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J van Pelt

Publications and source records attributed to J van Pelt.

66 records · Page 4Linked to original sources
PubMed1988

Fast atom bombardment/collisional activation mass spectrometry of beta-D-mannosyl-(1----4)-beta-D-N-acetylglucosaminyl (1----N) urea and related compounds.

A new compound, obtained during the isolation of oligosaccharides from the urine of two brothers affected with inherited beta-mannosidase deficiency, has been investigated using fast atom bombardment ionization and MS/MS techniques. The compound could be characterized as an N-acetylglucosamine molecule linked to a hexose and a urea molecule.

Disaccharides↗
PubMed1987

Separation of sialyl-oligosaccharides by medium pressure anion-exchange chromatography on Mono Q.

On columns prepacked with the recently introduced anion-exchange material, Mono Q (Pharmacia), sialyl-oligosaccharides could be fractionated excellently according to the sialic acid content. With u.v. absorption at 214 nm as the detection method, analytical runs of carbohydrate material on the microgram scale, were possible. The value of the method for preparative purposes was demonstrated for sialic acid-containing carbohydrates obtained from human serotransferrin by hydrazinolysis.

Anion Exchange Resins↗
PubMed1986

The metric analysis of three-dimensional dendritic tree patterns: a methodological review.

Metric analysis methods used to study neuronal arborizations are reviewed and discussed. The analysis methods considered are those examining the spatial orientation and density of the whole dendritic field of a neuron, the metrics of dendritic segments and the bifurcation angles. General variables indicating the size of the soma and the dendritic field are indicated. In addition, the instrumentation used for providing 3-dimensional data for metric analyses and the shrinkage of Golgi-stained neurons are discussed.

Animals↗
PubMed1986

Application of growth models to the topology of neuronal branching patterns.

The variation in topological structure of branching patterns may contain essential information with respect to the way these branching patterns have grown. For the understanding of how growth modes finally result in a particular variety in topological patterns, model studies may provide indispensible tools. These studies imply the mathematical formulation of growth models and the development of statistical procedures to compare model predictions with observed data. Recent literature shows two main approached in these model studies, viz. subtree partition analysis (SPA) and vertex analysis. This paper will briefly review the current status with respect to SPA and will apply the model approach to sets of dendritic trees taken from pyramidal, multipolar non-pyramidal and from Purkinje cells. The results show that the topological properties of many dendrites are not in agreement with the hypothesis of random terminal growth and that substantial branching of intermediate segments and/or branching dependent of the position of segments in the tree (topological distance from the cell body) must be assumed. Only two parameters are required to incorporate these assumptions in the model. In all cases up to now it is possible to find parameter values such that the model predictions of topological properties are in agreement with the observations.

Animals↗
PubMed1986

Descriptive and comparative analysis of geometrical properties of neuronal tree structures.

The morphology of neurons is an important factor for the identification and the study of the changes that occur in the nervous system during development or as a result of disease or an experimental treatment. A number of methods to describe the topological aspects of neuronal morphology is discussed. Furthermore it is illustrated how different groups of neurons can be compared. Although both topological and metrical aspects are considered in the comparative sections emphasis is put on counting instead of measuring. Our intention is to present quick and easy methods that are applicable to camera lucida drawings.

Animals↗
PubMed1985

A simple statistical test for the vertex ratio using Monte Carlo simulation.

The vertex ratio is the crucial quantity in vertex analysis, which is a method to characterize the mode of growth of neuronal tree structures (i.e. dendrites and axons). In this report we propose the use of the Monte Carlo test to calculate a level of significance for the vertex ratio. As a result the vertex ratio can be used to analyse neuronal trees with respect to a range of growth hypotheses, including terminal and segmental growth.

Animals↗
PubMed1983

A new method for the topological analysis of neuronal tree structures.

