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Biomedical subjects

G Brouns

Publications and source records attributed to G Brouns.

13 recordsLinked to original sources
PubMed2000

A defined window for efficient gene marking of severe combined immunodeficient-repopulating cells using a gibbon ape leukemia virus-pseudotyped retroviral vector.

We have investigated the minimal time required for efficient transduction of human hematopoietic repopulating cells using a surrogate nonobese diabetic (NOD)/severe combined immunodeficient (SCID) xenoengraftment assay. Cord blood CD34+ cells were transduced to high levels over 24-48 hr in the presence of Flt-3 ligand, stem cell factor, interleukin 3, and interleukin 6. Under these conditions, high levels of NOD/SCID repopulating activity were preserved, but the levels of gene marking in engrafting cell populations measured by expression of a reporter transgene were low. Extension of the transduction period by 24 hr (total culture period, 72 hr) under the same cytokine conditions resulted in high levels of gene marking, but on closer analysis expression was limited predominantly to the myeloid population. Efficient transduction of both lymphoid and myeloid lineages could be achieved only if the transduction protocol was extended by a further 24 hr (total culture period, 96 hr), suggesting that myeloid lineage-committed precursors are capable of repopulation, and that over shorter time periods transduction is largely restricted to this population. This adds to the emerging evidence of heterogeneity within the SRC compartment, and has important implications for the interpretation of this assay in stem cell transplantation and gene transfer studies.

Animals↗
PubMed1998

High efficiency gene transfer to human hematopoietic SCID-repopulating cells under serum-free conditions.

Stable gene transfer to human pluripotent hematopoietic stem cells (PHSCs) is an attractive strategy for the curative treatment of many genetic hematologic disorders. In clinical trials, the levels of gene transfer to this cell population have generally been low, reflecting deficiencies in both the vector systems and transduction conditions. In this study, we have used a pseudotyped murine retroviral vector to transduce human CD34(+) cells purified from bone marrow (BM) and umbilical cord blood (CB) under optimized conditions. After transduction, 71% to 97% of the hematopoietic cells were found to express a low-affinity nerve growth factor receptor (LNGFR) marker gene. Six weeks after transplantation into immunodeficient NOD/LtSz-scid/scid (NOD/SCID) mice, LNGFR expression was detected in 6% to 57% of CD45(+) cells in eight of nine engrafted animals. Moreover, proviral DNA was detected in 8.3% to 45% of secondary colonies derived from BM cells of engrafted NOD/SCID mice. Our data show consistent transduction of SCID-repopulating cells (SRCs) and suggest that the efficiency of gene transfer to human hematopoietic repopulating cells can be improved using existing retroviral vector systems and carefully optimized transduction conditions.

Animals↗
PubMed1996

Composition and function of T-cell receptor and B-cell receptor complexes on precursor lymphocytes.

The precursor T-cell receptors (TCRs) and B-cell receptors (BCRs) direct lymphocyte development to the mature T-cell and B-cell stage, respectively. Recent genetic and biochemical experiments reveal the striking parallel in structure and function of these receptors. They consist of TCR beta and BCR mu chains paired with surrogate TCR alpha and BCR light chains. Both receptors employ a two-component signal transduction unit: CD3 gamma epsilon for the pre-TCR, and CD79ab for the pre-BCR. Plasma membrane levels of pre-TCR/BCR complexes are kept extremely low, most probably by a mechanism involving specific retention in the endoplasmic reticulum. This mechanism may control the signalling activity of pre-TCR/BCR and therewith the lymphocyte differentiation process.

Animals↗
PubMed1994

[Social isolation in the psychiatric department].

In this article account is given of a validation study, according to the nursing diagnosis 'social isolation'. The label, definition and cluster of defining characteristics according to cluster of defining characteristics according to Townsend (1990) are the starting point, the related factors are left out of consideration. The validation mentioned above was carried out in accordance with the Delphi-method, that consisted of three Delphi rounds. A panel of experts was asked particularly to compile defining characteristics that are relevant for 'social isolation' and to indicate the critical defining characteristics. This procedure generated a cluster of seven defining characteristics for 'social isolation' of which the content validity turned out to be considerably increased with regard to the cluster formulated by Townsend. The distinction between critical defining characteristics and supporting defining characteristics was not clarified by this study.

Delphi Technique↗
PubMed1993

Validity testing of the Dutch translation of the appraisal of the self-care agency A.S.A.-scale.

The purpose of this study was translation and construct validity testing of the appraisal of the self-care agency ASA-scale. This scale measures operability of self-care agency. The original English version of the scale was translated into Dutch. Subsequently the Dutch version was retranslated into English and compared with the original for semantic and cross-cultural differences. Construct validity of the translated scale was tested on 140 elderly in the Netherlands. The scale was administered to 40 randomly selected patients of a nursing home, 30 residents of a personalized care facility, 30 residents of a service flat and 40 randomly selected elderly who lived independently in the adjacent community. As hypothesize, mean ASA scores of the four groups of elderly differed significantly. The less dependent on institutionalized nursing care the higher the operability of the self-care agency scores of the elderly.

Activities of Daily Living↗