrast to animal systems, there has been no direct evidence for inductive signalling in plants until now. Here we present evidence for such signalling using laser ablation of cells in the root meristem of Arabidopsis thaliana. Although these cells show rigid clonal relationships, we now demonstrate that it is positional control that is most important in the determination of cell fate. Positional signals can be perpetuated from more mature to initial cells to guide the pattern of meristem cell differentiation. This offers an alternative to the general opinion that meristems are the source of patterning information.

Arabidopsis↗
PubMed1995

Retrospective study of trisomy 18 in chorionic villi with fluorescent in situ hybridization on archival direct preparations.

Trisomy 18 in direct chorionic villus preparations needs further investigation since the chromosome abnormality may be confined to the placenta and may not represent the actual fetal karyotype. We performed, retrospectively, fluorescent in situ hybridization (FISH) with the chromosome 18 centromere probe (L1.84) on interphase nuclei of destained slides of all cases of full trisomy 18 (n = 22) and mosaic trisomy 18 (n = 8) detected among 7600 first-trimester chorionic villus samples during an 8-year period (1985-1992). More nuclei displaying three signals were encountered in cases of full and mosaic trisomy 18 confirmed in fetal tissue than in non-confirmed cases. FISH can be useful for the verification of trisomy 18 in direct chorionic villus preparations.

Chorionic Villi Sampling↗
PubMed1995

A chromosome 21-specific cosmid cocktail for the detection of chromosome 21 aberrations in interphase nuclei.

Fluorescent in situ hybridization (FISH) with a 21q11-specific probe (CB21c1) consisting of three non-overlapping cosmids has been applied to interphase amniocytes of pregnancies at increased risk for fetal aneuploidy (N = 78) and to interphase lymphocytes, cultured and uncultured, of patients referred for Down syndrome (N = 19 and 28, respectively). In the uncultured amniocytes, six chromosome aberrations were detected: three cases of trisomy 21, a triploidy, a de novo 46,XX,t(21q21q), and a mosaic 46,XY/47,XY,+dic(21)(q11)/48,XY,+dic(21)(q11),+del(21)(q11). In 15 cultured and 20 uncultured blood samples, FISH correctly diagnosed trisomy 21 (full or mosaic) at the interphase level, which was confirmed in all cases by subsequent karyotyping. Because of specific and strong signals in interphase nuclei, CB21c1 appears to be a useful tool for the rapid detection of chromosome 21 abnormalities.

Amniocentesis↗
PubMed1994

Septic shock: no correlation between plasma levels of nitric oxide metabolites and hypotension or lethality.

In the Wistar rat (Riv:TOX strain), Escherichia coli-derived lipopolysaccharide, up to 100 mg/kg, did not affect blood pressure. However, 6 h after administration of live E. coli or Staphylococcus aureus (a microorganism without lipopolysaccharide), both dosed at 12 x 10(9) colony forming units/kg, mean arterial blood pressure significantly decreased to 64% and 48% compared to control, respectively. In contrast to lipopolysaccharide, bacteria produced a dose-dependent lethality within 24 h. Live S. aureus increased plasma levels of nitric oxide metabolites (NOx) only four-fold, while both lipopolysaccharide and live E. coli approximately 20-fold. In conclusion, we demonstrated a lack of correlation between plasma NOx levels and hypotension or lethality.

Amino Acid Oxidoreductases↗