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J van der Schoot

Publications and source records attributed to J van der Schoot.

6 recordsLinked to original sources
PubMed2003

Ex-situ conservation of Black poplar in Europe: genetic diversity in nine gene bank collections and their value for nature development.

Populus nigra L. is a pioneer tree species of riparian ecosystems that is threatened with extinction because of the loss of its natural habitat. To evaluate the existing genetic diversity of P. nigra within ex-situ collections, we analyzed 675 P. nigra L. accessions from nine European gene banks with three amplified fragment length polymorphism (AFLP) and five microsatellite [or simple sequence repeat (SSR)] primer combinations, and 11 isozyme systems. With isozyme analysis, hybrids could be detected, and only 3% were found in the gene bank collection. AFLP and SSR analyses revealed effectively that 26% of the accessions were duplicated and that the level of clonal duplication varied from 0% in the French gene bank collection up to 78% in the Belgian gene bank collection. SSR analysis was preferred because AFLP was technically more demanding and more prone to scoring errors. To assess the genetic diversity, we grouped material from the gene banks according to topography of the location from which the accessions were originally collected (river system or regions separated by mountains). Genetic diversity was expressed in terms of the following parameters: percentage of polymorphic loci, observed and effective number of alleles, and Nei's expected heterozygosity or gene diversity (for AFLP). Genetic diversity varied from region to region and depended, to some extent, on the marker system used. The most unique alleles were identified in the Danube region (Austria), the Rhône region (France), Italy, the Rijn region (The Netherlands), and the Ebro region (Spain). In general, the diversity was largest in the material collected from the regions in Southern Europe. Dendrograms and principal component analysis resulted in a clustering according to topography. Material from the same river systems, but from different countries, clustered together. The genetic differentiation among the regions (F(st)/G(st)) was moderate.

Cluster Analysis↗
PubMed2002

Remediastinoscopy after neoadjuvant therapy for non-small cell lung cancer.

Despite technical difficulties due to mediastinal fibrosis, remediastinoscopy can be a valuable tool in the restaging of non-small cell lung cancer after neoadjuvant therapy. The aim of our study was to evaluate the feasibility, sensitivity and accuracy of remediastinoscopy. From November 1994 to July 2001 we performed a remediastinoscopy in 27 patients after neoadjuvant therapy. Their age ranged from 35 to 80 years (mean 61.9+/-11.9). In all 27 patients it was possible to perform a remediastinoscopy without major technical difficulties and take biopsies of the lymph nodes that were initially invaded by tumour. Remediastinoscopy was positive in 11 patients (40.7%) and negative in 16 (59.3%). In the 11 patients with a positive remediastinoscopy a complete resection was not judged possible and therefore, an unnecessary thoracotomy was avoided. In four patients, remediastinoscopy turned out to be false negative. So, in our series, sensitivity was 73%, specificity 100% and accuracy 85%. The positive and negative predictive values were 100 and 75%, respectively. Previous mediastinoscopy is no contra-indication for a repeat one after neoadjuvant therapy. Although sensitivity and accuracy are lower than that of a first mediastinoscopy, remediastinoscopy is useful to select patients for surgical resection after induction therapy.

Adult↗
PubMed1986

Radionuclides in detecting active granuloma formation. Gallium-67 scintigraphy and histopathology with autoradiographic findings.

Granuloma formation studies were performed on lungs of guinea pigs sensitized with FCA over 2 to 17 months. Prolonged time of sensitization revealed more granulomatous pulmonary tissue. An intravenous booster of FCA in the animals that had been sensitized for 3 months yielded enhanced granuloma formation within 5 days. The histopathology of these lungs was comparable with that seen in lungs of animals after 17 months of sensitization without booster. Enhanced local proliferation of macrophages, measured by [3H]thymidine incorporation and autoradiography, was seen in the lungs of the animals that had received boosters. Moreover, 67Ga scintigraphy was strongly positive in these animals. Scintigraphy of cell suspensions of pulmonary tissue from these animals showed that 67Ga was predominantly taken up (quantitatively as well as qualitatively) by the alveolar macrophages. Cell suspensions of sarcoidosis patients, prepared in the same way, showed only a low level of 67Ga uptake, one comparable to that of the pulmonary cell suspensions of the sensitized animals that had not received boosters. It is suggested that a negative scintigraphy in patients with chronic pulmonary granulomatous disorders could be (partly) explained by the absence of activated macrophages.

Animals↗
PubMed1983

Thallium-201 scanning to decide CCU admission in patients with non-diagnostic electrocardiograms.

To determine the value of thallium-201 scintigraphy as a decisive factor in admission policy for patients with acute chest pain and nondiagnostic electrocardiograms, we undertook a prospective study in 149 such patients. The interval between pain and scan never exceeded 12 hr. Of 57 patients in whom a defect was seen, 34 had an acute infarction, 7 developed infarction within 2 months, and in 11 coronary heart disease was proven by angiography or strongly suggested by stress tests (ECG and thallium-201 scan). In 13 patients with an equivocal scan, coronary heart disease was proven or strongly suggested in 5. Of 79 patients with a normal scan, only 1 had acute infarction, and stress tests were positive in 6 and negative in 72. In these 72 no cardiac event occurred during a 1-year follow-up. Thallium-201 scintigraphy can help to select those patients with acute chest pain and nondiagnostic electrocardiograms who need observation in a CCU.

Electrocardiography↗