Statistical analysis of the frequencies of observed branching patterns of neuronal arborescences is an important means of studying neuronal growth and of characterizing axonal or dendritic populations. We recently derived simple formulae for the exact probabilities of occurrence of types of neuronal trees for both segmental and terminal growth. Additionally, the existence of a natural ordering of the neuronal tree types enables the application of the Kolmogorov goodness-of-fit test. In the present report it is illustrated how these facilities can be incorporated in the analysis of neuronal arborizations. Interesting features are that very large neuronal arborizations can be analyzed completely and that only small sample sizes are required for the estimation of the critical level corresponding to the growth hypothesis. Further, it is indicated how populations of neuronal tree structures may be compared with each other without reference to a particular growth theory.

Animals↗
PubMedDate not supplied

CDTect-RIA and CDTect-EIA for determination of serum carbohydrate-deficient transferrin compared.

CDTect-RIA and CDTect-EIA for determination of serum carbohydrate-deficient transferrin (CDT) by radioimmunoassay and enzyme immunoassay respectively were tested for equality and precision in four European laboratories. For correlational studies, serum samples with CDT concentrations up to 130 U/l were analysed in accordance with a uniform trial schedule. The regression of CDT values obtained by the two procedures was computed for each laboratory using the method of Passing and Bablok. Slopes and intercepts of the regression functions did not differ significantly from the values 1 or 0, as proved by the corresponding 95% confidence intervals. Precision studies were computed using analysis of variance. For CDT concentrations at the upper reference limit for men, the within-day coefficients of variation (CVs) ranged between 0.7 and 6.4% (median 5.2%) for CDTect-RIA and from 4.3 to 9.2% (median 6.2%) for CDTect-EIA. The corresponding pure between-day CVs were 5.0-18.5% (median 9.8%) and 3.5-14.5% (median 10.9%). The study demonstrates the equality of CDT values obtained by CDTect-RIA and CDTect-EIA. According to this study, the two methods can be used interchangeably without getting fluctuating CDT values, e.g. in longitudinal studies.

Alcoholism↗
PubMedDate not supplied

Patients with ankylosing spondylitis and healthy relatives do not show increased small intestinal permeability with the lactulose-mannitol test.

Small intestinal permeability was measured in 71 subjects: 26 (24 B27+) patients with ankylosing spondylitis (AS); 20 healthy first degree relatives (13 B27+); 6 patients with active Crohn's disease and 19 healthy controls. We determined the urinary excretion ratio of two ingested sugar probes, lactulose (10 g) and mannitol (0.5 g) by gas-liquid chromatography. The median lactulose/mannitol excretion ratio in AS patients (0.0099) and relatives (0.0090) was not significantly different from the median ratio in healthy controls (0.0095). HLA status or use of NSAIDs did not significantly influence the results. In patients with Crohn's disease, on the other hand, the median lactulose/mannitol ratio (0.021) was significantly increased in comparison to healthy controls (0.0095). Our results confirm that the lactulose-mannitol test can be used to demonstrate increased intestinal permeability in Crohn's disease. For patients with AS and their relatives the lactulose-mannitol test may not be sufficiently sensitive. Alternatively, significantly increased permeability may not occur in most patients with AS.

Adult↗
PubMedDate not supplied

[The expression of desmin and cytokeratins No. 8 and 18 in the nonhematopoietic cells of the rat liver].

During prenatal ontogenesis of mammals, liver plays a role as the hemopoietic organ. We have studied the distribution of hepatocytes (antigenic markers--cytokeratins No 8 and 18) and Ito cells (antigenic marker--desmin) in the liver and the interaction of these two cell classes with hemopoietic cells. At days 14 and 15 of embryonic development, nonhemopoietic liver cells had many processes, expressed desmin and were stained with antibodies against cytokeratins No 8 and 18. The amount of desmin-positive cells shortly diminished on day 16 of gestation, when embryonic hepatoblasts (prehepatocytes) acquired cubical shape and expressed only cytokeratins, but not desmin. Morphometric analysis had shown that the amount of cells expressing desmin in the liver during the prenatal and neonatal periods is greater, than in the adult organ. We have observed tight association of desmin-positive cells and their processes with hemopoietic cells during prenatal and early postnatal ontogenesis. It is proposed that in the embryonic liver, desmin-positive cells may play a role of stromal elements involved in embryonic hemopoiesis; they also may support hepatocyte development.

Aging↗