Biomedical subjects

Marjolein Vinkenoog

Publications and source records attributed to Marjolein Vinkenoog.

3 recordsLinked to original sources

PubMed2005

Reliability of computerized image analysis for the evaluation of serial synovial biopsies in randomized controlled trials in rheumatoid arthritis.

Analysis of biomarkers in synovial tissue is increasingly used in the evaluation of new targeted therapies for patients with rheumatoid arthritis (RA). This study determined the intrarater and inter-rater reliability of digital image analysis (DIA) of synovial biopsies from RA patients participating in clinical trials. Arthroscopic synovial biopsies were obtained before and after treatment from 19 RA patients participating in a randomized controlled trial with prednisolone. Immunohistochemistry was used to detect CD3+ T cells, CD38+ plasma cells and CD68+ macrophages. The mean change in positive cells per square millimetre for each marker was determined by different operators and at different times using DIA. Nonparametric tests were used to determine differences between observers and assessments, and to determine changes after treatment. The intraclass correlations (ICCs) were calculated to determine the intrarater and inter-rater reliability. Intrarater ICCs showed good reliability for measuring changes in T lymphocytes (R = 0.87), plasma cells (R = 0.62) and macrophages (R = 0.73). Analysis by Bland-Altman plots showed no systemic differences between measurements. The smallest detectable changes were calculated and their discriminatory power revealed good response in the prednisolone group compared with the placebo group. Similarly, inter-rater ICCs also revealed good reliability for measuring T lymphocytes (R = 0.68), plasma cells (R = 0.69) and macrophages (R = 0.72). All measurements identified the same cell types as changing significantly in the treated patients compared with the placebo group. The measurement of change in total positive cell numbers in synovial tissue can be determined reproducibly for various cell types by DIA in RA clinical trials.

Arthritis, Rheumatoid↗

PubMed2005

Random or selective neuroanatomical connectivity. Study of the distribution of fibers over two populations of identified interneurons in cerebral cortex.

We present a neuroanatomical tracing method in a stereological approach to study the proportional distribution of fibers of a particular projection over two chemically different populations of neurons. The fiber projection from the presubiculum to the medial division of the entorhinal cortex of the rat serves as a model projection. Potential target interneurons express calcium binding proteins, either parvalbumin or calretinin. The three markers were simultaneously stained in one and the same histological section. The procedure is according to a three-phase procedure, i.e., in vivo tracer injection phase, histology phase, laserscanning phase. Steps involved are: (1) Surgical application to the presubiculum (injection) of the neuroanatomical tracer, biotinylated dextran amine (BDA), with the purpose of labeling fibers innervating the entorhinal cortex. After surgery, transport of the tracer takes place during the one-week survival period; (2) Fluorescence detection of the labeled fibers through staining with fluorochromated avidin (avidin-Alexa Fluor 488 [green fluorescence]); (3) Simultaneous Immunofluorescence detection of two interneuron markers (using the appropriate primary antibodies and secondary antibodies conjugated to the fluorochromes Alexa Fluor 594 [red fluorescence] and Alexa Fluor 633 [infrared fluorescence]); (4) Acquisition of low-magnification images in a confocal laserscanning microscope and the preparation on a computer of a montage image covering the entire entorhinal cortex; (5) Overlaying this montage with a sampling grid; (6) Acquisition at high magnification of Z-series of confocal images in a statistical valid way based on this grid. Each marker was visualized in its own laser excitation/emission channel: 488, 568 and 647 nm; (7) Image processing and 3D reconstruction followed by evaluation of the results. The present approach can be used to examine whether or not a particular class of chemically identified neurons receives preferential innervation by a particular fiber projection.

Animals↗

PubMed2002

Tracing tools to resolve neural circuits.

In this paper we summarize neuroanatomical tracing methods, in particular combinations of methods designed to achieve the combined goals of tracing connectivity and extracting extra information from the projection or the target neurons. These combinations include techniques that identify projection fibres together with the neurons from which they originate, methods which establish the morphological or chemical identity of the target neurons and techniques to verify the presence of contacts between the terminal boutons on fibres and prospective target neurons. In the second part of this paper we describe a method recently developed in our laboratory, which consists of fluorescence tracing (introducing marker #1) combined with immunofluorescence with different fluorochromes (markers #2 and #3). This method enables us to observe the distribution of terminals of a particular set of projection fibres in contact with neurons belonging to two chemically different populations of interneuron. Multifluorescence confocal laser scanning is used for image acquisition of fibres and processes of presumed target neurons, and follow-up is by three-dimensional computer reconstruction. These reconstructions are used to determine that the contacts between the differentially labelled structures are real, i.e. with no optically empty space in between regardless of the angle of inspection. The specific experiments reported in this paper comprise the tracing with biotinylated dextran amine of fibres in the rat brain running from the presubiculum to layer III of the medial division of the entorhinal cortex. We studied the possibility of contacts in the latter area between the terminal boutons of these projecting fibres in association with presumed target neurons, i.e. parvalbumin and calretinin expressing interneurons.

Animals↗