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Biomedical subjects

A Geurts

Publications and source records attributed to A Geurts.

7 recordsLinked to original sources
PubMed1999

ELISA for complexes of urokinase-type and tissue-type plasminogen activators with their type-1 inhibitor (uPA-PAI-1 and tPA-PAI-1).

An ELISA has been developed for the assessment of complexes between the urokinase-type (uPA) and the tissue-type plasminogen (tPA) activators with their inhibitor type-1 (PAI-1) in cell-culture medium and cytosolic extracts of breast tumours. The "4-stage/2-site" ELISA involves 2 polyclonal antibodies in the pre-analyte stage 2 and in the post-analyte stage. For the specific measurement of the uPA-PAI-1 complex, 2 assay formats may be employed, uPA/PAI-1 and PAI-1/uPA. This offers an attractive facility for quality-assessment studies of this kind of assays. Analogously, the tPA-PAI-1 complex was assessed using the formats tPA/PAI-1 and PAI-1/tPA. Only complexes are able to evoke a signal in their appropriate assay formats. The free component, however, which responds to the capture antibody, could interfere with the binding of the complex molecule, reducing the OD signal. Increasing the coating Ab concentration diminishes the signal-suppressing effect of the free component. In 15 cell-culture supernatants, uPA and PAI-1 concentrations were measured as well as the uPA of PAI-1 complex in different dilutions in 2 assay formats. The differences between the values of complex measured in the 2 assay formats could be accounted for by the free uPA and PAI-1 concentrations. At dilution 1:10, the measured values obtained in the 2 separate formats differed substantially (correlation coefficient r = 0.641). At dilution 1:20, the differences were already smaller between the values (agreement 0.945). At dilution 1:30, close agreement between the corresponding values was observed (r = 0.971). Extrapolation to infinite dilution of the results obtained resulted in an even closer estimation of the complex concentration. Comparable results have been observed when tPA, PAI-1 and tPA-PAI-1 values were measured in tumour biopsy extracts.

Animals↗
PubMed1993

Recovery of motor skill following nervous system disorders: a behavioural emphasis.

Recovery of motor behaviour is, for a large part, the complex reintegration of sensory processes and motor output against the background of a decreasing cognitive involvement. Therefore, the measurement of motor output under simple and unperturbed conditions, isolated from these processes, reflects only a minor part of the recovery of skill. It is argued that there is an urgent need for procedures aimed at the objective study of behavioural recovery across time. Until now, these procedures have been lacking. This chapter provides a modest contribution to the development of these procedures.

Attention↗
PubMed1977

Auditory evoked potentials recorded from chronic implanted gyrus of Heschl in man.

By means of implanted multileads electrodes, responses to clicks and prolonged sound stimulations were recorded from the Heschl gyrus of 2 human brains. These responses were strictly localized to this structure. Cortical averaged auditory evoked potentials (c.AEP) to clicks are consistent with scalp averaged auditory evoked potentials (s.AEP). So, Na Pa, Nb, P1, N1, waves have similar latencies and none of them in the s.AEP may be correlated with myogenic potentials (in opposition with the suggestions of Bickford et al. 1964 and Celesia et al. 1968). Increasing the duration of sound stimulation resulted in changes of the response. For a duration longer than 20ms, an "on-response" and an "off-response" were noted. No satisfying physiological explanation of these events is retained despite data obtained with monaural homo and heterolateral stimulations and with variation of tone of sound stimulation.

Auditory Cortex↗
PubMedDate not supplied

Predictive value of uPA, PAI-1, HER-2 and VEGF in the serum of ovarian cancer patients.

BACKGROUND: Tissue levels of uPA, PAI-1, HER-2 and VEGF are known to have prognostic value in different malignant tumors. The prognostic potential of serum concentrations of these markers is less clear and was investigated. PATIENTS AND METHODS: The response to 2nd line chemotherapy was studied in 61 patients with recurrent ovarian cancer. Marker analyses were performed using specific and sensitive ELISA tests and the response to therapy was evaluated using multiple CA 125 determinations and including these values in a simple and comprehensive formula. RESULTS: Correlations were observed between VEGF and CA 125, HER-2 (inversely) as well as PAI-1, and between uPA and PAI-1. However, no marker showed a significant relation to the overall survival of patients, nor to treatment response. CONCLUSIONS: Serum levels of uPA, PAI-1, HER-2 and VEGF do not have enough predictive potential in recurrent ovarian cancer. Most likely additional sources contribute to the serum levels of the markers studied so that their levels are not only tumor specific.

Biomarkers, Tumor↗